US20080268836A1 - Space-Based Network Architectures for Satellite Radiotelephone Systems - Google Patents

Space-Based Network Architectures for Satellite Radiotelephone Systems Download PDF

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US20080268836A1
US20080268836A1 US12/037,355 US3735508A US2008268836A1 US 20080268836 A1 US20080268836 A1 US 20080268836A1 US 3735508 A US3735508 A US 3735508A US 2008268836 A1 US2008268836 A1 US 2008268836A1
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canceled
satellite
radiotelephone
receive
transmit
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US12/037,355
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Peter D. Karabinis
Carson E. Agnew
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Individual
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Priority claimed from US10/074,097 external-priority patent/US6684057B2/en
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/14Relay systems
    • H04B7/15Active relay systems
    • H04B7/185Space-based or airborne stations; Stations for satellite systems
    • H04B7/1853Satellite systems for providing telephony service to a mobile station, i.e. mobile satellite service
    • H04B7/18539Arrangements for managing radio, resources, i.e. for establishing or releasing a connection
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/14Relay systems
    • H04B7/15Active relay systems
    • H04B7/185Space-based or airborne stations; Stations for satellite systems
    • H04B7/1851Systems using a satellite or space-based relay
    • H04B7/18513Transmission in a satellite or space-based system
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/14Relay systems
    • H04B7/15Active relay systems
    • H04B7/185Space-based or airborne stations; Stations for satellite systems
    • H04B7/1853Satellite systems for providing telephony service to a mobile station, i.e. mobile satellite service
    • H04B7/18532Arrangements for managing transmission, i.e. for transporting data or a signalling message
    • H04B7/18534Arrangements for managing transmission, i.e. for transporting data or a signalling message for enhancing link reliablility, e.g. satellites diversity
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/14Relay systems
    • H04B7/15Active relay systems
    • H04B7/185Space-based or airborne stations; Stations for satellite systems
    • H04B7/1853Satellite systems for providing telephony service to a mobile station, i.e. mobile satellite service
    • H04B7/18563Arrangements for interconnecting multiple systems
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/14Relay systems
    • H04B7/15Active relay systems
    • H04B7/204Multiple access
    • H04B7/216Code division or spread-spectrum multiple access [CDMA, SSMA]

Definitions

  • This invention relates to radiotelephone communications systems and methods, and more particularly to terrestrial cellular and satellite cellular radiotelephone communications systems and methods.
  • Satellite radiotelephone communications systems and methods are widely used for radiotelephone communications. Satellite radiotelephone communications systems and methods generally employ at least one space-based component, such as one or more satellites that are configured to wirelessly communicate with a plurality of satellite radiotelephones.
  • a satellite radiotelephone communications system or method may utilize a single antenna beam covering an entire area served by the system.
  • multiple beams are provided, each of which can serve distinct geographical areas in the overall service region, to collectively serve an overall satellite footprint.
  • a cellular architecture similar to that used in conventional terrestrial cellular radiotelephone systems and methods can be implemented in cellular satellite-based systems and methods.
  • the satellite typically communicates with radiotelephones over a bidirectional communications pathway, with radiotelephone communication signals being communicated from the satellite to the radiotelephone over a downlink or forward link, and from the radiotelephone to the satellite over an uplink or return link.
  • radiotelephone includes cellular and/or satellite radiotelephones with or without a multi-line display; Personal Communications System (PCS) terminals that may combine a radiotelephone with data processing, facsimile and/or data communications capabilities; Personal Digital Assistants (PDA) that can include a radio frequency transceiver and a pager, Internet/intranet access, Web browser, organizer, calendar and/or a global positioning system (GPS) receiver; and/or conventional laptop and/or palmtop computers or other appliances, which include a radio frequency transceiver.
  • PCS Personal Communications System
  • PDA Personal Digital Assistants
  • GPS global positioning system
  • terrestrial networks can enhance cellular satellite radiotelephone system availability, efficiency and/or economic viability by terrestrially reusing at least some of the frequency bands that are allocated to cellular satellite radiotelephone systems.
  • the satellite spectrum may be underutilized or unutilized in such areas.
  • the use of terrestrial retransmission can reduce or eliminate this problem.
  • the capacity of the overall system can be increased significantly by the introduction of terrestrial retransmission, since terrestrial frequency reuse can be much denser than that of a satellite-only system. In fact, capacity can be enhanced where it may be mostly needed, i.e., densely populated urban/industrial/commercial areas. As a result, the overall system can become much more economically viable, as it may be able to serve a much larger subscriber base.
  • satellite radiotelephones for a satellite radiotelephone system having a terrestrial component within the same satellite frequency band and using substantially the same air interface for both terrestrial and satellite communications can be more cost effective and/or aesthetically appealing.
  • Conventional dual band/dual mode alternatives such as the well known Thuraya, Iridium and/or Globalstar dual mode satellite/terrestrial radiotelephone systems, may duplicate some components, which may lead to increased cost, size and/or weight of the radiotelephone.
  • Satellite Telecommunications Repeaters are provided which receive, amplify, and locally retransmit the downlink signal received from a satellite thereby increasing the effective downlink margin in the vicinity of the satellite telecommunications repeaters and allowing an increase in the penetration of uplink and downlink signals into buildings, foliage, transportation vehicles, and other objects which can reduce link margin.
  • Both portable and non-portable repeaters are provided. See the abstract of U.S. Pat. No. 5,937,332.
  • Some embodiments of the present invention provide a space-based network for a satellite radiotelephone system that includes at least one receive-only satellite and at least one transmit satellite.
  • the transmit satellite is a transmit-only satellite, whereas in other embodiments, the transmit satellite is a transmit and receive satellite.
  • the at least one receive-only satellite is configured to receive wireless communications from a radiotelephone at a predetermined location over a satellite frequency band.
  • the at least one transmit satellite is configured to transmit wireless communications to the radiotelephone at the predetermined location over the satellite frequency band.
  • some embodiments of the invention provide a space-based network for a satellite radiotelephone system that comprises more receive satellites than transmit satellites.
  • Other embodiments of the invention provide a space-based network for a satellite radiotelephone system comprising a plurality of satellites that collectively provide greater uplink margin than downlink margin.
  • the at least one receive-only satellite consists of two receive-only satellites.
  • the at least one transmit satellite comprises at least one transmit-only satellite.
  • the at least one transmit-only satellite consists of a single transmit-only satellite.
  • one of the two receive-only satellites and a single transmit-only satellite are collocated in an orbital slot.
  • each of the receive-only satellites comprises first and second receive antennas. In other embodiments, the first and second receive-only antennas are about 24 meters in diameter.
  • the at least one transmit satellite comprises at least one transmit and receive satellite.
  • the at least one transmit and receive satellite consists of a single transmit and receive satellite that is collocated in an orbital slot with one of the two receive-only satellites.
  • the at least one transmit and receive satellite consists of two transmit and receive satellites, a respective one of which is collocated in an orbital slot with a respective one of the two receive-only satellites.
  • the single transmit and receive satellite includes a single transmit antenna and a single receive antenna. In other embodiments, the single transmit and receive satellite comprises a single transmit and receive antenna and a single receive antenna. In yet other embodiments, the two transmit and receive satellites each comprises a single transmit antenna and a single receive antenna. In still other embodiments, the two transmit and receive satellite antennas each comprises a single transmit and receive antenna and a single receive antenna.
  • each of the receive-only satellites includes first through fourth processors.
  • the first processor is configured to process wireless communications that are received by the first receive-only antenna in a first type of circular polarization.
  • the second processor is configured to process wireless communications that are received by the first receive-only antenna in a second type of circular polarization.
  • the third processor is configured to process wireless communications that are received by the second receive-only antenna in the first polarization, and the fourth processor is configured to process wireless communications that are received by the second receive-only antenna in the second polarization.
  • each of the receive-only satellites includes a feeder link signal generator.
  • the feeder link signal generator is configured to combine signals that are received by the first and second receive-only antennas into at least one feeder link signal, including a plurality of orthogonal dimensions and/or polarizations, such as in-phase and quadrature dimensions, horizontal and vertical polarizations, left hand circular and right hand circular polarizations and/or other orthogonal dimensions and/or polarizations.
  • Space-based networks also include a gateway that is configured to receive the feeder link signal from each of the two receive-only satellites.
  • the gateway may be configured to receive the feeder link signal from each of the two receive-only satellites when the feeder link signal has a bandwidth that is at least as wide as the signals that are received by the first and second receive-only antennas of one of the receive-only satellites.
  • the space-based network includes a plurality of gateways, a respective one of which is configured to receive a feeder link signal from each of the two receive-only satellites.
  • the signals that are received by the first and/or second receive-only antennas of one of the receive-only satellites have a bandwidth that is wider than the feeder link signal.
  • Still other embodiments of the present invention include a combiner that is configured to combine the feeder link signals that are received at least one of the plurality of gateways, in order to reconstruct the wireless communications from the radiotelephone.
  • Still other embodiments of the present invention include an ancillary terrestrial network that is configured to wirelessly communicate with the radiotelephone at the predetermined location over at least some of the satellite radiotelephone frequency band, to thereby terrestrially reuse the at least some of the satellite radiotelephone frequency band.
  • FIG. 1 is a schematic diagram of cellular radiotelephone systems and methods according to embodiments of the invention.
  • FIG. 2 is a block diagram of adaptive interference reducers according to embodiments of the present invention.
  • FIG. 3 is a spectrum diagram that illustrates satellite L-band frequency allocations.
  • FIG. 4 is a schematic diagram of cellular satellite systems and methods according to other embodiments of the present invention.
  • FIG. 5 illustrates time division duplex frame structures according to embodiments of the present invention.
  • FIG. 6 is a block diagram of architectures of ancillary terrestrial components according to embodiments of the invention.
  • FIG. 7 is a block diagram of architectures of reconfigurable radiotelephones according to embodiments of the invention.
  • FIG. 8 graphically illustrates mapping of monotonically decreasing power levels to frequencies according to embodiments of the present invention.
  • FIG. 9 illustrates an ideal cell that is mapped to three power regions and three associated carrier frequencies according to embodiments of the invention.
  • FIG. 10 depicts a realistic cell that is mapped to three power regions and three associated carrier frequencies according to embodiments of the invention.
  • FIG. 11 illustrates two or more contiguous slots in a frame that are unoccupied according to embodiments of the present invention.
  • FIG. 12 illustrates loading of two or more contiguous slots with lower power transmissions according to embodiments of the present invention.
  • FIG. 13 schematically illustrates the use of transmit-only and receive-only satellites in a space-based network architecture according to embodiments of the present invention.
  • FIG. 14 is a block diagram of architectures for space-based networks according to embodiments of the present invention.
  • FIG. 15 schematically illustrates architectures for space-based networks according to other embodiments of the present invention.
  • FIG. 1 is a schematic diagram of cellular satellite radiotelephone systems and methods according to embodiments of the invention.
  • these cellular satellite radiotelephone systems and methods 100 include at least one Space-Based Component (SBC) 110 , such as a satellite.
  • the space-based component 110 is configured to transmit wireless communications to a plurality of radiotelephones 120 a , 120 b in a satellite footprint comprising one or more satellite radiotelephone cells 130 - 130 ′′′′ over one or more satellite radiotelephone forward link (downlink) frequencies f D .
  • the space-based component 110 is configured to receive wireless communications from, for example, a first radiotelephone 120 a in the satellite radiotelephone cell 130 over a satellite radiotelephone return link (uplink) frequency f U .
  • uplink uplink
  • An ancillary terrestrial network comprising at least one ancillary terrestrial component 140 , which may include an antenna 140 a and an electronics system 140 b (for example, at least one antenna 140 a and at last one electronics system 140 b ), is configured to receive wireless communications from, for example, a second radiotelephone 120 b in the radiotelephone cell 130 over the satellite radiotelephone uplink frequency, denoted f′ U , which may be the same as f U .
  • radiotelephone 120 a may be communicating with the space-based component 110 while radiotelephone 120 b may be communicating with the ancillary terrestrial component 140 .
  • FIG. 1 radiotelephone 120 a may be communicating with the space-based component 110 while radiotelephone 120 b may be communicating with the ancillary terrestrial component 140 .
  • the space-based component 110 also undesirably receives the wireless communications from the second radiotelephone 120 b in the satellite radiotelephone cell 130 over the satellite radiotelephone frequency f′ U as interference. More specifically, a potential interference path is shown at 150 .
  • embodiments of satellite radiotelephone systems/methods 100 can include at least one gateway 160 that can include an antenna 160 a and an electronics system 160 b that can be connected to other networks 162 including terrestrial and/or other radiotelephone networks.
  • the gateway 160 also communicates with the space-based component 110 over a satellite feeder link 112 .
  • the gateway 160 also communicates with the ancillary terrestrial component 140 , generally over a terrestrial link 142 .
  • an Interference Reducer (IR) 170 a also may be provided at least partially in the ancillary terrestrial component electronics system 140 b .
  • an interference reducer 170 b may be provided at least partially in the gateway electronics system 160 b .
  • the interference reducer may be provided at least partially in other components of the cellular satellite system/method 100 instead of or in addition to the interference reducer 170 a and/or 170 b .
  • the interference reducer is responsive to the space-based component 110 and to the ancillary terrestrial component 140 , and is configured to reduce the interference from the wireless communications that are received by the space-based component 110 and is at least partially generated by the second radiotelephone 120 b in the satellite radiotelephone cell 130 over the satellite radiotelephone frequency f′ U .
  • the interference reducer 170 a and/or 170 b uses the wireless communications f′ U that are intended for the ancillary terrestrial component 140 from the second radiotelephone 120 b in the satellite radiotelephone cell 130 using the satellite radiotelephone frequency f′ U to communicate with the ancillary terrestrial component 140 .
  • the ancillary terrestrial component 140 generally is closer to the first and second radiotelephones 120 a and 120 b , respectively, than is the space-based component 110 , such that the wireless communications from the second radiotelephone 120 b are received by the ancillary terrestrial component 140 prior to being received by the space-based component 110 .
  • the interference reducer 170 a and/or 170 b is configured to generate an interference cancellation signal comprising, for example, at least one delayed replica of the wireless communications from the second radiotelephone 120 b that are received by the ancillary terrestrial component 140 , and to subtract the delayed replica of the wireless communications from the second radiotelephone 120 b that are received by the ancillary terrestrial component 140 from the wireless communications that are received from the space-based component 110 .
  • the interference reduction signal may be transmitted from the ancillary terrestrial component 140 to the gateway 160 over link 142 and/or using other conventional techniques.
  • adaptive interference reduction techniques may be used to at least partially cancel the interfering signal, so that the same, or other nearby, satellite radiotelephone uplink frequency can be used in a given cell for communications by radiotelephones 120 with the satellite 110 and with the ancillary terrestrial component 140 . Accordingly, all frequencies that are assigned to a given cell 130 may be used for both radiotelephone 120 communications with the space-based component 110 and with the ancillary terrestrial component 140 .
  • Conventional systems may avoid terrestrial reuse of frequencies within a given satellite cell that are being used within the satellite cell for satellite communications. Stated differently, conventionally, only frequencies used by other satellite cells may be candidates for terrestrial reuse within a given satellite cell.
  • embodiments of the invention can use an interference reducer to allow all frequencies assigned to a satellite cell to be used terrestrially and for satellite radiotelephone communications.
  • Embodiments of the invention according to FIG. 1 may arise from a realization that the return link signal from the second radiotelephone 120 b at f′ U generally will be received and processed by the ancillary terrestrial component 140 much earlier relative to the time when it will arrive at the satellite gateway 160 from the space-based component 110 via the interference path 150 . Accordingly, the interference signal at the satellite gateway 160 b can be at least partially canceled.
  • an interference cancellation signal such as the demodulated ancillary terrestrial component signal, can be sent to the satellite gateway 160 b by the interference reducer 170 a in the ancillary terrestrial component 140 , for example using link 142 .
  • a weighted (in amplitude and/or phase) replica of the signal may be formed using, for example, adaptive transversal filter techniques that are well known to those having skill in the art. Then, a transversal filter output signal is subtracted from the aggregate received satellite signal at frequency f′ U that contains desired as well as interference signals.
  • the interference cancellation need not degrade the signal-to-noise ratio of the desired signal at the gateway 160 , because a regenerated (noise-free) terrestrial signal, for example as regenerated by the ancillary terrestrial component 140 , can be used to perform interference suppression.
  • FIG. 2 is a block diagram of embodiments of adaptive interference cancellers that may be located in the ancillary terrestrial component 140 , in the gateway 160 , and/or in another component of the cellular radiotelephone system 100 .
  • one or more control algorithms 204 may be used to adaptively adjust the coefficients of a plurality of transversal filters 202 a - 202 n .
  • Adaptive algorithms such as Least Mean Square Error (LMSE), Kalman, Fast Kalman, Zero Forcing and/or various combinations thereof or other techniques may be used.
  • LMSE Least Mean Square Error
  • Kalman Kalman
  • Fast Kalman Zero Forcing
  • various combinations thereof or other techniques may be used.
  • FIG. 2 may be used with an LMSE algorithm.
  • conventional architectural modifications may be made to facilitate other control algorithms.
  • FIG. 3 illustrates L-band frequency allocations including cellular radiotelephone system forward links and return links.
  • the space-to-ground L-band forward link (downlink) frequencies are assigned from 1525 MHz to 1559 MHz.
  • the ground-to-space L-band return link (uplink) frequencies occupy the band from 1626.5 MHz to 1660.5 MHz.
  • Between the forward and return L-band links lie the GPS/GLONASS radionavigation band (from 1559 MHz to 1605 MHz).
  • GPS/GLONASS will be referred to simply as GPS for the sake of brevity.
  • ATC and SBC will be used for the ancillary terrestrial component and the space-based component, respectively, for the sake of brevity.
  • GPS receivers may be extremely sensitive since they are designed to operate on very weak spread-spectrum radionavigation signals that arrive on the earth from a GPS satellite constellation. As a result, GPS receivers may to be highly susceptible to in-band interference.
  • ATCs that are configured to radiate L-band frequencies in the forward satellite band (1525 to 1559 MHz) can be designed with very sharp out-of-band emissions filters to satisfy the stringent out-of-band spurious emissions desires of GPS.
  • some embodiments of the invention can provide systems and methods that can allow an ATC 140 to configure itself in one of at least two modes.
  • a first mode which may be a standard mode and may provide highest capacity
  • the ATC 140 transmits to the radiotelephones 120 over the frequency range from 1525 MHz to 1559 MHz, and receives transmissions from the radiotelephones 120 in the frequency range from 1626.5 MHz to 1660.5 MHz, as illustrated in FIG. 3 .
  • the ATC 140 transmits wireless communications to the radiotelephones 120 over a modified range of satellite band forward link (downlink) frequencies.
  • the modified range of satellite band forward link frequencies may be selected to reduce, compared to the unmodified range of satellite band forward link frequencies, interference with wireless receivers such as GPS receivers that operate outside the range of satellite band forward link frequencies.
