WO2001078255A1 - Procede et appareil de combinaison de temps de propagation de reception en diversite dans un repeteur de systeme sans fil - Google Patents

Procede et appareil de combinaison de temps de propagation de reception en diversite dans un repeteur de systeme sans fil Download PDF

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Publication number
WO2001078255A1
WO2001078255A1 PCT/US2000/009684 US0009684W WO0178255A1 WO 2001078255 A1 WO2001078255 A1 WO 2001078255A1 US 0009684 W US0009684 W US 0009684W WO 0178255 A1 WO0178255 A1 WO 0178255A1
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WIPO (PCT)
Prior art keywords
signal
cells
telecommunication system
wireless telecommunication
wireless
Prior art date
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PCT/US2000/009684
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English (en)
Inventor
Michael Komara
Thomas Schmutz
John R. Noll
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Airnet Communications Corporation
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Publication date
Application filed by Airnet Communications Corporation filed Critical Airnet Communications Corporation
Priority to PCT/US2000/009684 priority Critical patent/WO2001078255A1/fr
Priority to AU2000243410A priority patent/AU2000243410A1/en
Publication of WO2001078255A1 publication Critical patent/WO2001078255A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0891—Space-time diversity
    • H04B7/0894—Space-time diversity using different delays between antennas
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/155—Ground-based stations
    • H04B7/17—Ground-based stations employing pulse modulation, e.g. pulse code modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
    • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
    • H04B7/2603—Arrangements for wireless physical layer control
    • H04B7/2606—Arrangements for base station coverage control, e.g. by using relays in tunnels

Definitions

  • This invention relates generally to wireless communication systems. More specifically, this invention relates to remote repeaters in wireless communication systems and in particular to a method and apparatus for employing delay combining for receive diversity in a wireless system repeater.
  • GSM Global System for Mobile Communications
  • CMT Cellular Mobile Telephone
  • PCS Personal Communication Services
  • a type of base station equipment known as a multicarrier broadband Base Transceiver System (BTS) has been developed which is intended to serve a large number of active mobile stations in each cell .
  • BTS broadband Base Transceiver System
  • Such broadband BTS equipment can typically service ninety-six simultaneously active mobile stations, at a significant cost per channel .
  • While this equipment is cost effective to deploy when a large number of active mobile stations is expected in each cell, it is not particularly cost effective in most other situations. For example, during an initial system build out phase, a service provider does not actually need to use large numbers of radio channels. It is therefore typically not possible to justify the cost of deploying complex multicarrier broadband transceiver system equipment based only upon the initial number of subscribers. As a result, the investment in broadband multicarrier radio equipment may not be justified until such time as the number of subscribers increases to a point where the channels are busy most of the time. Furthermore, many areas exist where the need for wireless communication systems is considerable, but where signal traffic can be expected to remain low indefinitely (such as in rural freeway locations or large commercial/industrial parks) .
  • any device with a single uplink receive antenna will suffer from severe Rayleigh fading, or destructive wave inter erence, of widely varying magnitude, due to the wave cancellation effects of reflected and retransmitted signals.
  • severe Rayleigh fading, or destructive wave inter erence of widely varying magnitude, due to the wave cancellation effects of reflected and retransmitted signals.
  • the likelihood of Rayleigh fading or multipath distortion increases proportionally to an increase in the distance between the mobile unit and the base station.
  • the use of two spatially diverse antennas for the uplink signal from the mobile station will provide diversity gain and mitigate deep fades since fades will generally occur at a different time for one antenna relative to a spatially separated second antenna.
  • the use of multiple antennas can accompany increased frequency usage in the "backhaul" frequency band employed for communication between the BTS and the cell range-extending remote base station device.
  • the use of selective diversity will mitigate this effect.
  • GSM-1900 formerly PCS-1900
  • GSM-1800 (formerly PCS-1900)
  • the uplink signal strength from a mobile station can vary by as much as 80 dB, typically from -25 dBm to below -105 dBm.
  • the uplink signal strength can vary by as much as 92 dB, typically from -13 dBm to below -105 dBm. This large range of signal strength necessarily restricts the distance of successful propagation of the backhaul signal from the range extending remote base station device to the BTS.
  • Camarillo, California consists of a base station translator which samples downlink signal traffic and translates it to a selected offset frequency.
  • the offset carrier is transmitted to an expansion cell site via directional antennas .
