GB2456007A - Method and means of calibrating plural antennas of a communication device - Google Patents

Method and means of calibrating plural antennas of a communication device Download PDF

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Publication number
GB2456007A
GB2456007A GB0725349A GB0725349A GB2456007A GB 2456007 A GB2456007 A GB 2456007A GB 0725349 A GB0725349 A GB 0725349A GB 0725349 A GB0725349 A GB 0725349A GB 2456007 A GB2456007 A GB 2456007A
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United Kingdom
Prior art keywords
pilot signals
antenna
antennas
value
amplitude
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Granted
Application number
GB0725349A
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GB2456007B (en
GB0725349D0 (en
Inventor
Simon Gale
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Nortel Networks Ltd
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Nortel Networks Ltd
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Priority to GB0725349A priority Critical patent/GB2456007B/en
Publication of GB0725349D0 publication Critical patent/GB0725349D0/en
Publication of GB2456007A publication Critical patent/GB2456007A/en
Application granted granted Critical
Publication of GB2456007B publication Critical patent/GB2456007B/en
Priority to US14/744,798 priority patent/US20150288462A1/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/267—Phased-array testing or checking devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
    • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
    • H01Q1/246—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for base stations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/2605—Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays

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

Abstract

A method or means of calibrating a plurality of antennas 12-1, 12-2, 12-n of a first device 10 comprises transmitting pilot signals from each of the plurality of antennas 12 of a first device 10 to an antenna on a second device 14. The pilot signals received by the second device 14 are processed to find a first value relating to the amplitude and/or phase of each pilot signal relative to that of a selected pilot signal. Each of the said first values is then transmitted from the second device 14 to the first device 10. The second device 14 then transmits pilot signals to the first device 10. The pilot signals received at the first device 10 are processed to find a second value relating to the amplitude and/or phase of the pilot signal received at each antenna element 12 relative to that of a pilot signal received on a selected antenna element. Each of the first and second values found is then used to calculate correction factors for each of the antennas 12 of the first device 10. The pilot signals employed may cover a number of frequencies. The first device 10 may be a base station and the second device 14 may be a mobile terminal. Each antenna 12 of the first device 10 may relate to respective transmitters 18 and receivers 20.

