US 20050249245 A1
A device, network and method wherein a standard wireless modem is coupled to wiring for carrying a wireless baseband signal that may be OFDM based, and may be directly generated by the wireless IF modem, or extracted from the modem RF signal. The wiring may be a building utility wiring, such as telephone, AC power or CATV wiring. The baseband signal is carried simultaneously with the utility service signal over the utility wiring using Frequency Division Multiplexing. The device may be enclosed with a data unit, a standalone dedicated enclosure, within an outlet or as a plug-in outlet adapter. Data units may couple the device by a wiring port such as standard data connector, or via wireless connection. The device may be locally powered or via a power signal carried over the wiring. This abstract is not intended to limit or construe the scope of the claims.
1. A device for configuring a network over a telephone wire pair in a building, the telephone wire pair concurrently carrying an analog telephone signal in an analog telephone frequency band, and the network carrying a spread-spectrum digital data signal in a digital data frequency band separate from, and higher than, the analog telephone frequency band, said device comprising:
a first telephone connector connectable to the telephone wire pair;
a high pass filter coupled to said first telephone connector for passing only signals in the digital data frequency band;
a multi-carrier modem coupled to said high pass filter, said modem being constructed to conduct a first OFDM modulated digital data signal in the digital data frequency band over said telephone wire pair for conducting bi-directional packet-based digital data communication;
a data connector connectable to a data unit; and
a transceiver coupled between said data connector and said modem, said transceiver being constructed for bi-directional packet-based digital data communication with said data unit.
2. The device according to
a second telephone connector connectable to the analog telephone unit; and
a low pass filter coupled between said first and second telephone connectors and for passing only the analog telephone signal.
3. The device according to
4. The device according to
5. The device according to
a wireless modem constructed to receive and transmit signals in a radio frequency band; and
an up/down converter coupled to said wireless modem and constructed to convert from the radio frequency band to the digital data frequency band.
6. The device according to
7. The device according to
8. The device according to
9. A network for enabling communication between first and second digital data units over telephone wiring in a building using spread-spectrum based digital data signals, the network comprising:
a telephone wire pair at least in part in a wall within the building, said wire pair being connected for carrying an analog telephone signal in an analog telephone signal frequency band frequency multiplexed with an OFDM modulated packet-based digital data signal carried bi-directionally in a digital data signal frequency band distinct from, and higher than, the analog telephone signal frequency band;
a first single enclosure;
a first device housed within said first single enclosure and connected to said telephone wire pair, said first device being connectable to the first data unit and being constructed to couple the digital data signal to the first data unit;
a second single enclosure; and
a second device housed within said second single enclosure and connected to said telephone wire pair, said second device being connectable for bidirectional packet-based communication with the second data unit and being constructed to couple the digital data signal to the second data unit.
10. The network according to
11. The network according to
12. The network according to
13. The network according to
14. A device for transferring a digital data signal between a wireless medium and a wired medium, the wired medium being a telephone wire pair in a building, the telephone wire pair concurrently carrying an analog telephone signal in an analog telephone frequency band frequency multiplexed with the digital data signal carried in a wired digital data signal frequency band distinct from, and higher than, the analog telephone signal frequency band, the digital data signal being carried in the wireless medium in a wireless radio frequency band, said device comprising:
a first telephone connector connectable to the telephone wire pair;
a high pass filter coupled to said first telephone connector for passing only signals in the wired digital data frequency band in the wired medium;
an antenna connected for radiating and receiving signals in the wireless radio frequency band in the wireless medium; and
an up/down converter coupled between said antenna and said high pass filter and constructed to transfer the digital data signal from the radio frequency band to the wired digital data frequency band,
wherein the digital data signal is communicated bi-directionally as a packet-based data signal.
15. The device according to
a second telephone connector connectable to the analog telephone unit; and
a low pass filter coupled between said first and second telephone connectors for passing only the analog telephone signal.
16. The device according to
17. The device according to
18. The device according to
19. The device according to
20. The device according to
21. The device according to
22. A network for communication between first and second wireless digital data units over pre-existing telephone wiring in a building, said network comprising:
a telephone wire pair at least in part in a wall within the building, said wire pair being connected for concurrently carrying an analog telephone signal in an analog telephone signal frequency band frequency and a digital data signal in a digital data signal frequency band distinct from, and higher than, the analog telephone signal frequency band, the digital data signal being packet-based and being communicated bi-directionally over the telephone wire pair;
a first single enclosure;
a first device housed within said first single enclosure and connected to said telephone wire pair, said first device being couplable for bi-directional packet-based wireless communication with a first wireless digital data unit and being constructed to couple the digital data signal to the first wireless digital data unit;
a second single enclosure; and
a second device housed within said second single enclosure and connected to said telephone wire pair, said second device being couplable for bi-directional packet-based wireless communication with a second wireless digital data unit and being constructed to couple the digital data signal to the second wireless digital data unit;
wherein the digital data signal is an up/down frequency converted wireless signal.
23. The network according to
24. The network according to
25. The network according to
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27. The network according to
28. A device for transferring a digital data signal between a wireless medium and a wired medium, the wired medium being an AC power wire pair in a building, the AC power wire pair concurrently carrying an AC power signal in an AC power frequency band frequency multiplexed with the digital data signal carried in a wired digital data signal frequency band distinct from, and higher than, the AC power frequency band, the digital data signal being carried in the wireless medium in a radio frequency band, said device comprising:
a first AC power connector connectable to the AC power wire pair;
a high pass filter coupled to said first AC power connector for passing only signals in the wired digital data frequency band in the wired medium;
an antenna connected for radiating and receiving signals in the radio frequency band in the wireless medium; and
an up/down converter coupled between said antenna and said high pass filter and constructed to convert the digital data signal from the radio frequency band to the wired digital data frequency band,
wherein the digital data signal is communicated bi-directionally as a packet-based data signal.
29. The device according to
a second AC power connector connectable to the AC power unit; and
a low pass filter coupled between said first and second AC power connectors and for passing only the AC power signal.
30. The device according to
31. The device according to
32. The device according to
33. The device according to
34. The device according to
35. The device according to
36. A network for communication between first and second wireless digital data units over pre-existing AC power wiring in a building, said network comprising:
an AC power wire pair at least in part in a wall within the building, said wire pair being connected for concurrently carrying an AC power signal carried in an AC power signal frequency band frequency multiplexed with a digital data signal carried in a digital data signal frequency band distinct from, and higher than, the AC power signal frequency band, the digital data signal being packet-based and being communicated bi-directionally over the AC power wire pair;
a first single enclosure;
a first device housed within said first single enclosure and connected to said AC power wire pair, said first device being couplable for bi-directional packet-based wireless communication with a first wireless digital data unit and being constructed to couple the digital data signal to the first wireless digital data unit;
a second single enclosure; and
a second device housed within said second single enclosure and connected to said AC power wire pair, said second device being couplable for bi-directional packet-based wireless communication with a second wireless digital data unit and being constructed to couple the digital data signal to the second wireless digital data unit,
wherein the digital data signal is an up/down frequency converted wireless signal in the wireless medium.
37. The network according to
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39. The network according to
40. The network according to
41. The network according to
42. The network according to
43. A device for configuring a network over a telephone wire pair in a building, the telephone wire pair carrying an analog telephone signal in an analog telephone frequency band, and the network carrying a wireless-based digital data signal in a digital data frequency band distinct from, and higher than, the analog telephone frequency band, said device comprising:
a data connector connectable to a data unit;
a transceiver coupled to said data connector, said transceiver being constructed to conduct packet-based wired digital data communication bi-directionally with the data unit;
a wireless modem coupled to said transceiver, said wireless modem being constructed to convey an up/down frequency converted wireless signal in the digital data frequency band over the telephone wire pair, and being further constructed for bi-directional packet-based digital data communication via a first telephone connector connectable to the telephone wire pair; and a high pass filter coupled between said first telephone connector and said wireless modem for passing only signals in the digital data frequency band.
44. The device according to
a second telephone connector connectable to an analog telephone device; and
a low pass filter coupled between said first and second telephone connectors and for passing only the analog telephone signal.
