Spread spectrum interference cancellation

• US 6,816,541 B1
• Filed: 05/24/2000
• Issued: 11/09/2004
• Est. Priority Date: 05/24/1999
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Schmidl, Timothy M.
• Primary Examiner(s): Bayard, Emmanuel
• Assistant Examiner(s): Ghulamali, Qutbuddin
• Application Number:
  US09/578,017
• Time in Patent Office: 1,630 Days
• Field of Search: 375/148, 375/144, 375/147
• US Class Current: 375/148
• CPC Class Codes: H04B 1/71075 Parallel interference cancellation
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 2001/71077 Partial interference cancellation

Abstract

Iterative parallel interference cancellation estimations for signals received from multiple coded sources or a source with multiple coded outputs with updated estimates of interfering signals used during an iteration.

Claims

1. A method of reception for interfering signals, comprising:

(a) detect signals encoding information u₁, . . . u_n where n is a positive integer;

(b) estimate said u₁, . . . u_n from the results of step (a); and

then

(c) for each k in the range 1 to n;

(i) estimate the interference of said signals on said detection of step (a) for information u_k;

(ii) adjust the estimate of said u_k using the estimate of step (c)(i);

(d) repeat step (c) wherein for substep (c)(i) said estimate of the interference uses the results of substep (c)(ii) for said u_j for j<

k; and

(e) decide values for said u₁, . . . u_n from the results of step (d).

2. The method of claim 1, wherein:

(a) said detect signals of step (a) of claim 1 includes projection of said signals onto codes associated with said information u₁, . . . , u_n.

3. The method of claim 1, wherein:

(a) said adjust the estimate of substep (c)(ii) of claim 1 includes use of the estimate of said u_k.

4. The method of claim 1, wherein:

(a) said detect signals of step (a) of claim 1 includes maximal ratio combining of signals relating to a single information u_k.

5. The method of claim 1, wherein:

(a) said adjust the estimate of substep (c)(ii) of claim 1 is a soft decision.

6. The method of claim 1, wherein:

(a) said signals of step (a) of claim 1 arise from a single source.

7. A receiver for multiple interfering signal streams, comprising:

(a) detectors D₁, . . . , D_n for signals S₁, . . . , S_n where n is a positive integer, with said signals S₁, . . . , S_n encoding information u₁, . . . u_n;

(b) first estimators FE₁, . . . , FE_n and second estimators SE₁, . . . , SE_n with inputs of said first estimator FE_k from (i) said detector D_k and (ii) said second estimator SE_k, said first estimators capable of estimating said u₁, . . . u_n;

(c) said second estimator SE_j with inputs from all of said first estimators FE_i for i less than or equal to j, said second estimators SE_j capable of estimating interference of said signals; and

(d) a controller to iterate outputs from said second estimators back to said first estimators.

8. The receiver of claim 7, wherein:

(a) said first estimators FE_k include inputs of feedback from output of said FE_k.

9. The receiver of claim 7, wherein:

(a) said first estimators, said second estimators, and at least in part said detectors are implemented as a programmable processor together with a program.

10. The receiver of claim 7, wherein:

(a) said detectors include a RAKE detector.

11. The receiver of claim 7, wherein:

(a) said detectors include code projectors associated with said signals.