CA2112342A1

CA2112342A1 - Bothway rf repeater for personal communications system

Info

Publication number: CA2112342A1
Application number: CA002112342A
Authority: CA
Inventors: Yoshiro Niki
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-12-30
Filing date: 1993-12-23
Publication date: 1994-07-01
Also published as: EP0605182A3; EP0605182A2; US5812933A; AU5245493A; AU672054B2

Abstract

ABSTRACT OF THE DISCLOSURE

A both-way RF repeater for use in a Personal Hand Phone system (PHP), a Personal Communications System (PCS), or in a Digital European Cordless Telephone (DECT), which are operated under the FDMA/TDD or TDMA/TDD or CDMA scheme, includes "up-stream" coaxial connectors to connect a common coaxial cable and/or two mutually isolated coaxial cables and/or an antenna system directed toward a base station, and "down-stream" coaxial connectors to connect one or more coaxial cables and/or antenna systems and/or RF radiation cables directed toward the subscribers within micro-cell serving areas. In addition, two mutually isolated amplifiers are provided for amplifying up-link and down-link RF signals.
A control circuit ensures that undesired self-oscillations are avoided. The control means includes at least one RF signal detector and a control circuit, which controls the linearity, output level, and/or gain of the amplifiers. By using the control means, the down-link amplifier gain is increased and the up-link amplifier gain is decreased simultaneously when the detector on the down-link amplifier detects RF signals transmitted from the base station.

Description

21123'~2 BOTH-WAY RF REPEATER FOR PERSONAL COMMUNICATIONS SYSTEM
The present invention relates generally to an amplifying facility for RF (Radio-Frequency) signals which are transmitted/received to/from one or more FDMA or TDMA/TDD or CDMA base stations, and more specifically relates to a both-way amplifying repeater for com~ined FDMA/TDD or ~DMA/TDD or CDMA RF carriers Personal Hand Phone (PHP) systems, which are also known in the art as a Personal Communications system (PCS) or a Personal Communications Network (PCN), have recently been introduced in a number of outdoor and/or indoor areas to provide wireless public telephone coverage for people who need to have access to public telephones from either inside or outside of their offices, or who otherwise cannot conveniently use the public telephones that are hard-wired to a PBX and/or a central switching office through conventional public telephone lines.
In a PHP system (or PCS), an area is divided into a plurality of small regions, or "micro-cells", each of which is covered by very low power (lOmW) transmitters. Currently, PHP system (or PCS) services are being provided on the 1.9 GHz frequency bands and operated in the FDMA/TDD or TDMA/TDD or CDMA scheme. In addition one transmitter and receiver set shares the same frequency carrier by dividing the time domain into two divisions. One of these divisions is used for "down-link" transmissions from a base station to the subscribers.
The "micro-cell site" is the location of the antenna from which the transmissions are effected for the micro-cell.
Another time division is used for "up-link" transmissions from the subscribers within the micro-cell for reception by the base station receiver. Currently, a stand-alone base station is set on the central of the micro-cell site. Each frequency carrier assigned for the PHP system has a 300 kilohertz bandwidth and for the CT-2 system has a 100 kilohertz bandwidth.
U.S. Patent Application Serial No. 7~7,332 discloses several embodiments of a cell enhancer system, having an ~ , . . .

' ~ " ' - , 21123~2 amplifier in various configurations for receiving, amplifying, and re-transmitting down-link signals from a cell site into an obstructed area, and also for receiving up-link signals from subscribers in the obstructed area, amplifying them and re-transmitting the amplified signals to the cell site. In one embodiment disclosed in that application, a single wide-band amplifier has an input terminal that receives both up-link and down-link signals from antennas through a duplexer network, and that transfers through another duplexer network amplified up-link and down-link signals to appropriate antennas for transmission. The wide-band a~plifier amplifies all signals in at least the two-cellular radio telephone frequency bands.
Problems may arise with the above-described cell enhancer when applied to PHP systems. Since the enhancer amplifies signals in the different frequency bands for up-links and down-links, a duplexer network can separate the RF
signals between the up-link and down-link with very large RF
isolations, and the wide-band amplifier can amplify all signals without undesired self-oscillation caused by the over-coupling between up-link and down-link amplifiers. However, since PHP systems adopt the FDMA/TDD or TDMA/TDD or CDMA
scheme, the same frequency carrier is assigned for up-link and down-link transmissions, and since the transmission and reception to/from a base station are divided into two time divisions, it is not possible to isolate the up-link and down-link signals with the conventional duplexer networks.
It is therefore an ob~ect of the present invention to provide an improved apparatus for amplifying the RF signals to and from a base station to enhance the coverage of a serving area where obstructions otherwise reduce the RF signal levels, and for distributing one or more FDMA/TDD, TDMA/TDD
or CDMA carriers into a plurality of micro-cell serving areas to ensure a higher efficiency of channel usage.
Preferably, the amplifier system has sufficient isolations between up-link and down-link amplifiers to amplify and re-transmit the RF signals assigned for the PHP system so as to a~oid an undesired self-oscillation caused by over-coupling between up-link and down-link amplifiers.
The apparatus of the invention includes any one or more of an "up-stream" coaxial cable, an RF radiation cable, and an antenna system directed toward a base station for receiving and transmitting the RF signals to and from the base station, and any one or more of a "down-stream" coaxial cable, an antenna system, and an RF radiation cable directed toward subscribers within each of the micro-cell serving areas, so as to transfer and/or radiate RF signals to and from the subscribers within a micro-cell serving area.
The amplifier system includes at least two mutually isolated amplifiers and optionally a control means for ensuring sufficient isolation between up-link and down-link amplifiers to avoid undesired self-oscillation caused by an over-coupling between up-link and down-link amplifiers.
In one embodiment, one common "up-stream" coaxial connector to connect a coaxial cable and/or ~F radiation cable directing toward a base station, and one or more "downstream"
coaxial connectors to connect one or more coaxial cables and/or antenna systems and/or RF radiation cables are provided to enhance and/or distribute the RF signals into a plurality of the micro-cell serving areas. Two isolated up-link and down-link amplifiers amplify the RF signals. When a detector detects an RF 6ignal transmitted from the base station, the control means increases the down-link amplifier gain and decreases the up-link amplifier gain simultaneously to avoid the above-mentioned self-oscillation. Alternatively, the control means at least supervises the conditions which cause ~uch self-oscillating conditions by comparing these outputs from the detectors, and if the conditions exceed predetermined limits, the control means decreases the amplifiers' gain immediately.
In a second embodiment, mutually isolated coaxial connectors to connect the coaxial cables and/or antenna