  • the carrier is translated back to the original cellular channel and transmitted throughout the expansion cell site coverage area such as via an omnidirectional antenna.
  • a cellular signal received by the expansion cell site from a mobile unit is translated and then transmitted back to the base station translator, which in turn translates the signal back to its original carrier frequency.
  • TDMA Time Division Multiple Access
  • Such a system makes use of a technique in which multiple voice or data channels are provided by dividing the access to each radio carrier frequency into carefully synchronized time slots.
  • a timing advance In order to demodulate a TDMA signal properly at the base station, a timing advance must be taken into consideration for each radio pulse received from the mobile stations. The timing advance serves to compensate for the differences in signal propagation time since the distance to the base station is different for each mobile station.
  • a TDMA signal transmitted in the uplink direction must therefore arrive at the Base Transceiver System with proper time alignment. If this is not the case, the signal pulses from the various mobile stations will collide, and it will not be possible for the Base Transceiver System to demodulate the signals properly. As such, it has in most instances been necessary to limit the nominal radius of a TDMA cell so that proper time alignment may be maintained.
  • the Goedecker technique has been expanded in U.S. Patent No. 5,825,764, issued to Rudolph and also assigned to Alcatel N.V. Rudolph discloses a method of extending the range of a cell served by a GSM-type base transceiver station in concentric rings of 35 km width by co-locating an additional pair of standard TDMA receiver and auxiliary TDMA receiver for each successive ring, thereby theoretically permitting the range of a single cell to be extended continuously in any direction.
  • the Goedecker technique is intended for use where both radio transceivers can be located entirely within the base station site. This permits the timing signals for the auxiliary TDMA receiver to be directly connected to the timing signals for the standard TDMA receiver.
  • HPT, Goedecker, and Rudolph designs can be used to extend the radius of a single cell, they do not appear to suggest how to synchronize TDMA signals received from multiple mobile stations located in multiple cells simultaneously, and in the cases of HPT and Goedecker, they do not suggest any form of random access control channel processing of initial uplink transmissions from mobile' stations.
  • Kaisha discloses a mobile telephone system in which a number of repeater stations are installed at the boundary points of hexagonally shaped cells.
  • the repeaters define a small or minor array which is, in effect, superimposed on a major array of conventional base stations installed at the center of the cells. With this arrangement, any signals received in so-called minor service areas by the repeaters are relayed to the nearest base station.
  • Switched diversity techniques typically include two spatially separated antennas with an electronic selection mechanism to choose the strongest signal of the two paths. Multipath fading will normally occur at each separate receive antenna at a different time due to their spatial separation, so automatically selecting the stronger of the two signals mitigates the deep fades that would be intermittently or continually present if only one antenna were employed.
  • the diversity switching must be conducted independently for each of the 8 time slots on a given RF carrier.
  • the actual switch must be made during the 3 -bit guard period at the beginning of each signal burst, and not during the active 147 bits of data. This carefully timed switching can be accomplished by using rapid power detection of both receive signal paths while delaying the received signals through bulk delay elements and making the switch during the guard period.
  • this technique requires careful timing and additional hardware in order to engage.
  • An alternative to switched diversity is frequency diversity, wherein two separate backhaul signals-one for each antenna-are transmitted on separate frequencies from the translating repeater to the multichannel host BTS .
  • This technique has the disadvantage of being extremely hardware intensive, as nearly twice as much hardware is required to transmit the two separate backhaul signals. Also, twice as many backhaul frequencies are required in the uplink. Furthermore, the multichannel host BTS is required to receive both frequencies and make the diversity selection. This creates the need for the careful timing and additional hardware as earlier described, as well as increasing the number of costly receivers required for the multichannel host BTS.
  • Another object is to provide for spatial diversity to eliminate multi-path Rayleigh fading.
  • a further object is to employ delay combining to produce signal-to-noise ratio performance similar to that achieved with switching diversity methods.
  • the invention is based on an architecture for a wireless communication system in which cells are grouped into clusters.
  • a host cell location is identified within each cluster and a multicarrier broadband Base Transceiver System (BTS) is located at or near the host cell- site.
  • BTS Base Transceiver System
  • translating radio transceivers are located in the remote cells. These translating radio transceivers operate in-band, that is, within the frequencies assigned to the service provider.
