Method and system employing antenna arrays

• US 7,421,039 B2
• Filed: 06/04/2002
• Issued: 09/02/2008
• Est. Priority Date: 06/04/2002
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Valenzuela, Reinaldo A., Malaender, Laurence Eugene
• Primary Examiner(s): Ghebretinsae; Temesghen
• Application Number:
  US10/160,126
• Publication Number:
  US 20030223391A1
• Time in Patent Office: 2,282 Days
• Field of Search: 375/304, 375/267, 375/367, 375/299, 370/334, 370/252
• US Class Current: 375/304
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

In the method and system, a transmitter demultiplexes an input data stream into M substreams, where each of the M substreams have a data rate lower than a data rate of the input data stream. The substreams are transmitted as signals from a transmit array of M antennas to be received by a receiver array at a receiver in the system, based on a set of transmission parameters. The transmitter adjusts at least one of the transmission parameters based on a condition experienced by the receiver so as to increase data throughput in the system. The adjustable parameters include the number of antennas to employ, the on/off patterns for the antennas, and eigenmode values for the antennas used in order to determine transmit power. Accordingly, system data throughput may be improved while maintaining transmit power and system bandwidth constant.

Claims

1. A method for increasing data throughput in a communication system employing multiple antennas, comprising:

demultiplexing an input data stream into M substreams, each of the M substreams having a data rate lower than a data rate of the input data stream;

transmitting signals representing said M substreams from a transmit array of M antennas to at least one receiver based on at least one of a number of the M antennas to employ and on/off patterns that are specified for the M antennas; and

adjusting at least one parameter based on feedback information including at least one of an integer representing the number of the M antennas to employ for the transmitting and a vector including a pattern of ones and zeros representing the on/off patterns that are specified for the M antennas used for the transmitting,

wherein the number of M antennas is represented by a parameter s that is defined by the equation;

$s=\arg <br><br><br><br>\underset{s=1,M}{\max }<br><br>{\log }_2<br><br>\det <br><br>\left(I+\frac{\mathrm{\rho <br><br>}}{s}<br><br>H_s<br><br>H_s^H\right),$

wherein I represents an identity matrix, H_s is a channel coefficient matrix with s columns, and ρ

is a channel signal-to-noise ratio.

2. The method of claim 1, wherein at least one condition detected at a receiver is used to generate the feedback information, the at least one condition includes radio characteristics measured at the receiver to determine at least one of a transmitter configuration, a modulation order, and a spreading gain that is subject to a desired error rate.

3. The method of claim 1, wherein said step of transmitting includes mapping each substream of said M substreams to a corresponding antenna in the transmit array.

4. A method for increasing data throughput in a communication system employing multiple antennas, comprising:

demultiplexing an input data stream into M substreams, each of the M substreams having a data rate lower than a data rate of the input data stream;

transmitting signals representing said M substreams from a transmit array of M antennas to at least one receiver based on at least one of a number of the M antennas to employ and on/off patterns that are specified for the M antennas; and

adjusting at least one parameter based on feedback information including at least one of an integer representing the number of the M antennas to employ for the transmitting and a vector including a pattern of ones and zeros representing the on/off patterns that are specified for the M antennas used for the transmitting,

wherein the on/off patterns are determined by the equation;

$\underset{a}{\max }<br><br>{\log }_2<br><br>\det <br><br>\left(I+\frac{\mathrm{\rho <br><br>}}{n_{\mathrm{ta}}}<br><br>H_a<br><br>H_a^H\right),<br><br>\forall <br><br>a\in <br><br>{\left\{0,1\right\}}^M,a\ne <br><br>{\left\{0\right\}}^M,$

wherein α

denotes a vector indicating which of the physically existing M antennas to activate, where binary 1 denotes “

on”

, and binary 0 denotes “

off”

, H_α

denotes a column-punctured channel matrix of dimension M×

n_ta, ρ

is a channel signal-to-noise ratio, and n_ta is further defined by;

n_tα

=α

^Tα

.

5. The method of claim 4, wherein at least one condition detected at a receiver is used to generate the feedback information, the at least one condition includes radio characteristics measured at the receiver to determine at least one of a transmitter configuration, a modulation order, and a spreading gain that is subject to a desired error rate.

6. The method of claim 4, wherein said step of transmitting includes mapping each substream of said M substreams to a corresponding antenna in the transmit array.