2~123~

systems and/or RF radiation cables directed toward a base station, and one or more "downstream" coaxial connectors to connect one or more coaxial cables and/or antenna systems and/or RF radiation cables are provided to enhance and/or distribute the RF signals into a plurality of the micro-cell serving areas. Two isolated up-link and down-link amplifiers amplify the RF signals. When a detector detects the RF
signals transmitted from the base station, the control means increases the down-link amplifier gain and decreases the up-link amplifier gain simultaneously to avoid the above-mentioned self-oscillation. Alternatively the control means at least supervises the conditions which cause such self-oscillating conditions by compering the outputs from the detectors, and if the conditions exceed predetermined limits, the control means decreases the amplifiers' gain immediately.
In a third embodiment, inputs and/or outputs of a plurality of base stations are combined and distributed toward the both-way RF repeaters, which are conveniently installed in a building, under ground, on a top of poles, and/or on an overhead wire cable, for example, to ensure higher efficiency of channel usage.
Further objects, features and advantages of the invention will become apparent from the following description of preferred embodiments when read in conjunction with the accompanying drawings, in which:
Figure 1 shows an in~tallation scheme of the both-way RF repeaters in accordance with the invention;
Figure 2 ~hows a system block diagram including a both-way RF repeater constructed in accordance with the invention;
Figure 3 showæ a block diagram of a both-way RF
repeater constructed in accordance with the invention;
Figure 4 shows a block diagram of a detector constructed in accordance with the invention;
35Figure 5 shows a block diagram of a controller constructed in accordance with the invention;

21123~2 Figure 6 shows a block diagram of an another type of amplifier constructed in accordance with the invention;
Figure 7 shows a system block diagram including a both-way RF repeater of the second embodiment of the invention;
Figure 8 shows a block diagram of a both-way RF
repeater of the second embodiment of the invention;
Figure 9 shows a system block diagram inoluding a both-way RF repeater of the third embodiment o~ the invention;
Figure 10 shows a block diagram of a both-way RF
repeater of the third embodiment of the invention;
Figure 11 shows a system block diagram including a both-way RF repeater of the fourth embodiment of the invention;
Figure 12 shows a block diagram of a both-way RF
repeater of the fourth embodiment of the invention;
Figure 13 shows a block diagram of a both-way R~
repeater of the fifth embodiment of the invention;
Figure 14 shows an antenna structure constructed in accordance with the invention; and Figure 15 shows a block diagram of a base station constructed in accordance with the invention; and Figure 16 shows a block diagram of a cell enhancer known in the prior art.
With re~erence to Figure 16, which depicts a cell enhancer as described in the aforementioned U.S. patent application Serial No. 787,332 a prior art cell enhancer includes an antenna system 83 which is directed for the base station 81, a second antenna system 84 which is directed for the subscribers 82 in an obstructed region, and an amplifier 91 which receives the signals from the base station 81 by the way of antenna system 83, amplifies them, and transmits them into the shadow region through antenna system 84. In addition, the cell enhancer 92 receives signals from subscribers 82 in the shadow region through antenna system 84, ~123~2 amplifies them and transmits them to the base station 81 through antenna system 83.
In the cell enhancer 92 depicted in Figure 16, the amplifier 91 is a single wide-band amplifier that is capable of amplifying all frequency carriers in the two twenty-megahertz radio frequency bands allocated to the cellular service, one band being for down-link transmission from the base station 81 to the subscribers 82 and the other band being for up-link transmission from the subscribers 82 to the base station 81. A duplexer 87 connected to antenna system 83 through a connector 85 receives radio frequency signals from the antenna system and transfers those in the appropriate 870 to 890 megahertz band to a second duplexer 89.
Duplexer 89 also has a second input terminal, which receives radio frequency signals from another duplexer 88, in one of the bands 825 to 845 megahertz, from antenna system 84 originating at a subscriber 82. Duplexer 89 couples the radio-frequency signals in the selected bands from both duplexers 87 and 88 to an input terminal of a wide-band amplifier 91.

