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WO2002031999A1 - Systeme d'antennes multiples pour communications hertziennes - Google Patents

Systeme d'antennes multiples pour communications hertziennes Download PDF

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Publication number
WO2002031999A1
WO2002031999A1 PCT/US2001/021795 US0121795W WO0231999A1 WO 2002031999 A1 WO2002031999 A1 WO 2002031999A1 US 0121795 W US0121795 W US 0121795W WO 0231999 A1 WO0231999 A1 WO 0231999A1
Authority
WO
WIPO (PCT)
Prior art keywords
wireless communication
communication system
antenna
transmitter
antennas
Prior art date
Application number
PCT/US2001/021795
Other languages
English (en)
Inventor
Raviv Melamed
Original Assignee
Hlan Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hlan Inc. filed Critical Hlan Inc.
Priority to AU2002242351A priority Critical patent/AU2002242351A1/en
Priority to US10/362,795 priority patent/US20040014430A1/en
Publication of WO2002031999A1 publication Critical patent/WO2002031999A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/005—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
    • H04B1/0053—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band
    • H04B1/006—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges with common antenna for more than one band using switches for selecting the desired band
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/005—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/403—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency
    • H04B1/406—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency with more than one transmission mode, e.g. analog and digital modes
    • 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
    • H04B7/0802—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using antenna selection
    • H04B7/0805—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using antenna selection with single receiver and antenna switching
    • H04B7/0814—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using antenna selection with single receiver and antenna switching based on current reception conditions, e.g. switching to different antenna when signal level is below threshold