  • modified ranges of satellite band forward link frequencies may be provided according to embodiments of the present invention.
  • the modified range of satellite band forward link frequencies can be limited to a subset of the original range of satellite band forward link frequencies, so as to provide a guard band of unused satellite band forward link frequencies.
  • all of the satellite band forward link frequencies are used, but the wireless communications to the radiotelephones are modified in a manner to reduce interference with wireless receivers that operate outside the range of satellite band forward link frequencies. Combinations and subcombinations of these and/or other techniques also may be used, as will be described below.
  • multiple mode ATCs 140 that can operate in a first standard mode using the standard forward and return links of FIG. 3 , and in a second or alternate mode that uses a modified range of satellite band forward link frequencies and/or a modified range of satellite band return link frequencies.
  • These multiple mode ATCs can operate in the second, non-standard mode, as long as desirable, and can be switched to standard mode otherwise.
  • other embodiments of the present invention need not provide multiple mode ATCs but, rather, can provide ATCs that operate using the modified range of satellite band forward link and/or return link frequencies.
  • an ATC operates with an SBC that is configured to receive wireless communications from radiotelephones over a first range of satellite band return link frequencies and to transmit wireless communications to the radiotelephones over a second range of satellite band forward link frequencies that is spaced apart from the first range.
  • the ATC is configured to use at least one time division duplex frequency to transmit wireless communications to the radiotelephones and to receive wireless communications from the radiotelephones at different times.
  • the at least one time division duplex frequency that is used to transmit wireless communications to the radiotelephones and to receive wireless communications from the radiotelephones at different times comprises a frame including a plurality of slots.
  • At least a first one of the slots is used to transmit wireless communications to the radiotelephones and at least a second one of the slots is used to receive wireless communications from the radiotelephones.
  • the ATC transmits and receives, in Time Division Duplex (TDD) mode, using frequencies from 1626.5 MHz to 1660.5 MHz.
  • TDD Time Division Duplex
  • all ATCs across the entire network may have the stated configuration/reconfiguration flexibility. In other embodiments, only some ATCs may be reconfigurable.
  • FIG. 4 illustrates satellite systems and methods 400 according to some embodiments of the invention, including an ATC 140 communicating with a radiotelephone 120 b using a carrier frequency f′ U in TDD mode.
  • FIG. 5 illustrates an embodiment of a TDD frame structure. Assuming full-rate GSM (eight time slots per frame), up to four full-duplex voice circuits can be supported by one TDD carrier. As shown in FIG. 5 , the ATC 140 transmits to the radiotelephone 120 b over, for example, time slot number 0 . The radiotelephone 120 b receives and replies back to the ATC 140 over, for example, time slot number 4 . Time slots number 1 and 5 may be used to establish communications with another radiotelephone, and so on.
  • a Broadcast Control CHannel is preferably transmitted from the ATC 140 in standard mode, using a carrier frequency from below any guard band exclusion region.
  • a BCCH also can be defined using a TDD carrier.
  • radiotelephones in idle mode can, per established GSM methodology, monitor the BCCH and receive system-level and paging information. When a radiotelephone is paged, the system decides what type of resource to allocate to the radiotelephone in order to establish the communications link. Whatever type of resource is allocated for the radiotelephone communications channel (TDD mode or standard mode), the information is communicated to the radiotelephone, for example as part of the call initialization routine, and the radiotelephone configures itself appropriately.
  • TDD mode may co-exist with the standard mode over the same ATC, due, for example, to the ATC receiver LNA stage.
  • ATC receiver LNA stage In particular, assuming a mixture of standard and TDD mode GSM carriers over the same ATC, during the part of the frame when the TDD carriers are used to serve the forward link (when the ATC is transmitting TDD) enough energy may leak into the receiver front end of the same ATC to desensitize its LNA stage.
  • a switchable band-reject filter may be placed in front of the LNA stage. This filter would be switched in the receiver chain (prior to the LNA) during the part of the frame when the ATC is transmitting TDD, and switched out during the rest of the time.
  • An adaptive interference canceller can be configured at RF (prior to the LNA stage). If such techniques are used, suppression of the order of 70 dB can be attained, which may allow mixed standard mode and TDD frames. However, the ATC complexity and/or cost may increase.
  • TDD ATCs may be pure TDD, with the exception, perhaps, of the BCCH carrier which may not be used for traffic but only for broadcasting over the first part of the frame, consistent with TDD protocol.
  • Random Access CHannel (RACH) bursts may be timed so that they arrive at the ATC during the second half of the TDD frame.
  • all TDD ATCs may be equipped to enable reconfiguration in response to a command.
  • the forward link may use transmissions at higher rates than the return link.
  • mouse clicks and/or other user selections typically are transmitted from the radiotelephone to the system.
  • the system in response to a user selection, may have to send large data files to the radiotelephone.
  • other embodiments of the invention may be configured to enable use of an increased or maximum number of time slots per forward GSM carrier frame, to provide a higher downlink data rate to the radiotelephones.
  • a decision may be made as to how many slots will be allocated to serving the forward link, and how many will be dedicated to the return link. Whatever the decision is, it may be desirable that it be adhered to by all TDD carriers used by the ATC, in order to reduce or avoid the LNA desensitization problem described earlier.
  • the partition between forward and return link slots may be made in the middle of the frame as voice activity typically is statistically bidirectionally symmetrical. Hence, driven by voice, the center of the frame may be where the TDD partition is drawn.
  • data mode TDD carriers may use a more spectrally efficient modulation and/or protocol, such as the EDGE modulation and/or protocol, on the forward link slots.
  • the return link slots may be based on a less spectrally efficient modulation and/or protocol such as the GPRS (GMSK) modulation and/or protocol.
  • GMSK GPRS
  • the EDGE modulation/protocol and the GPRS modulation/protocol are well known to those having skill in the art, and need not be described further herein.
  • the return link vocoder may need to be comparable with quarter-rate GSM, while the forward link vocoder can operate at full-rate GSM, to yield six full-duplex voice circuits per GSM TDD-mode carrier (a voice capacity penalty of 25%).
  • FIG. 6 depicts an ATC architecture according to embodiments of the invention, which can lend itself to automatic configuration between the two modes of standard GSM and TDD GSM on command, for example, from a Network Operations Center (NOC) via a Base Station Controller (BSC).
  • NOC Network Operations Center
  • BSC Base Station Controller
  • an antenna 620 can correspond to the antenna 140 a of FIGS. 1 and 4
  • the remainder of FIG. 6 can correspond to the electronics system 140 b of FIGS. 1 and 4 .
  • a reconfiguration command for a particular carrier, or set of carriers occurs while the carrier(s) are active and are supporting traffic, then, via the in-band signaling Fast Associated Control CHannel (FACCH), all affected radiotelephones may be notified to also reconfigure themselves and/or switch over to new resources.
  • FACCH Fast Associated Control CHannel
  • all affected radiotelephones may be notified to also reconfigure themselves and/or switch over to new resources.
  • FACCH Fast Associated Control CHannel
  • a switch 610 may remain closed when carriers are to be demodulated in the standard mode. In TDD mode, this switch 610 may be open during the first half of the frame, when the ATC is transmitting, and closed during the second half of the frame, when the ATC is receiving. Other embodiments also may be provided.
  • FIG. 6 assumes N transceivers per ATC sector, where N can be as small as one, since a minimum of one carrier per sector generally is desired.
  • Each transceiver is assumed to operate over one GSM carrier pair (when in standard mode) and can thus support up to eight full-duplex voice circuits, neglecting BCCH channel overhead.
  • a standard GSM carrier pair can support sixteen full-duplex voice circuits when in half-rate GSM mode, and up to thirty two full-duplex voice circuits when in quarter-rate GSM mode.
  • FIG. 7 is a block diagram of a reconfigurable radiotelephone architecture that can communicate with a reconfigurable ATC architecture of FIG. 6 .
  • an antenna 720 is provided, and the remainder of FIG. 7 can provide embodiments of an electronics system for the radiotelephone.
  • the ability to reconfigure ATCs and radiotelephones according to embodiments of the invention may be obtained at a relatively small increase in cost.
  • the cost may be mostly in Non-Recurring Engineering (NRE) cost to develop software. Some recurring cost may also be incurred, however, in that at least an additional RF filter and a few electronically controlled switches may be used per ATC and radiotelephone. All other hardware/software can be common to standard-mode and TDD-mode GSM.
  • NRE Non-Recurring Engineering
  • the modified second range of satellite band forward link frequencies includes a plurality of frequencies in the second range of satellite band forward link frequencies that are transmitted by the ATCs to the radiotelephones at a power level, such as maximum power level, that monotonically decreases as a function of (increasing) frequency.
  • the modified second range of satellite band forward link frequencies includes a subset of frequencies proximate to a first or second end of the range of satellite band forward link frequencies that are transmitted by the ATC to the radiotelephones at a power level, such as a maximum power level, that monotonically decreases toward the first or second end of the second range of satellite band forward link frequencies.
  • the first range of satellite band return link frequencies is contained in an L-band of satellite frequencies above GPS frequencies and the second range of satellite band forward link frequencies is contained in the L-band of satellite frequencies below the GPS frequencies.
  • the modified second range of satellite band forward link frequencies includes a subset of frequencies proximate to an end of the second range of satellite band forward link frequencies adjacent the GPS frequencies that are transmitted by the ATC to the radiotelephones at a power level, such as a maximum power level, that monotonically decreases toward the end of the second range of satellite band forward link frequencies adjacent the GPS frequencies.
  • the power ( ⁇ ) is the power that an ATC uses or should transmit in order to reliably communicate with a given radiotelephone. This power may depend on many factors such as the radiotelephone's distance from the ATC, the blockage between the radiotelephone and the ATC, the level of multipath fading in the channel, etc., and as a result, will, in general, change as a function of time. Hence, the power used generally is determined adaptively (iteratively) via closed-loop power control, between the radiotelephone and ATC.
  • the frequency ( ⁇ ) is the satellite carrier frequency that the ATC uses to communicate with the radiotelephone.
  • the mapping is a monotonically decreasing function of the independent variable ⁇ . Consequently, in some embodiments, as the maximum ATC power increases, the carrier frequency that the ATC uses to establish and/or maintain the communications link decreases.
  • FIG. 8 illustrates an embodiment of a piece-wise continuous monotonically decreasing (stair-case) function. Other monotonic functions may be used, including linear and/or nonlinear, constant and/or variable decreases.
  • FACCH or Slow Associated Control CHannel (SACCH) messaging may be used in embodiments of the invention to facilitate the mapping adaptively and in substantially real time.
  • FIG. 9 depicts an ideal cell according to embodiments of the invention, where, for illustration purposes, three power regions and three associated carrier frequencies (or carrier frequency sets) are being used to partition a cell.
  • the frequency (or frequency set) f 1 is taken from substantially the upper-most portion of the L-band forward link frequency set, for example from substantially close to 1559 MHz (see FIG. 3 ).
  • the frequency (or frequency set) f M is taken from substantially the central portion of the L-band forward link frequency set (see FIG. 3 ).
  • the frequency (or frequency set) f O is taken from substantially the lowest portion of the L-band forward link frequencies, for example close to 1525 MHz (see FIG. 3 ).
  • a radiotelephone is being served within the outer-most ring of the cell, that radiotelephone is being served via frequency f O .
  • This radiotelephone being within the furthest area from the ATC, has (presumably) requested maximum (or near maximum) power output from the ATC.
  • the ATC uses its a priori knowledge of power-to-frequency mapping, such as a three-step staircase function of FIG. 9 .
  • the ATC serves the radiotelephone with a low-value frequency taken from the lowest portion of the mobile L-band forward link frequency set, for example, from as close to 1525 MHz as possible. This, then, can provide additional safeguard to any GPS receiver unit that may be in the vicinity of the ATC.
  • Embodiments of FIG. 9 may be regarded as idealized because they associate concentric ring areas with carrier frequencies (or carrier frequency sets) used by an ATC to serve its area. In reality, concentric ring areas generally will not be the case. For example, a radiotelephone can be close to the ATC that is serving it, but with significant blockage between the radiotelephone and the ATC due to a building. This radiotelephone, even though relatively close to the ATC, may also request maximum (or near maximum) output power from the ATC. With this in mind, FIG. 10 may depict a more realistic set of area contours that may be associated with the frequencies being used by the ATC to serve its territory, according to embodiments of the invention. The frequency (or frequency set) f 1 may be reused in the immediately adjacent ATC cells owing to the limited geographical span associated with f 1 relative to the distance between cell centers. This may also hold for f M .
  • At least one frequency in the modified second range of satellite band forward link frequencies that is transmitted by the ATC to the radiotelephones comprises a frame including a plurality of slots.
  • at least two contiguous slots in the frame that is transmitted by the ATC to the radiotelephones are left unoccupied.
  • three contiguous slots in the frame that is transmitted by the ATC to the radiotelephones are left unoccupied.
  • at least two contiguous slots in the frame that is transmitted by the ATC to the radiotelephones are transmitted at lower power than remaining slots in the frame.
  • three contiguous slots in the frame that is transmitted by the ATC to the radiotelephones are transmitted at lower power than remaining slots in the frame.
  • the lower power slots may be used with first selected ones of the radiotelephones that are relatively close to the ATC and/or are experiencing relatively small signal blockage, and the remaining slots are transmitted at higher power to second selected ones of the radiotelephones that are relatively far from the ATC and/or are experiencing relatively high signal blockage.
  • only a portion of the TDMA frame is utilized. For example, only the first four (or last four, or any contiguous four) time slots of a full-rate GSM frame are used to support traffic. The remaining slots are left unoccupied (empty). In these embodiments, capacity may be lost. However, as has been described previously, for voice services, half-rate and even quarter-rate GSM may be invoked to gain capacity back, with some potential degradation in voice quality.
  • the slots that are not utilized preferably are contiguous, such as slots 0 through 3 or 4 through 7 (or 2 through 5 , etc.). The use of non-contiguous slots such as 0 , 2 , 4 , and 6 , for example, may be less desirable.
  • FIG. 11 illustrates four slots ( 4 - 7 ) being used and four contiguous slots ( 0 - 3 ) being empty in a GSM frame.
  • GPS receivers can perform significantly better when the interval between interference bursts is increased or maximized. Without being bound by any theory of operation, this effect may be due to the relationship between the code repetition period of the GPS C/A code (1 msec.) and the GSM burst duration (about 0.577 msec.). With a GSM frame occupancy comprising alternate slots, each GPS signal code period can experience at least one “hit”, whereas a GSM frame occupancy comprising four to five contiguous slots allows the GPS receiver to derive sufficient clean information so as to “flywheel” through the error events.
  • embodiments of FIGS. 8-10 can be combined with embodiments of FIG. 11 .
  • an f 1 carrier of FIG. 9 or 10 is underutilized, because of the relatively small footprint of the inner-most region of the cell, it may be used to support additional traffic over the much larger outermost region of the cell.
  • these four f 1 slots are carrying relatively low power bursts, for example of the order of 100 mW or less, and may, therefore, appear as (almost) unoccupied from an interference point of view.
  • Loading the remaining four (contiguous) time slots of f 1 with relatively high-power bursts may have negligible effect on a GPS receiver because the GPS receiver would continue to operate reliably based on the benign contiguous time interval occupied by the four low-power GSM bursts.
  • FIG. 12 illustrates embodiments of a frame at carrier f 1 supporting four low-power (inner interval) users and four high-power (outer interval) users.
  • embodiments illustrated in FIG. 12 may be a preferred strategy for the set of available carrier frequencies that are closest to the GPS band. These embodiments may avoid undue capacity loss by more fully loading the carrier frequencies.
  • the experimental finding that interference from GSM carriers can be relatively benign to GPS receivers provided that no more than, for example, 5 slots per 8 slot GSM frame are used in a contiguous fashion can be very useful. It can be particularly useful since this experimental finding may hold even when the GSM carrier frequency is brought very close to the GPS band (as close as 1558.5 MHz) and the power level is set relatively high. For example, with five contiguous time slots per frame populated, the worst-case measured GPS receiver may attain at least 30 dB of desensitization margin, over the entire ATC service area, even when the ATC is radiating at 1558.5 MHz. With four contiguous time slots per frame populated, an additional 10 dB desensitization margin may be gained for a total of 40 dB for the worst-case measured GPS receiver, even when the ATC is radiating at 1558.5 MHz.
  • carriers which are subject to contiguous empty/low power slots are not used for the forward link. Instead, they are used for the return link. Consequently, in some embodiments, at least part of the ATC is configured in reverse frequency mode compared to the SBC in order to allow maximum data rates over the forward link throughout the entire network.
  • a radiotelephone On the reverse frequency return link, a radiotelephone may be limited to a maximum of 5 slots per frame, which can be adequate for the return link. Whether the five available time slots per frame, on a reverse frequency return link carrier, are assigned to one radiotelephone or to five different radiotelephones, they can be assigned contiguously in these embodiments. As was described in connection with FIG. 12 , these five contiguous slots can be assigned to high-power users while the remaining three slots may be used to serve low-power users.
  • an ATC transmits over the satellite return link frequencies while radiotelephones respond over the satellite forward link frequencies. If sufficient contiguous spectrum exists to support CDMA technologies, and in particular the emerging Wideband-CDMA 3G standard, the ATC forward link can be based on Wideband-CDMA to increase or maximize data throughput capabilities. Interference with GPS may not be an issue since the ATCs transmit over the satellite return link in these embodiments. Instead, interference may become a concern for the radiotelephones. Based, however, on embodiments of FIGS.
  • the radiotelephones can be configured to transmit GSM since ATC return link rates are expected, in any event, to be lower than those of the forward link. Accordingly, the ATC return link may employ GPRS-based data modes, possibly even EDGE. Thus, return link carriers that fall within a predetermined frequency interval from the GPS band-edge of 1559 MHz, can be under loaded, per embodiments of FIG. 11 or 12 , to satisfy GPS interference concerns.
  • the ATC forward link to the radiotelephones utilizes the frequencies of the satellite return link (1626.5 MHz to 1660.5 MHz) whereas the ATC return link from the radiotelephones uses the frequencies of the satellite forward link (1525 MHz to 1559 MHz).
  • the ATC forward link can be based on an existing or developing CDMA technology (e.g., IS-95, Wideband-CDMA, etc.).
  • the ATC network return link can also be based on an existing or developing CDMA technology provided that the radiotelephone's output is gated to cease transmissions for approximately 3 msec once every T msec. In some embodiments, T will be greater than or equal to 6 msec.
  • This gating may not be needed for ATC return link carriers at approximately 1550 MHz or below. This gating can reduce or minimize out-of-band interference (desensitization) effects for GPS receivers in the vicinity of an ATC.
  • the gating between all radiotelephones over an entire ATC service area can be substantially synchronized. Additional benefit to GPS may be derived from system-wide synchronization of gating.
  • the ATCs can instruct all active radiotelephones regarding the gating epoch. All ATCs can be mutually synchronized via GPS.
  • some embodiments of the present invention may employ a Space-Based Network (SBN) and an Ancillary Terrestrial Network (ATN) that both communicate with a plurality of radiotelephones using satellite radiotelephone frequencies.