  • the in-band translators operate in both an uplink and downlink direction. That is, uplink signals transmitted by a mobile station located in a remote cell are received at the in-band translator, translated to a different carrier frequency, and then transmitted to the host BTS. Likewise, downlink signals transmitted by the host BTS are first received by the in-band translator, translated to a different carrier frequency, and then repeated out to the mobile stations at high power.
  • the host BTS measures a time delay for each in-band translator channel during a calibration mode. This is accomplished by setting the inband translator to a loop-back mode whereby the high-power translated downlink signal received from the host BTS is coupled and mixed via frequency translation back to the BTS via the uplink transmit path.
  • a timing test signal in the form of, for example, a random access control channel (RACCH) burst is then transmitted by the host BTS such as would normally be sent by a mobile station.
  • the RACCH burst is received by the in-band translator and looped back to the host BTS .
  • the host BTS then demodulates the looped back signal, and measures the elapsed time interval between the transmission and reception of the loop-back signal at the host BTS.
  • a resulting round-trip time-of-arrival delay estimate as measured in the downlink and uplink path is then calculated and used by the host BTS to compensate for time alignments to be made in the time slots for the downlink and uplink signals during normal operation.
  • the time delay limitation on the backhaul distance of the cell site normally associated with Time Division Multiple Access protocols is avoided. Indeed the range of such a system is limited only by the expected attenuation in the radio link. The time delay limitation applies only to the distance of the mobile unit from the range extending repeater-translator remote base station.
  • the in-band translator introduces a small time delay between the two spatially separate receive paths, which serves to maximize the quality of the received signals. Both signals are broadly filtered
  • ALC fast automatic level control
  • the delay combining diversity of the present invention eliminates the need to detect signal strength of both uplink paths and switch to the stronger signal on a burst-by-burst basis with precise timing, as in prior art switched diversity systems.
  • delay combining diversity takes advantage of the "adaptive delay equalization" inherent in base station processing in GSM-based systems such as GSM-1900, GSM-1800, and GSM-900 systems.
  • the delay equalization processing removes up to 16 .sec of delay spread (4.33 bits at 1900 MHz) from a received signal .
  • the in-band translator compensates for deep Rayleigh fades occurring in uplink signals received from randomly positioned mobile stations, by allowing the stronger signal to dominate when the spatially separate receive path signals are separated and demodulated as one signal.
  • the combined signal has a similar signal-to-noise ratio as a signal selected through a switching diversity method, yet no switching hardware or slot-by-slot timing is required.
  • Fig. 1 is a view of a cell site cluster showing how a host Base Transceiver System (BTS) , in-band translators, and mobile stations are deployed according to the invention
  • Fig. 2 is a block diagram of the components of the system
  • Fig. 3 is a detailed block diagram of a translator embodying the present invention in a PCS-1900 system.
  • FIG. 1 illustrates a wireless communication system 100 such as a Cellular Mobile Telephone, Personal Communication System (PCS) , or similar system in which employing delay diversity combining in the uplink signal paths of a wireless system repeater translator enables proper demodulation at the BTS of signals received from in-band frequency translating- repeater remote base stations deployed in peripheral cells.
  • the system 100 provides voice and or data communication between mobile stations 19 and a Public Switched Telephone Network (PSTN) via radio signals.
  • PSTN Public Switched Telephone Network
  • the radio signaling protocol uses a Time Division Multiple Access (TDMA) technique such as the GSM- 1900 (formerly PCS-1900) standard promulgated by the Telecommunications Industry Association (TIA) in the United States which adopts all relevant aspects of the Global System for Mobile Communication (GSM) standard developed by the Groupe Special Mobile, and promulgated in Europe and elsewhere by the European Telecommunication Standards Institute (ETSI) .
  • TDMA Time Division Multiple Access
  • GSM- 1900 now PCS-1900
  • Telecommunications Industry Association Telecommunications Industry Association
  • GSM Global System for Mobile Communication
  • ETSI European Telecommunication Standards Institute
  • the in-band translators (IBTs) 120-1, 120-2, . . . , 120- n are each located in what is normally to be approximately the center of a respective cell site 220-1, 220-2, . . . , 220-n among a group or cluster 240 of cells.
  • the in-band translators 120 receive radio signals from the mobile stations
  • BTS 150 Base Transceiver System
  • radio signals originating at the host BTS 150 are forwarded by the translators 120 to the mobile stations 200.