Definitions

  • the invention relates to wireless communication systems and, more particularly to antenna arrays for transceivers in Wireless Local Loop (WLL) applications.
  • WLL Wireless Local Loop
  • a Wireless Local Loop sometimes referred to as radio-in-the-loop (RITL) or fixed-radio access (FRA) is a system that connects subscribers to the public switched telephone network (PSTN) using radio signals as a substitute for copper for all or part of the connection between the subscriber and the switch.
  • PSTN public switched telephone network
  • the local loop refers to the connection that runs from the subscriber's telephone set, PBX or telephone system to the telephone company's central office (CO).
  • CO telephone company's central office
  • WLL Wireless Local Loop
  • WLL service is a viable alternative for parts of the world that can leapfrog expensive and time-consuming wire installations in establishing modern telecommunications systems.
  • Multi-path occurs when copies of the desired signal arrive at the receiving antenna after bouncing from objects between the signal source and the receiving antenna.
  • a typical multi-path problem is "dropout", which is caused by multi-path phase canellations (multi-path nulls).
  • a signal which has taken an indirect path from transmitter to receiver will be out-of-phase with a signal which has taken an direct path to the receiver.
  • Multi-path conditions which can cause dropouts are very common indoors, since the output of a wireless transmitter radiates in all directions and bounces off many types of surfaces in a foom. In reality, a wireless system operating in a room will be generating perhaps hundreds of reflections around the room, but the system continues to operate since the direct path signal is normally the strongest of all the signals. Metal is an especially good reflector, so multi-path conditions can also occur outdoors, since the transmitter signal can be efficiently reflected from cars, trucks, trailers, metal building surfaces, etc.
  • a known way of confronting the multi-path problem is "space diversity" wherein two (or more) antennas are used.
  • the two antennas are connected to a switch, and the system decides at which of the two antenna the signal level is higher, and switches to it.
  • the antennas are physically spaced apart from one another (spatially diverse) to combat signal fading and improve signal quality.
  • the desired spacing depends on the degree of multi-path angle spread, but should be at least one half wavelength of the operating frequency to ensure that the antennas are receiving uncorrelated ("diverse") signals to gain the full benefit of diversity reception.
  • WLAN wireless Local Area Networks
  • a WLAN is a data transmission system designed to provide location-independent network access between computing devices by using radio waves rather than a cable infrastructure.
  • WLANs are usually implemented as the final link between the existing wired network and a group of client computers, giving these users wireless access to the full resources and services of the corporate network across a building or campus setting.
  • the .5 GigaHertz (GHz) band has become the new frontier for high bandwidth WLAN products. Being spectrally clean and wide, the 5GHz band attracts much attention as being the enabler of wide public acceptance for broadband WLAN products.
  • Figure 1 illustrates a typical transceiver of a wireless communication system 100, comprising the following major components, connected as shown: - an amplifier 102;
  • AGC automatic gain control
  • T/R transmit/receive
  • AGC automatic gain control
  • NCO voltage-controlled oscillator
  • the system 100 is shown in a configuration where a signal to be transmitted is supplied as an input intermediate frequency (IF) signal from a modem (not shown), and the received signal is provided as an output IF signal to the modem.
  • the transmitter portion of the transceiver comprises the amplifier 102, the up converter 104, the automatic gain control (AGC) 106 and the power amplifier 108.
  • the receiver portion of the transceiver comprises the amplifier 112, the down converter 114, the automatic gain control (AGC) 116, and the low noise amplifier 118.
  • the T/R switch 110 comprises two switches 110a and 110b, each serving a different purpose.
  • the switch 110a is for switching between transmit and receive.
  • the switch 110b is for selecting between two antennas 124 and 126. As illustrated in Figure 1, the output of the power amplifier 108 is provided through the T/R switch 110 to an antenna 124. With the switch 110b in the other position (not shown), the output of the power amplifier 108 would be provided to the antenna 126.
  • the switch 110a In a transmit mode, the switch 110a would be in the other position (not shown) so that a signal received by a selected one of the two antennas 124 and 126 (as determined by the position of the switch 110b), would be provided to the input of the low noise amplifier 118.
  • the switch 110a selects between the transmit and receive modes, and the switch 110b selects between the two antennas, in either mode.
  • the reason for having two antennas 124 and 126 is generally for providing space diversity to confront the multi-path problem, as described above.
  • a suitable mechanism for determining which of the two antennas to use (in other words, the position of the switch 110b) is well known, and can simply be a comparator which determines which antenna is receiving the strongest signal and causing the switch 110b to switch to that antenna, as described hereinabove.
  • the system 100 may use Time Division Multiple Access (TDMA) or Time Division Duplex (TDD).
  • Time Division Multiple Access is a method used in wireless technology to separate multiple conversations over set frequencies and bandwidth.
  • the frequency band is split into a number of channels which in turn are stacked into short time units so that several calls can share a single channel without interfering with one another.
  • Time Division Duplex is a method of multiplexing transmit/receive (uplink/downlink) parts of a wireless communications link together, wherein the exchange of uplink and downlink information takes place on the same frequency, but is distinguished by time-slot characteristics.
  • the switches 110a and 110b typically will each cause an attenuation of 1-1.5 (deciBel) dB, resulting in a total attenuation of 2-3 dB for the T/R switch 110. This degrades the performance of the system. The degradation results in a poor noise figure for the receiver, and lower (power) efficiency for the transmitter.
  • a multiple antenna system comprises two receive antennas connected by a switch to the receiver; and a third, transmit antenna connected to the transmitter.
  • the wireless communication system may be a wireless local loop (WLL), or a wireless local area network (WLAN).
  • the wireless communication system may suitably operate at frequencies from 2.4 GHz up to 40 GHz, including in the 5 GHz band.
  • a wireless communication system having a transceiver comprising a transmitter and a receiver
  • two antennas and spatial distribution are used for receiving signals
  • a third antenna is used for transmitting signals. This method improves the noise figure for the receiver, and improves the power efficiency of the transmitter.
  • Figure 1 is a block diagram of a transceiver with two antennas, according to the prior art.
  • FIG. 2 is a block diagram of a transceiver with three antennas, according to the invention.
  • FIG. 2 illustrates a typical transceiver portion of a wireless communication system 200, comprising the following major components, which may be identical to those of the wireless communication system 100 of Figure 1, connected as shown: - an amplifier 102;
  • AGC automatic gain control
  • AGC automatic gain control
  • VCO voltage-controlled oscillator
  • a switch 210 comparable to and performing a function similar to the switch 110b, is provided for selectively switching two antennas 224 and 226 (compare 124 and 126) to the input of the low noise amplifier 118 of the receiver portion of the transceiver, in order to overcome the multi-path problem, as described hereinabove.
  • a transmit/receive (T/R) switch (110) - more particularly, a switch (compare 110a) for switching an antenna between the transmitter and the receiver portions of the transceiver. Rather, a third antenna 228 is provided, and is dedicated solely to the transmitter of the transceiver.
  • the output of the power amplifier 108 is provided directly to the "transmit" antenna 228, and therefore need not pass through two switches (110a, 110b), resulting in improved power efficiency for the transmitter. Additionally, a received signal need only traverse one switch 210, rather than two switches (110a, 110b), resulting in an improved noise figure for the receiver.
  • the transmitter is connected directly (rather than through one or more switches) to the transmit antenna, 2-3 dB of power are saved. And, since there is also one less (one, instead of two) switch at the receiving channel, the noise figure improves in 1-1.5 dB. Altogether, for the transceiver, the gain is approximately 3-4.5 db from using this arrangement (topology) of three antennas (one transmit antenna and two receive antennas).