7. A method for increasing data throughput in a communication system employing multiple antennas, comprising:

demultiplexing an input data stream into M substreams, each of the M substreams having a data rate lower than a data rate of the input data stream;

transmitting signals representing said M substreams from a transmit array of M antennas to at least one receiver based on at least one of a number of the M antennas to employ and on/off patterns that are specified for the M antennas; and

adjusting at least one parameter based on feedback information including at least one of an integer representing the number of the M antennas to employ for the transmitting and a vector including a pattern of ones and zeros representing the on/off patterns that are specified for the M antennas used for the transmitting;

receiving said signals at a receive array of N antennas connected to said at least one receiver; and

processing said signals so as to effect separation of said M substreams into individual substreams, wherein said step of processing further includes;

(a) detecting one substream while nulling remaining substreams,

(b) subtracting the detected substream from array elements, and

(c) determining which substream should be detected next,

wherein steps (a) to (c) are repeated until all of received signals representing M substreams have been separated into individual substreams.

8. An apparatus employing multiple antennas for increasing data throughput in a communication system, comprising:

a demultiplexer for demultiplexing an input data stream into M substreams, each of the M substreams having a data rate lower than a data rate of the input data stream; and

a transmitter for transmitting signals representing said M substreams from a transmit array of M antennas to at least one receiver based on at least one of a number of the M antennas to employ and on/off patterns that are specified for the M antennas, the apparatus adjusting at least one parameter based on feedback information including at least one of an integer representing the number of the M antennas to employ for transmitting signals and a vector including a pattern of ones and zeros representing the on/off patterns that are specified for the M antennas used for transmitting,

wherein the number of M antennas is represented by a parameter s that is defined by the equation;

$s=\arg <br><br>\underset{s=1,M}{\max }<br><br>{\log }_2<br><br>\det <br><br>\left(I+\frac{\mathrm{\rho <br><br>}}{s}<br><br>H_s<br><br>H_s^H\right),$

wherein I represents an identity matrix, H_s is a channel coefficient matrix with s columns, and ρ

is a channel signal-to-noise ratio.

9. The apparatus of claim 8, wherein at least one condition detected at a receiver is used to provide the feedback information, the at least one condition includes radio characteristics measured at the receiver to determine at least one of a transmitter configuration, a modulation order, and a spreading gain that is subject to a desired error rate.

10. The apparatus of claim 8, wherein said transmitter maps each substream of said M substreams to a corresponding antenna in the transmit array.

11. An apparatus employing multiple antennas for increasing data throughput in a communication system, comprising:

means for demultiplexing an input data stream into M substreams, each of the M substreams having a data rate lower than a data rate of the input data stream;

means for transmitting signals representing said M substreams from a transmit array of M antennas to at least one receiver based on at least one of a number of the M antennas to employ and on/off patterns that are specified for the M antennas; and

means for adjusting at least one parameter based on feedback information including at least one of an integer representing the number of the M antennas to employ for transmitting signals and a vector including a pattern of ones and zeros representing the on/off patterns that are specified for the M antennas used for transmitting signal,

wherein the number of M antennas is represented by a parameter s that is defined by the equation;

$s=\arg <br><br>\underset{s=1,M}{\max }<br><br>{\log }_2<br><br>\det <br><br>\left(I+\frac{\mathrm{\rho <br><br>}}{s}<br><br>H_s<br><br>H_s^H\right),$

wherein I represents an identity matrix, H_s is a channel coefficient matrix with s columns, and ρ

is a channel signal-to-noise ratio.

12. The apparatus of claim 11, wherein at least one condition detected at a receiver is used to generate the feedback information, the at least one condition includes radio characteristics measured at the receiver to determine at least one of a transmitter configuration, a modulation order, and a spreading gain that is subject to a desired error rate.

13. The apparatus of claim 11, wherein said means for transmitting maps each substream of said M substreams to a corresponding antenna in the transmit array.

14. The apparatus of claim 11, wherein said means for transmitting maps substreams to weighted combinations of several transmit antennas corresponding to different eigenmodes in said transmit array.