45. The device according to
46. The device according to
47. The device according to
48. The device according to
49. The device according to
50. The device according to
51. A device for configuring wired and wireless networks, the wired network including a telephone wire pair in a building, the telephone wire pair concurrently carrying an analog telephone signal in an analog telephone frequency band, and the network carrying a wired digital data signal in a wired digital data frequency band distinct from, and higher than, the analog telephone frequency band, said device comprising:
a data connector for connectable to a data unit;
a transceiver coupled to said data connector and constructed for receiving digital data packets from the data unit;
an antenna for radiating signals in a radio frequency band;
a wireless modem coupled between said antenna and said transceiver and constructed to transmit packet-based digital data;
a first telephone connector connectable to the telephone wire pair; and
a high pass filter coupled between said first telephone connector and said transceiver for passing only signals in the wired digital data frequency band;
wherein packets received from the data units are concurrently passed to said wireless modem to be transmitted as a wireless signal by said antenna and to said high pass filter to be carried over the telephone wire pair.
52. The device according to
53. The device according to
54. The device according to
a second telephone connector connectable to the analog telephone unit; and
a low pass filter coupled between said first and second telephone connectors for passing only the analog telephone signal.
55. The device according to
56. The device according to claim 61, wherein said enclosure is attachable to a wall, or is integrated in a telephone outlet; or is mechanically and electrically attachable to and detachable from a telephone outlet.
57. The device according to
58. The device according to
The present invention relates to the field of wired communication, and, more specifically, to using wireless oriented signals over a wired medium.
Wired Home Networking.
Most existing offices and some of the newly built buildings facilitate a data network structure based on dedicated wiring. However, implementing such a network in existing buildings typically requires installation of new wiring infrastructure. Such installation of new wiring may be impractical, expensive and problematic. As a result, many technologies (referred to as “no new wires” technologies) have been proposed in order to facilitate a LAN in a building without adding new wiring. Some of these techniques use existing utility wiring installed primarily for other purposes such as telephone, electricity, cable television (CATV), and so forth. Such an approach offers the advantage of being able to install such systems and networks without the additional and often substantial cost of installing separate wiring within the building.
The technical aspect for allowing the wiring to carry both the service (such as telephony, electricity and CATV) and the data communication signal commonly involves using FDM technique (Frequency Division Multiplexing). In such configuration, the service signal and the data communication signals are carried across the respective utility wiring each using a distinct frequency spectrum band. The concept of FDM is known in the art, and provides means of splitting the bandwidth carried by a medium such as wiring. In the case of a telephone wiring carrying both telephony and data communication signals, the frequency spectrum is split into a low-frequency band capable of carrying an analog telephony signal and a high-frequency band capable of carrying data communication or other signals.
A network in a house based on using powerline-based home network is also known in the art. The medium for networking is the in-house power lines, which is used for carrying both the mains power and the data communication signals. A PLC (Power Line Carrier) modem converts a data communication signal (such as Ethernet IEEE802.3) to a signal which can be carried over the power lines, without affecting and being affected by the power signal available over those wires. A consortium named HomePlug Powerline Alliance, Inc. of San Ramon, Calif. USA is active in standardizing powerline technologies. A powerline communication system is described in U.S. Pat. No. 6,243,571 to Bullock et al., which also provides a comprehensive list of prior art publications referring to powerline technology and application. An example of such PLC modem housed as a snap-on module is HomePlug1.0 based Ethernet-to-Powerline Bridge model DHP-100 from D-Link® Systems, Inc. of Irvine, Calif., USA. Outlets with built in PLC modems for use with combined data and power using powerlines are described in U.S. Patent Application 2003/0062990 to Schaeffer et al. entitled ‘Powerline bridge apparatus’. Such power outlets are available as part of PlugLAN™ by Asoka USA Corporation of San Carlos, Calif. USA.
Similarly, carrying data over existing in home CATV coaxial cabling is also known in the art, for example in U.S. Patent application 2002/0166124 to Gurantz et al. An example of home networking over CATV coaxial cables using outlets is described in U.S. Patent application 2002/0194383 to Cohen et al. Such outlets are available as part of HomeRAN™ system from TMT Ltd. of Jerusalem, Israel.
Telephony Definitions and Background
The term “telephony” herein denotes in general any kind of telephone service, including analog and digital service, such as Integrated Services Digital Network (ISDN).
Analog telephony, popularly known as “Plain Old Telephone Service” (“POTS”) has been in existence for over 100 years, and is well-designed and well-engineered for the transmission and switching of voice signals in the 300-3400 Hz portion (or “voice band” or “telephone band”) of the audio spectrum. The familiar POTS network supports real-time, low-latency, high-reliability, moderate-fidelity voice telephony, and is capable of establishing a session between two end-points, each using an analog telephone set.
The terms “telephone”, “telephone set”, and “telephone device” herein denote any apparatus, without limitation, which can connect to a Public Switch Telephone Network (“PSTN”), including apparatus for both analog and digital telephony, non-limiting examples of which are analog telephones, digital telephones, facsimile (“fax”) machines, automatic telephone answering machines, voice (a.k.a. dial-up) modems, and data modems.
The terms “data unit”, “computer” and “personal computer” (“PC”) are used herein interchangeably to include workstations, Personal Digital Assistants (PDA) and other data terminal equipment (DTE) with interfaces for connection to a local area network, as well as any other functional unit of a data station that serves as a data source or a data sink (or both).
In-home telephone service usually employs two or four wires, to which telephone sets are connected via telephone outlets.
Home Networking Existing In-House Wiring.
Similarly to the powerlines and CATV cabling described above, it is often desirable to use existing telephone wiring simultaneously for both telephony and data networking. In this way, establishing a new local area network in a home or other building is simplified, because there is no need to install additional wiring. Using FDM technique to carry video over active residential telephone wiring is disclosed by U.S. Pat. No. 5,010,399 to Goodman et al. and U.S. Pat. No. 5,621,455 to Rogers et al.
Existing products for carrying data digitally over residential telephone wiring concurrently with active telephone service by using FDM commonly uses a technology known as HomePNA (Home Phoneline Networking Alliance) whose phonelines interface has been standardized as ITU-T (ITU Telecommunication Standardization Sector) recommendation G.989.1. The HomePNA technology is described in U.S. Pat. No. 6,069,899 to Foley, U.S. Pat. No. 5,896,443 to Dichter, U.S. Patent application 2002/0019966 to Yagil et al., U.S. Patent application 2003/0139151 to Lifshitz et al. and others. The available bandwidth over the wiring is split into a low-frequency band capable of carrying an analog telephony signal (POTS), and a high-frequency band is allocated for carrying data communication signals. In such FDM based configuration, telephony is not affected, while a data communication capability is provided over existing telephone wiring within a home.
Prior art technologies for using the in-place telephone wiring for data networking are based on single carrier modulation techniques, such as AM (Amplitude Modulation), FM (Frequency Modulation) and PM (Phase Modulation), as well as bit encoding techniques such as QAM (Quadrature Amplitude Modulation) and QPSK (Quadrature Phase Shift Keying) and CCK (Complementary Code Keying). Spread spectrum technologies, to include both DSSS (Direct Sequence Spread Spectrum) and FHSS (Frequency Hopping Spread Spectrum) are known in the art. Spread spectrum commonly employs Multi-Carrier Modulation (MCM) such as OFDM (Orthogonal Frequency Division Multiplexing). OFDM and other spread spectrum are commonly used in wireless communication systems, and in particular in WLAN networks. As explained in the document entitled “IEEE 802.11g Offers Higher Data Rates and Longer Range” to Jim Zyren et al. by Intersil which is incorporated herein by reference, multi-carrier modulation (such as OFDM) is employed in such wireless systems in order to overcome the signal impairment due to multipath. Since OFDM as well as other spread spectrum technologies are considered to be complex and expensive (requiring Digital Signal Processors—DSP), and since telephone wiring is considered a better communication medium wherein multipath is less considered as a major impairment than it is in wireless networks, OFDM technique (and any other spread spectrum or any multi-carrier modulation), which is considered to be powerful and high performance, has not been suggested as a dominant modulation for wired communication in general and over telephone wiring in particular.