  • the signals associated with all of the mobile stations 200 located within the cluster 240 of cells 220-1, . . . , 220-n are thereby processed at the host BTS 150.
  • the in-band translators 120 are configured as "base stations" in the sense that they are each associated with a particular cell 220 and in that they each receive and transmit multiple signals from and to the mobile stations 200.
  • the in-band translators 120 do not perform demodulation and modulation functions as does a. conventional base station. Rather, they serve only to perform in-band frequency-translation and amplification of signals received ' from the mobile stations 200 and then direct such signals on a different frequency to the multichannel host BTS 150.
  • the in- band translators 120 also perform the inverse function, to translate the frequency of signals received from the host BTS 150 and then direct them to the mobile stations 200.
  • the system 100 more particularly includes pairs of translator omni-directional antennas 300-1-la and 300-1-lb, . . , 300-l-12a and 300-1- 12b,. . .- , 300-n-la and 300-n-lb, . . , 300-n-12a and 300-n-
  • the antenna pairs are connected to in-band translator base stations (wireless translating range extenders) 310-1-1, . . . , 310-1-12, . . ., 310-n-l, . . . , 310-n-12, translator base station directional antennas (backhaul antennas) 320-1-1, . .
  • 320-1-12 . . ., 320-n-l, . . . , 320-n-12
  • BTS Base Transceiver Systems
  • 340-n one or more base station controllers 350, a mobile switching center 360, and mobile stations 370-1, 370-2.
  • the host BTSs 340-1, . . . , 340-n are responsible for demodulating radio signals as well as for connecting such signals to a landline network through one or more base station controllers 350 and the mobile switching center 360.
  • the landline network is typically a Public Switched Telephone Network (PSTN) or an Integrated Digital Service Network (ISDN) , but it may also be a Public Land Mobile Network (PLMN) , or a Packet Switched Data Network (PSDN) .
  • PSTN Public Switched Telephone Network
  • ISDN Integrated Digital Service Network
  • PLMN Public Land Mobile Network
  • PSDN Packet Switched Data Network
  • each particular host BTS e.g. multichannel host BTS 340-1 serves the multiple in-band translators associated with a given cluster 240 of cells 220, e.g. in-band translators 310-1-1, . . . , 310-1-12.
  • each multichannel host BTS 340-1 and 340- n is depicted as serving its maximum number of twelve in-band translators 310-1-1, . . . 310-1-12, and 310-n-l, . . . , 310- n-12, respectively.
  • the Base Station Controller (BSC) 350 of which there may be more than one, has a number of functions. The primary function is to manage the logical connections made between mobile stations 370 and the landline network. In order to do so, the Base Station Controller 350 assigns transmit and receive radio carrier frequencies to each individual mobile station 370, in-band translator 310, and host BTS 340.
  • Fig. 3 is a detailed block diagram of the components of an exemplary in-band translator 310 employing the delay combining of the present invention.
  • the translator 310 shifts the carrier frequency of the signals received from one link (e.g. ground, for communication with a mobile station), to the appropriate transmit frequency for the other link (e.g. backhaul, for communication with a multichannel base station) .
  • the illustrated translator 310 also acts as a type of spatial diversity converter for the uplink direction as has already been mentioned. In particular, because no signal uses a radio frequency which is in use in the same cell for more than one type of link, the translator 310 may take advantage of spatial diversity reception on the backhaul link and use delay combining diversity to maintain the information over the backhaul link.
  • the translator 310 consists of translated signals received from the mobile link by the pair of spatially diverse omnidirectional antennas, 300a and 300b.
  • omnidirectional antenna 300a is receive only, while omnidirectional antenna 300b is transmit/receive.
  • antennas 300a and 300b are spaced at least 8 wavelengths apart, or more than 4 feet at 1900 MHz, using the GSM-1900 standard of the current embodiment.
  • a separate receive filter 400 and the receive portion of a duplexer 405 provide a portion of the receive signal to a pair of intermediate frequency (IF) signal processing chains consisting of a pair of low noise amplifiers (LNA) 410a, 410b, receiver band-pass filter 415a, 415b that limits the received energy to the desired RF MHz band such as the GSM 1900 band allocated from 1850 to 1910 MHz.