Description

1 2456007
METHOD FOR CHANNEL CALIBRATION
FIELD OF THE INVENTION
This invention relates to a method of calibrating a terminal having multiple antennas. The invention is applicable to use within base stations of a cellular telecommunications network.
BACKGROUND OF THE INVENTION
In communications systems, such as a cellular communication system, it is advantageous to use multiple transmitters and receivers to exchange data wirelessly between two terminals.
The use of multiple transmitters and receivers results in an improved performance with, for :.:: example increased transmission range, an improved signal to noise ratio, interference S...
rejection for received signals and a reduced power requirement for transmitted signals.
*5***S * S In a known multiple antenna arrangement, such as that illustrated in Figure 1 and used in a S...
: cellular communication system, a base station 10 is provided with multiple antennas 12-1, *..
12-2, 12-n, arranged to both transmit and receive data to mobile terminals such as a cellular telephone 14. When the base station 10 transmits a signal to the mobile station 14 using the multiple antennas 12 each transmission by each signal will take a different path 16-1, 16-2, 16-n to the antenna at the mobile station 14.
In order to maximise the signal level at the mobile terminals' antenna it is advantageous to calibrate the phase and amplitude of the signals transmitted by the base station 10.
Traditionally, in order to achieve this hardware, such as directional couplers, is introduced into the base station. This results in extra expense when building networks and also additional complexity in the terminals. Furthermore, if tower top amplifiers are employed then further expense and complexity will be encountered as tower top calibration couplers and associated feeders will also be required.
Hence, what is needed is a more efficient way for calibrating a terminal having multiple antennas.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a method of calibrating a first device including a plurality of antennas comprising the steps of: transmitting pilot signals from each of the plurality of antennas to an antenna on a second device, the second device, upon receiving the pilot signals, calculating a second relative value of the amplitude and/or * phase of the pilot signals received from that antenna to the received pilot signals of a selected antenna, the second device transmitting the second relative value for each antenna to the first device, the second device transmitting pilot signals to the first device, the first *** device, upon receiving the pilot signals, calculating a first relative value of the amplitude and/or phase of the pilot signals received by that antenna to the pilot signals received by a selected antenna and the first device calculating correction factors for each of the antennas using the first and second relative values.
LU
By calculating correction factors in this way the need for extra hardware to perform calibration is negated.
The first device may include n antennas where n is an integer value; the transmitter value being the ratio of pilot signals received from an antenna between 1 and n to the pilot signals received from a first antenna.
The ratio may be calculated using the following equation: = aflT *H a1 * H1 where M is the transmitter value for aerial n cLfl.1-is the factor introduced by the transmission circuit and * * * . * *ia n indicates which aerial transmitted the pilot signals. S...
*.e*..
* S Correspondingly, the receiver value may be the ratio of pilot signals received on an antenna between I and n to the pilot signals received on a first antenna. S... * . S S. S
S S..
The ratio may be calculated using the following equation: B = aflR *H cxnR * H1 where B is the receiver value for aerial n, afl.R is the factor introduced by the receiver circuit, n indicates which aerial received the pilot signals.
The correction factors may be calculated for each of the antennas by comparing the transmitter value and the receiver value. This comparison may be performed for the phase correction factor using the following equation: Cço =arg(B-M) where Cço is the phase correction factor for aerial n, B is receiver value for aerial n, M is the transmitter value for aerial n.
Preferably, comparing the transmitter value and the receiver value comprises calculating * S.
SI S
CA =absl-
B
S.....
* where CA is the amplitude correction factor for aerial n, B is receiver value for aerial n, *.** * SS S. * * M is the transmitter value for aerial n. I.. n
I
Optionally, the pilot signals may be transmitted over a number of pilot frequencies. This means that the calibration correction factors for frequencies between the pilot frequencies can be calculated by interpolation.
The first device may be a base station and the second device may be a mobile terminal. In this instance, the mobile terminal velocity may be determined to see if it is below a threshold value in order to prevent use of a high velocity mobile terminal which will introduce errors into the calibration factors. The velocity may be determined by the base station using the Doppler spectrum for signals received from the mobile terminal.
The second device may also have a plurality of antennas and be arranged to transmit and receive pilot signals in an analogous manner to the first device in order that it can calculate correction factors for each of its plurality of antennas using the same method as the first device. The second device may exchange pilot signals with the first device or a separate terminal.
Advantageously, the first and second transmitters are arranged to transmit signals using time division duplex. a...
* a....
* In accordance with a second aspect of the present invention there is provided a device including a plurality of antennas, and processing means, the device being configured to *.
15: transmit pilot signals from each of the plurality of antennas, receive pilot signals at each of * *IS * the plurality of antennas; receive a relative value of the amplitude and/or phase of the pilot signals transmitted by each of the plurality of antennas compared to the pilot signals transmitted by a selected antenna, calculate, upon receiving the pilot signals, a first relative value of the amplitude and/or phase of the pilot signals received by each antenna compared to the pilot signals received by a selected antenna and determine correction factors for each of the antennas using the first and second relative values. The device may be, for example, a base station.
In accordance with a further aspect of the present invention there is provided a device comprising an antenna and processing means; the device being configured to receive pilot signals at the antenna transmit pilot signals from the antenna calculate, upon receiving the pilot signals, a relative value of the amplitude and/or phase of the pilot signals received by the antenna and transmit the relative value from the antenna.
The device may be arranged to receive the pilot signals from a device comprising a plurality of transmitters and the relative value of the amplitude and/or phase of the pilot signals is the value of the amplitude and/or phase of the pilot signals received from one antenna relative to the value of the amplitude and/or phase of the pilot signals received from a selected antenna. Additionally, the device may be a mobile station. * S.
BRIEF DESCRIPTION OF THE DRAWINGS