There is thus a widely recognized need for, and it would be highly advantageous to have a method and system for using spread spectrum modem technologies such as OFDM for wired applications, such as over utility wiring, and in particular over telephone wiring.
Wireless Home Networking.
A popular approach to home networking (as well as office and enterprise environments) is communication via radio frequency (RF) distribution system that transports RF signals throughout a building to and from data devices. Commonly referred to as Wireless Local Area Network (WLAN), such communication makes use of the Industrial, Scientific and Medical (ISM) frequency spectrum, which is unregulated and license free. In the US, three of the bands within the ISM spectrum are the A band, 902-928 MHz; the B band, 2.4-2.484 GHz (a.k.a. 2.4 GHz); and the C band, 5.725-5.875 GHz (a.k.a. 5 GHz). Overlapping and/or similar bands are used in different regions such as Europe and Japan.
In order to allow interoperability between equipments manufactured by different vendors, few WLAN standards have evolved, as part of the Institute of Electrical and Electronic Engineers (IEEE) 802.11 standard group, branded as WiFi by the Wi-Fi Alliance of Austin, Tex., USA. IEEE 802.11b describes a communication using the 2.4 GHz frequency band and supporting communication rate of 11 Mb/s, IEEE 802.11a uses the 5 GHz frequency band to carry 54 MB/s and IEEE 802.11g uses the 2.4 GHz band to support 54 Mb/s. This is described in an Intel White Paper entitled “54 Mbps IEEE 802.11 Wireless LAN at 2.4 GHz”, and a chip-set is described in an Agere Systems White Paper entitled “802.11 Wireless Chip Set Technology White Paper”, both of these documents being incorporated herein by reference.
A node/client with a WLAN interface is commonly referred to as STA (Wireless Station/Wireless client). The STA functionality may be embedded as part of the data unit, or alternatively may be a dedicated unit, referred to as bridge, coupled to the data unit. While STAs may communicate without any additional hardware (ad-hoc mode), such network usually involves Wireless Access Point (a.k.a. WAP or AP) as a mediation device. The WAP implements the Basic Stations Set (BSS) and/or ad-hoc mode based on Independent BSS (IBSS). STA, client, bridge and WAP will be collectively referred to herein as WLAN unit.
Bandwidth allocation for IEEE802.11g wireless in the USA is shown as graph 20 in
WLAN unit block diagram 10 is shown in
The WLAN unit 10 connects to the wired medium via port 11, supporting an IEEE802.3 10/100BaseT (Ethernet) interface. The physical layer of this interface is handled by a 10/100BaseT PHY function block 12, converting the incoming Manchester or MLT3 modulated signal (according to the 1 OBaseT or 100BaseTX coding, respectively) into a serial digital stream. Similarly, a WLAN outgoing digital data stream is modulated to the respective coded signal and transmitted via the port 11, implementing full duplex communication. The internal digital stream may be of proprietary nature of any standard such as MII (Media Independent Interface). Such MII to Ethernet PHY 12 (a.k.a. Ethernet physical layer or Ethernet transceiver) can be implemented based on LAN83C180 10/100 Fast Ethernet PHY Transceiver available from SMSC—Standard Microsystems Corporation of Hauppauge, N.Y. U.S.A. While this function can be implemented by using a single dedicated component, in many embodiments this function is integrated into single component including other functions, such as handling higher layers. The PHY block 12 also comprises the isolation magnetics, balancing, surge protection and connector (commonly RJ-45) required for proper and standard interface via port 11.
For the sake of simplicity, in the foregoing and subsequent description only Ethernet 10/100BaseT interface will be described. However, it will be appreciated that any wired interface, being proprietary or standard, packet or synchronous, serial or parallel may be equally used, such as IEEE1394, USB, PCI, PCMCIA or IEEE1284. Furthermore, multiple such interfaces (being of the same type or mixed) may also be used.
In the case wherein the WLAN unit is integrated and enclosed within another unit (such as data unit, e.g. computer) and does not support a dedicated and direct wired interface, the function of block 12 may be omitted.
MAC (Media Access Control) and higher layers are handled in function block 13, comprising two sub blocks, designated as 10/100 BaseT MAC block 13 a and IEEE802.11g MAC block 13 b (typically, the same MAC device is used for all IEEE802.11 variants, such as a/b/g). The MAC block 13 a handles the MAC layer according to IEEE802.3 MAC associated with the wired port 11. Such a function block 13 a may be implemented using LAN91C111 10/100 Non-PCI Ethernet Single Chip MAC+PHY available from SMSC—Standard Microsystems Corporation of Hauppauge, N.Y. U.S.A, which includes both the MAC 13 a and the PHY 12 functionalities. Reference is made to the manufacturer's data sheet: SMSC—Standard Microsystems Corporation, LAN91C111 10/100 Non-PCI Ethernet Single Chip MAC+PHY, Datasheet Rev. 15 (O2-20-04), which is incorporated herein by reference. Similarly, the MAC block 13 b handles the MAC layer according to IEEE802.11g MAC associated with the wireless port 22. Such MAC 13 b is designed to support multiple data rates, encryption algorithms and is commonly based on an embedded processor and various memories. Such a functional block 13 b may be implemented using WaveLAN™ WL60040 Multimode Wireless LAN media Access Controller (MAC) from Agere Systems of Allentown, Pa. U.S.A., whose a product brief is incorporated herein by reference, which is part of a full chip-set as described in WaveLAN™ 802.11a/b/g Chip Set document from Agere Systems of Allentown, Pa. U.S.A., which is incorporated herein by reference. Reference is made to the manufacturer's data sheet Agere Systems, WaveLAN™ WL60040 Multimode Wireless LAN Media Access Controller (MAC), Product Brief August 2003 PB03-164WLAN, which is incorporated herein by reference. All the bridging required in order to connect the wired IEEE802.3 MAC handled by block 13 a to the wireless IEEE802.11g MAC handled by block 13 b is also included in functional block 13, allowing for integrated and proper operation.
The data stream generated by the IEEE802.11 g MAC 13 b is converted to an OFDM-based baseband signal (and vice versa) by the baseband processor 18. In common applications, the baseband processor 18 (a.k.a. wireless modem and IF transceiver) is implemented by a transmitter/receiver 14 digitally processing the data stream, and an analog unit (I-Q modulator) 15 generating the actual signal. The communication channel in wireless environments imposes various impairments such as attenuation, fading, multi-path, interferences among others, and the transmitter may process the data stream according to the following functions:
Using digital to analog conversion, the processed digital from the transmitter 14 is used to generate the OFDM baseband signal in the modulator 15. The received OFDM baseband signal from functional block 16 is digitized by the modulator 15, processed by the receiver 14, transferred to MAC 13 and PHY 12 to be conveyed via port 11. Some implementations of WLAN chipsets provide the actual baseband signal, while others provides orthogonal analog I/Q modem signals which need to be further processed to provide the actual real analog form IF (Intermediate Frequency) OFDM baseband signal. In such a case, as known in the art, a Local Oscillator (LO) determining the IF frequency is used to generate a sine wave which is multiplied by the I signal, added to the Q signal multiplied by 90 degrees shifted LO signal, to produce the real analog IF baseband signal. Such function can be implemented based on Maxim MAX2450 3V, Ultra-Low-Power Quadrature Modulator/Demodulator from Maxim Integrated Products of Sunnyvale, Calif. U.S.A, a data sheet of which is incorporated herein by reference. The baseband processor block 18 may be implemented based on WaveLAN™ WL64040 Multimode Wireless LAN Baseband from Agere Systems of Allentown, Pa. U.S.A., whose product brief is incorporated herein by reference. SA5250 Multi-Protocol Baseband from Philips Semiconductors including both baseband processor 18 and MAC 13 b functionalities may be alternatively used.