  • the SBN may include one or more Space-Based Components (SBC) and one or more satellite gateways.
  • the ATN may include a plurality of Ancillary Terrestrial Components (ATC).
  • the SBN and the ATN may operate at L-band (1525-1559 MHz forward service link, and 1626.5-1660.5 MHz return service link).
  • the radiotelephones may be similar to conventional handheld cellular/PCS-type terminals that are capable of voice and/or packet data services.
  • terrestrial reuse of at least some of the mobile satellite frequency spectrum can allow the SBN to serve low density areas that may be impractical and/or uneconomical to serve via conventional terrestrial networks, while allowing the ATN to serve pockets of densely populated areas that may only be effectively served terrestrially.
  • the radiotelephones can be attractive, feature-rich and/or low cost, similar to conventional cellular/PCS-type terminals that are offered by terrestrial-only operators.
  • component count in the radiotelephones for example in the front end radio frequency (RF) section, may be reduced.
  • the same frequency synthesizer, RF filters, low noise amplifiers, power amplifiers and antenna elements may be used for terrestrial and satellite communications.
  • space-based network architectures can offer significant link margin over and above the clear sky conditions, represented by an Additive White Gaussian Noise (AWGN) channel, without the need to undesirably burden the radiotelephones themselves to achieve this link margin.
  • AWGN Additive White Gaussian Noise
  • the SBN may employ relatively large reflectors, for example on the order of about 24 meters in diameter, that can produce relatively small, high gain, agile spot beams.
  • Digital processors in the space-based component and/or at the satellite gateways can be used to improve or optimize performance with respect to each individual user.
  • space-based networks for a satellite radiotelephone system include at least one receive-only satellite and at least one transmit satellite.
  • the transmit satellite is a transmit-only satellite, whereas in other embodiments, the transmit satellite is a transmit and receive satellite.
  • receive and receive satellite are used relative to ground based radiotelephones and that a receive-only satellite and a transmit-only satellite also may transmit to and receive from a gateway or other ground station.
  • the at least one receive-only satellite is configured to receive wireless communications from a radiotelephone at a predetermined location over a satellite frequency band.
  • the at least one transmit satellite is configured to transmit wireless communications to the radiotelephone at the predetermined location over the satellite frequency band.
  • some embodiments of the invention provide a space-based network for a satellite radiotelephone system that comprises more receive satellites than transmit satellites.
  • FIG. 13 conceptually illustrates space-based network architectures according to some embodiments of the present invention.
  • at least one transmit-only (TX-only) satellite 1310 and at least one receive-only (RX-only) satellite 1320 a , 1320 b are used to communicate with radiotelephones such as the radiotelephone 1330 .
  • a space-based network may include a single TX-only satellite 1310 and first and second RX-only satellites 1320 a , 1320 b , also referred to as RX-only satellite 1 and RX-only satellite 2 , respectively.
  • the first RX-only satellite 1320 a may be co-located with the TX-only satellite 1310
  • the second RX-only satellite 1320 b may be located at a different orbital slot.
  • each RX-only satellite antenna 1340 a - 1340 d may be approximately 24 meters in diameter. This can provide a return link aggregate space-based aperture with an equivalent diameter of about 40 meters.
  • the RX-only satellite antennas 1340 a - 1340 d may be of same size or different sizes. This relatively large, effective return link aperture may be used to allow the SBN to accommodate a relatively low Effective Isotropic Radiated Power (EIRP) on the radiotelephones 1330 , for example about ⁇ 6 dBW.
  • EIRP Effective Isotropic Radiated Power
  • the TX-only satellite 1310 may contain an on-board digital processor that can perform various functions, such as feeder-link channelization, filtering, beam routing and/or digital beam forming.
  • functions such as feeder-link channelization, filtering, beam routing and/or digital beam forming.
  • each receive antenna 1340 a - 1340 d of each RX-only satellite 1320 a , 1320 b receives Left-Hand Circular Polarization (LHCP) energy and Right-Hand Circular Polarization (RHCP) energy. This may be received, since the radiotelephone 1330 may radiate linearly polarized energy, which contains half of its energy in LHCP and the remaining half in RHCP.
  • LHCP Left-Hand Circular Polarization
  • RHCP Right-Hand Circular Polarization
  • each RX-only satellite 1320 a , 1320 b may contain up to four digital processors.
  • a first digital processor may be configured to operate on the aggregate signal received by the first antenna, for example antenna 1340 a or 1340 c , in LHCP, and perform the functions of signal channelization, filtering, beam forming and/or routing of signals to the feeder link.
  • a second processor may be configured to perform the identical functions as the first, but on the RHCP signal received by the first antenna, such as antenna 1340 a or 1340 c .
  • the remaining two processors may be configured to repeat these functions on the RHCP and LHCP signals of the second RX-only antenna, such as antenna 1340 b or 1340 d . All eight sets of received signals, from both RX-only satellites 1320 a and 1320 b , may be sent via one or more feeder links to one or more gateways for combining, as will now be described.
  • FIG. 14 is a block diagram of portions of the space-based network that illustrates how the signals from the RX-only satellite 1 1320 a and RX-only satellite 2 1320 b may be combined according to some embodiments of the present invention.
  • Embodiments of FIG. 14 assume that the available feeder link bandwidth, from an RX-only satellite 1320 a , 1320 b to a gateway is X MHz, but that Y MHz is desired to transport the signals to the gateway, where Y is greater than X.
  • a first X MHz of LHCP signal spectrum 1410 a received from RX-only satellite 1 , antenna 1 1340 a via the first processor, and a first corresponding X MHz of RHCP signal spectrum 1410 b also received by RX-only satellite 1 , antenna 1 1340 a via the second processor, are mapped into in-phase (I) and quadrature (Q) dimensions of a first carrier.
  • the X MHz of signal spectrum that is mapped into the I and Q dimensions of the carrier need not be an RHCP signal received by satellite 1 , antenna 1 .
  • any appropriate mapping of signals from the RX-only satellite antennas 1340 a - 1340 b may be used, for example, by utilizing as many orthogonal polarizations and/or dimensions as possible, over the same available feeder bandwidth, so as to reduce or minimize the number of gateways or diversity sites that are used on the ground to transport the desired signals for processing thereof.
  • the X MHz bandwidth quadrature carrier may be transported to a first gateway 1440 a over the X MHz of available feeder link bandwidth using a vertically (V) polarized orientation.
  • a first X MHz of LHCP signal spectrum 1410 c from RX-only satellite 1 , antenna 2 1340 b via the third processor, and a first RHCP signal spectrum 1410 d from RX-only satellite 1 , antenna 2 1340 b via the fourth processor are mapped onto the I and Q dimensions of a second carrier, at the same frequency as the first carrier, and are concurrently transported to the first gateway 1440 a over the X MHz of available feeder link bandwidth using a horizontally (H) polarized orientation.
  • the transmission medium is indicated schematically by summing node 1430 to indicate a concurrence of the horizontally and vertically polarized signals in the transmission medium.
  • This mapping onto X MHz bandwidth carriers in the I and Q dimensions may be repeated up to n times, as shown in FIG. 14 by the summing nodes 1420 a , 1420 b , in order to transmit the entire signal bandwidth received by the RX-only satellite 1320 a corresponding to all satellite cells of each polarization (LHCP and RHCP) of each antenna.
  • the processors and summing nodes 1420 a , 1420 b may comprise a feeder link signal generator according to some embodiments of the invention, which is configured to combine signals that are received by the first and second receive only antennas 1340 a , 1340 b into the feeder link signal 1490 that is transmitted on at least one carrier in a plurality of orthogonal dimensions.
  • FIG. 14 Similar operations may take place with respect to the second RX-only satellite 1320 b .
  • This mapping only is shown generally in FIG. 14 at 1450 , for the sake of clarity.
  • a plurality of gateways 1440 a - 1440 n may be provided to spatially reuse the same available feeder link spectrum, up to n times in FIG. 14 , and thus transport all the satellite receive signals to the ground, for demodulation and combining.
  • the gateways 1440 a - 1440 n can function as frequency reuse sites, as well as providing for diversity combining according to some embodiments of the present invention, as will be described below. It will be understood that if Y is less than or equal to X, only one gateway location 1440 may need to be used.
  • other polarization schemes may be used at the various stages of FIG. 14 , instead of the LHCP/RHCP and/or V/H polarization.
  • a given user signal will reach the ground via the plurality of polarizations (LHCP and RHCP) of each satellite antenna, via the plurality of satellite antennas 1340 a - 1340 d of each RX-only satellite 1320 a , 1320 b , and via the plurality of RX-only satellites 1320 a , 1320 b .
  • LHCP and RHCP polarizations
  • a plurality of satellite beams (cells) of each polarization, of each antenna, and of each RX-only satellite may be contributing a desired signal component relative to the given user, particularly when the user is geographically close to the intersection of two or more of the satellite beams.
  • embodiments of demodulation and combining may include processing of multiple signal components that are received by the various RX-only satellite antennas 1340 a - 1340 d from a given radiotelephone 1330 , in order to reconstruct the wireless communications from the radiotelephone.
  • up to three cells may be receiving useful signal contributions in a seven-cell frequency reuse plan.
  • each of the plurality of signal components may be weighted in accordance with, for example, a least mean squared error performance index, and then summed, for example, in a combiner such as an optimum combiner 1460 , to yield the received signal output S, shown in FIG. 14 .
  • a receiver decision stage 1470 then may be used to generate symbol estimates ⁇ .
  • each gateway site 1440 a - 1440 n may also receive interference between the I and Q dimensions (also referred to as cross-rail interference) and/or cross-polarization interference between the vertical and horizontal polarizations, for example due to the non-ideal passband characteristics of the channel and/or the system.
  • some known symbols may be transmitted over at least some of the orthogonal dimensions that were described above, to enable an adaptive receiver at a gateway site, to compensate at least in part for any such effect.
  • precompensation may be performed for the channel and/or system non-ideal passband characteristics at the satellite, prior to transmission over a feeder link.
  • error information may be sent back to the satellite from a processing gateway site.
  • the overhead of the known symbols may be avoided by relying on the decisions of the receiver.
  • the reliability of the receiver's demodulation process may be increased by transporting the known symbols.
  • the overhead due to a known symbol sequence can be small, since the feeder link channel generally is quasi-static.
  • FIG. 15 conceptually illustrates space-based network architectures according to other embodiments of the present invention.
  • these embodiments of the present invention include at least one receive-only satellite and at least one transmit and receive satellite.
  • a first receive-only satellite 1510 a and a first transmit and receive satellite 1520 a are co-located, for example at orbital slot 101° W.
  • a second receive-only satellite 1510 b and a second transmit and receive satellite 1520 b also are co-located, for example at orbital slot 107.3° W.
  • the transmit and receive satellites 1520 a , 1520 b can each include a respective first antenna 1540 a , 1540 c that is configured as a receive-only antenna, and a respective second antenna 1540 b , 1540 d that is configured to perform both transmit and receive functions.
  • the second antenna 1540 b , 1540 d may be configured to perform transmit-only functions.
  • the first antenna 1540 a , 1540 c also may be configured to perform transmit and receive functions. In all embodiments, the antennas may be of same and/or different sizes.
  • Embodiments of FIG. 15 also can be used to obtain a relatively high return link (uplink) margin. For example, a comparison will be made relative to the Thuraya satellite. It will now be shown that a return link margin of approximately 13 dB higher may be obtained using space-based architectures according to some embodiments of the present invention.
  • the return link margin may be increased by an additional 3 dB, for a total of 7 dB over Thuraya, assuming that both antennas 1540 a , 1540 b on the satellite 1520 a are of the same size and that combining of their outputs is performed.
  • embodiments of the present invention can obtain 7 dB more return link margin than may be obtained in the Thuraya system.
  • first receive-only satellite 1510 a can add 3 dB more to the above link margin, since it includes two additional 24 meter receive-only L band antennas.
  • satellites 1520 b and 1510 b can add 3 dB more to the above, for a total of 13 dB over and above that which may be obtained with Thuraya without even having considered diversity gains.
  • each satellite receive antenna may be assumed to be receiving both RHCP and LHCP.
  • the polarizations may be combined in a manner similar to that described in FIG. 14 .

Abstract

A space-based network for a satellite radiotelephone system includes at least one receive-only satellite and at least one transmit satellite. The transmit satellite can be a transmit-only satellite or a transmit and receive satellite. The receive-only satellite(s) are configured to receive wireless communications from a radiotelephone at a location over a satellite frequency band. The transmit satellite(s) are configured to transmit wireless communications to the radiotelephone at the location over the satellite frequency band. By providing at least one receive-only satellite and at least one transmit satellite, space-based networks can offer a significant link margin, without the need to undesirably burden the radiotelephones themselves to achieve this link margin.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • This application is a continuation of U.S. patent application Ser. No. 11/241,519, filed Sep. 30, 2005, entitled Space-Based Network Architecture for Satellite Radiotelephone Systems, which itself is a continuation of U.S. patent application Ser. No. 10/225,623, filed Aug. 22, 2002, now U.S. Pat. No. 7,006,789, entitled Space-Based Network Architectures for Satellite Radiotelephone Systems, which claims the benefit of provisional Application No. 60/322,240, filed Sep. 14, 2001, entitled Systems and Methods for Terrestrial Re-Use of Mobile Satellite Spectrum and provisional Application No. 60/392,771, filed Jul. 1, 2002, entitled Space-Based Network Architectures for Satellite Radiotelephone Systems, all of which are assigned to the assignee of the present application, the disclosures of all of which are hereby incorporated herein by reference in their entirety as if set forth fully herein. application Ser. No. 10/225,623 also is a continuation-in-part (CIP) of application Ser. No. 10/074,097, filed Feb. 12, 2002, entitled Systems and Methods for Terrestrial Reuse of Cellular Satellite Frequency Spectrum, now U.S. Pat. No. 6,684,057, assigned to the assignee of the present application, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein.
  • FIELD OF THE INVENTION
  • This invention relates to radiotelephone communications systems and methods, and more particularly to terrestrial cellular and satellite cellular radiotelephone communications systems and methods.
  • BACKGROUND OF THE INVENTION
  • Satellite radiotelephone communications systems and methods are widely used for radiotelephone communications. Satellite radiotelephone communications systems and methods generally employ at least one space-based component, such as one or more satellites that are configured to wirelessly communicate with a plurality of satellite radiotelephones.
  • A satellite radiotelephone communications system or method may utilize a single antenna beam covering an entire area served by the system. Alternatively, in cellular satellite radiotelephone communications systems and methods, multiple beams are provided, each of which can serve distinct geographical areas in the overall service region, to collectively serve an overall satellite footprint. Thus, a cellular architecture similar to that used in conventional terrestrial cellular radiotelephone systems and methods can be implemented in cellular satellite-based systems and methods. The satellite typically communicates with radiotelephones over a bidirectional communications pathway, with radiotelephone communication signals being communicated from the satellite to the radiotelephone over a downlink or forward link, and from the radiotelephone to the satellite over an uplink or return link.
  • The overall design and operation of cellular satellite radiotelephone systems and methods are well known to those having skill in the art, and need not be described further herein. Moreover, as used herein, the term “radiotelephone” includes cellular and/or satellite radiotelephones with or without a multi-line display; Personal Communications System (PCS) terminals that may combine a radiotelephone with data processing, facsimile and/or data communications capabilities; Personal Digital Assistants (PDA) that can include a radio frequency transceiver and a pager, Internet/intranet access, Web browser, organizer, calendar and/or a global positioning system (GPS) receiver; and/or conventional laptop and/or palmtop computers or other appliances, which include a radio frequency transceiver.
  • As is well known to those having skill in the art, terrestrial networks can enhance cellular satellite radiotelephone system availability, efficiency and/or economic viability by terrestrially reusing at least some of the frequency bands that are allocated to cellular satellite radiotelephone systems. In particular, it is known that it may be difficult for cellular satellite radiotelephone systems to reliably serve densely populated areas, because the satellite signal may be blocked by high-rise structures and/or may not penetrate into buildings. As a result, the satellite spectrum may be underutilized or unutilized in such areas. The use of terrestrial retransmission can reduce or eliminate this problem.
  • Moreover, the capacity of the overall system can be increased significantly by the introduction of terrestrial retransmission, since terrestrial frequency reuse can be much denser than that of a satellite-only system. In fact, capacity can be enhanced where it may be mostly needed, i.e., densely populated urban/industrial/commercial areas. As a result, the overall system can become much more economically viable, as it may be able to serve a much larger subscriber base. Finally, satellite radiotelephones for a satellite radiotelephone system having a terrestrial component within the same satellite frequency band and using substantially the same air interface for both terrestrial and satellite communications can be more cost effective and/or aesthetically appealing. Conventional dual band/dual mode alternatives, such as the well known Thuraya, Iridium and/or Globalstar dual mode satellite/terrestrial radiotelephone systems, may duplicate some components, which may lead to increased cost, size and/or weight of the radiotelephone.
  • One example of terrestrial reuse of satellite frequencies is described in U.S. Pat. No. 5,937,332 to the present inventor Karabinis entitled Satellite Telecommunications Repeaters and Retransmission Methods, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein. As described therein, satellite telecommunications repeaters are provided which receive, amplify, and locally retransmit the downlink signal received from a satellite thereby increasing the effective downlink margin in the vicinity of the satellite telecommunications repeaters and allowing an increase in the penetration of uplink and downlink signals into buildings, foliage, transportation vehicles, and other objects which can reduce link margin. Both portable and non-portable repeaters are provided. See the abstract of U.S. Pat. No. 5,937,332.
  • In view of the above discussion, there continues to be a need for systems and methods for terrestrial reuse of cellular satellite frequencies that can allow improved reliability, capacity, cost effectiveness and/or aesthetic appeal for cellular satellite radiotelephone systems, methods and/or satellite radiotelephones.
  • SUMMARY OF THE INVENTION
  • Some embodiments of the present invention provide a space-based network for a satellite radiotelephone system that includes at least one receive-only satellite and at least one transmit satellite. In some embodiments, the transmit satellite is a transmit-only satellite, whereas in other embodiments, the transmit satellite is a transmit and receive satellite. The at least one receive-only satellite is configured to receive wireless communications from a radiotelephone at a predetermined location over a satellite frequency band. The at least one transmit satellite is configured to transmit wireless communications to the radiotelephone at the predetermined location over the satellite frequency band. By providing at least one receive-only satellite and at least one transmit satellite, space-based networks according to some embodiments of the present invention can offer a significant link margin, without the need to undesirably burden the radiotelephones themselves to achieve this link margin.
  • Accordingly, some embodiments of the invention provide a space-based network for a satellite radiotelephone system that comprises more receive satellites than transmit satellites. Other embodiments of the invention provide a space-based network for a satellite radiotelephone system comprising a plurality of satellites that collectively provide greater uplink margin than downlink margin.