Other aspects and features of the present invention will become apparent to those ordinarily * S....
* skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. 0S*S
* iP * J.
I I..
Figure 1 illustrates a prior art cellular communications system; Figure 2 illustrates a communications system in accordance with the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention will be discussed with reference to a cellular communications system including base stations and mobile terminals. However, it may be implemented between any two terminals that are connected by wireless communication channels.
Figure 2 illustrates the apparatus of the present invention. As in conventional wireless cellular communications systems there is a base station 10 having n antennas 12-1, 12-2...
12-n. Each antenna 12-1, 12-2... 12-n is connected to a transmission circuit 18-1, 18-2...
18-n and a receiver circuit 20-1, 20-2... 20-n.
The transmission circuit is responsible for processing the signals prior to them being transmitted by the antenna and the receiver circuit is responsible for processing the signals that are received by the antenna. Each circuit introduces particular complex frequency dependent factors that vary according to the circuit and radio channel being used. The introduced factors are denoted in Figure 2 as ac.x where C is the channel, T indicates that it is introduced by the transmission circuit and R indicates that it is introduced by the receiver circuit.
e. U. US To calibrate the system each antenna 12-1, 12-2... 12-n at the base station 10 transmits a I...
: set of pilot symbols to the mobile terminal 14. Each set of pilot signals being processed by 5.
the transmission circuit associated with the antenna. The mobile terminal 14 receives the signal and calculates a series of channel measurements where all the antennas 12-1, 12-2...
12-n are provided with a number in relation to a selected antenna in the base station 10.
For example, the mobile terminal 14 may calculate the ratio of the received signal transmitted by each antenna 12-1, 12-2... 12-n with reference to the first antenna 12-1.
Thus the relative measurement obtained by the mobile terminal 14 for the second antenna 12-2 will be: M2 = a2, * H2 * and the relative measurement obtained for the nth antenna 12-1 will be: M -a7. * anT * H1 The results of these calculations are then transmitted to the base station.
The mobile terminal 14 also transmits pilot symbols to the base station 10. The pilot symbols are received by each antenna 12-1, 12-2... 12-n at the base station 10 and is passed through the appropriate receiver circuit 20-1, 20-2... 20-n. Upon receiving the pilot signals the base station 10 also makes a series of channel measurement calculations for * *I ** * * 1Y each antenna 12-1, 12-2... 12-n. The measurements being calculated relative to the pilot **** * . **I* symbols received by selected antenna, in this instance the first antenna 12-1, on the base * * * station 10. ****
: For example, the base station 10 may calculate the ratio of the signal received by each T antenna 12-1, 12-2... 12-n with reference to the first antenna 12-1. Thus the relative measurement obtained by the base station 10 for the second antenna 12-2 will be: B2 y*JJ and the relative measurement obtained for the nth antenna 12-n will be: B aflR H fi a JJ Preferably, the channel measurements are made over a number of pilot frequencies in the bandwidth used by the transmitters. This enables calibration to occur accurately at multiple frequencies.
Once the base station has calculated the relative values it can then calculate a phase correction to be applied to either the receiver or transmitter circuits. The phase corrections may be defined by the following equation: Cço arg(B -Ma) for n> 1 10. ** S * S*
. as, in this example, all measurements are made relative to antenna 1 when n1 Cq&0 as the ratios calculated using the equations for measurements above will always be 1.
*.*.*. * S
*:::: The correction factors can be applied for the pilot frequencies at which the pilot symbols 1 were transmitted. Interpolation may be used to determine the correction factors that are to
S
be applied when transmitting/receiving at frequencies between the pilot frequencies.
The present method may also be used to provide amplitude correction. When a signal is to be transmitted it is passed through a power amplifier (which may be linearized). This means that the amplitude of a transmitted signal is tightly calibrated and it can be assumed that the transmission amplitudes for each receiver are approximately equal.
However, calibration of the receiver circuitry may still be required. This may be achieved by calculating amplitude correction scaling factors. The amplitude correction scaling factors may be calculated using the following equations: CA =abs--forn>1 LB) As discussed with reference to phase when n=1 the correction scaling factor is always 1 because the ratio is calculated with reference to antenna 1.
Although any mobile terminal may be used to calculate the scaling factors and thereby :1: calibrate the base station transmitter and receiver circuits it is preferable tha t a slow moving I...
or static mobile terminal is selected in order that the scaling factors calculated are not * S....
* affected by the change in channel state caused by the movement of the terminal.
: The base station may be configured to determine the amount of movement using the *.
I Doppler spectrum received from the mobile terminal to determine the velocity of a mobile terminal and, if the Doppler spectrum is below a certain value it is suitable to use for calibration.
Preferabiy, the mobiie terminal has a high Camer to interference-plus-Noise Ratio. This means that the effect of factors external to the channel are minimised in the channel measurements.
If desired the calibration may occur using channel measurements from multiple separate mobile terminals. The correction factors obtained from each of the mobile terminals being averaged and then applied to the circuitry. This increases the accuracy of the calibration and reduces the effect of erroneous measurements on the base station.
Advantageously the mobile terminal measurement timing is selected to produce a channel branch ratio that is close to unity. This further minimises the effect of changing channel conditions on the ratios calculated.
The correction factors may be calculated repeatedly in order to mitigate for changes in the circuits that affect the transmission reception of signals. The period of time between iO* calculation of correction factors may be predetermined, for example a timer may cause calibration signals to be transmitted after a predetermined amount of time has elapsed.
Calibration errors tend to change relatively slowly and therefore the period of time may be * relatively long, for example 10 minutes or more.
: The method may be applied to a MIMO system where both terminals are provided with
U
multiple antennas having both transmitter and receiver circuits. In this instance both terminals calculate calibration factors according to the methods above and apply the calibration factors in the usual manner.
Preferably, the method is implemented in a system where the same channel is used to transmit and receive signals between the two terminals. This enables reciprocity of the signals and means that channel effects are cancelled out as they affect the base station and mobile station measurements equally. For example, the method may be implemented upon transmitters using time division duplex.