The RF-IF Converter functional block 16 shifts the IF OFDM baseband signal from the IF band to the ISM RF band. For example, an OFDM baseband signal symmetrically centered around 10 MHz and required to use channel 2 centered at 2417 MHz, is required to be frequency shifted by 2417-10=2407 MHz. Such frequency conversion may use many methods known in the art. A direct modulation transmitter/receiver may be used, such as WaveLAN™ WL54040 Dual-Band Wireless LAN Transceiver from Agere Systems of Allentown, Pa. U.S.A., for directly converting the orthogonal I-Q analog signal to the 2.4 GHz RF band. A product brief is incorporated herein by reference. Alternatively, superheterodyne (dual conversion, for example) architecture may be used, as described for SA5251 Multiband RF Transceiver from Philips Semiconductors. The converter 16 and the baseband processor 18 constitute the wireless path physical layer processor 17.
A T/R switch 19 is used to connect the antenna 22 to the transmitter path and disconnect the receiver path (to avoid receiver saturation) only upon a control signal signaling transmission state of the WLAN unit 10. PIN Diode switch based design is commonly used, such as PIN Diode switch SWX-05 from MCE-KDI Integrated Products of Whippany, N.J. U.S.A., whose data sheet is incorporated herein by reference. The antenna 22 is coupled via a RF filter 21 in order to ensure transmitting limited to the defined band mask (removing unwanted residual signals), and to filter out noise and out of band signal in the receiving mode. Such RF filter 21 may use SAW (Surface Acoustic wave) technology, such as 2441.8 MHz SAW Filter from SAWTEK (A TriQuint company) of Orlando, Fla. U.S.A., whose data sheet is incorporated herein by reference.
Actual implementation of the WLAN unit 10 may also involve amplifiers, attenuators, limiters, AGC (Automatic Gain Control) and similar circuits involved with signal level functions. For example, a Low Noise Amplifier (LNA), such as MAX2644 2.4 GHz SiGe, High IP3 Low-Noise Amplifier is commonly connected in the receive path near the antenna 22. Similarly, a Power Amplifier (PA) is used in the transmit path, such as MAX2247 Power Amplifier for IEEE802.11g WLAN. Both the LNA and the PA are available from Maxim Integrated Products of Sunnyvale, Calif. U.S.A. For the sake of simplicity, such functions are omitted in
The term “outlet” herein denotes an electromechanical device, which facilitates easy, rapid connection and disconnection of external devices to and from wiring installed within a building. An outlet commonly has a fixed connection to the wiring, and permits the easy connection of external devices as desired, commonly by means of an integrated connector in a faceplate. The outlet is normally mechanically attached to, or mounted in, a wall or similar surface. Non-limiting examples of common outlets include: telephone outlets for connecting telephones and related devices; CATV outlets for connecting television sets, VCR's, and the like; outlets used as part of LAN wiring (a.k.a. structured wiring) and electrical outlets for connecting power to electrical appliances. The term “wall” herein denotes any interior or exterior surface of a building, including, but not limited to, ceilings and floors, in addition to vertical walls.
Most existing wireless technologies such as IEEE802.11x (e.g. IEEE802.11a/g/b), BlueTooth™, UWB (Ultra WideBand) and others are limited to tens of meters in free line of sight environment. In common building environments, wherein walls and other obstacles are present, the range may be dramatically reduced. As such, in most cases a single wireless unit (such as an access point) cannot efficiently cover the whole premises. In order to improve the coverage, multiple access points (or any other WLAN units) are commonly used, distributed throughout the premises.
In order to allow the access points to interconnect in order to form a single communication cluster in which all the WLAN units can communicate with each other and/or with wired data units, a wired backbone is commonly used, to which the access points are connected. Such a network combining wired and wireless segments is disclosed for example in U.S. Pat. No. 6,330,244 to Swartz et al. Such a configuration is popular today in offices, businesses, enterprises, industrial facilities and other premises having a dedicated wiring network structure, commonly based on Category 5 cabling (a.k.a. structured wiring). The access points interface the existing wiring based on local area network (LAN), commonly by a standard data interface such as Ethernet based 10/100BaseT.
However, installing a dedicated network wiring infrastructure in existing houses is not practical as explained above. The prior art discloses using existing AC power wiring also as the wired backbone for interconnecting WLAN units. Examples of such prior art includes U.S. Pat. No. 6,535,110 to Arora et al., U.S. Pat. No. 6,492,897 to Mowery, Jr., U.S. Patent application 2003/0224728 to Heinonen et al., U.S. Pat. No. 6,653,932 to Beamish et al. Using powerlines as a backbone for connecting WLAN units involves several drawbacks. The type of wiring, noise and the general hostile environment results in a poor and unreliable communication medium, providing low data rates and requiring complex and expensive modems. In addition, the connection of a WLAN unit to the powerline requires both wireless and powerline modems for handling the physical layer over the two media involved, as well as a complex MAC (Media Access control) to bridge and handle the two distinct protocols involved. As such, this solution is complex, expensive and offers low reliability due to the amount of hardware required.
There is thus a widely recognized need for, and it would be highly advantageous to have a method and system for using wireless modem technologies and components in a wired applications. Furthermore, it would be highly advantageous to have a method and system for cost effectively enlarging the coverage of a wireless network by carrying a wireless signal over a wired medium without converting to a dedicated wired modem signal.
It is therefore an object of the invention to provide a method and system for using standard existing wireless components for wired communication.
According to the invention, a standard wireless baseband signal that is conducted by existing wireless components (widely used for wireless transmission), is coupled and carried by a wiring, as a substitute for a dedicated wiring modem. As such, a network (such as local area network) can be configured over the wiring, either in bus topology, point-to-point or any other arbitrary network topology. The invention is based on a WLAN unit design, comprising a wired data port and a wireless port (e.g. antenna) and enabling a data unit connected to the wired data port (either proprietary or standard) to wirelessly communicate with other data unit.
In one aspect of the present invention, a device is based on a WLAN data design. However, only the baseband signal is used, so that the baseband to RF portion (hereinafter ‘RF portion’) of the WLAN unit may be obviated. The baseband signal may be coupled to the wiring via isolation, analog switching, driver and receiver, filtering and impedance matching functionalities, allowing for networking over the wiring with one or more similar devices coupled thereto.
In another aspect of the present invention, the RF portion of the WLAN unit is also used. In this case, an up/down converter is connected to the RF port (instead of connecting antenna thereto). The converter shifts the center frequency down to a band usable over the wiring.
In another aspect of the present invention, the full functionality of the WLAN unit is retained, including both the antenna and the RF portion. A wiring port coupled either directly to the baseband signal or to the RF signal via an up/down converter is added. In this case, a three ports sharing device is formed, having a wiring port, wireless (antenna) port and data unit port. Data units connected to a network comprising such multiple devices may be interconnected by the wired medium (via the wiring) or via the air using the RF signals propagating through the air.
In another aspect of the present invention, the device comprises only the RF portion of a WLAN unit (including antenna). The antenna RF signal is frequency shifted by an up/down converter to a frequency band usable by the wiring (e.g. baseband signal). A similar device or a device according to any of the above embodiments connected to the wiring may couple to the signal, and use it for coupling to a data unit either directly or wirelessly.
Any single pair wiring may be used as a medium for the baseband signal. In another aspect of the present invention, the wiring is utility wiring in a building, such as telephone, CATV or AC power wiring. In the case wherein the utility wiring also carries an active service signal (e.g. telephone, CATV or AC power signal respectively), FDM technique is used, wherein the service signal and the baseband signal are carried in distinct frequency bands. In another aspect of the present invention, the device further provides a service connector allowing a service unit to be connected thereto. In any case of wiring carrying active service signal, various filters are employed in order to isolate the service signal from the baseband signal, to avoid any interference between the two signals.
In another aspect of the present invention, the device may be comprised in a data unit. Alternatively, the device may be enclosed as a stand-alone dedicated unit. In another aspect of the present invention, the device is comprised within a service outlet. Alternatively, the device may be enclosed as outlet add-on module.
The device may be locally powered by a dedicated connection to a local power source (e.g. AC power, directly or via AC/DC converter). Alternatively, the device is power fed from a power signal carried over the wiring. In the latter case, a circuitry isolating the power signal carried over the wiring is employed. In another aspect of the present invention, the device is powered by a data unit connected thereto.