  • In some embodiments of the invention, the at least one receive-only satellite consists of two receive-only satellites. In other embodiments, the at least one transmit satellite comprises at least one transmit-only satellite. In other embodiments, the at least one transmit-only satellite consists of a single transmit-only satellite. In some embodiments, one of the two receive-only satellites and a single transmit-only satellite are collocated in an orbital slot.
  • In some embodiments, each of the receive-only satellites comprises first and second receive antennas. In other embodiments, the first and second receive-only antennas are about 24 meters in diameter.
  • In other embodiments, the at least one transmit satellite comprises at least one transmit and receive satellite. In other embodiments, the at least one transmit and receive satellite consists of a single transmit and receive satellite that is collocated in an orbital slot with one of the two receive-only satellites. In other embodiments, the at least one transmit and receive satellite consists of two transmit and receive satellites, a respective one of which is collocated in an orbital slot with a respective one of the two receive-only satellites.
  • In some embodiments, the single transmit and receive satellite includes a single transmit antenna and a single receive antenna. In other embodiments, the single transmit and receive satellite comprises a single transmit and receive antenna and a single receive antenna. In yet other embodiments, the two transmit and receive satellites each comprises a single transmit antenna and a single receive antenna. In still other embodiments, the two transmit and receive satellite antennas each comprises a single transmit and receive antenna and a single receive antenna.
  • In other embodiments, each of the receive-only satellites includes first through fourth processors. The first processor is configured to process wireless communications that are received by the first receive-only antenna in a first type of circular polarization. The second processor is configured to process wireless communications that are received by the first receive-only antenna in a second type of circular polarization. The third processor is configured to process wireless communications that are received by the second receive-only antenna in the first polarization, and the fourth processor is configured to process wireless communications that are received by the second receive-only antenna in the second polarization.
  • In other embodiments, each of the receive-only satellites includes a feeder link signal generator. The feeder link signal generator is configured to combine signals that are received by the first and second receive-only antennas into at least one feeder link signal, including a plurality of orthogonal dimensions and/or polarizations, such as in-phase and quadrature dimensions, horizontal and vertical polarizations, left hand circular and right hand circular polarizations and/or other orthogonal dimensions and/or polarizations.
  • Space-based networks according to other embodiments of the invention also include a gateway that is configured to receive the feeder link signal from each of the two receive-only satellites. In other embodiments, the gateway may be configured to receive the feeder link signal from each of the two receive-only satellites when the feeder link signal has a bandwidth that is at least as wide as the signals that are received by the first and second receive-only antennas of one of the receive-only satellites. In other embodiments, the space-based network includes a plurality of gateways, a respective one of which is configured to receive a feeder link signal from each of the two receive-only satellites. In some embodiments, the signals that are received by the first and/or second receive-only antennas of one of the receive-only satellites have a bandwidth that is wider than the feeder link signal.
  • Still other embodiments of the present invention include a combiner that is configured to combine the feeder link signals that are received at least one of the plurality of gateways, in order to reconstruct the wireless communications from the radiotelephone. Still other embodiments of the present invention include an ancillary terrestrial network that is configured to wirelessly communicate with the radiotelephone at the predetermined location over at least some of the satellite radiotelephone frequency band, to thereby terrestrially reuse the at least some of the satellite radiotelephone frequency band.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a schematic diagram of cellular radiotelephone systems and methods according to embodiments of the invention.
  • FIG. 2 is a block diagram of adaptive interference reducers according to embodiments of the present invention.
  • FIG. 3 is a spectrum diagram that illustrates satellite L-band frequency allocations.
  • FIG. 4 is a schematic diagram of cellular satellite systems and methods according to other embodiments of the present invention.
  • FIG. 5 illustrates time division duplex frame structures according to embodiments of the present invention.
  • FIG. 6 is a block diagram of architectures of ancillary terrestrial components according to embodiments of the invention.
  • FIG. 7 is a block diagram of architectures of reconfigurable radiotelephones according to embodiments of the invention.
  • FIG. 8 graphically illustrates mapping of monotonically decreasing power levels to frequencies according to embodiments of the present invention.
  • FIG. 9 illustrates an ideal cell that is mapped to three power regions and three associated carrier frequencies according to embodiments of the invention.
  • FIG. 10 depicts a realistic cell that is mapped to three power regions and three associated carrier frequencies according to embodiments of the invention.
  • FIG. 11 illustrates two or more contiguous slots in a frame that are unoccupied according to embodiments of the present invention.
  • FIG. 12 illustrates loading of two or more contiguous slots with lower power transmissions according to embodiments of the present invention.
  • FIG. 13 schematically illustrates the use of transmit-only and receive-only satellites in a space-based network architecture according to embodiments of the present invention.
  • FIG. 14 is a block diagram of architectures for space-based networks according to embodiments of the present invention.
  • FIG. 15 schematically illustrates architectures for space-based networks according to other embodiments of the present invention.
  • DETAILED DESCRIPTION
  • The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
  • FIG. 1 is a schematic diagram of cellular satellite radiotelephone systems and methods according to embodiments of the invention. As shown in FIG. 1, these cellular satellite radiotelephone systems and methods 100 include at least one Space-Based Component (SBC) 110, such as a satellite. The space-based component 110 is configured to transmit wireless communications to a plurality of radiotelephones 120 a, 120 b in a satellite footprint comprising one or more satellite radiotelephone cells 130-130″″ over one or more satellite radiotelephone forward link (downlink) frequencies fD. The space-based component 110 is configured to receive wireless communications from, for example, a first radiotelephone 120 a in the satellite radiotelephone cell 130 over a satellite radiotelephone return link (uplink) frequency fU. An ancillary terrestrial network, comprising at least one ancillary terrestrial component 140, which may include an antenna 140 a and an electronics system 140 b (for example, at least one antenna 140 a and at last one electronics system 140 b), is configured to receive wireless communications from, for example, a second radiotelephone 120 b in the radiotelephone cell 130 over the satellite radiotelephone uplink frequency, denoted f′U, which may be the same as fU. Thus, as illustrated in FIG. 1, radiotelephone 120 a may be communicating with the space-based component 110 while radiotelephone 120 b may be communicating with the ancillary terrestrial component 140. As shown in FIG. 1, the space-based component 110 also undesirably receives the wireless communications from the second radiotelephone 120 b in the satellite radiotelephone cell 130 over the satellite radiotelephone frequency f′U as interference. More specifically, a potential interference path is shown at 150. In this potential interference path 150, the return link signal of the second radiotelephone 120 b at carrier frequency f′U interferes with satellite communications. This interference would generally be strongest when f′U=fU, because, in that case, the same return link frequency would be used for space-based component and ancillary terrestrial component communications over the same satellite radiotelephone cell, and no spatial discrimination between satellite radiotelephone cells would appear to exist.
  • Still referring to FIG. 1, embodiments of satellite radiotelephone systems/methods 100 can include at least one gateway 160 that can include an antenna 160 a and an electronics system 160 b that can be connected to other networks 162 including terrestrial and/or other radiotelephone networks. The gateway 160 also communicates with the space-based component 110 over a satellite feeder link 112. The gateway 160 also communicates with the ancillary terrestrial component 140, generally over a terrestrial link 142.
  • Still referring to FIG. 1, an Interference Reducer (IR) 170 a also may be provided at least partially in the ancillary terrestrial component electronics system 140 b. Alternatively or additionally, an interference reducer 170 b may be provided at least partially in the gateway electronics system 160 b. In yet other alternatives, the interference reducer may be provided at least partially in other components of the cellular satellite system/method 100 instead of or in addition to the interference reducer 170 a and/or 170 b. The interference reducer is responsive to the space-based component 110 and to the ancillary terrestrial component 140, and is configured to reduce the interference from the wireless communications that are received by the space-based component 110 and is at least partially generated by the second radiotelephone 120 b in the satellite radiotelephone cell 130 over the satellite radiotelephone frequency f′U. The interference reducer 170 a and/or 170 b uses the wireless communications f′U that are intended for the ancillary terrestrial component 140 from the second radiotelephone 120 b in the satellite radiotelephone cell 130 using the satellite radiotelephone frequency f′U to communicate with the ancillary terrestrial component 140.
  • In embodiments of the invention, as shown in FIG. 1, the ancillary terrestrial component 140 generally is closer to the first and second radiotelephones 120 a and 120 b, respectively, than is the space-based component 110, such that the wireless communications from the second radiotelephone 120 b are received by the ancillary terrestrial component 140 prior to being received by the space-based component 110. The interference reducer 170 a and/or 170 b is configured to generate an interference cancellation signal comprising, for example, at least one delayed replica of the wireless communications from the second radiotelephone 120 b that are received by the ancillary terrestrial component 140, and to subtract the delayed replica of the wireless communications from the second radiotelephone 120 b that are received by the ancillary terrestrial component 140 from the wireless communications that are received from the space-based component 110. The interference reduction signal may be transmitted from the ancillary terrestrial component 140 to the gateway 160 over link 142 and/or using other conventional techniques.
  • Thus, adaptive interference reduction techniques may be used to at least partially cancel the interfering signal, so that the same, or other nearby, satellite radiotelephone uplink frequency can be used in a given cell for communications by radiotelephones 120 with the satellite 110 and with the ancillary terrestrial component 140. Accordingly, all frequencies that are assigned to a given cell 130 may be used for both radiotelephone 120 communications with the space-based component 110 and with the ancillary terrestrial component 140. Conventional systems may avoid terrestrial reuse of frequencies within a given satellite cell that are being used within the satellite cell for satellite communications. Stated differently, conventionally, only frequencies used by other satellite cells may be candidates for terrestrial reuse within a given satellite cell. Beam-to-beam spatial isolation that is provided by the satellite system was relied upon to reduce or minimize the level of interference from the terrestrial operations into the satellite operations. In sharp contrast, embodiments of the invention can use an interference reducer to allow all frequencies assigned to a satellite cell to be used terrestrially and for satellite radiotelephone communications.
  • Embodiments of the invention according to FIG. 1 may arise from a realization that the return link signal from the second radiotelephone 120 b at f′U generally will be received and processed by the ancillary terrestrial component 140 much earlier relative to the time when it will arrive at the satellite gateway 160 from the space-based component 110 via the interference path 150. Accordingly, the interference signal at the satellite gateway 160 b can be at least partially canceled. Thus, as shown in FIG. 1, an interference cancellation signal, such as the demodulated ancillary terrestrial component signal, can be sent to the satellite gateway 160 b by the interference reducer 170 a in the ancillary terrestrial component 140, for example using link 142. In the interference reducer 170 b at the gateway 160 b, a weighted (in amplitude and/or phase) replica of the signal may be formed using, for example, adaptive transversal filter techniques that are well known to those having skill in the art. Then, a transversal filter output signal is subtracted from the aggregate received satellite signal at frequency f′U that contains desired as well as interference signals. Thus, the interference cancellation need not degrade the signal-to-noise ratio of the desired signal at the gateway 160, because a regenerated (noise-free) terrestrial signal, for example as regenerated by the ancillary terrestrial component 140, can be used to perform interference suppression.
  • FIG. 2 is a block diagram of embodiments of adaptive interference cancellers that may be located in the ancillary terrestrial component 140, in the gateway 160, and/or in another component of the cellular radiotelephone system 100. As shown in FIG. 2, one or more control algorithms 204, known to those having skill in the art, may be used to adaptively adjust the coefficients of a plurality of transversal filters 202 a-202 n. Adaptive algorithms, such as Least Mean Square Error (LMSE), Kalman, Fast Kalman, Zero Forcing and/or various combinations thereof or other techniques may be used. It will be understood by those having skill in the art that the architecture of FIG. 2 may be used with an LMSE algorithm. However, it also will be understood by those having skill in the art that conventional architectural modifications may be made to facilitate other control algorithms.
  • Additional embodiments of the invention now will be described with reference to FIG. 3, which illustrates L-band frequency allocations including cellular radiotelephone system forward links and return links. As shown in FIG. 3, the space-to-ground L-band forward link (downlink) frequencies are assigned from 1525 MHz to 1559 MHz. The ground-to-space L-band return link (uplink) frequencies occupy the band from 1626.5 MHz to 1660.5 MHz. Between the forward and return L-band links lie the GPS/GLONASS radionavigation band (from 1559 MHz to 1605 MHz).
  • In the detailed description to follow, GPS/GLONASS will be referred to simply as GPS for the sake of brevity. Moreover, the acronyms ATC and SBC will be used for the ancillary terrestrial component and the space-based component, respectively, for the sake of brevity.
  • As is known to those skilled in the art, GPS receivers may be extremely sensitive since they are designed to operate on very weak spread-spectrum radionavigation signals that arrive on the earth from a GPS satellite constellation. As a result, GPS receivers may to be highly susceptible to in-band interference. ATCs that are configured to radiate L-band frequencies in the forward satellite band (1525 to 1559 MHz) can be designed with very sharp out-of-band emissions filters to satisfy the stringent out-of-band spurious emissions desires of GPS.
  • Referring again to FIG. 1, some embodiments of the invention can provide systems and methods that can allow an ATC 140 to configure itself in one of at least two modes. In accordance with a first mode, which may be a standard mode and may provide highest capacity, the ATC 140 transmits to the radiotelephones 120 over the frequency range from 1525 MHz to 1559 MHz, and receives transmissions from the radiotelephones 120 in the frequency range from 1626.5 MHz to 1660.5 MHz, as illustrated in FIG. 3. In contrast, in a second mode of operation, the ATC 140 transmits wireless communications to the radiotelephones 120 over a modified range of satellite band forward link (downlink) frequencies. The modified range of satellite band forward link frequencies may be selected to reduce, compared to the unmodified range of satellite band forward link frequencies, interference with wireless receivers such as GPS receivers that operate outside the range of satellite band forward link frequencies.
  • Many modified ranges of satellite band forward link frequencies may be provided according to embodiments of the present invention. In some embodiments, the modified range of satellite band forward link frequencies can be limited to a subset of the original range of satellite band forward link frequencies, so as to provide a guard band of unused satellite band forward link frequencies. In other embodiments, all of the satellite band forward link frequencies are used, but the wireless communications to the radiotelephones are modified in a manner to reduce interference with wireless receivers that operate outside the range of satellite band forward link frequencies. Combinations and subcombinations of these and/or other techniques also may be used, as will be described below.
  • It also will be understood that embodiments of the invention that will now be described in connection with FIGS. 4-12 will be described in terms of multiple mode ATCs 140 that can operate in a first standard mode using the standard forward and return links of FIG. 3, and in a second or alternate mode that uses a modified range of satellite band forward link frequencies and/or a modified range of satellite band return link frequencies. These multiple mode ATCs can operate in the second, non-standard mode, as long as desirable, and can be switched to standard mode otherwise. However, other embodiments of the present invention need not provide multiple mode ATCs but, rather, can provide ATCs that operate using the modified range of satellite band forward link and/or return link frequencies.
  • Embodiments of the invention now will be described, wherein an ATC operates with an SBC that is configured to receive wireless communications from radiotelephones over a first range of satellite band return link frequencies and to transmit wireless communications to the radiotelephones over a second range of satellite band forward link frequencies that is spaced apart from the first range. According to these embodiments, the ATC is configured to use at least one time division duplex frequency to transmit wireless communications to the radiotelephones and to receive wireless communications from the radiotelephones at different times. In particular, in some embodiments, the at least one time division duplex frequency that is used to transmit wireless communications to the radiotelephones and to receive wireless communications from the radiotelephones at different times, comprises a frame including a plurality of slots. At least a first one of the slots is used to transmit wireless communications to the radiotelephones and at least a second one of the slots is used to receive wireless communications from the radiotelephones. Thus, in some embodiments, the ATC transmits and receives, in Time Division Duplex (TDD) mode, using frequencies from 1626.5 MHz to 1660.5 MHz. In some embodiments, all ATCs across the entire network may have the stated configuration/reconfiguration flexibility. In other embodiments, only some ATCs may be reconfigurable.
  • FIG. 4 illustrates satellite systems and methods 400 according to some embodiments of the invention, including an ATC 140 communicating with a radiotelephone 120 b using a carrier frequency f′U in TDD mode. FIG. 5 illustrates an embodiment of a TDD frame structure. Assuming full-rate GSM (eight time slots per frame), up to four full-duplex voice circuits can be supported by one TDD carrier. As shown in FIG. 5, the ATC 140 transmits to the radiotelephone 120 b over, for example, time slot number 0. The radiotelephone 120 b receives and replies back to the ATC 140 over, for example, time slot number 4. Time slots number 1 and 5 may be used to establish communications with another radiotelephone, and so on.
  • A Broadcast Control CHannel (BCCH) is preferably transmitted from the ATC 140 in standard mode, using a carrier frequency from below any guard band exclusion region. In other embodiments, a BCCH also can be defined using a TDD carrier. In any of these embodiments, radiotelephones in idle mode can, per established GSM methodology, monitor the BCCH and receive system-level and paging information. When a radiotelephone is paged, the system decides what type of resource to allocate to the radiotelephone in order to establish the communications link. Whatever type of resource is allocated for the radiotelephone communications channel (TDD mode or standard mode), the information is communicated to the radiotelephone, for example as part of the call initialization routine, and the radiotelephone configures itself appropriately.
  • It may be difficult for the TDD mode to co-exist with the standard mode over the same ATC, due, for example, to the ATC receiver LNA stage. In particular, assuming a mixture of standard and TDD mode GSM carriers over the same ATC, during the part of the frame when the TDD carriers are used to serve the forward link (when the ATC is transmitting TDD) enough energy may leak into the receiver front end of the same ATC to desensitize its LNA stage.
  • Techniques can be used to suppress the transmitted ATC energy over the 1600 MHz portion of the band from desensitizing the ATC's receiver LNA, and thereby allow mixed standard mode and TDD frames. For example, isolation between outbound and inbound ATC front ends and/or antenna system return loss may be increased or maximized. A switchable band-reject filter may be placed in front of the LNA stage. This filter would be switched in the receiver chain (prior to the LNA) during the part of the frame when the ATC is transmitting TDD, and switched out during the rest of the time. An adaptive interference canceller can be configured at RF (prior to the LNA stage). If such techniques are used, suppression of the order of 70 dB can be attained, which may allow mixed standard mode and TDD frames. However, the ATC complexity and/or cost may increase.
  • Thus, even though ATC LNA desensitization may be reduced or eliminated, it may use significant special engineering and attention and may not be economically worth the effort. Other embodiments, therefore, may keep TDD ATCs pure TDD, with the exception, perhaps, of the BCCH carrier which may not be used for traffic but only for broadcasting over the first part of the frame, consistent with TDD protocol. Moreover, Random Access CHannel (RACH) bursts may be timed so that they arrive at the ATC during the second half of the TDD frame. In some embodiments, all TDD ATCs may be equipped to enable reconfiguration in response to a command.
  • It is well recognized that during data communications or other applications, the forward link may use transmissions at higher rates than the return link. For example, in web browsing with a radiotelephone, mouse clicks and/or other user selections typically are transmitted from the radiotelephone to the system. The system, however, in response to a user selection, may have to send large data files to the radiotelephone. Hence, other embodiments of the invention may be configured to enable use of an increased or maximum number of time slots per forward GSM carrier frame, to provide a higher downlink data rate to the radiotelephones.