After being amplified by the wide-band amplifier 91, the signals are coupled to the input terminal of another duplexer 90. Duplexer 90 couples the portion of the signals in the 825 to 845 megahertz band to an input terminal of duplexer 87 which couples the signals to antenna Cystem 83 for transmission to the base station 81. The duplexer 90 also couplQs the portion of the signal from the wide-band amplifier that is in the 870 to 890 megahertz band to an input terminal of duplexer 88, which couples the signal to antenna system 84 for transmission into the shadow area.
With reference to Figure 1, both-way RF repeaters 92A and 92B constructed in accordance with this invention are installed on a top of poles lOlA and lOlB, and connected toward the base station 81 through coaxial cables 13, 14 and RF radiation cable 15. RF signals transmitted from the base station 81 are sent through the coaxial cables 13, 14 and RF
radiation cable 15 (must be equal length to the base station if to get the equal time delay) to both-way RF repeaters 92A
and 92B, and amplified and radiated through antenna to the subscribers 82. Since the RF signals from the base station 81 are attenuated ~y the loss of the coaxial cables 13 and 14, the both-way RF repeaters s2A and 92B must amplify the RF
signals up to the required signal level. RF signals transmitted from subscribers 82 are pre-amplified by the both-way repeater 92B and 92A, and transferred through the coaxialcable 14 and 13 to the base station 81. The antenna 84 performs Microcell Serving Areas to serve these subscribers within these Areas. Instead of the antenna systems and/or coaxial cables, RF radiation cables (or leaky coaxial cable) can be used to radiate the RF signals totfrom subscribers.
With reference to Figure 2, both-way RF repeaters 92A and 92B constructed in accordance with this invention are connected toward a base station 81, which consists of one or more FDMA/TDD or TDMA/TDD or CDMA transmitters 2 and receivers

3, a RF combiner/divider 4, and a telephone line combiner 1, through a common coaxial cable 13, 14 and RF radiation cable 15. The both-way RF repeater 92A and 92B includes, as depicted in Figure 3, amplifiers 6 and 7, RF signal detectors 21-24, combiners 5 and 8A/8B, dividers 43A and 43B, coaxial connectors 11 and 12A/12B, and a control means 25. Since the transmitters 2 and receivers 3 are operated under the FDMA/TDD
or TDMA/TDD or CDMA scheme, these are not excited at the same time. When the base station transmit~ RF signals, the combiner 5 combines the down-link RF signals and lead them to the detector 21. The RF signals are amplified by the amplifier 6 and detected by the detector 23. If the detector 21 detects the RF signals and the output of the detector 21 is connected to the control means 25, the control means 25 controls the linearity of the amplifier 6 compering the output of the detector 21 with that of the detector 23 and decreases the gain of the amplifier 7 simultaneously. The RF signals ~. ,: - .

amplified and linearized are divided by the 43A and one of the output is combined by the combiner 8 and led them to the coaxial connectors 12A and 12B which are terminated by the "down-stream" antenna system 84A or 84B and RF radiation cable 15. When a subscriber transmits RF signals, the combiner 8A
or 8B combines the up-link RF signals and transfers them to a detector 24 through divider 43B. The RF signals are amplified by an amplifier 7 and then detected by a detector 22. If the detector 24 and 22 detect the up-link RF signals, the control means 25 controls the linearity of the amplifier 7, if needed, compering the output of the detector 22 with that of the detector 24, and decreases the gain of the amplifier 6 simultaneously unless the detector 21 detect any RF signals. The said RF signals are combined together by the combiner 5 and are lead to the coaxial connector 11 which is terminated by the "upstream" coaxial cable and/or antenna system. The control process are continued adaptively and the control parameters are memsrized even during the power supply is failed. Some of the detectors may be eliminated according to the design progress. The control means 25 is at least supervising the conditions which cause any self oscillating condition by compering these outputs from the detectors 21, 22, 23, and 24 and if the conditions exceed the limits, the control means 25 decreases the gain of amplifiers 6 and 7 immediately. If the more combiners are provided, the more coaxial cables and/or antenna systems and/or RF radiation cables can be connected to serve the different directions of the serving areas.
Figure 4 is a block diagram of the detector 21 which includes a directional coupler 44, a coupling loop 46, a terminated load 48, a detecting diode 45, and a by-pass capacitor 47. When the RF signals is applied from the terminal 30 to the terminal 31, a portion of them is coupled by a loop 46 and which is detected by a diode 45 and by-pass by a capacitor 47 and led to the terminal 35. Another end of the loop 46 is terminated by a load 48. If the RF signals are : .. : . .: ,,: ~- ., ~