  • the mixers 420a, 420b which are driven by a first synthesizer, uplink downconvert synthesizer 425, convert the received signals to an intermediate frequency, and IF band pass filters 430a, 430b, limit the IF signal to a single channel.
  • Uplink downconvert synthesizer 425 and other synthesizers in the translator 310 share a common 10 MHz reference 505.
  • the IF center frequency is typically chosen to be approximately 100 MHz, with a 300 KHz channel bandwidth associated with the IF bandpass filters.
  • one of the signal paths is delayed by up to 16 /.sec, before being combined with the second signal path.
  • the signal path originating at receive antenna 300a is delayed by 15 sec at bulk delay element 440.
  • the delayed signal is directed through power combiner 445, where it is combined with the IF signal from the second uplink IF path.
  • Delaying one IF uplink signal by 15 ⁇ sec will ensure that there is no destructive interference when the two signals are combined, since as earlier disclosed, the spacing of the receive antennas provides a time difference of approximately 8 nsec, and the delay between the two signals represents more than 4 bits of GSM data.
  • the omnidirectional receive antennas 300a and 300b are spaced at least 8 wavelengths apart, there is minimal co- variance between them, and the multipath fades occur at different times on each antenna.
  • the stronger signal dominates. This dominance of the stronger signal will remain until the signal is received at the multichannel host BTS 340 for processing.
  • adaptive delay equalization inherent in GSM Base Station processing removes up to 16 ⁇ sec of delay spread, so the combined diversity signals can be separated and demodulated as one signal at the multichannel host BTS 340.
  • the delay combining technique of the present invention produces a combined diversity signal with a similar signal-to-noise ratio as a signal selected through a switched diversity selection method, yet without the requirement of switching hardware or careful slot-by-slot timing.
  • ALC automatic level control
  • Transmit bandpass filters 460 and 470 limit transmitted energy to the desired single channel range, after receiving the signal from amplifiers 455 and 465 respectively.
  • uplink upconvert synthesizer 480 drives the mixer 475 by phase-locking to the common 10 MHz reference 505.
  • Uplink transmit bandpass filter 485 further limits transmitted energy to the desired RF frequency range, and power amplifier 490 provides the output signal to duplexer 500.
  • Detector 495 provides the energy output of power amplifier 490 back to the automatic level control circuit 450.
  • Duplexer 500 transmits the signal to directional transmit/receive antenna 320, for transmission to multichannel host BTS 340, where the signal is received by omnidirectional antenna 330.
  • the signal is first received on the directional transmit/receive antenna 320 from the multichannel home base station and forwarded to the duplexer 500.
  • the RF signal output provided by the duplexer 500 is passed to a first low noise amplifier 510, receive bandpass filter 515, and mixer 520, which is driven by downlink downconvert synthesizer 525, which is phase-locked to the common 10 MHz reference 505.
  • Intermediate bandpass filter 530 provides the first limitation of the transmit frequency of the downlink IF signal.
  • intermediate frequency bandpass filters 540 and 550 limit transmitted energy to the desired single channel, after receiving the signal from amplifiers 535 and 545 respectively.
  • Loopback tone detector 555 accepts as an input a coupled signal from the output of the IF band pass filter 550 in the downlink signal path.
  • the loopback tone detector 555 controls the loopback circuitry 560, which couples and mixes signals from the transmit path into the tow receive paths.
  • the output of the intermediate frequency bandpass filter 550 is forwarded to the automatic level control attenuator
  • ALC attenuator 570 which feeds in sequence a RF mixer 575 and transmit bandpass filter 585 where- the signal is up-converted back to the RF transmit band, being in the present embodiment 1930- 1990 MHz'.
  • Downlink upconvert synthesizer 580 like all synthesizers in the in-band translator 310, is phase-locked to a common 10 MHz reference 505.
  • the output of transmit bandpass filter 585 is in turn fed to the power amplifier 590 prior to being fed to the transmit portion of the duplexer 405, ultimately out to the antenna 300b.
  • ALC attenuator 570 is controlled based on the energy output of power amplifier 590 measured by detector 565.
  • class A/B linear amplifiers are used throughout the translator 310 in both the forward and reverse paths and the translator 310 is typically implemented with software programmable synthesizers so that the channel settings deployed may be easily selected during installation or when the system needs to be reconfigured.