  • Thus, when a carrier frequency is configured to provide service in TDD mode, a decision may be made as to how many slots will be allocated to serving the forward link, and how many will be dedicated to the return link. Whatever the decision is, it may be desirable that it be adhered to by all TDD carriers used by the ATC, in order to reduce or avoid the LNA desensitization problem described earlier. In voice communications, the partition between forward and return link slots may be made in the middle of the frame as voice activity typically is statistically bidirectionally symmetrical. Hence, driven by voice, the center of the frame may be where the TDD partition is drawn.
  • To increase or maximize forward link throughput in data mode, data mode TDD carriers according to embodiments of the invention may use a more spectrally efficient modulation and/or protocol, such as the EDGE modulation and/or protocol, on the forward link slots. The return link slots may be based on a less spectrally efficient modulation and/or protocol such as the GPRS (GMSK) modulation and/or protocol. The EDGE modulation/protocol and the GPRS modulation/protocol are well known to those having skill in the art, and need not be described further herein. Given an EDGE forward/GPRS return TDD carrier strategy, up to (384/2)=192 kbps may be supported on the forward link while on the return link the radiotelephone may transmit at up to (115/2)≈64 kbps.
  • In other embodiments, it also is possible to allocate six time slots of an eight-slot frame for the forward link and only two for the return link. In these embodiments, for voice services, given the statistically symmetric nature of voice, the return link vocoder may need to be comparable with quarter-rate GSM, while the forward link vocoder can operate at full-rate GSM, to yield six full-duplex voice circuits per GSM TDD-mode carrier (a voice capacity penalty of 25%). Subject to this non-symmetrical partitioning strategy, data rates of up to (384)(6/8)=288 kbps may be achieved on the forward link, with up to (115)(2/8)≈32 kbps on the return link.
  • FIG. 6 depicts an ATC architecture according to embodiments of the invention, which can lend itself to automatic configuration between the two modes of standard GSM and TDD GSM on command, for example, from a Network Operations Center (NOC) via a Base Station Controller (BSC). It will be understood that in these embodiments, an antenna 620 can correspond to the antenna 140 a of FIGS. 1 and 4, and the remainder of FIG. 6 can correspond to the electronics system 140 b of FIGS. 1 and 4. If a reconfiguration command for a particular carrier, or set of carriers, occurs while the carrier(s) are active and are supporting traffic, then, via the in-band signaling Fast Associated Control CHannel (FACCH), all affected radiotelephones may be notified to also reconfigure themselves and/or switch over to new resources. If carrier(s) are reconfigured from TDD mode to standard mode, automatic reassignment of the carrier(s) to the appropriate standard-mode ATCs, based, for example, on capacity demand and/or reuse pattern can be initiated by the NOC. If, on the other hand, carrier(s) are reconfigured from standard mode to TDD mode, automatic reassignment to the appropriate TDD-mode ATCs can take place on command from the NOC.
  • Still referring to FIG. 6, a switch 610 may remain closed when carriers are to be demodulated in the standard mode. In TDD mode, this switch 610 may be open during the first half of the frame, when the ATC is transmitting, and closed during the second half of the frame, when the ATC is receiving. Other embodiments also may be provided.
  • FIG. 6 assumes N transceivers per ATC sector, where N can be as small as one, since a minimum of one carrier per sector generally is desired. Each transceiver is assumed to operate over one GSM carrier pair (when in standard mode) and can thus support up to eight full-duplex voice circuits, neglecting BCCH channel overhead. Moreover, a standard GSM carrier pair can support sixteen full-duplex voice circuits when in half-rate GSM mode, and up to thirty two full-duplex voice circuits when in quarter-rate GSM mode.
  • When in TDD mode, the number of full duplex voice circuits may be reduced by a factor of two, assuming the same vocoder. However, in TDD mode, voice service can be offered via the half-rate GSM vocoder with almost imperceptible quality degradation, in order to maintain invariant voice capacity. FIG. 7 is a block diagram of a reconfigurable radiotelephone architecture that can communicate with a reconfigurable ATC architecture of FIG. 6. In FIG. 7, an antenna 720 is provided, and the remainder of FIG. 7 can provide embodiments of an electronics system for the radiotelephone.
  • It will be understood that the ability to reconfigure ATCs and radiotelephones according to embodiments of the invention may be obtained at a relatively small increase in cost. The cost may be mostly in Non-Recurring Engineering (NRE) cost to develop software. Some recurring cost may also be incurred, however, in that at least an additional RF filter and a few electronically controlled switches may be used per ATC and radiotelephone. All other hardware/software can be common to standard-mode and TDD-mode GSM.
  • Referring now to FIG. 8, other radiotelephone systems and methods according to embodiments of the invention now will be described. In these embodiments, the modified second range of satellite band forward link frequencies includes a plurality of frequencies in the second range of satellite band forward link frequencies that are transmitted by the ATCs to the radiotelephones at a power level, such as maximum power level, that monotonically decreases as a function of (increasing) frequency. More specifically, as will be described below, in some embodiments, the modified second range of satellite band forward link frequencies includes a subset of frequencies proximate to a first or second end of the range of satellite band forward link frequencies that are transmitted by the ATC to the radiotelephones at a power level, such as a maximum power level, that monotonically decreases toward the first or second end of the second range of satellite band forward link frequencies. In still other embodiments, the first range of satellite band return link frequencies is contained in an L-band of satellite frequencies above GPS frequencies and the second range of satellite band forward link frequencies is contained in the L-band of satellite frequencies below the GPS frequencies. The modified second range of satellite band forward link frequencies includes a subset of frequencies proximate to an end of the second range of satellite band forward link frequencies adjacent the GPS frequencies that are transmitted by the ATC to the radiotelephones at a power level, such as a maximum power level, that monotonically decreases toward the end of the second range of satellite band forward link frequencies adjacent the GPS frequencies.
  • Without being bound by any theory of operation, a theoretical discussion of the mapping of ATC maximum power levels to carrier frequencies according to embodiments of the present invention now will be described. Referring to FIG. 8, let ν=
    Figure US20080268836A1-20081030-P00001
    (ρ) represent a mapping from the power (ρ) domain to the frequency (ν) range. The power (ρ) is the power that an ATC uses or should transmit in order to reliably communicate with a given radiotelephone. This power may depend on many factors such as the radiotelephone's distance from the ATC, the blockage between the radiotelephone and the ATC, the level of multipath fading in the channel, etc., and as a result, will, in general, change as a function of time. Hence, the power used generally is determined adaptively (iteratively) via closed-loop power control, between the radiotelephone and ATC.
  • The frequency (ν) is the satellite carrier frequency that the ATC uses to communicate with the radiotelephone. According to embodiments of the invention, the mapping
    Figure US20080268836A1-20081030-P00001
    is a monotonically decreasing function of the independent variable ρ. Consequently, in some embodiments, as the maximum ATC power increases, the carrier frequency that the ATC uses to establish and/or maintain the communications link decreases. FIG. 8 illustrates an embodiment of a piece-wise continuous monotonically decreasing (stair-case) function. Other monotonic functions may be used, including linear and/or nonlinear, constant and/or variable decreases. FACCH or Slow Associated Control CHannel (SACCH) messaging may be used in embodiments of the invention to facilitate the mapping adaptively and in substantially real time.
  • FIG. 9 depicts an ideal cell according to embodiments of the invention, where, for illustration purposes, three power regions and three associated carrier frequencies (or carrier frequency sets) are being used to partition a cell. For simplicity, one ATC transmitter at the center of the idealized cell is assumed with no sectorization. In embodiments of FIG. 9, the frequency (or frequency set) f1 is taken from substantially the upper-most portion of the L-band forward link frequency set, for example from substantially close to 1559 MHz (see FIG. 3). Correspondingly, the frequency (or frequency set) fM is taken from substantially the central portion of the L-band forward link frequency set (see FIG. 3). In concert with the above, the frequency (or frequency set) fO is taken from substantially the lowest portion of the L-band forward link frequencies, for example close to 1525 MHz (see FIG. 3).
  • Thus, according to embodiments of FIG. 9, if a radiotelephone is being served within the outer-most ring of the cell, that radiotelephone is being served via frequency fO. This radiotelephone, being within the furthest area from the ATC, has (presumably) requested maximum (or near maximum) power output from the ATC. In response to the maximum (or near maximum) output power request, the ATC uses its a priori knowledge of power-to-frequency mapping, such as a three-step staircase function of FIG. 9. Thus, the ATC serves the radiotelephone with a low-value frequency taken from the lowest portion of the mobile L-band forward link frequency set, for example, from as close to 1525 MHz as possible. This, then, can provide additional safeguard to any GPS receiver unit that may be in the vicinity of the ATC.
  • Embodiments of FIG. 9 may be regarded as idealized because they associate concentric ring areas with carrier frequencies (or carrier frequency sets) used by an ATC to serve its area. In reality, concentric ring areas generally will not be the case. For example, a radiotelephone can be close to the ATC that is serving it, but with significant blockage between the radiotelephone and the ATC due to a building. This radiotelephone, even though relatively close to the ATC, may also request maximum (or near maximum) output power from the ATC. With this in mind, FIG. 10 may depict a more realistic set of area contours that may be associated with the frequencies being used by the ATC to serve its territory, according to embodiments of the invention. The frequency (or frequency set) f1 may be reused in the immediately adjacent ATC cells owing to the limited geographical span associated with f1 relative to the distance between cell centers. This may also hold for fM.
  • Referring now to FIG. 11, other modified second ranges of satellite band forward link frequencies that can be used by ATCs according to embodiments of the present invention now will be described. In these embodiments, at least one frequency in the modified second range of satellite band forward link frequencies that is transmitted by the ATC to the radiotelephones comprises a frame including a plurality of slots. In these embodiments, at least two contiguous slots in the frame that is transmitted by the ATC to the radiotelephones are left unoccupied. In other embodiments, three contiguous slots in the frame that is transmitted by the ATC to the radiotelephones are left unoccupied. In yet other embodiments, at least two contiguous slots in the frame that is transmitted by the ATC to the radiotelephones are transmitted at lower power than remaining slots in the frame. In still other embodiments, three contiguous slots in the frame that is transmitted by the ATC to the radiotelephones are transmitted at lower power than remaining slots in the frame. In yet other embodiments, the lower power slots may be used with first selected ones of the radiotelephones that are relatively close to the ATC and/or are experiencing relatively small signal blockage, and the remaining slots are transmitted at higher power to second selected ones of the radiotelephones that are relatively far from the ATC and/or are experiencing relatively high signal blockage.
  • Stated differently, in accordance with some embodiments of the invention, only a portion of the TDMA frame is utilized. For example, only the first four (or last four, or any contiguous four) time slots of a full-rate GSM frame are used to support traffic. The remaining slots are left unoccupied (empty). In these embodiments, capacity may be lost. However, as has been described previously, for voice services, half-rate and even quarter-rate GSM may be invoked to gain capacity back, with some potential degradation in voice quality. The slots that are not utilized preferably are contiguous, such as slots 0 through 3 or 4 through 7 (or 2 through 5, etc.). The use of non-contiguous slots such as 0, 2, 4, and 6, for example, may be less desirable. FIG. 11 illustrates four slots (4-7) being used and four contiguous slots (0-3) being empty in a GSM frame.
  • It has been found experimentally, according to these embodiments of the invention, that GPS receivers can perform significantly better when the interval between interference bursts is increased or maximized. Without being bound by any theory of operation, this effect may be due to the relationship between the code repetition period of the GPS C/A code (1 msec.) and the GSM burst duration (about 0.577 msec.). With a GSM frame occupancy comprising alternate slots, each GPS signal code period can experience at least one “hit”, whereas a GSM frame occupancy comprising four to five contiguous slots allows the GPS receiver to derive sufficient clean information so as to “flywheel” through the error events.
  • According to other embodiments of the invention, embodiments of FIGS. 8-10 can be combined with embodiments of FIG. 11. Furthermore, according to other embodiments of the invention, if an f1 carrier of FIG. 9 or 10 is underutilized, because of the relatively small footprint of the inner-most region of the cell, it may be used to support additional traffic over the much larger outermost region of the cell.
  • Thus, for example, assume that only the first four slots in each frame of f1 are being used for inner region traffic. In embodiments of FIGS. 8-10, these four f1 slots are carrying relatively low power bursts, for example of the order of 100 mW or less, and may, therefore, appear as (almost) unoccupied from an interference point of view. Loading the remaining four (contiguous) time slots of f1 with relatively high-power bursts may have negligible effect on a GPS receiver because the GPS receiver would continue to operate reliably based on the benign contiguous time interval occupied by the four low-power GSM bursts. FIG. 12 illustrates embodiments of a frame at carrier f1 supporting four low-power (inner interval) users and four high-power (outer interval) users. In fact, embodiments illustrated in FIG. 12 may be a preferred strategy for the set of available carrier frequencies that are closest to the GPS band. These embodiments may avoid undue capacity loss by more fully loading the carrier frequencies.
  • The experimental finding that interference from GSM carriers can be relatively benign to GPS receivers provided that no more than, for example, 5 slots per 8 slot GSM frame are used in a contiguous fashion can be very useful. It can be particularly useful since this experimental finding may hold even when the GSM carrier frequency is brought very close to the GPS band (as close as 1558.5 MHz) and the power level is set relatively high. For example, with five contiguous time slots per frame populated, the worst-case measured GPS receiver may attain at least 30 dB of desensitization margin, over the entire ATC service area, even when the ATC is radiating at 1558.5 MHz. With four contiguous time slots per frame populated, an additional 10 dB desensitization margin may be gained for a total of 40 dB for the worst-case measured GPS receiver, even when the ATC is radiating at 1558.5 MHz.
  • There still may be concern about the potential loss in network capacity (especially in data mode) that may be incurred over the frequency interval where embodiments of FIG. 11 are used to underpopulate the frame. Moreover, even though embodiments of FIG. 12 can avoid capacity loss by fully loading the carrier, they may do so subject to the constraint of filling up the frame with both low-power and high-power users. Moreover, if forward link carriers are limited to 5 contiguous high power slots per frame, the maximum forward link data rate per carrier that may be aimed at a particular user, may become proportionately less.
  • Therefore, in other embodiments, carriers which are subject to contiguous empty/low power slots are not used for the forward link. Instead, they are used for the return link. Consequently, in some embodiments, at least part of the ATC is configured in reverse frequency mode compared to the SBC in order to allow maximum data rates over the forward link throughout the entire network. On the reverse frequency return link, a radiotelephone may be limited to a maximum of 5 slots per frame, which can be adequate for the return link. Whether the five available time slots per frame, on a reverse frequency return link carrier, are assigned to one radiotelephone or to five different radiotelephones, they can be assigned contiguously in these embodiments. As was described in connection with FIG. 12, these five contiguous slots can be assigned to high-power users while the remaining three slots may be used to serve low-power users.
  • Other embodiments may be based on operating the ATC entirely in reverse frequency mode compared to the SBC. In these embodiments, an ATC transmits over the satellite return link frequencies while radiotelephones respond over the satellite forward link frequencies. If sufficient contiguous spectrum exists to support CDMA technologies, and in particular the emerging Wideband-CDMA 3G standard, the ATC forward link can be based on Wideband-CDMA to increase or maximize data throughput capabilities. Interference with GPS may not be an issue since the ATCs transmit over the satellite return link in these embodiments. Instead, interference may become a concern for the radiotelephones. Based, however, on embodiments of FIGS. 11-12, the radiotelephones can be configured to transmit GSM since ATC return link rates are expected, in any event, to be lower than those of the forward link. Accordingly, the ATC return link may employ GPRS-based data modes, possibly even EDGE. Thus, return link carriers that fall within a predetermined frequency interval from the GPS band-edge of 1559 MHz, can be under loaded, per embodiments of FIG. 11 or 12, to satisfy GPS interference concerns.
  • Finally, other embodiments may use a partial or total reverse frequency mode and may use CDMA on both forward and return links. In these embodiments, the ATC forward link to the radiotelephones utilizes the frequencies of the satellite return link (1626.5 MHz to 1660.5 MHz) whereas the ATC return link from the radiotelephones uses the frequencies of the satellite forward link (1525 MHz to 1559 MHz). The ATC forward link can be based on an existing or developing CDMA technology (e.g., IS-95, Wideband-CDMA, etc.). The ATC network return link can also be based on an existing or developing CDMA technology provided that the radiotelephone's output is gated to cease transmissions for approximately 3 msec once every T msec. In some embodiments, T will be greater than or equal to 6 msec.
  • This gating may not be needed for ATC return link carriers at approximately 1550 MHz or below. This gating can reduce or minimize out-of-band interference (desensitization) effects for GPS receivers in the vicinity of an ATC. To increase the benefit to GPS, the gating between all radiotelephones over an entire ATC service area can be substantially synchronized. Additional benefit to GPS may be derived from system-wide synchronization of gating. The ATCs can instruct all active radiotelephones regarding the gating epoch. All ATCs can be mutually synchronized via GPS.
  • Space-Based Network (SBN) Architectures
  • As was described above, some embodiments of the present invention may employ a Space-Based Network (SBN) and an Ancillary Terrestrial Network (ATN) that both communicate with a plurality of radiotelephones using satellite radiotelephone frequencies. The SBN may include one or more Space-Based Components (SBC) and one or more satellite gateways. The ATN may include a plurality of Ancillary Terrestrial Components (ATC). In some embodiments, the SBN and the ATN may operate at L-band (1525-1559 MHz forward service link, and 1626.5-1660.5 MHz return service link). Moreover, in some embodiments, the radiotelephones may be similar to conventional handheld cellular/PCS-type terminals that are capable of voice and/or packet data services. In some embodiments, terrestrial reuse of at least some of the mobile satellite frequency spectrum can allow the SBN to serve low density areas that may be impractical and/or uneconomical to serve via conventional terrestrial networks, while allowing the ATN to serve pockets of densely populated areas that may only be effectively served terrestrially. The radiotelephones can be attractive, feature-rich and/or low cost, similar to conventional cellular/PCS-type terminals that are offered by terrestrial-only operators. Moreover, by operating the SBN and ATN modes over the same frequency band, component count in the radiotelephones, for example in the front end radio frequency (RF) section, may be reduced. In particular, in some embodiments, the same frequency synthesizer, RF filters, low noise amplifiers, power amplifiers and antenna elements may be used for terrestrial and satellite communications.
  • Some embodiments of space-based network architectures according to embodiments of the present invention can offer significant link margin over and above the clear sky conditions, represented by an Additive White Gaussian Noise (AWGN) channel, without the need to undesirably burden the radiotelephones themselves to achieve this link margin. In some embodiments, the SBN may employ relatively large reflectors, for example on the order of about 24 meters in diameter, that can produce relatively small, high gain, agile spot beams. Digital processors in the space-based component and/or at the satellite gateways can be used to improve or optimize performance with respect to each individual user.