3 ~ 2 given to the terminal 30, then the most of the RF signals are transferred to the terminal 31. Some amount of the RF signals are coupled to the loop 46 and detected into the DC voltage.
This block diagram depicts the case that the detectors detect the envelope or amplitude of the RF signals, but these detectors may detect the phase and/or frequency modulated signals over the RF signals and output the other signal schemes.
Figure 5 is a block diagram of the control means 25 which includes A/D converters 51-54, D/A converters 55 and 56, a control circuit 57, a random access memory (RAM) 58, and a read only memory (ROM) 59. When the detector 21 detects the RF signals and output the DC voltage and/or other signal schemes to the terminal 35, the output signal is converted from an analog signal to a digital signal by A/D converter 51.
By the same manner, the output signals from detectors 22, 23, and 24 are converted from an analog signal to digital signals by A/D converters 52-54. The control software is burned in the ROM 59 and according to which the linearity and/or gain of amplifiers 6 and 7 are controlled through the D/A
converters 55 and 56. These control parameters are memorized in the RAM 58 even when the power supply is failed. -Figure 6 is a block diagram of the amplifiers 6 or 7 which are usually constructed with only straight amplifiers 61 and 66. Besides of the straight amplifiers 61 and 66, mixers 62 and 65, a local oscillator 63, and a filter 64 are added. When RF signals are applied to the terminal 31, these RF signals are amplified by the amplifier 62, converted to an intermediate frequency by the mixer 62 combining the local .
frequency generated by the local oscillator 63, filtered by the filter 64, converted to an original frequency by the mixer 65 combining the local frequency generated by the oscillator 63, and then amplified and transferred to the terminal 32 by the straight amplifier 66 which gain is controlled through the terminal 36.

.: , . - ::
'' ' : ~ ' '' ' .
:

~23~2 With reference to Figure 7, both-way RF repeaters 92A and 92B of the second embodiment of the invention are connected toward a base station 81, which consists of one or more FDMA/TDD or TDMA/TDD or CDMA transmitters 2 and receivers S 3, and a telephone line combiner 1, through mutually isolated coaxial cables 13A/13B and 14A/14B and 15A/ 15B. The both-way RF repeater 92A and 92B includes, as depicted in Figure 8(A) and 8(B), amplifiers 6 and 7, dividers 43A and 43B, a combiner 8, and coaxial connectors llA, llB, 12A, 12B and 12C, though the both-way RF repeater 92B includes an additional coaxial connector 12D instead of a combiner 8. Since the transmitters 2 and receivers 3 have isolated terminals lOA and lOB and are operated under the FDMA/TDD or TDMA/TDD or CDMA scheme, these transmitters and receivers are isolated enough and not excited at the same time. When a base station 81 transmits RF
eignals, these RF signals are sent through coaxial cable 13A
and transferred to the terminal llA. These RF signals are amplified by the isolated amplifier 6, divided by the divider 43A, combined by the combiner 8, and led to the coaxial connector 12C which is terminated by the "downstream" antenna system 84. And another side of the divider 43A is terminated by the connector 12A. When a subscriber transmits RF signals, the combiner 8 and divider 43B led the up-link RF signals to the isolated amplifier 7. After amplified, the RF signals are led to the isolated terminal llB, connected to the isolated coaxial cable llB, and then lead to the receiver 3 in the base ~tation 81. Since all circuits except combiner 8 in the both-way RF repeaters 92A are isolated enough, there are enough margins to avoid an undesired self-oscillation caused by the over-coupling between up-link and down-link amplifiers.
Conditions between these parameters are:
2S + 2L + T/R > 2G
Where; S = Isolation of the combiner 8 in dB
L = Loss of the coaxial cables 14A and 14B in dB
T/R = Loss between Txansmitter and Receiver in dB
G = Gain of the amplifiers 6 and 7 in dB

. : - .. . . . :

.
- -:. : ; ~.,, " . .

2~123~

Since the gain of the amplifiers is set equal to the loss of coaxial cables (2L=2G), (2S+T/R)dB is a margin to avoid an undesired self-oscillations. If more combiners and dividers are provided in a RF repeater, RF signals can be distributed to the multiple directions. Since the both-way RF repeater 92B, as depicted in Figure 8(B), includes a coaxial connector 12D instead of the combiner 8, two isolated "downstream" antenna system and/or RF radiation cables can be connected to ensure the larger isolations between up-link and down-link amplifiers than that of the combiner 8.
With reference to Figure 9, both-way RF repeaters 92A and 92B of the third embodiment of the invention are connected toward a base station 81, which consists of one or more FDMA/TDD or TDMA/TDD or CDMA transmitters 2 and power amplifiers 16 and receivers 3, a RF combiner 4, and a telephone line combiner 1, through the common coaxial cables 13 and RF radiation cables 14 and 15. The RF radiation cables 14 and 15 radiates RF signals toward the vertical direction from the surface of the cables and couples RF signals to the subscribers and ensures Radio communications between the base station and subscribers. The both-way RF repeater 92A
includes, as depicted in Figure lO(A), an amplifier 7, an RF
~ignal detector 23, combiners 5 and 8, coaxial connectors 11 and 12, and a control mean6 25. Since the transmitter 2 and receiver 3 are operated under the FDMA/TDD or TDMA/TDD or CDMA
scheme, theee are not excited at the same time, but the power output of the transmitters 2 are amplified several times by the high power amplifiers 16. When the base station transmits RF signals, the combiner 5 combines the down-link RF signals and leads them to a detector 23. The RF signals are big enough and need not to amplify with an amplifier in the RF
repeater 92A and/or 92B. If the RF signals are detected by a detector 23, the control means 25 decreases the gain of the amplifier 7 simultaneously. The RF signals are combined by the combiner 8 and are led to the coaxial connector 12 which is terminated by the "downstream" RF radiation cable 14. When : ~ :

