Closed-loop transmit diversity scheme in frequency selective multipath channels

• US 20030139194A1
• Filed: 11/21/2002
• Published: 07/24/2003
• Est. Priority Date: 11/21/2001
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Texas Instruments, Inc.
• Inventors: Onggosanusi, Eko N., Dabak, Anand G.
• Granted Patent: US 8,018,903 B2
• Time in Patent Office: Days
• US Class Current: 455/506
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0848 Joint weighting
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]

Abstract

Closed loop multiple-antenna wireless communications system with antenna weights determined by maximizing a composite channel signal-to-interference-plus-noise ratio minimum. Multiplexed symbol streams over subsets of antennas enhance throughput.

Claims

1. A method of transmission, comprising:

(a) providing P transmit antennas where P is an integer greater than or equal to 2;

(b) providing weights for said P antennas, said weights determined from information of communication channels from said P antennas to Q receive antenna(s) where Q is a positive integer, said information including effects of multipath interference; and

(c) transmitting symbols modified by said weights from said P antennas.

2. The method of claim 1, wherein:

(a) said weights determined in step (b) of claim 1 includes off-diagonal minimization of elements of the channel matrix premultiplied by its Hermitian conjugate.

3. The method of claim 1, wherein:

(a) said weights determined in step (b) of claim I includes information of a detection method to account for said multipath interference.

4. The method of claim 3, wherein:

(a) said weights determined in step (b) of claim 1 includes minimization of an error rate when using said detection method of claim 3.

5. The method of claim 4, wherein:

(a) said weights determined in claim 3 includes minimization of symbol error rate for a maximum likelihood detection method.

6. The method of claim 3, wherein:

(a) said weights determined in step (b) of claim 1 includes maximization of a signal-to-interference-plus-noise ratio when using said detection method of claim 3.

7. The method of claim 6, wherein:

(a) said weights determined in step (b) of claim 1 includes maximization of minimum signal-to-interference-plus-noise ratio for a detection method selected from the group consisting of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, and iterative minimum mean square error.

8. The method of claim 3, wherein:

(a) said providing weights in step (b) of claim 1 includes channel information estimated from reception of signals from said Q antenna(s).

9. The method of claim 1, wherein:

(a) said providing weights in step (b) of claim 1 includes reception of channel information from said Q antenna(s).

10. The method of claim 1, wherein:

(a) said providing weights in step (b) of claim 1 includes reception of said weights from said Q antenna(s).

11. The method of claim 1, wherein:

(a) said communication channel is a wideband or CDMA channel with a single user using multiple codes having the same weights.

12. The method of claim 11, wherein:

(a) said detection method of claim 3 is multicode interference cancellation with method selected from the group consisting of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, and iterative minimum mean square error.

13. The method of claim 3, wherein:

(a) said communication channel is a wideband or CDMA channel with multiple users having differing weights; and

(b) said differing weights are from claim 3 by joint maximization.

14. The method of claim 13, wherein:

(a) said detection method of claim 3 is multiuser interference cancellation with method selected from the group consisting of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, and iterative minimum mean square error.

15. The method of claim 3, wherein:

(a) said weights of step (b) of claim 1 are updated.

16. The method of claim 1, wherein:

(a) said integer Q is greater than or equal to said integer P.

17. A transmitter, comprising:

(a) P transmit antennas where P is an integer greater than or equal to 2; and

(b) multipliers with weights coupled to said P antennas, said weights determined from (i) information of communication channels from said P antennas to Q receive antenna(s) where Q is a positive integer, said information including effects of multipath interference and/or (ii) a detection method to account for said multipath interference.

18. The transmitter of claim 17, wherein:

(a) said weights are determined by a processor coupled to said multipliers.

19. The transmitter of claim 17, wherein:

(a) said weights are determined outside of said transmitter and received by said transmitter from said signals from said Q antenna(s).

20. A receiver, comprising:

(a) Q antenna(s) where Q is a positive integer;

(b) a detector coupled to said Q antenna(s), said detector adapted to detect signals from P transmit antennas where P is an integer greater than or equal to 2 and with weights applied to said P antennas, where said weights are determined from (i) information of communication channels from said P antennas to said Q receive antenna(s), said information including effects of multipath interference and/or (ii) a detection method of said detector to account for said multipath interference.

21. The receiver of claim 20, wherein:

(a) said detection method is selected from the group consisting of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, and iterative minimum mean square error; and

(b) said weights determination includes maximization of minimum signal-to-interference-plus-noise ratio.

22. The receiver of claim 20, wherein:

(a) said detection method is maximum likelihood; and

(b) said weights determination includes minimization of symbol error rate.