  • In general, space-based networks for a satellite radiotelephone system according to some embodiments of the invention include at least one receive-only satellite and at least one transmit satellite. In some embodiments, the transmit satellite is a transmit-only satellite, whereas in other embodiments, the transmit satellite is a transmit and receive satellite. It will be understood that the terms “receive” and “transmit” are used relative to ground based radiotelephones and that a receive-only satellite and a transmit-only satellite also may transmit to and receive from a gateway or other ground station. The at least one receive-only satellite is configured to receive wireless communications from a radiotelephone at a predetermined location over a satellite frequency band. The at least one transmit satellite is configured to transmit wireless communications to the radiotelephone at the predetermined location over the satellite frequency band. By providing at least one receive-only satellite, link margins may be improved compared to the use of a conventional transmit and receive satellite of comparable antenna sizes, according to some embodiments of the present invention. Accordingly, some embodiments of the invention provide a space-based network for a satellite radiotelephone system that comprises more receive satellites than transmit satellites.
  • FIG. 13 conceptually illustrates space-based network architectures according to some embodiments of the present invention. As shown in FIG. 13, at least one transmit-only (TX-only) satellite 1310 and at least one receive-only (RX-only) satellite 1320 a, 1320 b, are used to communicate with radiotelephones such as the radiotelephone 1330. As also shown in FIG. 13, a space-based network according to some embodiments of the invention may include a single TX-only satellite 1310 and first and second RX- only satellites 1320 a, 1320 b, also referred to as RX-only satellite 1 and RX-only satellite 2, respectively. Finally, as also shown in FIG. 13, in some embodiments of the present invention, the first RX-only satellite 1320 a may be co-located with the TX-only satellite 1310, and the second RX-only satellite 1320 b may be located at a different orbital slot.
  • Referring again to FIG. 13, in some embodiments, each RX-only satellite antenna 1340 a-1340 d may be approximately 24 meters in diameter. This can provide a return link aggregate space-based aperture with an equivalent diameter of about 40 meters. The RX-only satellite antennas 1340 a-1340 d may be of same size or different sizes. This relatively large, effective return link aperture may be used to allow the SBN to accommodate a relatively low Effective Isotropic Radiated Power (EIRP) on the radiotelephones 1330, for example about −6 dBW.
  • The TX-only satellite 1310 may contain an on-board digital processor that can perform various functions, such as feeder-link channelization, filtering, beam routing and/or digital beam forming. Such functions have already been implemented in the Thuraya satellite that is currently providing service in the Middle East, and are well known to those having skill in the art. These functions therefore need not be described in further detail herein.
  • Referring again to FIG. 13, in some embodiments of the present invention, each receive antenna 1340 a-1340 d of each RX- only satellite 1320 a, 1320 b receives Left-Hand Circular Polarization (LHCP) energy and Right-Hand Circular Polarization (RHCP) energy. This may be received, since the radiotelephone 1330 may radiate linearly polarized energy, which contains half of its energy in LHCP and the remaining half in RHCP.
  • In some embodiments, each RX- only satellite 1320 a, 1320 b may contain up to four digital processors. In each satellite 1320 a or 1320 b, a first digital processor may be configured to operate on the aggregate signal received by the first antenna, for example antenna 1340 a or 1340 c, in LHCP, and perform the functions of signal channelization, filtering, beam forming and/or routing of signals to the feeder link. A second processor may be configured to perform the identical functions as the first, but on the RHCP signal received by the first antenna, such as antenna 1340 a or 1340 c. The remaining two processors may be configured to repeat these functions on the RHCP and LHCP signals of the second RX-only antenna, such as antenna 1340 b or 1340 d. All eight sets of received signals, from both RX- only satellites 1320 a and 1320 b, may be sent via one or more feeder links to one or more gateways for combining, as will now be described.
  • FIG. 14 is a block diagram of portions of the space-based network that illustrates how the signals from the RX-only satellite 1 1320 a and RX-only satellite 2 1320 b may be combined according to some embodiments of the present invention. Embodiments of FIG. 14 assume that the available feeder link bandwidth, from an RX- only satellite 1320 a, 1320 b to a gateway is X MHz, but that Y MHz is desired to transport the signals to the gateway, where Y is greater than X.
  • As shown in FIG. 14, a first X MHz of LHCP signal spectrum 1410 a, received from RX-only satellite 1, antenna 1 1340 a via the first processor, and a first corresponding X MHz of RHCP signal spectrum 1410 b also received by RX-only satellite 1, antenna 1 1340 a via the second processor, are mapped into in-phase (I) and quadrature (Q) dimensions of a first carrier. In other embodiments, the X MHz of signal spectrum that is mapped into the I and Q dimensions of the carrier need not be an RHCP signal received by satellite 1, antenna 1. Instead, it may be a corresponding X MHz of signal spectrum (LHCP or RHCP) from satellite 1, antenna 2 1340 b. In some embodiments, any appropriate mapping of signals from the RX-only satellite antennas 1340 a-1340 b may be used, for example, by utilizing as many orthogonal polarizations and/or dimensions as possible, over the same available feeder bandwidth, so as to reduce or minimize the number of gateways or diversity sites that are used on the ground to transport the desired signals for processing thereof.
  • Returning again to FIG. 14, the X MHz bandwidth quadrature carrier may be transported to a first gateway 1440 a over the X MHz of available feeder link bandwidth using a vertically (V) polarized orientation. Concurrently, a first X MHz of LHCP signal spectrum 1410 c from RX-only satellite 1, antenna 2 1340 b via the third processor, and a first RHCP signal spectrum 1410 d from RX-only satellite 1, antenna 2 1340 b via the fourth processor, are mapped onto the I and Q dimensions of a second carrier, at the same frequency as the first carrier, and are concurrently transported to the first gateway 1440 a over the X MHz of available feeder link bandwidth using a horizontally (H) polarized orientation. The transmission medium is indicated schematically by summing node 1430 to indicate a concurrence of the horizontally and vertically polarized signals in the transmission medium.
  • This mapping onto X MHz bandwidth carriers in the I and Q dimensions may be repeated up to n times, as shown in FIG. 14 by the summing nodes 1420 a, 1420 b, in order to transmit the entire signal bandwidth received by the RX-only satellite 1320 a corresponding to all satellite cells of each polarization (LHCP and RHCP) of each antenna. Accordingly, the processors and summing nodes 1420 a, 1420 b, along with other conventional components such as frequency translators, phase shifters, and/or filters, may comprise a feeder link signal generator according to some embodiments of the invention, which is configured to combine signals that are received by the first and second receive only antennas 1340 a, 1340 b into the feeder link signal 1490 that is transmitted on at least one carrier in a plurality of orthogonal dimensions.
  • Still referring to FIG. 14, similar operations may take place with respect to the second RX-only satellite 1320 b. This mapping only is shown generally in FIG. 14 at 1450, for the sake of clarity. A plurality of gateways 1440 a-1440 n may be provided to spatially reuse the same available feeder link spectrum, up to n times in FIG. 14, and thus transport all the satellite receive signals to the ground, for demodulation and combining. Thus, the gateways 1440 a-1440 n can function as frequency reuse sites, as well as providing for diversity combining according to some embodiments of the present invention, as will be described below. It will be understood that if Y is less than or equal to X, only one gateway location 1440 may need to be used. Moreover, it also will be understood that other polarization schemes may be used at the various stages of FIG. 14, instead of the LHCP/RHCP and/or V/H polarization.
  • Demodulation and combining of the received signals for each user, according to some embodiments of the present invention, now will be described. In particular, in some embodiments, a given user signal will reach the ground via the plurality of polarizations (LHCP and RHCP) of each satellite antenna, via the plurality of satellite antennas 1340 a-1340 d of each RX- only satellite 1320 a, 1320 b, and via the plurality of RX- only satellites 1320 a, 1320 b. Furthermore, a plurality of satellite beams (cells) of each polarization, of each antenna, and of each RX-only satellite, may be contributing a desired signal component relative to the given user, particularly when the user is geographically close to the intersection of two or more of the satellite beams. Thus, embodiments of demodulation and combining may include processing of multiple signal components that are received by the various RX-only satellite antennas 1340 a-1340 d from a given radiotelephone 1330, in order to reconstruct the wireless communications from the radiotelephone.
  • In one example, up to three cells may be receiving useful signal contributions in a seven-cell frequency reuse plan. Moreover, in embodiments of FIGS. 13 and 14, there are two polarizations per cell, two antennas per satellite, and a total of two RX-only satellites. Thus, there may be 3×2×2×2 or 24 signal components per user that may be combined in some embodiments. In some embodiments, each of the plurality of signal components may be weighted in accordance with, for example, a least mean squared error performance index, and then summed, for example, in a combiner such as an optimum combiner 1460, to yield the received signal output S, shown in FIG. 14. A receiver decision stage 1470 then may be used to generate symbol estimates Ŝ.
  • Finally, as was described above, in transporting a plurality of X MHz signal segments to the ground, each gateway site 1440 a-1440 n may also receive interference between the I and Q dimensions (also referred to as cross-rail interference) and/or cross-polarization interference between the vertical and horizontal polarizations, for example due to the non-ideal passband characteristics of the channel and/or the system.
  • In order to reduce or minimize these interferences, some known symbols may be transmitted over at least some of the orthogonal dimensions that were described above, to enable an adaptive receiver at a gateway site, to compensate at least in part for any such effect. In other embodiments, precompensation may be performed for the channel and/or system non-ideal passband characteristics at the satellite, prior to transmission over a feeder link. When using precompensation, error information may be sent back to the satellite from a processing gateway site.
  • In still other embodiments, the overhead of the known symbols, as was described above, may be avoided by relying on the decisions of the receiver. However, the reliability of the receiver's demodulation process may be increased by transporting the known symbols. Moreover, the overhead due to a known symbol sequence can be small, since the feeder link channel generally is quasi-static.
  • FIG. 15 conceptually illustrates space-based network architectures according to other embodiments of the present invention. As shown in FIG. 15, these embodiments of the present invention include at least one receive-only satellite and at least one transmit and receive satellite. In particular, in some embodiments, a first receive-only satellite 1510 a and a first transmit and receive satellite 1520 a are co-located, for example at orbital slot 101° W. A second receive-only satellite 1510 b and a second transmit and receive satellite 1520 b also are co-located, for example at orbital slot 107.3° W.
  • Moreover, in still other embodiments of the invention, as also illustrated in FIG. 15, the transmit and receive satellites 1520 a, 1520 b can each include a respective first antenna 1540 a, 1540 c that is configured as a receive-only antenna, and a respective second antenna 1540 b, 1540 d that is configured to perform both transmit and receive functions. In still other embodiments of the invention, the second antenna 1540 b, 1540 d may be configured to perform transmit-only functions. In yet other embodiments, the first antenna 1540 a, 1540 c also may be configured to perform transmit and receive functions. In all embodiments, the antennas may be of same and/or different sizes.
  • Embodiments of FIG. 15 also can be used to obtain a relatively high return link (uplink) margin. For example, a comparison will be made relative to the Thuraya satellite. It will now be shown that a return link margin of approximately 13 dB higher may be obtained using space-based architectures according to some embodiments of the present invention.
  • In particular, assuming a single satellite with a single 24 meter diameter antenna, about 4 dB of additional margin may practically be obtained relative to the Thuraya 12 meter antenna. However, as shown in FIG. 15, if the satellite 1520 a has two receive antennas 1540 a, 1540 b, the return link margin may be increased by an additional 3 dB, for a total of 7 dB over Thuraya, assuming that both antennas 1540 a, 1540 b on the satellite 1520 a are of the same size and that combining of their outputs is performed. Thus, using only a single satellite 1520 a of FIG. 15, with one dual purpose 24 meter transmit and receive antenna 1540 b, and one receive-only 24 meter antenna 1540 a, embodiments of the present invention can obtain 7 dB more return link margin than may be obtained in the Thuraya system.
  • The addition of the first receive-only satellite 1510 a can add 3 dB more to the above link margin, since it includes two additional 24 meter receive-only L band antennas. Finally, satellites 1520 b and 1510 b can add 3 dB more to the above, for a total of 13 dB over and above that which may be obtained with Thuraya without even having considered diversity gains.
  • As was described above in connection with FIG. 14, each satellite receive antenna may be assumed to be receiving both RHCP and LHCP. The polarizations may be combined in a manner similar to that described in FIG. 14.
  • In the drawings and specification, there have been disclosed embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.

Claims (130)

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48. A space-based network for a satellite radiotelephone system comprising a first number of antennas each of which is configured to receive information and a second number of antennas each of which is configured to transmit information, wherein the first number of antennas equals or exceeds the second number of antennas, at least one antenna of the first number of antennas is configured to receive information from a radiotelephone over at least two substantially orthogonal polarizations and the radiotelephone is configured to radiate electromagnetic energy substantially concurrently over each one of the least two substantially orthogonal polarizations and to radiate substantially the same information over each one of the at least two substantially orthogonal polarizations.
49. A space-based network according to claim 48 further comprising:
a gateway that is configured to process at least two signals associated respectively with at least two antennas of the first number of antennas in order to recover information transmitted to the space-based network by a radiotelephone.
50. A space-based network according to claim 48 further comprising:
a gateway that is configured to process at least two signals associated respectively with the at least two substantially orthogonal polarizations in order to recover information transmitted to the space-based network by a radiotelephone.
51. An antenna for a space-based network, the antenna comprising:
a plurality of elements configured to receive information from a radiotelephone over at least two substantially orthogonal polarizations, wherein the radiotelephone is configured to transmit information to the antenna via at least one direct Line-of-Sight (LOS) wireless link between the radiotelephone and the antenna and the radiotelephone is further configured to radiate electromagnetic energy substantially concurrently over each one of the at least two substantially orthogonal polarizations and to radiate substantially the same information over each one of the at least two substantially orthogonal polarizations.
52. An antenna according to claim 51 further comprising:
an electronics subsystem that is configured to receive signals from the antenna and to transmit signals to a gateway that is configured to process signals associated respectively with the at least two substantially orthogonal polarizations in order to recover information transmitted to the space-based network by the radiotelephone.