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Transceivers (AREA)

Abstract

L'invention concerne un système de communications hertziennes (200) comprenant: un émetteur-récepteur, un système d'antennes multiples qui comporte deux antennes de réception (224,226) reliées selon une topologie spatiale, aux fins de réduction des occurrences de trajets multiples, et une troisième antenne d'émission (228) reliée à l'émetteur. Le système de communications hertziennes peut être une ligne locale sans fil, ou un réseau local sans fil, et il peut fonctionner de manière appropriée à partir de 2,4 GHz, y compris la bande des 5GHz.
PCT/US2001/021795 2000-10-06 2001-07-11 Systeme d'antennes multiples pour communications hertziennes WO2002031999A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU2002242351A AU2002242351A1 (en) 2000-10-06 2001-07-11 Multiple antenna system for wireless communication
US10/362,795 US20040014430A1 (en) 2001-07-11 2001-07-11 Multiple antenna system for wireless communication

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US23804900P 2000-10-06 2000-10-06
US60/238,049 2000-10-06

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US10362795 Continuation-In-Part

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US10/425,633 A-371-Of-International US20030190903A1 (en) 2002-07-22 2003-04-30 Zero-loss front end for wireless communication

Publications (1)

Publication Number Publication Date
WO2002031999A1 true WO2002031999A1 (fr) 2002-04-18

Family

ID=22896288

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2001/021795 WO2002031999A1 (fr) 2000-10-06 2001-07-11 Systeme d'antennes multiples pour communications hertziennes

Country Status (3)

Country Link
AU (1) AU2002242351A1 (fr)
TW (1) TW527752B (fr)
WO (1) WO2002031999A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003092997A3 (fr) * 2002-05-03 2004-03-18 Atheros Comm Inc Reseau local sans fil a bande de frequences duale

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI419409B (zh) * 2009-11-16 2013-12-11 Acer Inc 具有多組天線的行動裝置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5523768A (en) * 1991-05-30 1996-06-04 Conifer Corporation Integrated feed and down converter apparatus
US6278864B1 (en) * 1995-04-20 2001-08-21 Fujitsu Limited (Japan) Radio tranceiver for data communications

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5523768A (en) * 1991-05-30 1996-06-04 Conifer Corporation Integrated feed and down converter apparatus
US6278864B1 (en) * 1995-04-20 2001-08-21 Fujitsu Limited (Japan) Radio tranceiver for data communications

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003092997A3 (fr) * 2002-05-03 2004-03-18 Atheros Comm Inc Reseau local sans fil a bande de frequences duale
US7251459B2 (en) 2002-05-03 2007-07-31 Atheros Communications, Inc. Dual frequency band wireless LAN
US7865150B2 (en) 2002-05-03 2011-01-04 Atheros Communications, Inc. Dual frequency band wireless LAN

Also Published As

Publication number Publication date
AU2002242351A1 (en) 2002-04-22
TW527752B (en) 2003-04-11

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