~1123~2 lZ
a subscriber transmits RF signals, the RF signals are coupled to the RF radiation cable 14 and the combiner 8 combines the up-link RF signals and transfers them to the amplifier 7 and then detected by a detector 22. When the detector 22 detects the RF signals, the control means 25 decreases the gain of the amplifier 7 simultaneously. The RF signals amplified are combined by the combiner 5 and led them to the coaxial connector 11 which is terminated by the "upstream" coaxial cable. These control process are continued adaptively as described above. The both-way RF repeater 92B, as depicted in Figure lO(B), the detector 21 and amplifier 6 are added to the above both-way RF repeater 92A which amplifies the down-link RF signals though it is pre-amplified by the power amplifier 16, since the repeater 92B is located far from the ba~e station 81.
With reference to Figure 11, a both-way RF repeater 92 of the fourth embodiment of the invention is coupled toward a base station 81, which consists of one or more FDMA/TDD or TDMA/TDD or CDMA transmitters 2 and receivers 3, a RF combiner

4, a "down-stream" antenna system 13, and a telephone line combiner 1, through the "up-stream" antenna system 83A and 83B
of the both-way RF repeater 92. The both-way RF repeater 91, as depicted in Figure 12, includes amplifiers 6 and 7, RF
signal detectors 21-24, coaxial connectors llA, llB, 12A and 12B, and a control means 25. The "down-stream" RF radiation cables and/or antenna systems 84A and 84B are connected to the connector 12A and 12B to couple through RF signals with subscribers within the micro-cell serving area. Since one or more transmitters 2 and receivers 3 are operated under the FDMA/TDD or TDMA/TDD or CDMA scheme, these are not excited at the same time. When the base station transmits RF signals, an antenna 83A receives the RF signals from the base station and which is transferred to a detector 21 which may be installed at the middle stage of the amplifier 6. The RF
signals are amplified by an amplifier 6 and detected by a detsctor 23. If the detector 21 detects the large RF signals, : : : , .: . , 3~

the control means 25 controls the linearity of the amplifier 6 compering the output of the detector 23 with that of the detector 21, and decreases the gain of the amplifier 7 simultaneously. The ~F signals amplified and linearized are led to the coaxial connector 12A which is terminated by the "down-stream" RF radiation cables and/or antenna systems 84A.
And a subscriber can recei~es these RF signals accordingly.
When a subscriber 82 transmits RF signals, the "down stream"
RF radiation cables and/or antenna systems 84B receives the up-link RF signals and transfer them to a detector 24 which may be installed at the middle stage of the amplifier 7. The RF signals are amplified by an amplifier 7 and then detected by a detector 22. If the detector 24 and 22 detect the up-link RF signals, the control means 25 controls the linearity of the amplifier 7 compering the output of the detector 22 with that of the detector 24, and decreases the gain of the amplifier 6 simultaneously if the detector 21 does not detect larger RF signals. The RF signals amplified and linearized by the amplifier 7 are led to the coaxial connector llB which is terminated by the "up-stream" antenna system 83B. These controls are continued adaptively and the control parameters are memorized even when the power supply is failed. Some of the detectors may be eliminated according to the design progres~.
With reference to Figure 13, both-way RF repeaters 92A and 92B of the fifth embodiment of the inventions are connected toward a base station 81, which consists of one or more FDMA/TDD or TDMA/TDD or CDMA transmitters 2 and receivers 3, and a telephone line combiner 1, through isolated coaxial cables 13A and 13B and/or 14A and 14B. The both-way RF
repeater 92A and 92B includes both-way amplifiers 6 and 7, a combiner 8, directional couplers 43A and 43B, and coaxial connectors llA, llB, 12A and 12B, though the both-way RF
repeater 92B includes the coaxial connector 12D instead of the combiner 8. Since the transmitters 2 and receivers 3 are isolated at the terminals lOA and lOB, and are operated under ., . ; ~ -21123~2 the FDMA/TDD or TDMA/TDD or CDMA scheme, these are isolated enough and not excited at the same time. When the base station transmits RF signals, the signals are transferred through the coaxial cable 13A and reached to the terminal llA.
These signals are coupled with the directional coupler 43A and amplified by the isolated amplifier 6, combined by the combiner 8, and led to the coaxial connector 12C which is terminated by the "down-stream" antenna systems and/or RF
radiation cables 84A. When a subscriber 82 transmits RF
signals, the combiner 8 combines the up-link RF signals and led to the isolated amplifier 7. After amplified, the RF
signals are led to the directional coupler 43B and then isolated terminal llB. The RF signals then sent out to the isolated coaxial cable 13B, and led to the receivers 3 in the base station 81. Since the all circuits except combiner 8 in the both-way RF repeaters 92A are isolated enough, there are enough margins to avoid an undesired self-oscillation caused by the over-coupling between up-link and down-link amplifiers.
Conditions between parameters are:
2S + 2C + 2L + T/R > 2G
Where; S = Isolation of the divider 8 in dB
C = Loss of the directional coupler in dB
L = Loss of the coaxial cables 14A and 14B in dB
T/R = Loss between Transmitter and Receiver in dB
G = Gain of the amplifiers 6 and 7 in dB
Since the gain of the amplifiers is set equal to the 1058 of coaxial cables, (2S+2C+T/R) dB is a margin to avoid an undesired self-oscillations. This method is applicable for the usage of common coaxial cables as in Figure 2 or 9 with a common directional coupler. Since the both-way RF repeater ~2B includes a coaxial connector 12D instead of the combiner 8, two isolated "downstream" antenna systems and/or RF
radiation cables can be connected to ensure the larger isolations between up-link and down-link amplifiers than that of the combiner 8.