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US32224001P 2001-09-14 2001-09-14
US10/074,097 US6684057B2 (en) 2001-09-14 2002-02-12 Systems and methods for terrestrial reuse of cellular satellite frequency spectrum
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US10/225,623 US7006789B2 (en) 2001-09-14 2002-08-22 Space-based network architectures for satellite radiotelephone systems
US11/241,519 US7437123B2 (en) 2001-09-14 2005-09-30 Space-based network architectures for satellite radiotelephone systems
US11/560,226 US20070072545A1 (en) 2001-09-14 2006-11-15 Space-Based Network Architectures for Satellite Radiotelephone Systems
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Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7783287B2 (en) 2001-09-14 2010-08-24 Atc Technologies, Llc Satellite radiotelephone systems, methods, components and devices including gated radiotelephone transmissions to ancillary terrestrial components
US7792488B2 (en) 2000-12-04 2010-09-07 Atc Technologies, Llc Systems and methods for transmitting electromagnetic energy over a wireless channel having sufficiently weak measured signal strength
US7796985B2 (en) 2002-05-28 2010-09-14 Atc Technologies, Llc Systems and methods for packing/unpacking satellite service links to/from satellite feeder links
US7890050B2 (en) 2005-03-15 2011-02-15 Atc Technologies, Llc Methods of reducing interference including determination of feeder link signal error and related systems
US7890097B2 (en) 2001-09-14 2011-02-15 Atc Technologies, Llc Systems and methods for monitoring selected terrestrially used satellite frequency signals to reduce potential interference
US7899002B2 (en) 2005-01-27 2011-03-01 Atc Technologies, Llc Satellite/terrestrial wireless communications systems and methods using disparate channel separation codes
US7917135B2 (en) 2005-07-29 2011-03-29 Atc Technologies, Llc Satellite communications apparatus and methods using asymmetrical forward and return link frequency reuse
US7953373B2 (en) 2004-12-16 2011-05-31 Atc Technologies, Llc Prediction of uplink interference potential generated by an ancillary terrestrial network and/or radioterminals
US7957694B2 (en) 2004-08-11 2011-06-07 Atc Technologies, Llc Satellite-band spectrum utilization for reduced or minimum interference
US7974619B2 (en) 2003-09-23 2011-07-05 Atc Technologies, Llc Systems and methods for mobility management in overlaid mobile communications systems
US7978135B2 (en) 2008-02-15 2011-07-12 Atc Technologies, Llc Antenna beam forming systems/methods using unconstrained phase response
US7999735B2 (en) 2005-04-04 2011-08-16 Atc Technologies, Llc Radioterminals and associated operating methods that transmit position information responsive to rate of change of position
US8023954B2 (en) 2001-09-14 2011-09-20 Atc Technologies, Llc Systems and methods for controlling a cellular communications system responsive to a power level associated with a wireless transmitter
US8045975B2 (en) 2003-09-11 2011-10-25 Atc Technologies, Llc Systems and methods for inter-system sharing of satellite communications frequencies within a common footprint
US8055257B2 (en) 2004-04-12 2011-11-08 Atc Technologies, Llc Systems and methods with different utilization of satellite frequency bands by a space-based network and an ancillary terrestrial network
US8068828B2 (en) 2001-09-14 2011-11-29 Atc Technologies, Llc Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex mode
US8078101B2 (en) 2001-09-14 2011-12-13 Atc Technologies, Llc Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex and/or frequency-division duplex mode
US8169955B2 (en) 2006-06-19 2012-05-01 Atc Technologies, Llc Systems and methods for orthogonal frequency division multiple access (OFDMA) communications over satellite links
US20120131618A1 (en) * 2009-05-20 2012-05-24 Donald Lester Content broadcast
US8193975B2 (en) 2008-11-12 2012-06-05 Atc Technologies Iterative antenna beam forming systems/methods
US8238818B2 (en) 2004-05-18 2012-08-07 Atc Technologies, Llc Satellite communications systems and methods using radiotelephone location-based beamforming
US8265637B2 (en) 2000-08-02 2012-09-11 Atc Technologies, Llc Systems and methods for modifying antenna radiation patterns of peripheral base stations of a terrestrial network to allow reduced interference
US8270898B2 (en) 2001-09-14 2012-09-18 Atc Technologies, Llc Satellite-band spectrum utilization for reduced or minimum interference
US8274925B2 (en) 2010-01-05 2012-09-25 Atc Technologies, Llc Retaining traffic channel assignments for satellite terminals to provide lower latency communication services
US8285225B2 (en) 2004-12-07 2012-10-09 Atc Technologies, Llc Broadband wireless communications systems and methods using multiple non-contiguous frequency bands/segments
US8340592B2 (en) 2003-03-24 2012-12-25 Atc Technologies, Llc Radioterminals and operating methods that receive multiple measures of information from multiple sources
US8339308B2 (en) 2009-03-16 2012-12-25 Atc Technologies Llc Antenna beam forming systems, methods and devices using phase adjusted least squares beam forming
US8369776B2 (en) 2004-11-02 2013-02-05 Atc Technologies, Llc Apparatus and methods for power control in satellite communications systems with satellite-linked terrestrial stations
US8369775B2 (en) 2000-08-02 2013-02-05 Atc Technologies, Llc Integrated or autonomous system and method of satellite-terrestrial frequency reuse using signal attenuation and/or blockage, dynamic assignment of frequencies and/or hysteresis
US8412126B2 (en) 2005-06-21 2013-04-02 Atc Technologies, Llc Communications systems including adaptive antenna systems and methods for inter-system and intra-system interference reduction
US8433241B2 (en) 2008-08-06 2013-04-30 Atc Technologies, Llc Systems, methods and devices for overlaid operations of satellite and terrestrial wireless communications systems
US8520561B2 (en) 2009-06-09 2013-08-27 Atc Technologies, Llc Systems, methods and network components that provide different satellite spot beam return carrier groupings and reuse patterns
US8576769B2 (en) 2009-09-28 2013-11-05 Atc Technologies, Llc Systems and methods for adaptive interference cancellation beamforming
US8655398B2 (en) 2004-03-08 2014-02-18 Atc Technologies, Llc Communications systems and methods including emission detection
US8744360B2 (en) 2005-01-05 2014-06-03 Atc Technologies, Inc. Adaptive beam forming with multi-user detection and interference reduction in satellite communication systems and methods
US10110288B2 (en) 2009-11-04 2018-10-23 Atc Technologies, Llc Frequency division duplex (FDD) return link transmit diversity systems, methods and devices using forward link side information

Families Citing this family (80)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7714778B2 (en) * 1997-08-20 2010-05-11 Tracbeam Llc Wireless location gateway and applications therefor
US7174127B2 (en) 1999-08-10 2007-02-06 Atc Technologies, Llc Data communications systems and methods using different wireless links for inbound and outbound data
US20030149986A1 (en) * 1999-08-10 2003-08-07 Mayfield William W. Security system for defeating satellite television piracy
US7558568B2 (en) * 2003-07-28 2009-07-07 Atc Technologies, Llc Systems and methods for modifying antenna radiation patterns of peripheral base stations of a terrestrial network to allow reduced interference
CA2381811C (en) * 2000-08-02 2007-01-30 Mobile Satellite Ventures Lp Coordinated satellite-terrestrial frequency reuse
US7792069B2 (en) 2001-09-14 2010-09-07 Atc Technologies, Llc Systems and methods for terrestrial reuse of cellular satellite frequency spectrum using different channel separation technologies in forward and reverse links
US7603081B2 (en) * 2001-09-14 2009-10-13 Atc Technologies, Llc Radiotelephones and operating methods that use a single radio frequency chain and a single baseband processor for space-based and terrestrial communications
US7890098B2 (en) * 2001-09-14 2011-02-15 Atc Technologies, Llc Staggered sectorization for terrestrial reuse of satellite frequencies
US7181161B2 (en) * 2001-09-14 2007-02-20 Atc Technologies, Llc Multi-band/multi-mode satellite radiotelephone communications systems and methods
US6785543B2 (en) 2001-09-14 2004-08-31 Mobile Satellite Ventures, Lp Filters for combined radiotelephone/GPS terminals
US7218931B2 (en) * 2001-09-14 2007-05-15 Atc Technologies, Llc Satellite radiotelephone systems providing staggered sectorization for terrestrial reuse of satellite frequencies and related methods and radiotelephone systems
US7006789B2 (en) * 2001-09-14 2006-02-28 Atc Technologies, Llc Space-based network architectures for satellite radiotelephone systems
US7155340B2 (en) * 2001-09-14 2006-12-26 Atc Technologies, Llc Network-assisted global positioning systems, methods and terminals including doppler shift and code phase estimates
US7062267B2 (en) * 2001-09-14 2006-06-13 Atc Technologies, Llc Methods and systems for modifying satellite antenna cell patterns in response to terrestrial reuse of satellite frequencies
US7623859B2 (en) * 2001-09-14 2009-11-24 Atc Technologies, Llc Additional aggregate radiated power control for multi-band/multi-mode satellite radiotelephone communications systems and methods
US6999720B2 (en) * 2001-09-14 2006-02-14 Atc Technologies, Llc Spatial guardbands for terrestrial reuse of satellite frequencies
US7593691B2 (en) * 2002-02-12 2009-09-22 Atc Technologies, Llc Systems and methods for controlling a level of interference to a wireless receiver responsive to a power level associated with a wireless transmitter
US6856787B2 (en) 2002-02-12 2005-02-15 Mobile Satellite Ventures, Lp Wireless communications systems and methods using satellite-linked remote terminal interface subsystems
US7092708B2 (en) * 2002-12-12 2006-08-15 Atc Technologies, Llc Systems and methods for increasing capacity and/or quality of service of terrestrial cellular and satellite systems using terrestrial reception of satellite band frequencies
US7421342B2 (en) * 2003-01-09 2008-09-02 Atc Technologies, Llc Network-assisted global positioning systems, methods and terminals including doppler shift and code phase estimates
US7444170B2 (en) * 2003-03-24 2008-10-28 Atc Technologies, Llc Co-channel wireless communication methods and systems using nonsymmetrical alphabets
US6879829B2 (en) * 2003-05-16 2005-04-12 Mobile Satellite Ventures, Lp Systems and methods for handover between space based and terrestrial radioterminal communications, and for monitoring terrestrially reused satellite frequencies at a radioterminal to reduce potential interference
US20040240525A1 (en) * 2003-05-29 2004-12-02 Karabinis Peter D. Wireless communications methods and apparatus using licensed-use system protocols with unlicensed-use access points
US7340213B2 (en) * 2003-07-30 2008-03-04 Atc Technologies, Llc Intra- and/or inter-system interference reducing systems and methods for satellite communications systems
US8670705B2 (en) * 2003-07-30 2014-03-11 Atc Technologies, Llc Additional intra-and/or inter-system interference reducing systems and methods for satellite communications systems
US20050041619A1 (en) * 2003-08-22 2005-02-24 Karabinis Peter D. Wireless systems, methods and devices employing forward- and/or return-link carriers having different numbers of sub-band carriers
US8380186B2 (en) * 2004-01-22 2013-02-19 Atc Technologies, Llc Satellite with different size service link antennas and radioterminal communication methods using same
US7418236B2 (en) * 2004-04-20 2008-08-26 Mobile Satellite Ventures, Lp Extraterrestrial communications systems and methods including ancillary extraterrestrial components
US7453920B2 (en) 2004-03-09 2008-11-18 Atc Technologies, Llc Code synchronization in CDMA satellite wireless communications system using uplink channel detection
US7933552B2 (en) * 2004-03-22 2011-04-26 Atc Technologies, Llc Multi-band satellite and/or ancillary terrestrial component radioterminal communications systems and methods with combining operation
US7606590B2 (en) 2004-04-07 2009-10-20 Atc Technologies, Llc Satellite/hands-free interlock systems and/or companion devices for radioterminals and related methods
US20050239399A1 (en) * 2004-04-21 2005-10-27 Karabinis Peter D Mobile terminals and set top boxes including multiple satellite band service links, and related systems and methods
US20050260984A1 (en) * 2004-05-21 2005-11-24 Mobile Satellite Ventures, Lp Systems and methods for space-based use of terrestrial cellular frequency spectrum
WO2006012348A2 (en) * 2004-06-25 2006-02-02 Atc Technologies, Llc Method and system for frequency translation on-board a communications satellite
US20060094420A1 (en) * 2004-11-02 2006-05-04 Karabinis Peter D Multi frequency band/multi air interface/multi spectrum reuse cluster size/multi cell size satellite radioterminal communicaitons systems and methods
AU2005307841B2 (en) 2004-11-16 2010-03-25 Atc Technologies, Llc Satellite communications systems, components and methods for operating shared satellite gateways
US7747229B2 (en) * 2004-11-19 2010-06-29 Atc Technologies, Llc Electronic antenna beam steering using ancillary receivers and related methods
US7636546B2 (en) * 2005-02-22 2009-12-22 Atc Technologies, Llc Satellite communications systems and methods using diverse polarizations
US7738837B2 (en) * 2005-02-22 2010-06-15 Atc Technologies, Llc Satellites using inter-satellite links to create indirect feeder link paths
EP1851877A2 (en) * 2005-02-22 2007-11-07 ATC Technologies, LLC Reusing frequencies of a fixed and/or mobile communications system
US7756490B2 (en) * 2005-03-08 2010-07-13 Atc Technologies, Llc Methods, radioterminals, and ancillary terrestrial components for communicating using spectrum allocated to another satellite operator
US7796986B2 (en) * 2005-03-11 2010-09-14 Atc Technologies, Llc Modification of transmission values to compensate for interference in a satellite down-link communications
US7627285B2 (en) * 2005-03-14 2009-12-01 Atc Technologies, Llc Satellite communications systems and methods with distributed and/or centralized architecture including ground-based beam forming
WO2006099501A1 (en) * 2005-03-15 2006-09-21 Atc Technologies, Llc Methods and systems providing adaptive feeder links for ground based beam forming and related systems and satellites
US7970345B2 (en) * 2005-06-22 2011-06-28 Atc Technologies, Llc Systems and methods of waveform and/or information splitting for wireless transmission of information to one or more radioterminals over a plurality of transmission paths and/or system elements
US7907944B2 (en) * 2005-07-05 2011-03-15 Atc Technologies, Llc Methods, apparatus and computer program products for joint decoding of access probes in a CDMA communications system
US8190114B2 (en) * 2005-07-20 2012-05-29 Atc Technologies, Llc Frequency-dependent filtering for wireless communications transmitters
US7461756B2 (en) * 2005-08-08 2008-12-09 Plastipak Packaging, Inc. Plastic container having a freestanding, self-supporting base
US7831202B2 (en) * 2005-08-09 2010-11-09 Atc Technologies, Llc Satellite communications systems and methods using substantially co-located feeder link antennas
US20070082648A1 (en) * 2005-10-06 2007-04-12 Staccato Communications, Inc. Powering down inphase or quadrature related components
US7636067B2 (en) * 2005-10-12 2009-12-22 The Directv Group, Inc. Ka/Ku antenna alignment
US20070123252A1 (en) * 2005-10-12 2007-05-31 Atc Technologies, Llc Systems, methods and computer program products for mobility management in hybrid satellite/terrestrial wireless communications systems
WO2007084681A1 (en) * 2006-01-20 2007-07-26 Atc Technologies, Llc Systems and methods for satellite forward link transmit diversity using orthogonal space coding
US8705436B2 (en) * 2006-02-15 2014-04-22 Atc Technologies, Llc Adaptive spotbeam broadcasting, systems, methods and devices for high bandwidth content distribution over satellite
US7729657B1 (en) * 2006-04-12 2010-06-01 Abel Avellan Noise reduction system and method thereof
US8238817B1 (en) * 2006-04-12 2012-08-07 Emc Satcom Technologies, Llc Noise reduction system and method thereof
US8923850B2 (en) 2006-04-13 2014-12-30 Atc Technologies, Llc Systems and methods for controlling base station sectors to reduce potential interference with low elevation satellites
US7751823B2 (en) * 2006-04-13 2010-07-06 Atc Technologies, Llc Systems and methods for controlling a level of interference to a wireless receiver responsive to an activity factor associated with a wireless transmitter
US9014619B2 (en) 2006-05-30 2015-04-21 Atc Technologies, Llc Methods and systems for satellite communications employing ground-based beam forming with spatially distributed hybrid matrix amplifiers
WO2008027109A2 (en) * 2006-06-29 2008-03-06 Atc Technologies, Llc Apparatus and methods for mobility management in hybrid terrestrial-satellite mobile communications systems
US10142013B2 (en) * 2006-12-20 2018-11-27 The Boeing Company Method of optimizing an interplanetary communications network
US7978142B2 (en) * 2007-01-09 2011-07-12 The Directv Group, Inc. ODU alignment procedure using circularly polarized squint
US8044872B2 (en) * 2007-01-09 2011-10-25 The Directv Group, Inc. ODU alignment procedure using circularly polarized signals allocated to specific satellites
US7706787B2 (en) * 2007-03-21 2010-04-27 Com Dev International Ltd. Multi-beam communication system and method
US8031646B2 (en) * 2007-05-15 2011-10-04 Atc Technologies, Llc Systems, methods and devices for reusing spectrum of another operator
US20080311022A1 (en) * 2007-06-14 2008-12-18 Battelle Energy Alliance, Llc Methods and apparatuses for ammonia production
US8064824B2 (en) * 2007-07-03 2011-11-22 Atc Technologies, Llc Systems and methods for reducing power robbing impact of interference to a satellite
FR2928794A1 (en) * 2008-03-17 2009-09-18 Eutelsat Sa TELECOMMUNICATION NETWORK
US7522877B1 (en) * 2008-08-01 2009-04-21 Emc Satcom Technologies, Inc. Noise reduction system and method thereof
US8451171B1 (en) 2008-08-05 2013-05-28 The Directv Group, Inc. Tool to automatically align outdoor unit
US8134512B1 (en) 2008-11-12 2012-03-13 The Directv Group, Inc. Antenna peak strength finder
US8634760B2 (en) 2010-07-30 2014-01-21 Donald C. D. Chang Polarization re-alignment for mobile terminals via electronic process
US8862050B2 (en) 2010-07-30 2014-10-14 Spatial Digital Systems, Inc. Polarization diversity with portable devices via wavefront muxing techniques
US8571499B1 (en) * 2010-10-12 2013-10-29 Harold Kirkpatrick Wireless terrestrial communications systems using a line-of-sight frequency for inbound data and a non-line-of-sight frequency for outbound data
US9490893B2 (en) * 2013-09-26 2016-11-08 The Boeing Company Interference suppression in a satellite communication system using onboard beamforming and ground-based processing
USD910608S1 (en) 2018-05-09 2021-02-16 Darpan Tandon Smartphone
US10560562B1 (en) 2018-05-09 2020-02-11 Darpan Tandon Multi-mode smartphone or mobile computing device
CN111835396B (en) * 2019-04-18 2022-03-29 华为技术有限公司 Method and device for processing data packet
US11533103B2 (en) * 2021-01-07 2022-12-20 Hughes Network Systems, Llc Compensation for attenuation of carrier power by a transmission path
EP4231546A1 (en) 2022-02-16 2023-08-23 Nokia Solutions and Networks Oy Hybrid mimo over multiple multi-antenna satellites

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5691727A (en) * 1995-01-03 1997-11-25 State Of Israel-Ministry Of Defense Armament Development Authority-Rafael Adaptive polarization diversity system
US6032041A (en) * 1997-06-02 2000-02-29 Hughes Electronics Corporation Method and system for providing wideband communications to mobile users in a satellite-based network
US6226493B1 (en) * 1996-05-31 2001-05-01 Motorola, Inc. Geosynchronous satellite communication system and method
US6823170B1 (en) * 2000-07-26 2004-11-23 Ericsson Inc. Satellite communications system using multiple earth stations

Family Cites Families (104)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5303286A (en) * 1991-03-29 1994-04-12 Space Systems/Loral, Inc. Wireless telephone/satellite roaming system
JPS6218841A (en) * 1985-07-18 1987-01-27 Nec Corp Satellite repeating communication system
US4901307A (en) 1986-10-17 1990-02-13 Qualcomm, Inc. Spread spectrum multiple access communication system using satellite or terrestrial repeaters
US5327572A (en) 1990-03-06 1994-07-05 Motorola, Inc. Networked satellite and terrestrial cellular radiotelephone systems
US5878329A (en) * 1990-03-19 1999-03-02 Celsat America, Inc. Power control of an integrated cellular communications system
US5446756A (en) * 1990-03-19 1995-08-29 Celsat America, Inc. Integrated cellular communications system
US5073900A (en) * 1990-03-19 1991-12-17 Mallinckrodt Albert J Integrated cellular communications system
US5835857A (en) * 1990-03-19 1998-11-10 Celsat America, Inc. Position determination for reducing unauthorized use of a communication system
US5526404A (en) 1991-10-10 1996-06-11 Space Systems/Loral, Inc. Worldwide satellite telephone system and a network coordinating gateway for allocating satellite and terrestrial gateway resources
US6067442A (en) 1991-10-10 2000-05-23 Globalstar L.P. Satellite communications system having distributed user assignment and resource assignment with terrestrial gateways
US5233626A (en) * 1992-05-11 1993-08-03 Space Systems/Loral Inc. Repeater diversity spread spectrum communication system
