Method and system employing antenna arrays

• US 20030223391A1
• Filed: 06/04/2002
• Published: 12/04/2003
• Est. Priority Date: 06/04/2002
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Valenzuela, Reinaldo A., Malaender, Laurence Eugene
• Granted Patent: US 7,421,039 B2
• Time in Patent Office: Days
• US Class Current: 370/334
• 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 a set of parameters selected from a group comprising at least a number of the M antennas to employ, on/off patterns that are specified for the M antennas, and eigenmodes specified for the M antennas; and

adjusting at least one of said parameters based on at least one condition detected at a receiver so as to increase data throughput in the system.

2. The method of claim 1, wherein the eigenmodes are selected in order to determine a transmit power used to transmit the M substreams.

3. The method of claim 2, wherein the transmit power, P_T, is defined by the equation:

4. The method of claim 1, wherein the number of M antennas is represented by a parameter s that is defined by the equation:

5. The method of claim 1, wherein the on/off patterns are determined by the equation:

6. The method of claim 1, wherein data throughput is increased without changing system bandwidth or without increasing transmit power.

7. The method of claim 1, further comprising:

receiving said signals at a receive array of N antennas connected to said at least one receiver, where N<

M; and

processing said signals so as to effect separation of said M substreams into individual substreams.

8. The method of claim 7, 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.

9. The method of claim 1, wherein said at least one condition detected at a receiver 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 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.

11. The method of claim 1, wherein said step of transmitting includes mapping substreams to weighted combinations of several transmit antennas corresponding to different eigenmodes in said transmit array.

12. 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 a set of parameters selected from a group comprising at least a number of the M antennas to employ, on/off patterns that are specified for the M antennas, and eigenmodes specified for the M antennas, the apparatus adjusting at least one of said parameters based on at least one condition detected at a receiver so as to increase data throughput in the system.

13. The apparatus of claim 12, wherein data throughput is increased without changing system bandwidth or without increasing transmit power.

14. The apparatus of claim 12, wherein said at least one condition detected at a receiver 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.

15. The apparatus of claim 12, wherein said transmitter maps each substream of said M substreams to a corresponding antenna in the transmit array.

16. The apparatus of claim 12, wherein said transmitter maps substreams to weighted combinations of several transmit antennas corresponding to different eigenmodes in said transmit array.

17. 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 a set of parameters selected from a group comprising at least a number of the M antennas to employ, on/off patterns that are specified for the M antennas, and eigenmodes specified for the M antennas, and

means for adjusting at least one of said parameters based on at least one condition detected at a receiver so as to increase data throughput in the system.

18. The apparatus of claim 17, wherein data throughput is increased without changing system bandwidth or without increasing transmit power.

19. The apparatus of claim 17, wherein said at least one condition detected at a receiver 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.

20. The apparatus of claim 17, wherein said means for transmitting maps each substream of said M substreams to a corresponding antenna in the transmit array.

21. The apparatus of claim 17, wherein said means for transmitting maps substreams to weighted combinations of several transmit antennas corresponding to different eigenmodes in said transmit array.

22. 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 a set of parameters selected from a group comprising at least a number of the M antennas to employ, on/off patterns that are specified for the M antennas, and eigenmodes specified for the M antennas; and

adjusting at least one of said parameters based on at least one condition detected at a receiver so as to increase data throughput in the system.

23. The method of claim 22, further comprising:

receiving said signals at a receive array of N antennas connected to said at least one receiver, where N<

M; and

processing said signals so as to effect separation of said M substreams into individual substreams.

24. The method of claim 23, 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.

25. The method of claim 22, wherein said at least one condition detected at the receiver 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.