Claims (23)

  1. What is claimed is: 1. A method of calibrating a first device including a plurality of antennas comprising the steps of: a. transmitting pilot signals from each of the plurality of antennas to an antenna on a second device; b. the second device, upon receiving the pilot signals, calculating a second relative value of the amplitude and/or phase of the pilot signals received from that antenna to the received pilot signals of a selected antenna; *i9 c. the second device transmitting the second relative value for each antenna to the first device; d. the second device transmitting pilot signals to the first device *..
    * e. the first device, upon receiving the pilot signals, calculating a first relative value of the amplitude and/or phase of the pilot signals received by that **** : antenna to the pilot signals received by a selected antenna; and S..
    f. the first device calculating correction factors for each of the antennas using the first and second relative values.
  2. 2. The method of Claim 1 wherein the first device includes n antennas where n is an integer value and the second relative value is the ratio of pilot signals received from an antenna between 1 and n to the pilot signals received from a first antenna.
  3. 3. The method of Claim 2 wherein the ratio is calculated using the following equation: M = anT * where M is the transmitter value for aerial n anT is the factor introduced by the transmission circuit and n indicates which aerial transmitted the pilot signals.
  4. 4. The method of Claim 1 wherein the first device includes n antennas where n is an integer value and the first relative value is the ratio of pilot signals received on an antenna between 1 and n to the pilot signals received on a first antenna. * S. * a.
    10.
  5. 5. The method of Claim 4 wherein the ratio is calculated using the following equation: *.,. a *H n,R n
    **.**. J_Jn - * S aflR *H S...
    * : where B is the receiver value for aerial n, S..
    afl.R is the factor introduced by the receiver circuit, n indicates which aerial received the pilot signals.
  6. 6. The method of Claim 1 wherein the step of calculating correction factors for each of the antennas comprises the step of comparing the first and second relative values.
  7. 7. The method of Claim 6 wherein comparing the first relative value and the second relative value comprises calculating Cçi =arg(B,, -Ma) where Cço is the phase correction factor for aerial n, B is receiver value for aerial n, M is the transmitter value for aerial n.
  8. 8. The method of Claim 6 wherein comparing the first and second relative values comprises calculating CA =absl& where CA is the amplitude correction factor for aerial n, B is receiver value for aerial n, * M is the transmitter value for aerial n. * S
  9. 9. The method of Claim 1 wherein the pilot signals are transmitted over a number of pilot * frequencies. S..
    S
  10. 10. The method of Claim 9 wherein the calibration correction factor for frequencies between the pilot frequencies is calculated by interpolation.
  11. 11. The method of Claim I wherein the first device is a base station and the second device is a mobile terminal.
  12. 12. The method of Claim 11 further comprising the step of determining whether the mobile terminal has a velocity below a threshold value.
  13. 13. The method of Claim 12 wherein the velocity is determined by the base station using the Doppler spectrum for signals received from the mobile terminal.
  14. 14. The method of Claim I wherein the second device comprises a plurality of antennas and is arranged to calculate correction factors for each of the plurality of antennas using the method of Claim 1.
  15. 15. The method of Claim I wherein the first and second transmitters are arranged to transmit *::* signals using time division duplex. * * ****
  16. 16. A device including a plurality of antennas, and processing means, the device being ****** * configured to: a. transmit pilot signals from each of the plurality of antennas, **** * rs b. receive pilot signals at each of the plurality of antennas; S..
    c. receive a relative value of the amplitude and/or phase of the pilot signals transmitted by each of the plurality of antennas compared to the pilot signals transmitted by a selected antenna; d. calculate, upon receiving the pilot signals, a first relative value of the amplitude and/or phase of the pilot signals received by each antenna compared to the pilot signals received by a selected antenna; e. determine correction factors for each of the antennas using the first and second relative values.
  17. 17. The device of Claim 16 wherein the device is a base station.
  18. 18. A device comprising an antenna and processing means; the device being configured to: a. receive pilot signals at the antenna; b. transmit pilot signals from the antenna; c. calculate, upon receiving the pilot signals, a relative value of the amplitude and/or phase of the pilot signals received by the antenna; d. transmit the relative value from the antenna.
  19. 19. The device of Claim 18 wherein the device is arranged to receive the pilot signals from a device comprising a plurality of transmitters and the relative value of the amplitude and/or phase of the pilot signals is the value of the amplitude and/or phase of the pilot signals received from one antenna relative to the value of the amplitude and/or phase of * the pilot signals received from a selected antenna. ****
    :
  20. 20. The device of Claim 18 wherein the device is a mobile terminal. ***
  21. 21. A method of calibrating a first device including a plurality of antennas substantially as herein described with reference to and as shown in any combination of the accompanying drawings.
  22. 22. A device including a plurality of antennas substantially as herein described with reference to and as shown in any combination of the accompanying drawings.
  23. 23. A device comprising an antenna and processing means substantially as herein described with reference to and as shown in any combination of the accompanying drawings. * ** * S S * S. *.*. * . -.
    * 0*SS* * S *..* * .. ** .
    I *
    I
GB0725349A 2007-12-31 2007-12-31 Method for channel calibration Expired - Fee Related GB2456007B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB0725349A GB2456007B (en) 2007-12-31 2007-12-31 Method for channel calibration
US14/744,798 US20150288462A1 (en) 2007-12-31 2015-06-19 Method for Channel Calibration