2~23~

With reference to Figure 14, an antenna structure which constructed in accordance with this invention includes a ground plane 71, a shielding box 72, a helical antenna 73, and a coaxial connector 11. Standing waves are so often observed under the indoor radio propagation conditions and these degrade the ~uality of the indoor radio communications.
If an antenna has a ground plan 71, such standing waves always generate the "zero potential" at the surface of the ground plan 71. Since this type of antenna is dasigned by considering the fact that the potential of the ground surface i8 always "zero", a good reception of the RF signals are always being maintained even if the standing waves are existing. To minimize the connection loss between the "down-stream" antenna system and a both-way RF repeater and to keep a compact size, it is essential to put a both-way RF repeater within a shielding box 72. Instead of a helical antenna, other types of ground plan type antennas are applicable such as an ground plan array antenna, a parabolic antenna, corner reflector antenna, patch antenna, or etc.
With reference to Figure 15, a base station which constructed in accordance with this invention includes telephone line interface circuits 1, two or more FDMA/TDD or TDMA/TDD or CDMA transmitters 2a, 2b and 2c, two or more FDMA/TDD or TDMA/TDD or CDMA receivers 3a, 3b and 3c, a transmitter combiner 4A, a receiver divider 4B, and isolated coaxial connectors lOA and lOB. Comparison table is shown hereunder which describes the number of TDMA/TDD transmitters and receivers vs traffic capacity, when the TDMA/TDD has 4 time slots, and one control slot per one base station is a8signed, and 1% of blocking rate i~ applied. As ~hown in the Table, if the Transmitter outputs and Receiver inputs are combined and/or divided, the traffic capacities are increased drastically according to the increment of the number of Transmitters and Receivers.

21~23~2 _ ..
No. of B/S Stand alone Combined & Distributed 1 0.45 Erlang 0.45 Erlang 2 0.45 x 2 = 0.9 2.48 x 1 = 2.48 3 0.45 x 3 = 1.35 5.1 x 1 = 5.1 4 0.45 x 4 = 1.8 8.0 x 1 = 8.0 Another problem area for the digital signal transmissions over the radio frequencies is the bad Bit Error Rate under the delay spread circumstances caused by the multi-path propagations. A RF radiation cable (or a Leaky coaxialcable) and/or a RF radiation wave guide are very much effective to eliminate such problem and to ensure the good Bit Error Rate even under the delay spread circumstances. For such purposes, coaxial cables and/or antenna systems shown in Figure~ 1, 2, 7, 9, 11 and 13 can be replaced by an RF
radiation cable (or leaky coaxial cable) or a RF radiation wave guide or similar means.
When the Listen-before-talk is required, either a base station or subscriber must monitor the RF carriers wether occupied or not. When the transceivers and receivers are operated under the FDMA/TDD or TDMA/TDD or CDMA scheme, the receiver in the base station must have the capability to monitor the RF carriers even if the transmitter, which is located close to the said receiver, is transmitting the RF
signals, and which may desensitize the receiver sensitivity.
The separated antenna systems and/or RF radiation cables as depicted as the both-way RF repeater 92B in Figure 7 or Figure 13 are very much effective to resolve these problems.
The foregoing descriptions are limited to a specific embodiment of this invention. It will be apparent, however, that this invention can be practised in systems having diverse basic constructions or that use different internal circuitry than is described in the specifications with some or all of the appended claims to cover all such variations and - ~1123~2 modifications which come within the true spirit and scope of this invention.

. ,.i -~

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A both-way RF repeater for combining, distributing, and enhancing at least one of the group of FDMA/TDD(Frequency Division Multiple Access/Time Division Duplex), TDMA/TDD (Time Division Multiple Access/Time Division Duplex), and CDMA (Code Division Multiple Access) carrier signals in a Personal Communications System, said RF repeater comprising:
(a) isolated up-link and down-link amplifiers for amplifying respective RF signals;
(b) first isolated up-link and down-link connectors for connecting transmission means directed toward a base station; and c) second isolated up-link and down-link connectors for connecting transmission means directed toward subscribers and/or a next stage of said both-way RF repeater;
each said transmission means comprising any one or more of the group of mutually isolated coaxial cables, antenna systems, and RF radiation cables;
whereby a high efficiency of frequency usage in a serving area, and good quality communications between a base station and a subscriber, can be obtained.

