Single-antenna interference cancellation receiver in time slot communication system

• US 20050201493A1
• Filed: 10/18/2004
• Published: 09/15/2005
• Est. Priority Date: 02/26/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Onggosanusi, Eko N., Dabak, Anand G., Schmidl, Timothy M.
• Granted Patent: US 7,565,111 B2
• Time in Patent Office: Days
• US Class Current: 375/340
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/0236 using estimation of the other symbols
• CPC Class Codes: H04L 25/025 using least-mean-square [LMS] method
• CPC Class Codes: H04L 25/03292 with channel estimation circuitry
• CPC Class Codes: H04L 25/03299 with noise-whitening circuitry
• CPC Class Codes: H04L 25/03305 Joint sequence estimation and interference removal joint detection of several desired signals H04L25/03331

Abstract

A receiver (MST) for use in a modulated communications system wherein data is communicated in a time-slotted format. The receiver comprises circuitry (22) for providing samples of a group of data from the time-slotted format and circuitry (46, 42) for determining a first set of channel estimates in response to a first set of the samples. The receiver also comprises circuitry (30) for first predicting decisions for data in the group of data in response to the first set of channel estimates and circuitry (46, 42) for determining a second set of channel estimates in response to the predicted decisions. Lastly, the circuitry for predicting is further for second predicting decisions for data in the group of data in response to the second set of channel estimates.

Claims

1. A receiver for use in a modulated communications system wherein data is communicated in a time-slotted format, the receiver comprising:

circuitry for providing samples of a group of data from the time-slotted format;

circuitry for determining a first set of channel estimates in response to a first set of the samples;

circuitry for first predicting decisions for data in the group of data in response to the first set of channel estimates;

circuitry for determining a second set of channel estimates in response to the predicted decisions; and

wherein the circuitry for predicting is further for second predicting decisions for data in the group of data in response to the second set of channel estimates.

2. The receiver of claim 1 and further comprising:

circuitry for determining a first set of interference estimates in response to the first set of the samples;

wherein the circuitry for first predicting decisions for data in the group of data in response to the first set of channel estimates predicts the decisions for data in the group of data also in response to the first set of interference estimates;

circuitry for determining a second set of interference estimates in response to the predicted decisions; and

wherein the circuitry for second predicting decisions for the data in the group of data in response to the second set of channel estimates also predicts the decisions for the data in the group of data in response to the second set of interference estimates.

3. The receiver of claim 2 and further comprising circuitry for performing single-antenna interference cancellation on the samples, wherein the circuitry for first and second predicting decisions for data in the group of data is further responsive to the single-antenna interference cancellation.

4. The receiver of claim 3 wherein the single-antenna interference cancellation comprises spatial whitening.

5. The receiver of claim 2 wherein the circuitry for first predicting decisions for data in the group of data in response to the first set of channel estimates and a first set of interference estimates comprises circuitry for predicting hard decisions.

6. The receiver of claim 2 wherein the circuitry for first predicting decisions for data in the group of data in response to the first set of channel estimates and a first set of interference estimates comprises circuitry for predicting soft decisions.

7. The receiver of claim 2 wherein the circuitry for first predicting decisions for data in the group of data in response to the first set of channel estimates and a first set of interference estimates comprises circuitry for predicting soft decisions in response to a function selected from a group consisting of a non-linear function and linear clipping.

8. The receiver of claim 2 wherein the circuitry for determining a first set of channel estimates and a first set of interference estimates in response to a first set of the samples is for determining the first set of channel estimates and the first set of interference estimates in response to at least a portion of a training sequence code.

9. The receiver of claim 8 wherein the training sequence code comprises a GSM training sequence code.

10. The receiver of claim 8:

wherein the training sequence code comprises a GSM training sequence code; and

wherein the circuitry for determining a first set of channel estimates and a first set of interference estimates in response to a first set of the samples is for determining the first set of channel estimates and the first set of interference estimates in response to an entirety of the training sequence code.

11. The receiver of claim 8:

wherein the training sequence code comprises a GSM training sequence code; and

wherein the circuitry for determining a first set of channel estimates and a first set of interference estimates in response to a first set of the samples is for determining the first set of channel estimates and the first set of interference estimates in response to a portion of the training sequence code.

