Multichannel multiuser detection

• US 6,745,050 B1
• Filed: 02/14/2001
• Issued: 06/01/2004
• Est. Priority Date: 10/23/2000
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Bliss, Daniel W., Forsythe, Keith W.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): TRINH, TAN H
• Application Number:
  US09/783,723
• Time in Patent Office: 1,203 Days
• Field of Search: 455/561, 455/562.1, 455/272, 455/273, 455/277.1, 455/277.2, 455/278.1, 455/63.1, 370/310, 370/342, 375/130, 375/140
• US Class Current: 455/561
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04B 7/0897 using beamforming per multi-path, e.g. to cope with different directions of arrival [DOA] at different multi-paths

Abstract

For multichannel multiuser detection in a wireless communication system such as a CDMA system, for a set of user spreading codes, coefficients to delay lines are adjusted and the delay line output processed to estimate a symbol. The symbol is estimated based on a space-time correlation for an antenna space delay time correlation. The estimated symbol is then remodulated and subtracted from the received antenna signal corresponding to other users of the wireless communication system. The adjusting and processing are iterated until the estimated symbols converge such that they correspond to a predetermined symbol decision criteria.

Claims

1. A method of multichannel multiuser detection in a wireless communication system comprising:

evaluating signals from plural antennas to tapped delay lines;

for each of at least one users, dependent on a set of user spreading codes, adjusting coefficients to a delay line and processing the delay line and antenna outputs to estimate a symbol based on an estimated space-time correlation between antenna space and delay time; and

remodulating the estimated symbol and applying the remodulated symbol to the antenna signals corresponding to other users of the wireless communication system.

2. The method of claim 1 further comprising a sequence of the spreading codes used to construct a particular space-time response for all possible symbols.

3. The method of claim 1 wherein each of the spreading codes is indicative of a particular user.

4. The method of claim 1 further comprising receiving a plurality of delays in the delay line.

5. The method of claim 4 further wherein each of the delays corresponds to receiving a wireless transmission at an antenna.

6. The method of claim 5 wherein the wireless transmissions have a range of received power.

7. The method of claim 6 wherein the range of received power is sufficient to increase the convergence of the estimating.

8. The method of claim 4 wherein the delays are indicative of a vector quantity corresponding to a space-time array response.

9. The method of claim 8 wherein the spreading code and the estimated symbol is indicative of the space-time array response.

10. The method of claim 4 wherein the delays are received by a base station processor via a reverse link of the wireless communication system.

11. The method of claim 1 wherein the estimated symbol corresponds to a particular user of interest.

12. The method of claim 1 wherein the received signal from other users comprises noise.

13. The method of claim 1 wherein a plurality of the spreading codes and a plurality of the antennas correspond to a particular user.

14. The method of claim 1 wherein the wireless communication system is a multiple input-multiple output (MIMO) system.

15. A wireless communication system operable for multichannel multiuser detection comprising:

a plurality of antennas each operable to receive a wireless signal;

tapped delay lines adapted to receive the wireless signals, wherein the wireless signals correspond to a set of user spreading codes;

a space-time correlator operable to adjust coefficients to the received wireless signals and process delay line outputs corresponding to the plurality of wireless signals to estimate a symbol based on an estimated space-time array response for an antenna space and delay time correlation; and

a remodulator operable to remodulate the estimated symbol using the estimated space-time array response and subtract it from the received antenna signals of other users.

16. The system of claim 15 wherein the space-time correlator is further operable to construct a particular space-time response using the spreading sequence for all possible symbols.

17. The system of claim 15 further comprising receiving the plurality of delays at the delay line.

18. The system of claim 17 wherein each space-time array response corresponds to a wireless transmission.

19. The system of claim 18 wherein the wireless transmissions correspond to a range of received power.

20. The system of claim 19 wherein the range of received power is sufficient to increase convergence of the multichannel multiuser detector.

21. The system of claim 18 wherein the wireless communications are received via a reverse link.

22. The system of claim 17 wherein the delays are indicative of a vector quantity corresponding to a space-time array response.

23. The system of claim 22 wherein the space-time array response is indicative of the spreading code and the estimated symbol.

24. The system of claim 15 wherein each of the spreading codes corresponds to a particular user.

25. The system of claim 15 wherein the estimated symbol corresponds to a user of interest.

26. The system of claim 15 wherein a plurality of the spreading codes and a plurality of the antennas correspond to a particular user.

27. The system of claim 15 wherein the wireless communication system is a multiple input-multiple output (MIMO) system.

28. The system of claim 15 further comprising repeating the adjusting and processing step.

29. The system of claim 15 further comprising a decision evaluator operable to evaluate the estimated symbol against a predetermined symbol decision criterion, and further operable to iterate through the adjusting, processing, and remodulating until the estimated symbol corresponds to the predetermined symbol decision criteria.

30. A computer program product having computer program code for multichannel multiuser detection in a wireless communication system comprising:

computer program code for evaluating signals from plural antennas to a tapped delay line;

computer program code for adjusting coefficients to a delay line for each of a plurality of users, the users dependent on a set of user spreading codes, and processing the delay line and antenna outputs to estimate a symbol based on an estimated space-time correlation between antenna space and delay time; and

computer program code for remodulating the estimated symbol and applying the remodulated symbol to the antenna signals corresponding to other users of the wireless communication system.

31. A computer data signal on a computer readable medium for multichannel multiuser detection in a wireless communication system comprising:

program code for evaluating signals from plural antennas to a tapped delay line;

program code for adjusting coefficients to a delay line for each of a plurality of users, the users dependent on a set of user spreading codes, and processing the delay line and antenna outputs to estimate a symbol based on an estimated space-time correlation between antenna space and delay time; and

program code for remodulating the estimated symbol and applying the remodulated symbol to the antenna signals corresponding to other users of the wireless communication system.

32. A wireless communication system operable for multichannel multiuser detection comprising:

means for evaluating signals from plural antennas to a tapped delay line;

means for adjusting coefficients to a delay line for each of a plurality of users, the users dependent on a set of user spreading codes, and processing the delay line and antenna outputs to estimate a symbol based on an estimated space-time correlation between antenna space and delay time; and

means for remodulating the estimated symbol and applying the remodulated symbol to the antenna signals corresponding to other users of the wireless communication system.