2. A both-way RF repeater for combining, distributing, and enhancing at least one of the group of FDMA/TDD, TDMA/TDD and CDMA carrier signals in a Personal Communications System, said RF repeater comprising:
(a) isolated up-link and down-link amplifiers for amplifying respective RF signals;
(b) isolated up-link and down-link connectors for connecting transmission means directed toward a base station;
and (c) at least one combiner for combining said up-link amplifier and down-link amplifier, said combiner being capable of connecting "down-stream" emitter/receiver means directed toward subscribers, and cable means directed toward a next stage of the both-way RF repeater;
said transmission means comprising any one or more of the group of mutually isolated coaxial cables, antenna systems, and RF radiation cables;
said cable means comprising of any one or more of the group of common coaxial cables and mutually isolated coaxial cables;
said emitter/receiver means comprising any one or more of the group of antenna systems and RF radiation cables;
whereby a high efficiency of frequency usage in a serving area, and good quality communications between a base station and a subscriber, can be obtained.

3. A both-way RF repeater as claimed in claim 2, further comprising at least one divider for dividing said up-link amplifier and down-link amplifier, said divider being capable of connecting "down-stream" emitter/receiver means directed toward subscribers, and cable means directed toward a next stage of the both-way RF repeater.

4. A both-way RF repeater for combining, distributing, and enhancing at least one of the group of FDMA/TDD, TDMA/TDD and CDMA carrier signals in a Personal Communications System, said RF repeater comprising:
(a) isolated up-link and down-link amplifiers for amplifying respective RF signals;
(b) isolated up-link and down-link connectors for connecting transmission means directed toward a base station;
and (c) at least one divider for dividing said up-link amplifier and down-link amplifier, said divider being capable of connecting "down-stream" emitter/receiver means directed toward subscribers, and cable means directed toward a next stage of the both-way RF repeater;

said transmission means comprising any one or more of the group of mutually isolated coaxial cables, antenna systems, and RF radiation cables;
said cable means comprising of any one or more of the group of common coaxial cables and mutually isolated coaxial cables;
said emitter/receiver means comprising any one or more of the group of antenna systems and RF radiation cables;
whereby a high efficiency of frequency usage in a serving area, and good quality communications between a base station and a subscriber, can be obtained.

5. A both-way RF repeater as claimed in claim 4, further comprising at least one combiner for combining said up-link amplifier and down-link amplifier, said combiner being capable of connecting "down-stream" emitter/receiver means directed toward subscribers, and cable means directed toward a next stage of the both-way RF repeater.

6. A both-way RF repeater for combining, distributing, and enhancing at least one of the group of FDMA/TDD, TDMA/TDD and CDMA carrier signals in a Personal Communications System, said RF repeater comprising:
(a) isolated up-link amplifier and down-link amplifier for amplifying respective RF signals;
(b) at least one combiner to combine said up-link amplifier and down-link amplifier, and to connect at least one of the group of cable means and RF radiation cables directed toward a base station; and (c) isolated up-link connector and down-link connector to connect at least one transmission means directed toward subscribers;
said transmission means comprising any one or more of the group of mutually isolated coaxial cables, antenna systems, and RF radiation cables;

said cable means comprising of any one or more of the group of common coaxial cables and mutually isolated coaxial cables;
whereby a high efficiency of frequency usage in a serving area, and good quality communications between a base station and a subscriber, can be obtained.

7. A both-way RF repeater as claimed in claim 6, further comprising at least one divider to divide said up-link amplifier and down-link amplifier, and to connect at least one of the group of cable means and RF radiation cables directed toward a base station.

8. A both-way RF repeater for combining, distributing, and enhancing at least one of the group of FDMA/TDD, TDMA/TDD and CDMA carrier signals in a Personal Communications System, said RF repeater comprising:
(a) isolated up-link amplifier and down-link amplifier for amplifying respective RF signals;
(b) at least one divider to divide said up-link amplifier and down-link amplifier, and to connect at least one of the group of cable means and RF radiation cables directed toward a base station; and (c) isolated up-link connector and down-link connector to connect at least one transmission means directed toward subscribers;
said transmission means comprising any one or more of the group of mutually isolated coaxial cables, antenna systems, and RF radiation cables;
said cable means comprising of any one or more of the group of common coaxial cables and mutually isolated coaxial cables;
whereby a high efficiency of frequency usage in a serving area, and good quality communications between a base station and a subscriber, can be obtained.

9. A both-way RF repeater as claimed in claim 8, further comprising at least one combiner to combine said up-link amplifier and down-link amplifier, and to connect at least one of the group of cable means and RF radiation cables directed toward a base station.

10. A both-way RF repeater for combining, distributing, and enhancing at least one of the group of FDMA/TDD, TDMA/TDD and CDMA carrier signals in a Personal Communications System, said RF repeater comprising:
(a) isolated up-link amplifier and down-link amplifier to amplify RF signals;
(b) at least one first combiner for combining said up-link amplifier and down-link amplifier, and to connect at least one of the group of cable means and RF radiation cables directed toward a base station; and (c) at least one second combiner for combining said up-link amplifier and down-link amplifier, and to connect one or more "down-stream" emitter/receiver means directed toward subscribers, and at least one cable means directed toward the next stage of the both-way RF repeaters;
said cable means comprising any one or more of the group of common coaxial cables and mutually isolated coaxial cables;
said emitter/receiver means comprising any one or more of the group of antenna systems and RF radiation cables;
whereby a high efficiency of frequency usage in a serving area, and good quality communications between a base station and a subscriber, can be obtained.