CA2118355C (en) * 1993-11-30 2002-12-10 Michael James Gans Orthogonal polarization and time varying offsetting of signals for digital data transmission or reception
US6157811A (en) 1994-01-11 2000-12-05 Ericsson Inc. Cellular/satellite communications system with improved frequency re-use
US5619503A (en) 1994-01-11 1997-04-08 Ericsson Inc. Cellular/satellite communications system with improved frequency re-use
US5511233A (en) * 1994-04-05 1996-04-23 Celsat America, Inc. System and method for mobile communications in coexistence with established communications systems
WO1995034153A1 (en) 1994-06-08 1995-12-14 Hughes Aircraft Company Apparatus and method for hybrid network access
GB2321831B (en) * 1994-07-22 1999-02-17 Int Mobile Satellite Org Satellite communication method and apparatus
US5584046A (en) 1994-11-04 1996-12-10 Cornell Research Foundation, Inc. Method and apparatus for spectrum sharing between satellite and terrestrial communication services using temporal and spatial synchronization
FR2729025B1 (en) 1995-01-02 1997-03-21 Europ Agence Spatiale METHOD AND SYSTEM FOR TRANSMITTING RADIO SIGNALS VIA A SATELLITE NETWORK BETWEEN A FIXED EARTH STATION AND MOBILE USER TERMINALS
US5608722A (en) * 1995-04-03 1997-03-04 Qualcomm Incorporated Multi-user communication system architecture with distributed receivers
AU700251B2 (en) * 1995-06-06 1998-12-24 Globalstar L.P. Satellite repeater diversity resource management system
US5619525A (en) 1995-06-06 1997-04-08 Globalstar L.P. Closed loop power control for low earth orbit satellite communications system
US6240124B1 (en) 1995-06-06 2001-05-29 Globalstar L.P. Closed loop power control for low earth orbit satellite communications system
JPH0992717A (en) * 1995-09-21 1997-04-04 Mitsubishi Electric Corp Semiconductor and fabrication thereof
US5991345A (en) * 1995-09-22 1999-11-23 Qualcomm Incorporated Method and apparatus for diversity enhancement using pseudo-multipath signals
US6449461B1 (en) * 1996-07-15 2002-09-10 Celsat America, Inc. System for mobile communications in coexistence with communication systems having priority
US5926758A (en) 1996-08-26 1999-07-20 Leo One Ip, L.L.C. Radio frequency sharing methods for satellite systems
US6072768A (en) 1996-09-04 2000-06-06 Globalstar L.P. Automatic satellite/terrestrial mobile terminal roaming system and method
GB2317074B (en) 1996-09-09 1998-10-28 I Co Global Communications Communications apparatus and method
GB2317303B (en) 1996-09-09 1998-08-26 I Co Global Communications Communications apparatus and method
US5761605A (en) * 1996-10-11 1998-06-02 Northpoint Technology, Ltd. Apparatus and method for reusing satellite broadcast spectrum for terrestrially broadcast signals
US6064859A (en) * 1996-11-04 2000-05-16 Motorola, Inc. Transmit and receive payload pair and method for use in communication systems
US5896558A (en) 1996-12-19 1999-04-20 Globalstar L.P. Interactive fixed and mobile satellite network
US6091933A (en) 1997-01-03 2000-07-18 Globalstar L.P. Multiple satellite system power allocation by communication link optimization
JPH10256974A (en) * 1997-03-14 1998-09-25 Mitsubishi Electric Corp Satellite communication system for mobile object
JPH10261987A (en) 1997-03-19 1998-09-29 Fujitsu Ltd Two-layer constitution satellite communication system and its geostationary satellite
US5937332A (en) * 1997-03-21 1999-08-10 Ericsson, Inc. Satellite telecommunications repeaters and retransmission methods
EP0869628A1 (en) 1997-04-01 1998-10-07 ICO Services Ltd. Interworking between telecommunications networks
GB2324218A (en) 1997-04-09 1998-10-14 Ico Services Ltd Satellite acquisition in navigation system
US5884142A (en) 1997-04-15 1999-03-16 Globalstar L.P. Low earth orbit distributed gateway communication system
US6134437A (en) 1997-06-13 2000-10-17 Ericsson Inc. Dual-mode satellite/cellular phone architecture with physically separable mode
US6011951A (en) 1997-08-22 2000-01-04 Teledesic Llc Technique for sharing radio frequency spectrum in multiple satellite communication systems
US6085094A (en) 1997-08-29 2000-07-04 Nortel Networks Corporation Method for optimizing spectral re-use
US6052586A (en) 1997-08-29 2000-04-18 Ericsson Inc. Fixed and mobile satellite radiotelephone systems and methods with capacity sharing
US5907541A (en) 1997-09-17 1999-05-25 Lockheed Martin Corp. Architecture for an integrated mobile and fixed telecommunications system including a spacecraft
US6101385A (en) * 1997-10-09 2000-08-08 Globalstar L.P. Satellite communication service with non-congruent sub-beam coverage
US6052560A (en) 1997-10-15 2000-04-18 Ericsson Inc Satellite system utilizing a plurality of air interface standards and method employing same
US6173155B1 (en) * 1997-10-17 2001-01-09 Hughes Electronics Corporation Method and apparatus for spacecraft amplification of multi-channel signals
US6157834A (en) 1997-12-29 2000-12-05 Motorola, Inc. Terrestrial and satellite cellular network interoperability
US6418147B1 (en) 1998-01-21 2002-07-09 Globalstar Lp Multiple vocoder mobile satellite telephone system
US6735437B2 (en) * 1998-06-26 2004-05-11 Hughes Electronics Corporation Communication system employing reuse of satellite spectrum for terrestrial communication
JP3999900B2 (en) * 1998-09-10 2007-10-31 株式会社東芝 Nonvolatile semiconductor memory
US6775251B1 (en) 1998-09-17 2004-08-10 Globalstar L.P. Satellite communication system providing multi-gateway diversity and improved satellite loading
US6198730B1 (en) 1998-10-13 2001-03-06 Motorola, Inc. Systems and method for use in a dual mode satellite communications system
US6198921B1 (en) 1998-11-16 2001-03-06 Emil Youssefzadeh Method and system for providing rural subscriber telephony service using an integrated satellite/cell system
US6424831B1 (en) * 1999-03-30 2002-07-23 Qualcomm, Inc. Apparatus and method for paging a user terminal in a satellite communication system
US6317420B1 (en) * 1999-06-25 2001-11-13 Qualcomm Inc. Feeder link spatial multiplexing in a satellite communication system
US6253080B1 (en) 1999-07-08 2001-06-26 Globalstar L.P. Low earth orbit distributed gateway communication system
US7174127B2 (en) * 1999-08-10 2007-02-06 Atc Technologies, Llc Data communications systems and methods using different wireless links for inbound and outbound data
US20030149986A1 (en) * 1999-08-10 2003-08-07 Mayfield William W. Security system for defeating satellite television piracy
US6522865B1 (en) * 1999-08-10 2003-02-18 David D. Otten Hybrid satellite communications system
GB2365677A (en) 2000-02-29 2002-02-20 Ico Services Ltd Satellite communications with satellite routing according to channels assignment
US6526278B1 (en) * 2000-03-03 2003-02-25 Motorola, Inc. Mobile satellite communication system utilizing polarization diversity combining
US20040203393A1 (en) 2002-03-13 2004-10-14 Xiang Chen System and method for offsetting channel spectrum to reduce interference between two communication networks
US6675013B1 (en) * 2000-06-26 2004-01-06 Motorola, Inc. Doppler correction and path loss compensation for airborne cellular system
US6859652B2 (en) 2000-08-02 2005-02-22 Mobile Satellite Ventures, Lp Integrated or autonomous system and method of satellite-terrestrial frequency reuse using signal attenuation and/or blockage, dynamic assignment of frequencies and/or hysteresis
US7558568B2 (en) 2003-07-28 2009-07-07 Atc Technologies, Llc Systems and methods for modifying antenna radiation patterns of peripheral base stations of a terrestrial network to allow reduced interference
CA2381811C (en) 2000-08-02 2007-01-30 Mobile Satellite Ventures Lp Coordinated satellite-terrestrial frequency reuse
US6628919B1 (en) 2000-08-09 2003-09-30 Hughes Electronics Corporation Low-cost multi-mission broadband communications payload
US20030003815A1 (en) 2000-12-20 2003-01-02 Yoshiko Yamada Communication satellite/land circuits selection communications system
US6950625B2 (en) 2001-02-12 2005-09-27 Ico Services Limited Communications apparatus and method
US6714760B2 (en) 2001-05-10 2004-03-30 Qualcomm Incorporated Multi-mode satellite and terrestrial communication device
US7155340B2 (en) 2001-09-14 2006-12-26 Atc Technologies, Llc Network-assisted global positioning systems, methods and terminals including doppler shift and code phase estimates
US6785543B2 (en) 2001-09-14 2004-08-31 Mobile Satellite Ventures, Lp Filters for combined radiotelephone/GPS terminals
US7218931B2 (en) 2001-09-14 2007-05-15 Atc Technologies, Llc Satellite radiotelephone systems providing staggered sectorization for terrestrial reuse of satellite frequencies and related methods and radiotelephone systems
US7039400B2 (en) 2001-09-14 2006-05-02 Atc Technologies, Llc Systems and methods for monitoring terrestrially reused satellite frequencies to reduce potential interference
US7181161B2 (en) 2001-09-14 2007-02-20 Atc Technologies, Llc Multi-band/multi-mode satellite radiotelephone communications systems and methods
US7006789B2 (en) 2001-09-14 2006-02-28 Atc Technologies, Llc Space-based network architectures for satellite radiotelephone systems
US6999720B2 (en) * 2001-09-14 2006-02-14 Atc Technologies, Llc Spatial guardbands for terrestrial reuse of satellite frequencies
US7062267B2 (en) 2001-09-14 2006-06-13 Atc Technologies, Llc Methods and systems for modifying satellite antenna cell patterns in response to terrestrial reuse of satellite frequencies
US7664460B2 (en) 2001-09-14 2010-02-16 Atc Technologies, Llc Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex and/or frequency-division duplex mode
US7447501B2 (en) * 2001-09-14 2008-11-04 Atc Technologies, Llc Systems and methods for monitoring selected terrestrially used satellite frequency signals to reduce potential interference
US7113778B2 (en) 2001-09-14 2006-09-26 Atc Technologies, Llc Aggregate radiated power control for multi-band/multi-mode satellite radiotelephone communications systems and methods
US6684057B2 (en) 2001-09-14 2004-01-27 Mobile Satellite Ventures, Lp Systems and methods for terrestrial reuse of cellular satellite frequency spectrum
US7031702B2 (en) 2001-09-14 2006-04-18 Atc Technologies, Llc Additional systems and methods for monitoring terrestrially reused satellite frequencies to reduce potential interference
US7593724B2 (en) 2001-09-14 2009-09-22 Atc Technologies, Llc Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex mode
US6856787B2 (en) 2002-02-12 2005-02-15 Mobile Satellite Ventures, Lp Wireless communications systems and methods using satellite-linked remote terminal interface subsystems
US6937857B2 (en) 2002-05-28 2005-08-30 Mobile Satellite Ventures, Lp Systems and methods for reducing satellite feeder link bandwidth/carriers in cellular satellite systems
US8121605B2 (en) 2002-06-27 2012-02-21 Globalstar, Inc. Resource allocation to terrestrial and satellite services
US7068975B2 (en) 2002-11-26 2006-06-27 The Directv Group, Inc. Systems and methods for sharing uplink bandwidth among satellites in a common orbital slot
US7092708B2 (en) 2002-12-12 2006-08-15 Atc Technologies, Llc Systems and methods for increasing capacity and/or quality of service of terrestrial cellular and satellite systems using terrestrial reception of satellite band frequencies
US6975837B1 (en) 2003-01-21 2005-12-13 The Directv Group, Inc. Method and apparatus for reducing interference between terrestrially-based and space-based broadcast systems
US7444170B2 (en) 2003-03-24 2008-10-28 Atc Technologies, Llc Co-channel wireless communication methods and systems using nonsymmetrical alphabets
US7203490B2 (en) 2003-03-24 2007-04-10 Atc Technologies, Llc Satellite assisted push-to-send radioterminal systems and methods
US6879829B2 (en) * 2003-05-16 2005-04-12 Mobile Satellite Ventures, Lp Systems and methods for handover between space based and terrestrial radioterminal communications, and for monitoring terrestrially reused satellite frequencies at a radioterminal to reduce potential interference
US20040240525A1 (en) 2003-05-29 2004-12-02 Karabinis Peter D. Wireless communications methods and apparatus using licensed-use system protocols with unlicensed-use access points
US8670705B2 (en) 2003-07-30 2014-03-11 Atc Technologies, Llc Additional intra-and/or inter-system interference reducing systems and methods for satellite communications systems
US7340213B2 (en) 2003-07-30 2008-03-04 Atc Technologies, Llc Intra- and/or inter-system interference reducing systems and methods for satellite communications systems
US20050041619A1 (en) 2003-08-22 2005-02-24 Karabinis Peter D. Wireless systems, methods and devices employing forward- and/or return-link carriers having different numbers of sub-band carriers
US7113743B2 (en) 2003-09-11 2006-09-26 Atc Technologies, Llc Systems and methods for inter-system sharing of satellite communications frequencies within a common footprint
JP2007507184A (en) 2003-09-23 2007-03-22 エイティーシー・テクノロジーズ,リミテッド・ライアビリティ・カンパニー Mobility management system and method in an overlaid mobile communication system
US8380186B2 (en) 2004-01-22 2013-02-19 Atc Technologies, Llc Satellite with different size service link antennas and radioterminal communication methods using same
US7453920B2 (en) * 2004-03-09 2008-11-18 Atc Technologies, Llc Code synchronization in CDMA satellite wireless communications system using uplink channel detection
US7176468B2 (en) * 2004-09-16 2007-02-13 Kla-Tencor Technologies Corporation Method for charging substrate to a potential

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5691727A (en) * 1995-01-03 1997-11-25 State Of Israel-Ministry Of Defense Armament Development Authority-Rafael Adaptive polarization diversity system
US6226493B1 (en) * 1996-05-31 2001-05-01 Motorola, Inc. Geosynchronous satellite communication system and method
US6032041A (en) * 1997-06-02 2000-02-29 Hughes Electronics Corporation Method and system for providing wideband communications to mobile users in a satellite-based network
US6823170B1 (en) * 2000-07-26 2004-11-23 Ericsson Inc. Satellite communications system using multiple earth stations

Cited By (45)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8369775B2 (en) 2000-08-02 2013-02-05 Atc Technologies, Llc Integrated or autonomous system and method of satellite-terrestrial frequency reuse using signal attenuation and/or blockage, dynamic assignment of frequencies and/or hysteresis
US8265637B2 (en) 2000-08-02 2012-09-11 Atc Technologies, Llc Systems and methods for modifying antenna radiation patterns of peripheral base stations of a terrestrial network to allow reduced interference
US7792488B2 (en) 2000-12-04 2010-09-07 Atc Technologies, Llc Systems and methods for transmitting electromagnetic energy over a wireless channel having sufficiently weak measured signal strength
US7890097B2 (en) 2001-09-14 2011-02-15 Atc Technologies, Llc Systems and methods for monitoring selected terrestrially used satellite frequency signals to reduce potential interference
US8023954B2 (en) 2001-09-14 2011-09-20 Atc Technologies, Llc Systems and methods for controlling a cellular communications system responsive to a power level associated with a wireless transmitter
US8285278B2 (en) 2001-09-14 2012-10-09 Atc Technologies, Llc Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex mode
US8270898B2 (en) 2001-09-14 2012-09-18 Atc Technologies, Llc Satellite-band spectrum utilization for reduced or minimum interference
US8068828B2 (en) 2001-09-14 2011-11-29 Atc Technologies, Llc Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex mode
US8078101B2 (en) 2001-09-14 2011-12-13 Atc Technologies, Llc Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex and/or frequency-division duplex mode
US7783287B2 (en) 2001-09-14 2010-08-24 Atc Technologies, Llc Satellite radiotelephone systems, methods, components and devices including gated radiotelephone transmissions to ancillary terrestrial components
US7796985B2 (en) 2002-05-28 2010-09-14 Atc Technologies, Llc Systems and methods for packing/unpacking satellite service links to/from satellite feeder links
US8340592B2 (en) 2003-03-24 2012-12-25 Atc Technologies, Llc Radioterminals and operating methods that receive multiple measures of information from multiple sources
US8238819B2 (en) 2003-09-11 2012-08-07 Atc Technologies, Llc Systems and methods for inter-system sharing of satellite communications frequencies within a common footprint
US8045975B2 (en) 2003-09-11 2011-10-25 Atc Technologies, Llc Systems and methods for inter-system sharing of satellite communications frequencies within a common footprint
US7974619B2 (en) 2003-09-23 2011-07-05 Atc Technologies, Llc Systems and methods for mobility management in overlaid mobile communications systems
US8131293B2 (en) 2003-09-23 2012-03-06 Atc Technologies, Llc Systems and methods for mobility management in overlaid mobile communications systems
US8655398B2 (en) 2004-03-08 2014-02-18 Atc Technologies, Llc Communications systems and methods including emission detection
US8055257B2 (en) 2004-04-12 2011-11-08 Atc Technologies, Llc Systems and methods with different utilization of satellite frequency bands by a space-based network and an ancillary terrestrial network
US8238818B2 (en) 2004-05-18 2012-08-07 Atc Technologies, Llc Satellite communications systems and methods using radiotelephone location-based beamforming
US8145126B2 (en) 2004-08-11 2012-03-27 Atc Technologies, Llc Satellite-band spectrum utilization for reduced or minimum interference
US7957694B2 (en) 2004-08-11 2011-06-07 Atc Technologies, Llc Satellite-band spectrum utilization for reduced or minimum interference
US8369776B2 (en) 2004-11-02 2013-02-05 Atc Technologies, Llc Apparatus and methods for power control in satellite communications systems with satellite-linked terrestrial stations
US9037078B2 (en) 2004-11-02 2015-05-19 Atc Technologies, Llc Apparatus and methods for power control in satellite communications systems with satellite-linked terrestrial stations
US8285225B2 (en) 2004-12-07 2012-10-09 Atc Technologies, Llc Broadband wireless communications systems and methods using multiple non-contiguous frequency bands/segments
US7953373B2 (en) 2004-12-16 2011-05-31 Atc Technologies, Llc Prediction of uplink interference potential generated by an ancillary terrestrial network and/or radioterminals
US8073394B2 (en) 2004-12-16 2011-12-06 Atc Technologies, Llc Prediction of uplink interference potential generated by an ancillary terrestrial network and/or radioterminals
US8744360B2 (en) 2005-01-05 2014-06-03 Atc Technologies, Inc. Adaptive beam forming with multi-user detection and interference reduction in satellite communication systems and methods
US7899002B2 (en) 2005-01-27 2011-03-01 Atc Technologies, Llc Satellite/terrestrial wireless communications systems and methods using disparate channel separation codes
US7970346B2 (en) 2005-03-15 2011-06-28 Atc Technologies, Llc Methods of reducing interference including calculation of weights based on errors and related systems
US7974575B2 (en) 2005-03-15 2011-07-05 Atc Technologies, Llc Methods of reducing interference including applying weights to provide correction signals and related systems
US7890050B2 (en) 2005-03-15 2011-02-15 Atc Technologies, Llc Methods of reducing interference including determination of feeder link signal error and related systems
US7999735B2 (en) 2005-04-04 2011-08-16 Atc Technologies, Llc Radioterminals and associated operating methods that transmit position information responsive to rate of change of position
US8412126B2 (en) 2005-06-21 2013-04-02 Atc Technologies, Llc Communications systems including adaptive antenna systems and methods for inter-system and intra-system interference reduction
US7917135B2 (en) 2005-07-29 2011-03-29 Atc Technologies, Llc Satellite communications apparatus and methods using asymmetrical forward and return link frequency reuse
US8169955B2 (en) 2006-06-19 2012-05-01 Atc Technologies, Llc Systems and methods for orthogonal frequency division multiple access (OFDMA) communications over satellite links
US7978135B2 (en) 2008-02-15 2011-07-12 Atc Technologies, Llc Antenna beam forming systems/methods using unconstrained phase response
US8433241B2 (en) 2008-08-06 2013-04-30 Atc Technologies, Llc Systems, methods and devices for overlaid operations of satellite and terrestrial wireless communications systems
US8193975B2 (en) 2008-11-12 2012-06-05 Atc Technologies Iterative antenna beam forming systems/methods
US8339308B2 (en) 2009-03-16 2012-12-25 Atc Technologies Llc Antenna beam forming systems, methods and devices using phase adjusted least squares beam forming
US20120131618A1 (en) * 2009-05-20 2012-05-24 Donald Lester Content broadcast
US9369223B2 (en) * 2009-05-20 2016-06-14 Astrium Limited Content broadcast
US8520561B2 (en) 2009-06-09 2013-08-27 Atc Technologies, Llc Systems, methods and network components that provide different satellite spot beam return carrier groupings and reuse patterns
US8576769B2 (en) 2009-09-28 2013-11-05 Atc Technologies, Llc Systems and methods for adaptive interference cancellation beamforming
US10110288B2 (en) 2009-11-04 2018-10-23 Atc Technologies, Llc Frequency division duplex (FDD) return link transmit diversity systems, methods and devices using forward link side information
US8274925B2 (en) 2010-01-05 2012-09-25 Atc Technologies, Llc Retaining traffic channel assignments for satellite terminals to provide lower latency communication services

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