In another aspect of the present invention, spread spectrum (either DSSS or FHSS) techniques such as employing a multi-carrier modulation (e.g. OFDM, DMT or CDMA) modem, which due to its complexity is mainly used for wireless applications, may be used over a wired medium such as utility wiring in a building (e.g. telephone wiring).
It is understood that other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein are shown and described only embodiments of the invention by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all without departing from the scope of the present invention as defined by the claims. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
The invention is herein described, by way of non-limiting example only, with reference to the accompanying drawings, wherein:
The principles and operation of a network according to the present invention may be understood with reference to the drawings and the accompanying description wherein similar components appearing in different figures are denoted by identical reference numerals. The drawings and descriptions are conceptual only. In actual practice, a single component can implement one or more functions; alternatively, each function can be implemented by a plurality of components and circuits. In the drawings and descriptions, identical reference numerals indicate those components that are common to different embodiments or configurations.
A wireless based OFDM modem 30 adapted for operating over telephone wiring according to one or more embodiments of the present invention is described in
As a non-limiting example, in the case wherein the WLAN unit 30 is using channel 10 (shown as curve 25 in
In order to avoid interference to and from the other signals (POTS 41 and ADSL 42) carried over the same telephone pair, a High Pass Filter (HPF) 32 is connected between the converter 31 and the telephone wiring connector 36. The telephone wiring connector 36 in commonly a telephone standard RJ-11 plug used in North America, allowing for coupling the OFDM modem 30 to the telephone pair. The HPF 32 may use passive components implementing a Butterworth filter scheme. In some cases, a telephone unit is required to share the same telephone wiring connector 35. In such a case, a Low Pass Filter (LPF) 34 is used to isolate the POTS frequency band, allowing a telephone set to couple to the telephone connector 35 via a telephone jack (e.g. RJ-11 jack). Any common filter used to isolate POTS and ADSL signals (a.k.a. micro-filter) may be used as LPF 34, comprising discrete capacitors and inductors). Such configuration of connecting modem and telephone via a set of LPF and HPF units is known in the art and commonly used also in HomePNA environment.
OFDM and other spread spectrum modulation techniques are known to be powerful, robust and high-performance. Yet, their implementation complexity and associated costs have militated against their use in communication systems. Even the first WLAN technologies introduced used single-carrier technologies, such as IEEE802.11b using CCK. As such, the OFDM modem 30 shown in
Up/Down converter 31 used for shifting the frequency as described above is well known in the art. Such converters are known to use mixing and filtering techniques, and may use single or multiple stages (Superheterodyne scheme) as well as Direct Conversion (DC) architecture. A non-limiting example for Up/Down Converter function block 37, shown in
While transmitting to the telephone pair via connector 36, a RF signal received in port 51 (from the RF-IF converter 16) is first filtered by the BPF 52 to remove any unwanted signals residing outside the frequency band of the RF channel (e.g. the ISM RF channel band). Since the converter 50 allows conversion in only one direction at a time, either up or down, ganged switches 56 a and 56 b are used, having a center pole marked as (1) and two throw states marked as (2) and (3). When converting from RF to IF, both switches 56 a and 56 b are in the (2) state, hence the down channel is operative. Such a switch may be based on PIN diode as explained above regarding switch 19. The RF signal from the RF port 51 couples to mixer 57 a via BPF 52 and switch 56 a. The mixer 57 a multiplies the local oscillator 54 sine wave signal provided to its LO port via a splitter 55 by the RF signal coupled to its RF port (using its non linear characteristics), yielding in its IF port a signal having two main components, one around the sum of the frequencies and one around their difference. The frequencies' sum signal is then filtered out by the BPF 58 a, and fed to the IF port 68 via the switch 56 b. A driver 59 may also be included in order to allow proper driving of the load connected to port 68. In a similar way, when receiving from the telephone pair, an IF signal from port 68 (originated in the telephone pair, and coupled via connector 36 and HPF 32), is routed via the switch 56 b (now in state (3)) to the IF port of mixer 57 b, via BPF 58 b. A signal is also fed from the local oscillator 54 via splitter 55 to the LO port of the mixer 57 b, which outputs an RF signal to port 51 via the switch 56 a (now in state (3)) and BPF 52. A level detector (or comparator) 53 is used to monitor the level of the revived RF signal, and accordingly operate the switches 56 a and 56 b via control channels 69 b and 69 a respectively.
The converter 50 has been described above as having dedicated up and down channels. However, since only one channel is used at a time and the two channels are not used simultaneously, a single channel (mixer) may also be used, wherein an appropriate switching mechanism is employed.
A level detector 53 may be designed based on LM311 Voltage Comparator available from National Semiconductors headquartered in Santa-Clara, Calif. U.S.A. The local oscillator 54 may be based on quartz crystal oscillator, wherein the frequency is multiplied using Phase Locked Loop (PLL) circuits, and may comprise T83027 PLL Clock Generator IC with VCXO available from TLSI Incorporated of Huntington, N.Y. U.S.A., whose data sheet is incorporated herein by reference. A mixer 57 may be designed based on MAX9993 High Linearity 1700 MHz Down-Conversion Mixer with LO Buffer/Switch available from Maxim Integrated Products of Sunnyvale, Calif. U.S.A, whose data sheet is incorporated herein by reference. It should be noted that other techniques and methods to implement the converter block 50 functionality are known in the art and may be equally used. Typically, converter block 50 may connect to the telephone wiring using line interface functionalities such as isolation, impedance matching, driving/receiving and filtering, as will be described below for line interface 76 shown in
The OFDM modem 30 inherently employs double frequency conversions: from IF to RF by converter 16 and back to low frequency by converter 31. This redundancy may be obviated by directly extracting the baseband signal without going through the RF stage, as shown in OFDM modem functional block diagram 60 illustrated in
Similar to modem 30, modem 60 is based on WLAN unit 10 described in
A functional block diagram of the line interface 76 is shown in
Similarly, a signal received from the telephone wiring is isolated by the isolation unit 182, and routed via the analog switch 183 to an AGC 187. A 100 Ohm resistor 185 serves as a termination, matching the telephone wiring characteristic impedance to avoid reflection. After being filtered by a BPF 188 b, the signal is I-Q modulated by the modulator 191 and coupled to the baseband processor 18.
A sample network 75 over a telephone line using OFDM modems is shown in
OFDM Modems 30 and 60 may be connected to and networked over the telephone wiring 62 by connecting to the respective RJ-11 telephone connector 64 in outlet 63, and via cable 74 to the OFDM modem connector 36, marked as ‘wiring’ connection. A network may include only OFDM modems 30 as shown functionally in
Simultaneously with the data network formed over the telephone line, the standard telephone service is also provided. Telephone set 65 a is connected to the wiring 62 (so as to connect to the PSTN 61) via the ‘TEL.’ Port (port 35 in
In order to enable the computers 66 a and 66 b to connect to an external network (such as the Internet), a device connected to the external network (either broadband or narrowband) is commonly employed, non-limiting examples including a DOCSIS based cable modem, an ADSL modem, wireless (such as WiMax) and others. Such a device should be connected to the ‘data’ port of any OFDM modem, hence allowing sharing the external connection to data units connected throughout the building. In one example, an ADSL modem 67 is used. The ADSL modem is shown to connect to the telephone outlet 63 a via cable 74 e for coupling to the ADSL signal 42 (depicted in
While network 75 has been described with regard to ‘bus’ topology wherein all the modems are connected to the same medium (telephone wiring 62), it is known that better communication performance (e.g. data-rate) may be achieved in point-to-point structure, wherein two modems are connected at the ends of a wiring segment. Such configuration may exist in newly installed infrastructures (e.g. structured wiring in a newly constructed building) or in MDU (Multiple Dwelling Unit), MTU (Multiple Tenant Unit) and MHU (Multiple Hospitality Unit). In all the above, the wiring segments are in ‘star’ topology, wherein each wiring segment connects a remote site (e.g. apartment) to a center (e.g. basement).
