Space-time transmit diversity

• US 20030063654A1
• Filed: 04/30/2002
• Published: 04/03/2003
• Est. Priority Date: 05/01/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Onggosanusi, Eko N., Dabak, Anand G.
• Granted Patent: US 7,778,355 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0055 MAP-decoding
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0618 Space-time coding

Abstract

A linear transformation of parallel space-time transmit diversity encoded streams; also, asymmetrical symbol mapping of parallel streams. Separately or together, these improve error rate performance as well as system throughput. Preferred embodiments include CDMA wireless systems with multiple antennas.

Claims

1. A method of transmitting, comprising:

(a) providing space-time transmit diversity encoded streams X₁, x₂, . . . , X_Pwhere P is an integer greater than 3;

(b) linearly transforming said x₁, x₂, . . . , x_P into Y₁, Y₂, . . . , y_P and

(c) transmitting said y₁, Y₂, . . . , Y_P.

(d) wherein said linearly transforming of step (b) derives from transmission channel coefficients.

2. The method of claim 1, wherein:

(a) said linear transforming of step (b) of claim 1 is selection from a finite set of linear transformations.

3. The method of claim 1, wherein:

(a) said linear transforming of step (b) of claim 1 is a permutation of said x₁, X₂, . . . , X_P.

4. The method of claim 1, wherein:

(a) said linear transforming of step (b) of claim 1 is a weighted permutation of said x₁, x₂, . . . , x_P.

5. The method of claim 1, wherein:

(a) P=4;

(b) said x₁ and x₂ are STTD encodings of a first symbol stream; and

(c) said x₃ and x₄ are STTD encodings of a second symbol stream.

6. The method of claim 1, wherein:

(a) said linear transforming of step (b) of claim 1 is with parameters provided by a recipient of said transmitting of step (c) of claim 1.

7. The method of claim 6, wherein:

(a) said recipient provides said parameters via a feedback channel.

8. The method of claim 1, wherein:

(a) said linear transforming of step (b) of claim 1 is with parameters derived from receipt of signals from a recipient of said transmitting of step (c) of claim 1.

9. The method of claim 8, further comprising:

(a) transmitting said parameters to said recipient via a signaling channel.

10. The method of claim 1, wherein:

(a) said linear transforming of step (b) of claim 1 is with parameters arising from transforming a channel from a recipient of said transmitting of step (c) of claim 1, said transforming a channel approximates an independent, identically distributed or uncorrelated channel.

11. The method of claim 1, wherein:

(a) said linear transforming of step (b) of claim 1 is with a P×

P matrix M determined by combinations of estimations of E[Mh_p* Mh_p′

] approximating a multiple of the P×

P identity matrix where hp are coefficients of a channel to a recipient of said transmitting of step (c) of claim 1.

12. The method of claim 11, wherein:

(a) the elements of M are quantized.

13. The method of claim 11, wherein:

(a) said coefficient of a channel are estimated with pilot symbols from said recipient.

14. The method of claim 1, further comprising:

(a) spreading said y₁, Y₂, . . . , y_p prior to transmission.

15. A method of receiving, comprising:

(a) treating received signals as a linear transform of P/2 parallel STTD encoded signals from P antennas, with P an even integer greater than 3;

(b) providing said linear transform;

(c) detecting said signals using said linear transform applied to channel coefficient estimates.

16. The method of claim 15, wherein:

(a) said step (c) of claim 15 is an interference resistant detecting.

17. The method of claim 15, wherein:

(a) said step (c) of claim 15 is an iterative minimum mean square error detecting.

18. The method of claim 15, wherein:

(a) P=4; and

(b) said received signals of step (a) of claim 15 is with Q antennas, with Q an integer greater than 1.

19. The method of claim 15, wherein:

P=4; and

(a) said receiving of step (a) of claim 15 is with 1 antenna.

20. The method of claim 15, wherein:

(a) said linear transform of step (b) of claim 15 is with parameters provided by a source of said signals of step (a) of claim 15.

21. The method of claim 15, wherein:

(a) said linear transform of step (b) of claim 15 is with parameters derived from channel estimates using second signals from a source of said signals of step (a) of claim 15.

22. The method of claim 15 wherein:

(a) said linear transform of step (b) of claim 15 is with a P×

P matrix M determined by combinations of estimations of E[Mh_p* Mh_p′

] approximating a multiple of the P×

P identity matrix where hp are coefficients of a channel of said received signals of step (a) of claim 15.

23. The method of claim 22, wherein:

(a) said M represents a permutation.

24. The method of claim 15, wherein:

(a) said treating of step (a) of claim 15 includes resolving multiple signal paths; and

(b) said detecting of step (c) of claim 15 includes multipath interference suppression.

25. A transmitter, comprising:

(a) at least two space-time transmit diversity encoders, each of said encoders coupled to a corresponding data stream;

(b) a linear transformer coupled to said encoders; and

(c) transmit antennas couple to said linear transformer.

26. A receiver, comprising:

(a) a channel coefficient estimator;

(b) a linear transformation source coupled to said estimator; and

(c) a detector coupled to said estimator and said linear transformation source, said detector including space-time diversity combining.