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0725349A GB2456007B (en) 2007-12-31 2007-12-31 Method for channel calibration

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GB0725349D0 GB0725349D0 (en) 2008-02-06
GB2456007A true GB2456007A (en) 2009-07-01
GB2456007B GB2456007B (en) 2012-10-17

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5546090A (en) * 1991-12-12 1996-08-13 Arraycomm, Inc. Method and apparatus for calibrating antenna arrays
US6124824A (en) * 1999-01-29 2000-09-26 Cwill Telecommunications, Inc. Adaptive antenna array system calibration
US20020042290A1 (en) * 2000-10-11 2002-04-11 Williams Terry L. Method and apparatus employing a remote wireless repeater for calibrating a wireless base station having an adaptive antenna array
US20020089447A1 (en) * 1999-08-10 2002-07-11 China Academy Of Telecommunications Technology Method and device for calibrating smart antenna array
US20030032423A1 (en) * 1998-05-01 2003-02-13 Tibor Boros Determining a calibration function using at least one remote terminal
US20040048584A1 (en) * 2002-09-10 2004-03-11 Chandra Vaidyanathan Techniques for correcting for phase and amplitude offsets in a MIMO radio device
US20070099573A1 (en) * 2005-11-02 2007-05-03 Qualcomm Incorporated Antenna array calibration for multi-input multi-output wireless communication systems

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6131016A (en) * 1997-08-27 2000-10-10 At&T Corp Method and apparatus for enhancing communication reception at a wireless communication terminal
SE513340C2 (en) * 1998-11-27 2000-08-28 Radio Design Innovation Tj Ab Calibration method for phase controlled group antenna
US6983127B1 (en) * 2001-07-31 2006-01-03 Arraycomm, Inc. Statistical calibration of wireless base stations
EP1453223A1 (en) * 2001-11-30 2004-09-01 Fujitsu Limited Transmission diversity communication device
US7747250B2 (en) * 2003-12-30 2010-06-29 Telefonaktiebolaget Lm Ericsson (Publ) Calibration method to achieve reciprocity of bidirectional communication channels
GB2418536B (en) * 2004-09-27 2008-12-03 Nortel Networks Ltd Method of antenna calibration

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5546090A (en) * 1991-12-12 1996-08-13 Arraycomm, Inc. Method and apparatus for calibrating antenna arrays
US20030032423A1 (en) * 1998-05-01 2003-02-13 Tibor Boros Determining a calibration function using at least one remote terminal
US6124824A (en) * 1999-01-29 2000-09-26 Cwill Telecommunications, Inc. Adaptive antenna array system calibration
US20020089447A1 (en) * 1999-08-10 2002-07-11 China Academy Of Telecommunications Technology Method and device for calibrating smart antenna array
US20020042290A1 (en) * 2000-10-11 2002-04-11 Williams Terry L. Method and apparatus employing a remote wireless repeater for calibrating a wireless base station having an adaptive antenna array
US20040048584A1 (en) * 2002-09-10 2004-03-11 Chandra Vaidyanathan Techniques for correcting for phase and amplitude offsets in a MIMO radio device
US20070099573A1 (en) * 2005-11-02 2007-05-03 Qualcomm Incorporated Antenna array calibration for multi-input multi-output wireless communication systems

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Publication number Publication date
GB2456007B (en) 2012-10-17
GB0725349D0 (en) 2008-02-06

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