An application of OFDM modems to such topology is shown as a non-limiting example as network 70 in
Outlet Enclosed Modem.
Outlets in general (to include LAN structured wiring, electrical power outlets, telephone outlets, and cable television outlets) have traditionally evolved as passive devices being part of the wiring system house infrastructure and solely serving the purpose of providing access to the in-wall wiring. However, there is a trend towards embedding active circuitry in the outlet in order to use them as part of the home/office network, and typically to provide a standard data communication interface. In most cases, the circuits added serve the purpose of adding data interface connectivity to the outlet, added to its basic passive connectivity function.
An outlet supporting both telephony and data interfaces for use with telephone wiring is disclosed in U.S. Pat. No. 6,549,616 entitled ‘Telephone outlet for implementing a local area network over telephone lines and a local area network using such outlets’ to Binder. Such outlets are available as part of NetHome™ system from SercoNet Inc. of Southborough, Mass. U.S.A.
Another telephone outlet is described in U.S. Pat. No. 6,216,160 to Dichter, entitled ‘Automatically configurable computer network’. An example of home networking over CATV coaxial cables using outlets is described in U.S. Patent Application 2002/0194383 to Cohen et al. entitled: ‘Cableran Networking over Coaxial Cables’ to Cohen et al. Such outlets are available as part of HomeRAN™ system from TMT Ltd. of Jerusalem, Israel. Outlets for use in conjunction with wiring carrying telephony, data and entertainment signals are disclosed in U.S. Patent Application 2003/0099228 to Alcock entitled ‘Local area and multimedia network using radio frequency and coaxial cable’. Outlets for use with combined data and power using powerlines are described in U.S. Patent Application 2003/0062990 to Schaeffer et al. entitled ‘Powerline bridge apparatus’. Such power outlets are available as part of PlugLAN™ by Asoka USA Corporation of San Carlos, Calif. USA.
While the active outlets have been described above with regard to networks formed over wiring used for basic services (e.g. telephone, CATV and power), it will be appreciated that the invention can be equally applied to outlets used in networks using dedicated wiring. In such a case, the outlet circuitry is used to provide additional interfaces to an outlet, beyond the basic service of single data connectivity interface. As a non-limiting example, it may be used to provide multiple data interfaces wherein the wiring supports single such data connection. An example of such outlet is the Network Jack™ product family manufactured by 3Com™ of Santa-Clara, Calif., U.S.A. In addition, such outlets are described in U.S. Pat. No. 6,108,331 to Thompson entitled ‘Single Medium Wiring Scheme for Multiple Signal Distribution in Building and Access Port Therefor’ as well as U.S. Patent Application 2003/0112965 Published Jun. 19, 2003 to McNamara et al. entitled ‘Active Wall Outlet’.
While the outlets described above use active circuitry for splitting the data and service signals, passive implementations are also available. An example of such passive outlet is disclosed in WO 02/25920 to Binder entitled ‘Telephone communication system and method over local area network wiring’. Such outlets are available as part of the etherSPLIT™ system from QLynk Communication Inc. of College Station, Tex. USA.
As known in the art, from the data communication (high frequency band) point of view, the cables 74 connected to the outlets 63 in system 75 are known as ‘taps’. Cable 74 c, terminated in the LPF 34 is considered an ‘open tap’ or ‘bridged tap’. The same goes for cable 74 e, terminating the ADSL band, but open for higher frequencies. Cable 74 b (as a non-limiting example) is considered a ‘terminated tap’, since appropriate termination is expected to be part of the OFDM modem 60 a. Taps in general and non-terminated taps in particular, are considered a major impairment in any wired communication system. Reflections are generated at the tap points and at the ends of open taps, resulting in a ‘notch’ pattern in the appropriate frequency. Such characteristics render part of the spectrum non-usable. As such, taps results in lower communication performance, and it is therefore desirable to eliminate taps as much as practical.
Wireless system in general, and WLAN systems in particular are associated with mobile and handheld devices such as PDA (Personal Digital Assistant), cellular phone, remote-controller and laptop computers. Being mobile and man-carried, the space and weight of the wireless components is critical. As such, a lot of resources are allocated to integration and miniaturization efforts in order to make the wireless components as small as possible. Vendors are increasingly focusing on integrating more and more functions into a minimum set of chips and peripherals. Hence, the small dimension featured by the wireless components makes them well suitable to be housed within small enclosures such as outlets.
In one or more embodiments of the present invention, the OFDM modem (partially or completely) is integrated into a telephone outlet. In addition to providing all the advantages described in the aforementioned prior art, such configuration eliminates the tap related impairments, thus improving the communication performance. As a non-limiting example, in the case the OFDM modem functionality is integrated into outlet 63 d, the cable 74 d is effectively zero in length, hence effectively eliminating the tap existence.
A pictorial view of such outlet integrating OFDM modem functionality is shown as outlet 80 in
The above-described outlet 80 is a complete and self-contained device. As such, it can be easily installed in new houses instead of regular passive simple outlets. However, such solutions are not appropriate in the case of retrofitting existing wiring systems. In most cases, any such modification will require dismantling the existing outlets and installing the new ones having the improved features. Such activity is cumbersome, expensive and will often require professional skill. Furthermore, owing to safety aspects involved while handling hazardous voltages (such as in the powerlines and telephone lines), local regulations may require only certified personnel to handle the wiring, making it expensive and militating against a do-it-yourself approach.
Furthermore, as technology and circumstances change in time, a need to upgrade, modify or change the outlet functionalities, features and characteristics may arise. For example, the data interface may need to be upgraded to interconnect with new standards. In another example, the circuitry may need to be upgraded to support higher bandwidth. Similarly, management and Quality of Service (QoS) functionalities may need to be either introduced or upgraded. In yet another example, additional functionalities and interfaces may need to be added. Using complete self-contained outlets as a substitute to the existing ones also introduces the disadvantages described above.
One approach to adding functionality to existing outlets is by using a plug-in module. Such plug-in modules for use with powerline communication are described in U.S. Patent Application 2002/0039388 to Smart et al. entitled ‘High data-rate powerline network system and method’, U.S. Patent Application 2002/0060617 to Walbeck et al. entitled ‘Modular power line network adaptor’ and also in U.S. Patent Application 2003/0062990 to Schaeffer, JR et al. entitled ‘Powerline bridge apparatus’. Such a module using Homeplug™ technology are available from multiple sources such as part of PlugLink™ products by Asoka USA Corporation of San Carlos, Calif., USA. However, such plug-in modules are known only with regards to power outlets, and are not available for telephone or CATV outlets.
A plug-in module according to one or more embodiments of the present invention is shown as module 90 in
Both OFDM modems 30 and 60 described above offer two wired ports, namely the data unit port 33 and the telephone wiring port 36, and function to convert signals between those ports. Adding a wireless port will enable the OFDM modems also to network with data units over a non-wired medium.
Such an OFDM modem 100 comprising an antenna 22 as a wireless port is shown in
The sharing device 101 is a three ports device and functions to share the three RF signals, such that an RF signal received in any one of the ports is replicated and shared by the other two ports. One RF signal relates to the wireless radio communication via the antenna 22, a second signal relates to the telephone wiring carried signal via connector 36 and the third RF signal is associated with the data port 33.
In such a configuration, the OFDM modem 100 communicates via three ports: Wireless port via antenna 22, wired data unit port via connector 33 and wired telephone wiring connector 36. A data packet (such as Ethernet packet) received from the data unit connected via port 33 will be converted to an OFDM RF signal at the RF-IF Converter 16 port, and then fed via sharing device 101 to both the telephone wiring after being down converted to a baseband signal by the Up/Down Converter 31 and through HPF 32 (as described above for modem 30), and in parallel (via sharing device 101) to the antenna 22 to be transmitted over the air. Similarly, an OFDM RF signal received in the antenna 22 is fed via the sharing device 101 to both the telephone wiring port 36 in analog baseband form and data unit port 33 as digital packets. Baseband signals received via the telephone wiring port will be converted to RF and then transmitted to the air by the antenna 22 in parallel to being down frequency converted and encoded into a packet in digital form in port 33. In some cases, an RF signal may be received from both the antenna 22 and the telephone wiring (via port 36). Since wireless systems are able to handle the through-air multi-path phenomenon, the signal received via the telephone wiring channel should be appreciated as another signal path, hence being handled by the baseband processor 18.