12. The receiver of claim 2:

wherein the circuitry for determining the first set of channel estimates and the first set of interference estimates comprises correlation circuitry; and

wherein the circuitry for determining the second set of channel estimates and the second set of interference estimates comprises single user least squares circuitry.

13. The receiver of claim 2:

wherein the circuitry for determining the first set of channel estimates and the first set of interference estimates comprises single user least squares circuitry; and

wherein the circuitry for determining the second set of channel estimates and the second set of interference estimates comprises single user least squares circuitry.

14. The receiver of claim 2 wherein the circuitry for predicting is selected from a set consisting of an equalizer, a maximum likelihood sequence estimator, an interference canceller, and a matched filter.

15. The receiver of claim 2 wherein the circuitry for providing samples comprises:

a sampler for sampling an incoming signal at a rate Q greater than a sample rate and to provide a discrete-time output;

a de-rotater for applying de-rotation to the discrete time sequence;

circuitry for extracting a real component for each input sample; and

circuitry for extracting an imaginary component for each input sample.

16. The receiver of claim 1 and further comprising:

a deinterleaver coupled to receive decisions predicted by the circuitry for predicting second predicting decisions;

a decoder coupled to receive an output of the deinterleaver; and

a cyclic redundancy check circuit for evaluating cyclic redundancy check accuracy of at least a portion of data output by the decoder.

17. The receiver of claim 1 wherein the circuitry for first predicting decisions for data in the group of data in response to the first set of channel estimates comprises circuitry for predicting hard decisions.

18. The receiver of claim 1 wherein the circuitry for first predicting decisions for data in the group of data in response to the first set of channel estimates comprises circuitry for predicting soft decisions.

19. The receiver of claim 1 wherein the circuitry for providing samples comprises:

a sampler for sampling an incoming signal at a rate Q greater than a sample rate and to provide a discrete-time output;

a de-rotater for applying de-rotation to the discrete time sequence;

circuitry for extracting a real component for each input sample; and

circuitry for extracting an imaginary component for each input sample.

20. The receiver of claim 19 and further comprising:

a deinterleaver coupled to receive decisions predicted by the circuitry for predicting second predicting decisions;

a decoder coupled to receive an output of the deinterleaver; and

a cyclic redundancy check circuit for evaluating cyclic redundancy check accuracy of at least a portion of data output by the decoder.

21. The receiver of claim 1 wherein the modulation is selected from a set consisting of GMSK and 8PSK modulation.

22. A method of operating a receiver in a modulated communications system wherein data is communicated in a time-slotted format, the method comprising:

receiving communications in the time-slotted format;

providing samples of a group of data from the time-slotted format;

determining a first set of channel estimates in response to a first set of the samples;

first, predicting decisions for data in the group of data in response to the first set of channel estimates;

determining a second set of channel estimates in response to the predicted decisions; and

second, predicting decisions for data in the group of data in response to the second set of channel estimates.

23. The method of claim 22 and further comprising:

determining a first set of interference estimates in response to the first set of the samples;

wherein the step of first predicting decisions for data in the group of data in response to the first set of channel estimates predicts the decisions for data in the group of data also in response to the first set of interference estimates;

determining a second set of interference estimates in response to the predicted decisions; and

wherein the step of second predicting decisions for the data in the group of data in response to the second set of channel estimates also predicts the decisions for the data in the group of data in response to the second set of interference estimates.

24. The method of claim 23 and further comprising performing single-antenna interference cancellation on the samples, wherein the steps of first and second predicting decisions for data in the group of data are further responsive to the single-antenna interference cancellation.

25. The method of claim 24 wherein the single-antenna interference cancellation comprises spatial whitening.

26. The method of claim 23 wherein the step of first predicting decisions for data in the group of data in response to the first set of channel estimates and a first set of interference estimates comprises predicting hard decisions.

27. The method of claim 23 wherein the step of first predicting decisions for data in the group of data in response to the first set of channel estimates and a first set of interference estimates comprises predicting soft decisions.

28. The method of claim 22 wherein the steps of determining a first set of channel estimates and a first set of interference estimates in response to a first set of the samples comprise determining the first set of channel estimates and the first set of interference estimates in response to at least a portion of a training sequence code.

29. The method of claim 22 wherein the data comprises a GSM data.