15. A method of receiving data in a communication system employing multiple antennas, comprising:

receiving signals representing M substreams from a transmit array of M antennas that are transmitted based on at least one of a number of the M antennas to employ and on/off patterns that are specified for the M antennas;

providing feedback information to effect transmissions of the transmit array, the feedback information including at least one of an integer representing the number of the M antennas to employ for the transmissions and a vector including a pattern of ones and zeros representing the on/off patterns that are specified for the M antennas for the transmissions;

receiving said signals at a receive array of N antennas connected to at least one receiver;

and processing said signals so as to effect separation of said M substreams into individual substreams, wherein

said step of processing further includes;

(a) detecting one substream while nulling remaining substreams,

(b) subtracting the detected substream from array elements, and

(c) determining which substream should be detected next,

wherein steps (a) to (c) are repeated until all of received signals representing M substreams have been separated into individual substreams.

16. The method of claim 15, further comprising:

measuring radio characteristics at a receiver to determine at least one of a transmitter configuration, a modulation order, and a spreading gain that is subject to a desired error rate; and

generating the feedback information based on the measuring.

17. An apparatus employing multiple antennas for increasing data throughput in a communication system, comprising:

a demultiplexer for demultiplexing an input data stream into M substreams, each of the M substreams having a data rate lower than a data rate of the input data stream; and

a transmitter for transmitting signals representing said M substreams from a transmit array of M antennas to at least one receiver based on at least one of a number of the M antennas to employ and on/off patterns that are specified for the M antennas, the apparatus adjusting at least one parameter based on feedback information including at least one of an integer representing the number of the M antennas to employ for transmitting signals and a vector including a pattern of ones and zeros representing the on/off patterns that are specified for the M antennas used for transmitting,

wherein the on/off patterns are determined by the equation;

$\underset{a}{\max }<br><br>{\log }_2<br><br>\det <br><br>\left(I+\frac{\mathrm{\rho <br><br>}}{\mathrm{nta}}<br><br>H_a<br><br>H_a^H\right),\forall <br><br>a\in <br><br>{\left\{0,1\right\}}^M,a\ne <br><br>{\left\{0\right\}}^M,$

wherein α

denotes a vector indicating which of the physically existing M antennas to activate, where binary 1 denotes “

on”

, and binary 0 denotes “

off”

, H_α

denotes a column-punctured channel matrix of dimension M×

n_ta, ρ

is a channel signal-to-noise ratio, and n_tα

is further defined by;

n_tα

=α

^Tα

.

18. The apparatus of claim 17, wherein at least one condition detected at a receiver is used to provide the feedback information, the at least one condition includes radio characteristics measured at the receiver to determine at least one of a transmitter configuration, a modulation order, and a spreading gain that is subject to a desired error rate.

19. The apparatus of claim 17, wherein said transmitter maps each substream of said M substreams to a corresponding antenna in the transmit array.

20. An apparatus employing multiple antennas for increasing data throughput in a communication system, comprising:

means for demultiplexing an input data stream into M substreams, each of the M sub streams having a data rate lower than a data rate of the input data stream;

means for transmitting signals representing said M substreams from a transmit array of M antennas to at least one receiver based on at least one of a number of the M antennas to employ and on/off patterns that are specified for the M antennas; and

means for adjusting at least one parameter based on feedback information including at least one of an integer representing the number of the M antennas to employ for transmitting signals and a vector including a pattern of ones and zeros representing the on/off patterns that are specified for the M antennas used for transmitting signals

wherein the on/off patterns are determined by the equation;

$\underset{a}{\max }<br><br>{\log }_2<br><br>\det <br><br>\left(I+\frac{\mathrm{\rho <br><br>}}{\mathrm{nta}}<br><br>H_a<br><br>H_a^H\right),\forall <br><br>a\in <br><br>{\left\{0,1\right\}}^M,a\ne <br><br>{\left\{0\right\}}^M,$

wherein α

denotes a vector indicating which of the physically existing M antennas to activate, where binary 1 denotes “

on”

, and binary 0 denotes “

off”

, H_α

denotes a column-punctured channel matrix of dimension M×

n_ta, ρ

is a channel signal-to-noise ratio, and n_tα

is further defined by;

n_tα

=α

^Tα

.

21. The apparatus of claim 20, wherein at least one condition detected at a receiver is used to generate the feedback information, the at least one condition includes radio characteristics measured at the receiver to determine at least one of a transmitter configuration, a modulation order, and a spreading gain that is subject to a desired error rate.

22. The apparatus of claim 20, wherein said means for transmitting maps each substream of said M substreams to a corresponding antenna in the transmit array.

23. The apparatus of claim 20, wherein said means for transmitting maps substreams to weighted combinations of several transmit antennas corresponding to different eigenmodes in said transmit array.