The three ports modem 100 is shown to share the three RF signals by sharing device 101. In one or more embodiments of the present invention, the sharing function is performed in the baseband (or IF) frequency spectrum. Such a modem 105 is shown in
Similar to the above discussion relating to OFDM modems 30 and 60, wireless-port equipped modems 100 and 105 may be equally enclosed within a telephone outlet or snap-on module. Such a snap-on module 110 attached to a telephone outlet 91 is shown in
A network 120 utilizing a wireless port equipped OFDM modem 100 is shown in
While a single modem 100 or 105 is part of network 120, it should be appreciated that multiple such modems may be used, each covering a different area in the premises, hence enlarging the actual wireless coverage. Furthermore, such network 120 offers the user the flexibility of adding data units either through wiring (by connecting to the data ports of the OFDM modems) or wirelessly (via the wireless port).
In some cases, only wireless ports may be required, thus tethered data unit connection may be obviated. According to one or more embodiments of the present inventions a wireless adaptor 130 supporting only wireless port is shown in
A network 140 employing the wireless adaptor 130 is shown in
Antennas 22 b and 22 d may be sufficiently close to enable direct wireless communication between bridges 121 a and 121 b. In such case, in addition to the path (or multiple paths) formed through the air, a telephone wiring path is added. As a non-limiting example, bridge 22 d may receive signals transmitted by bridge 121 a via the air. In addition, the transmitted signal is received by adaptor 130 a (via antenna 22 a), and converted to baseband and carried over the telephone wiring segments 62 d and 62 c. The signal is then extracted by adaptor 130 b, up frequency shifted and transmitted through the air via antenna 22 c to the bridge 121 b, hence forming an additional path. Since most wireless technologies and IEEE802.11g in particular are well equipped to handle multi-path, this phenomenon is not expected to degrade the communication performance.
While the invention has been described with regard to ‘bus’ topology telephone wiring, it will be appreciated that wireless-port equipped modems and adaptors may equally be used in point to point topology, ‘star’ topology or any combination thereof.
While the invention has been described with regard to a single specific channel frequency shifted to a specific band for use over the telephone wiring, it will be appreciated that the invention equally applies to any channel that can be used (as shown in graph 20) and may be located at any usable frequency band over the telephone wiring (not limited to the example shown as curve 43 of graph 40). Furthermore, several products are currently available using multiple channels in order to improve data rate performance, as well as using other techniques to improve throughput such as compression. Such techniques are sometimes known as ‘Turbo-G’, ‘Dynamic Turbo’, ‘Super G’ and other brands. Such a solution may be equally employed in one or more embodiments of the invention, using larger baseband signal bandwidth. Exemplary techniques to improve effective data rate are described in Atheros Communication White Paper entitled “Super G Maximizing Wireless Performance”, which is incorporated herein by reference.
While the invention has been described with regard to modems and adaptors supporting telephone port 35, it will be appreciated that the invention equally applies to the case wherein the telephone wiring is not carrying a telephone (POTS) signal. In such a case, telephone connector 35, LPF 34 may be omitted, and HPF 32 may be omitted and bypassed. Furthermore, such configuration may apply to any type of wiring dedicated for carrying the baseband signal, not limited to telephone wiring of any kind.
In one or more embodiments according to the present invention, other utility wiring (not limited to telephone oriented wiring) is used, carrying a service signal. For example, powerlines may be used to carry both the AC power signal and the OFDM signal according to one or more embodiments according to the present invention. In such a case, the HPF 32 should be substituted with HPF filtering out the low frequency band (i.e. 60 Hz in North America and 50 Hz in Europe) carrying the AC signal and its associated noises. Similarly, in the case wherein the modem is required also to provide AC power connection, the telephone connector 35 should be substituted with a two or three prongs power jack suitable for connecting powered appliances, and the telephone-oriented LPF 34 should be substituted by a LPF passing the 50/60 Hz AC signal. Furthermore, similar to the above discussion about housing the modem within a telephone outlet and telephone outlet snap-on module, the powerline OFDM modem may be equally enclosed within an AC power outlet and snap-on module respectively, with the warranted modifications.
In one or more embodiments according to the present invention, the OFDM baseband signal is carried over CATV cabling, carrying a CATV service signal. In one or more embodiments, the baseband signal may be employed over a band not used for carrying CATV signals (e.g. over 750 MHz in some implementations). The CATV analog video channels are usually carried each occupying a 6 MHz wide band. In such a case, an allocation of four adjacent channels will result in a total bandwidth of 6*4=24 MHz, which may contain the 22 MHz wide OFDM baseband signal. In such case, the Up/Down Converter 31 used should shift the band to the allocated bandwidth, for example by tuning the local oscillator 54 frequency to the required value. Similarly, The HPF 32 should be substituted with a BPF passing the allocated 24 MHz, and the LPF 34 should be substituted with a BSP (Band Stop Filter) blocking the OFDM signal and passing the CATV channels, to be coupled to via RF connector (BNC or F-Type) substituting for the telephone connector 35.
A non-limiting example of generalizing OFDM modem 30 to be used with any type of utility wiring is shown as modem 150 in
In most of the embodiments according to the present invention, the OFDM modems (or wireless adaptor) include active components (such as Up/Down converter 31), and as such need to be powered. Three non-limiting powering schemes are described hereinafter including local feeding, power over wiring and via the interface module. The powering schemes apply to the modem/adaptor being a stand-alone enclosure, housed within an outlet, enclosed within a snap-on outlet module or as part of a data unit.
In this implementation the module is connected to an external power source for feeding its active components. A common small AC/DC converter may be connected to the modem/adaptor via a dedicated power connection.
A power adaptor may be used in the modem/adaptor, for adapting the external power to the internal needs. Such an adaptor may include voltage conversion (such as DC to DC converter) in order to adapt to specific voltages required, protection circuits (such as fuse or current limiting), regulation and noise filtration, as well as other functionality as known in the art.
Power Over Wiring.
In one or more embodiments according to the present invention, the OFDM modem (or the wireless adaptor) is fed by power carried over the wiring to which the module is connected. The power may be carried over separated conductors. In this case, the same wiring connector (such as 36 or 151) may be used to connect to the power carrying conductors using separated pins. Alternatively, an additional power dedicated connector may be used.
In one or more preferred embodiments, the power is carried simultaneously over the wiring carrying the data network signals and/or the basic service signal. The implementation of such a mechanism is trivial when the basic service is AC power. In such a case the power is extracted from the AC power signal carried, commonly via AC/DC converter and LPF filter.
Similarly, a recent technique known as Power over Ethernet (PoE) (a.k.a. Power over LAN) and standardized under IEEE802.3af, also explained in U.S. Pat. No. 6,473,609 to Lehr et al. titled: “Structure Cabling System”, describes a method to carry power over LAN wiring, using the phantom mechanism. Such technology, as well as others, may be used to provide power to any of the modems/adaptors described above, in the case where appropriate cabling (such as CAT. 5) is used as the wired medium. As a non-limiting example, in the case of using a different spectrum for the power signal, a filter should be used. In the case of phantom type of feeding, two transformers are required as known in the art.
Recent techniques developed allow for carrying simultaneously power and basic service (and data) over the same wiring infrastructure. U.S. patent publication 2002/0003873 to Rabenko et al. titled: “System and method for providing power over a home phone line network” teaches carrying AC power over telephone wiring carrying both telephony and data, by using a part of the spectrum not used by the other signals. Such a technique may be used for powering a modem or adaptor according to the current invention. As a non-limiting example, AC power using a sine wave power signal of 50 KHz may be used. As shown in graph 40, a 50 KHz signal is in a non-allocated frequency band, and hence may be used for power distribution with minimum or no interference to the other signals carried over the same telephone wire pair.