11. A both-way RF repeater as claimed in claim 10, further comprising at least one first divider for dividing said up-link amplifier and down-link amplifier, and to connect at least one of the group of cable means and RF radiation cables directed toward a base station.

12. A both-way RF repeater as claimed in claim 10 or 11, further comprising at least one second divider for dividing said up-link amplifier and down-link amplifier, and to connect one or more "down-stream" emitter/receiver means directed toward subscribers, and at least one cable means directed toward the next stage of the both-way RF repeaters.

13. A both-way RF repeater for combining, distributing, and enhancing at least one of the group of FDMA/TDD, TDMA/TDD and CDMA carrier signals in a Personal Communications System, said RF repeater comprising:
(a) isolated up-link amplifier and down-link amplifier to amplify RF signals;
(b) at least one first divider for dividing said up-link amplifier and down-link amplifier, and to connect at least one of the group of cable means and RF radiation cables directed toward a base station; and (c) at least one second divider for dividing said up-link amplifier and down-link amplifier, and to connect one or more "down-stream" emitter/receiver means directed toward subscribers, and at least one cable means directed toward the next stage of the both-way RF repeaters;
said cable means comprising any one or more of the group of common coaxial cables and mutually isolated coaxial cables;
said emitter/receiver means comprising any one or more of the group of antenna systems and RF radiation cables;
whereby a high efficiency of frequency usage in a serving area, and good quality communications between a base station and a subscriber, can be obtained.

14. A both-way RF repeater as claimed in claim 13, further comprising at least one first combiner for combining said up-link amplifier and down-link amplifier, and to connect at least one of the group of cable means and RF radiation cables directed toward a base station.

15. A both-way RF repeater as claimed in claim 13 or 14, further comprising at least one second combiner for combining said up-link amplifier and down-link amplifier, and to connect one or more "down-stream" emitter/receiver means directed toward subscribers, and at least one cable means directed toward the next stage of the both-way RF repeaters.

16. A both-way RF repeater as defined in claim 1, 2, 4, 6, 8, 10 or 13, wherein said amplifiers comprise:
at least one detector means to detect RF signal levels; and control means to control one or more of the gain, linearity and output level of said amplifiers.

27. A both-way RF repeater as defined in claim 1, 2, 4, 6, 8, 10 or 13, wherein said amplifiers comprise at least one of the group of a straight amplifier and a mixer and bandpass filter.

18. A both-way RF repeater as defined in claim 2, 4, 6, 8, 10 or 13, wherein said combiner comprises a circulator, an electronic switch, a directional coupler, a hybrid circuit, and at least one of the group of a multi-branch divider and a multi-branch combiner.

19. A both-way RF repeater as defined in claim 2, 4, 6, 8, 10 or 13, wherein said divider comprises a circulator, an electronic switch, a hybrid circuit, a directional coupler, and at least one of the group of a multi-branch divider and a multi-branch combiner.

20. A both-way RF repeater as defined in claim 16 wherein:
(a) said detector means are connected in relation to any one or more of the input stage, middle stage, and output stage of the amplifiers; and (b) said control means at least control the output level of the down-link amplifier and/or the gain of the up-link amplifier.

21. A both-way RF repeater as defined in claim 1, 2, 4, 6, 8, 10 or 13, wherein said antenna systems comprise an anti-standing-wave RF reception means which has a ground plane or reflector and a radiating element or slot, and further comprising one of;
(a) an array antenna with reflector;
(b) a parabolic antenna or a corner reflector antenna;
(c) other type of antenna which has a ground plane or reflector;
(d) an RF radiation coaxial cable (or leaky coaxial cable) and/or a RF radiation wave guide or similar structures having an outer (ground) conductor and radiating slots; or (e) a RF radiation cable which has an inner (ground) conductor and radiating surfaces.

22. A both-way RF repeater as defined in claim 1, 2, 4, 6, 8, 10 or 13, wherein the transmission means comprise at least one of;
RF transmission and/or radiation/reception means which constitute RF radiating/receiving elements or slots disposed in a line; and RF transmission and/or radiation/reception means which are mutually isolated between up-link and down-link circuits.

23. A both way RF repeater as defined in claim 1, 2, 4, 6, 8, 10 or 13, wherein said base station comprises;
(a) at least one transmitter and receiver operated in any one of the FDMA/TDD, TDMA/TDD, or CDMA schemes; and (b) at least one combiner to combine one or more transmitters.

24. A both-way RF repeater as defined in claim 1, 2, 4, 6, 8, 10 or 13, wherein said base station comprises;
(a) at least one transmitter and receiver operated in any one of the FDMA/TDD, TDMA/TDD, or CDMA schemes; and (b) at least one divider to divide one or more receivers.

25. A both-way RF repeater as defined in claim 1, 2, 4, 6, 8, 10 or 13, wherein said both-way RF repeaters can be:
(a) installed within a building, underground, on top of a pole, on an overhead wire cable, and/or on a constructed structure;
(b) connected toward a base station in series and/or in parallel through either one of coaxial cables and RF radiation cables;
(c) supplied with electric power through a conductor of either of said coaxial cables and RF radiation cables; and (d) composed with the CATV signals and/or other signals through RF transmission cables.