  • the translator 310 is capable of receiving downlink signals at relatively low levels (-65 dBm to -95 dBm) and then retransmitting ' them with up to 141 dB of gain, at relatively high power levels (+46 dBm) over the mobile link with the automatic level control amplifier typically designed to control the transmitted forward path signal at a nominal 40 Watts .
  • the translator 310 In the reverse, or uplink path, that is from the mobile, to the backhaul link, the translator 310 is designed to receive a low-level mobile signal (-25 dBm to -110 dBm) from its omni-directional antennas 300a, 300b and to retransmit to the base transceiver system 340 with up to approximately 115 dB of signal gain with power of as high as 1 Watt (+30 dB) over the directional antenna 320.
  • a low-level mobile signal 25 dBm to -110 dBm
  • the base transceiver system 340 with up to approximately 115 dB of signal gain with power of as high as 1 Watt (+30 dB) over the directional antenna 320.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un procédé destiné à étendre la portée d'un système à accès multiple à répartition dans le temps (AMRT) dans lequel des composants de traduction intrabande sont situés au centre de cellules éloignées contenant normalement un système émetteur-récepteur de base (BTS). Les éléments de traduction intrabande utilisent la combinaison de temps de propagation de façon à préserver la diversité de réception et atténuer l'évanouissement de Rayleigh. La combinaison de temps de propagation permet d'obtenir un effet de diversité grâce à l'introduction d'un temps de propagation court entre les deux voies de réception spatialement séparées, servant à maximiser la qualité des signaux reçus. Le même signal de porteuse est reçu par deux antennes de liaison montante séparées d'au moins 8 longueurs d'onde (plus de 4 pieds à 1900 MHz). Les deux voies de réception sont largement filtrées (sur toute la bande de réception RF autorisée), amplifiées à l'aide d'un amplificateur à faible bruit, abaissées à une fréquence intermédiaire (FI), puis soumises à un filtrage à bande étroite de façon à constituer une seule porteuse. Une des voies est alors différée jusqu'à 16 νsec puis combinée avec l'autre voie. Le signal composite est alors envoyé grâce à un rapide réglage automatique de niveau (ALC) et maintenu à un niveau constant. Ce signal est alors transposé par montée en fréquence jusqu'à la fréquence RF de liaison terrestre montante désirée puis transmis à haute puissance au système émetteur-récepteur de base (BTS) de desserte via une antenne directionnelle. Un traitement adaptatif de compensation de temps dans ledit système permet de supprimer l'étalement du temps de propagation de façon que les signaux combinés puissent être séparés et démodulés en un seul signal. Le rapport signal-bruit du signal combiné est semblable à celui obtenu avec un procédé de diversité de commutation, sans nécessiter de matériel de commutation ou de calcul de la durée tranche par tranche.
PCT/US2000/009684 2000-04-11 2000-04-11 Procede et appareil de combinaison de temps de propagation de reception en diversite dans un repeteur de systeme sans fil WO2001078255A1 (fr)

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PCT/US2000/009684 WO2001078255A1 (fr) 2000-04-11 2000-04-11 Procede et appareil de combinaison de temps de propagation de reception en diversite dans un repeteur de systeme sans fil
AU2000243410A AU2000243410A1 (en) 2000-04-11 2000-04-11 Method and apparatus employing delay combining for receive diversity in a wireless system repeater

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Cited By (6)

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WO2004051882A1 (fr) * 2002-12-04 2004-06-17 Koninklijke Philips Electronics N.V. Diversite de retard dans un systeme de communication sans fil
KR100499928B1 (ko) * 2002-09-03 2005-07-07 포유텔레콤 주식회사 이동통신 시스템의 씨디엠에이 기지국 커버리지 확장을위한 알에프 시간지연 보정장치
WO2006099302A2 (fr) * 2005-03-14 2006-09-21 Nextel Communications, Inc. Systemes et procedes destines a la reutilisation des frequences dans des reseaux sans fil
EP1890403A2 (fr) * 2006-08-17 2008-02-20 Fujitsu Ltd. Procédé de radiocommunication via un relais, station de base radio, et station de relais radio dans un système de radiocommunication
KR100865854B1 (ko) 2007-02-14 2008-10-29 에스케이 텔레콤주식회사 다중 안테나 기반의 비재생 중계 시스템 및 방법
WO2008150534A2 (fr) * 2007-06-01 2008-12-11 Nextivity, Inc. Amplificateur à courte portée ayant de multiples antennes

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