Space-time transmit diversity

• US 7,778,355 B2
• Filed: 04/30/2002
• Issued: 08/17/2010
• 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.
• Primary Examiner(s): Payne; David C
• Assistant Examiner(s): Panwalkar; Vineeta S
• Application Number:
  US10/135,611
• Publication Number:
  US 20030063654A1
• Time in Patent Office: 3,031 Days
• Field of Search: 375295-297, 375/299, 375/219, 375/135, 375/130, 375/146, 455/101
• US Class Current: 375/299
• 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) applying symbol streams s₁, s₂, . . . , s_P to a plurality of space-time transmit diversity encoders at a first time, where P is an integer greater than 3;

(b) encoding s₁ to produce streams x₁, x₂;

(c) encoding stream s_P to produce streams x_2P-1x_2P;

(d) linearly transforming said x₁, x₂, . . . x_2p into y₁, y₂, . . . , y_2P; and

(e) transmitting to a recipient said y₁, y₂, . . . , y_2P,

(f) wherein said linearly transforming of step (d) is a weighted permutation of said x₁, x₂ derived from transmission channel coefficients, and wherein said weighted permutation changes the order of symbols from streams x₁, x₂, . . . , x_2P to streams y₁, y₂, . . . , y_2P.

2. The method of claim 1, wherein said linear transforming of step (d) of claim 1 is selection from a finite set of linear transformations.

3. The method of claim 1, wherein said symbol streams s₁, s₂, s_p of step (a) are orthogonal frequency division multiplexing (OFDM) symbol streams.

4. The method of claim 1, wherein P=4.

5. The method of claim 1, wherein:

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

6. The method of claim 1, wherein:

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

P matrix W determined by combinations of estimations of the elements of the matrix {hacek over (R)}_TX=W^HR_TX W.

7. The method of claim 6, wherein:

said coefficients of a channel are estimated with pilot symbols from said recipient.

8. The method of claim 1, further comprising:

spreading said y₁, y₂, . . . , y_2P prior to transmission.

9. A method of transmitting, comprising:

(a) providing symbol stream s₁ to a first space-time transmit diversity encoder at a first time;

(b) providing space-time transmit diversity encoded streams x₁, x₂ from said first space-time transmit diversity encoder;

(c) providing symbol stream s₂ to a second space-time transmit diversity encoder at the first time;

(d) providing space-time transmit diversity encoded streams x₃, x₄ from said second space-time transmit diversity encoder, wherein said streams x₃, x₄ are different from said streams x₁, x₂;

(e) linearly transforming said x₁, x₂, x₃, x₄ into y₁, y₂, y₃, y₄ by a permutation of said x₁, x₂, x₃, x₄ in response to channel coefficients, wherein said permutation changes the order of symbols from streams x₁, x₂, x₃, x₄ to streams y₁, y₂, y₃, y₄; and

(f) transmitting said y₁, y₂, y₃, y₄.

10. The method of claim 9, wherein said linear transforming of step (e) of claim 9 is selection from a finite set of linear transformations.

11. The method of claim 9, wherein said symbol streams s₁ and s₂ of steps (a) and (c), respectively, are orthogonal frequency division multiplexing (OFDM) symbol streams.

12. The method of claim 9, wherein said linear transforming of step (e) of claim 9 is a weighted permutation of said x₁, x₂, x₃, x₄.

13. The method of claim 9, wherein said linear transforming of step (e) of claim 9 is with parameters provided by a recipient of said transmitting of step (f) of claim 9.

14. The method of claim 13, wherein said recipient provides said parameters via a feedback channel.

15. The method of claim 9, wherein said linear transforming of step (e) of claim 9 is with parameters derived from receipt of signals from a recipient of said transmitting of step (f) of claim 9.

16. The method of claim 15, comprising transmitting said parameters to said recipient via a signaling channel.

17. The method of claim 9, wherein said linear transforming of step (e) of claim 9 is with parameters arising from transforming a channel from a recipient of said transmitting of step (f) of claim 9, said transforming a channel approximates an independent, identically distributed or uncorrelated channel.

18. The method of claim 9, wherein space-time transmit diversity encoded stream x₁ comprises x_1(j) and x_1(j+1) where j is a positive integer, comprising the steps of:

producing x_1(j) at a first time;

producing x_1(j+1) at a second time;

producing a first transform of x_1(j+1) at the first time; and

producing a second transform different from the first transform of x_1(j) at the second time.

19. The method of claim 18, wherein said first transform is a negative conjugation and wherein said second transform is a conjugation.