In most prior-art systems involving carrying a power over a non-power dedicated wiring (e.g. powerlines), the amount of power that can be carried is limited either due to safety regulations and limitations, ensuring minimum interference with the other signals carried over the same wires or due to the power dissipation in the wires. For example, power carried over telephone lines may not exceed 60 VDC due to safety limitations, and power carried over coaxial wiring (e.g. CATV) may degrade its signal carrying characteristics.
Wireless system in general, and WLAN systems in particular are associated with mobile and handheld devices such as PDA (Personal Digital Assistant), cellular phone, remote-controller and laptop computers. Being battery operated, the power consumption of the wireless components is critical. As such, a lot of resources are allocated to make the wireless components consume very low power, and the power consumption of any wireless components is considered as one of its main features. This approach is described for example in Texas Instruments White Paper entitled “Low Power Advantage of 802.11a/g vs. 802.11b” which is incorporated herein by reference. Hence, the low power feature of the wireless components makes them well suitable to be used in any power over wiring scheme, and also in any non-local feeding scenarios.
An additional advantage of carrying power over the same wires carrying the OFDM signal relates to the superior characteristics of the OFDM signal. Known single carrier modulations use the whole spectrum for the whole data rates (single ‘bin’ approach), and as such are greatly susceptible to both white noise and single frequency noise. In contrast, OFDM uses multiple ‘bins’, each carrying part of the data, and hence is less impaired by either white or narrowband noise. Power supplies are known to be noisy, and in particular at specific frequencies, such as harmonies of the PWM frequency (in the case of PWM based supply). Furthermore, the wires connecting the wired medium to the power supply and to the loads also serve as antennas and receive noise from the environment. Since the OFDM is much more robust, the effects described are less severe, allowing better performance, and obviating the need for complex and expensive filters.
Furthermore, since the networks described above are used to serve wireless clients (STAs) which are battery operated and thus are operative even in the case of power outage, carrying power over the wiring allows for continuing network operation in such a case. The power is typically sourced from a central back-up power source (e.g. UPS—Uninterruptible Power Supply), and allows continuous operation of the network even in the case of power outage via the wiring medium.
A non-limiting example of an OFDM modem 160 capable of being power fed via the telephone wiring is shown in
The BPF 162 and BSF 163 constitute the power/signal splitter/combiner 166. In the case wherein the power is carried in any other way, this function block 166 should be accordingly modified to split/combine the power and other signals carried over the wiring.
A network 170 employing AC power over telephone wiring is shown in
Powering Via Connected Appliance.
As explained above, several data interface standards also carry power over the interface. As a non-limiting example, in the case where the module is connected to USB host unit, the USB interface may feed the module. The same applies when the data port 33 is an Ethernet port implementing PoE technology as described above.
While the invention has been described with regard to a single power source, it will be appreciated that the invention equally applies to the case wherein multiple power sources are used either for redundancy or load sharing.
While the invention has been described with regard to the configuration wherein OFDM signal is carried over telephone wiring (or any other utility or dedicated wiring LAN), it will be appreciated that the invention equally applies to any other spread spectrum signaling (using either DSSS or FHSS). As a non-limiting example, any multi-carrier modulation technique may be used such as DMT (Discrete MultiTone) and CDMA (Code Division Multiple Access). The term ‘OFDM modem’ used herein is to be considered as an example only, and not as limited to solely using OFDM based signal.
While the invention has been exampled above with regard to using standard IEEE 802.11g technology, signals and components, it will be appreciated that the invention equally applies to any other wireless based technology, using either single or multi carrier signals for implementing either spread spectrum or narrowband, using either unlicensed bands (such as ISM) or licensed spectrum. Such technology may be part of the IEEE 802.11 (such as IEEE 802.11b or IEEE 802.11a), ETSI HiperLAN/2 or any technology used for WLAN, home networking or PAN (Personal Area Network). One non-limiting example is using IEEE 802.11b based on CCK (Complementary Code Keying). Other non-limiting examples are BlueTooth™, ZigBee, UWB and HomeRF™. Furthermore, WAN (Wide Area Network) and other wireless technologies may be equally used, such as cellular technologies (e.g. GSM, GPRS, 2.5G, 3G, UMTS, DCS, PCS and CDMA) and Local Loop oriented technologies (WLL—Wireless Local Loop) such as WiMax, WCDMA and other Fixed Wireless technologies, including microwave based. Similarly, satellite based technologies and components may be equally used. While the technologies mentioned above are all standards-based, proprietary and non-standards technologies may be equally used according to present invention. Furthermore, the invention may equally apply to using technologies and components used in non-radio based through-the-air wireless systems such light (e.g. infrared) or audio (e.g. ultrasonic) based communication systems.
While the invention has been described with regard to the configuration wherein a single wireless oriented signal is carried over the wiring medium (such as utility or dedicated wiring LAN), it will be appreciated that the invention equally applies to the case wherein multiple such signal are carried using FDM. For example, additional IEEE802.1 g signal may be added to graph 40, occupying the frequency band of 32-54 Mb/s, hence not overlapping the signals shown. Furthermore, different such signals may be combined, and thus not limited to the same wireless oriented signal.
While the invention has been described with regard to networks using the same wireless technology (such as IEEE802.11g) by all modems connected to the wired medium, it will be appreciated that the invention equally applies to other embodiments wherein different but interoperable signals are employed.
While the invention has been described with regard to embodiments using a complete wireless solution based on existing components, including wireless MAC 13 b, baseband processor 18 and converter 16, it will be appreciated that the invention equally applies to other embodiments wherein one or more of theses components are used. As a non-limiting example, the MAC 13 b may be substituted with a wired-dedicated MAC, still employing all physical layer components. Similarly, other physical layer components may be used, still using the powerful wireless MAC 13 b. Furthermore, while the wireless signal, either as baseband, IF or RF form, has been described as only being frequency shifted, additional processing may also apply to the standard wireless signals and components, such as amplitude/level handling such as amplification and attenuation and frequency handling such as filtering. Such processing may be warranted in order to better adapt to the wired medium, improve reliability or reduce costs.
While the invention has been described with regard to wireless signals and systems carrying digital data, it will be appreciated that the invention equally applies to other embodiments wherein the wireless signals (and system) are used to carry analog signals. One non-limiting example involves cordless telephony. Cordless telephones are known to carry telephone (and control) signals over the air using ISM bands. Applying the invention allows for carrying the signals over any wired medium in general and over a utility wiring in particular. In the case of carrying the signals over telephone wiring, the above advantages are apparent, such as enlarging the coverage. Furthermore, such configuration may allow carrying multiple telephone signals over a single telephone pair.
Those of skill in the art will understand that the various illustrative logical blocks, modules and circuits described in connection with the embodiments disclosed herein may be implemented in any number of ways including electronic hardware, computer software, or combinations of both. The various illustrative components, blocks, modules and circuits have been described generally in terms of their functionality. Whether the functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans recognize the interchangeability of hardware and software under these circumstances, and how best to implement the described functionality for each particular application.
Although exemplary embodiments of the present invention have been described, this should not be construed to limit the scope of the appended claims. Those skilled in the art will understand that modifications may be made to the described embodiments. Moreover, to those skilled in the various arts, the invention itself herein will suggest solutions to other tasks and adaptations for other applications. It is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than the foregoing description to indicate the scope of the invention.
While the invention has been described in terms of preferred embodiments and generally associated methods, the inventor contemplates that alterations and permutations of the preferred embodiments and methods will become apparent to those skilled in the art upon a reading of the specification and a study of the drawings.
Accordingly, neither the above description of preferred exemplary embodiments nor the abstract defines or constrains the invention. Rather, the issued claims variously define the invention. Each variation of the invention is limited only by the recited limitations of its respective claim, and equivalents thereof, without limitation by other terms not present in the claim. In addition, aspects of the invention are particularly pointed out in the claims using terminology that the inventor regards as having its broadest reasonable interpretation; more specific interpretations of 35 U.S.C. section. 112 (6) are only intended in those instances where the term “means” is actually recited. The words “comprising,” “including,” and “having” are intended as open-ended terminology, with the same meaning as if the phrase “at least” were appended after each instance thereof.