Communications device with adaptive decoding and associated methods

• US 7,265,715 B2
• Filed: 03/10/2006
• Issued: 09/04/2007
• Est. Priority Date: 09/23/2004
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Goldberg, Steven J., Briancon, Alain Charles Louis
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): MULL, FRED H
• Application Number:
  US11/373,367
• Publication Number:
  US 20060202893A1
• Time in Patent Office: 543 Days
• Field of Search: 342/373, 342377-378, 342/380, 342382-383, 702190-197, 702/FOR.164
• US Class Current: 342/378
• CPC Class Codes: H01Q 1/242 specially adapted for hand-held use
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H01Q 3/30 varying the relative phase between the radiating elements of an array H01Q3/2605, H01Q3/2658, H01Q3/2682, H01Q3/44 take precedence
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0248 Eigen-space methods
• CPC Class Codes: H04L 25/03331 Arrangements for the joint estimation of multiple sequences
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

In a communications device operating with a blind signal separation (BSS) processor, an initial mixing matrix is formed based upon the different summations of the source signals received by the antenna array. The initial mixing matrix is evaluated to determine a minimum rank that is necessary for at least one source signal to be useable after having been separated from the initial mixing matrix and decoded. An additional mixing matrix is then formed, and also includes the different summations of the source signals. If the rank of the additional mixing matrix is less than the minimum rank associated with the initial mixing matrix, then the source signals are modified so that the rank of the additional mixing matrix is increased.

Claims

1. A method for decoding signals in a communications device comprising an antenna array, a transceiver coupled to the antenna array, and a processor coupled to the transceiver, the method comprising;

receiving source signals at the antenna array, the antenna array comprising N antenna elements for receiving N different summations of the source signals;

providing the N different summations of the source signals to the transceiver;

evaluating the N different summations of the source signals in the processor by

forming an initial mixing matrix comprising the N different summations of the source signals, the initial mixing matrix having a rank equal to or less than N,

separating at least one desired source signal from the initial mixing matrix,

decoding the at least one desired source signal after the separating,

determining a minimum rank of the initial mixing matrix necessary for the at least one desired source signal to be useable after the decoding; and

forming an additional mixing matrix comprising the N different summations of the source signals, and if the rank of the additional mixing matrix is less than the minimum rank associated with the initial mixing matrix, then modifying the source signals so that the rank of the additional mixing matrix is increased.

2. A method according to claim 1 wherein the N different summations of the source signals used for the additional mixing matrix are the same as the N different summations of the source signals used for the initial mixing matrix, except time delayed.

3. A method according to claim 1 wherein the N different summations of the source signals used for the additional mixing matrix are different than the N different summations of the source signals used for the initial mixing matrix.

4. A method according to claim 1 wherein the communications device further comprises a signal splitter between the antenna array and the transceiver;

and wherein the modifying comprises splitting the source signals so that the rank of the additional mixing matrix is increased.

5. A method according to claim 4 wherein the signal splitter comprises a code despreader for decoding the N different summations of the source signals, each one of the N different summations including k codes for providing k different summations of the source signals associated therewith, the additional mixing matrix comprising kN different summations of the source signals so that a rank of kN is provided.

6. A method according to claim 5 wherein the signal splitter further comprises in-phase (I) and quadrature (Q) modules downstream from the code despreader, and if the rank of kN is less than the minimum rank associated with the initial mixing matrix, then the I and Q modules separate each one of the kN different summations of the source signals into I and Q component sets so that a rank of 2kN is provided.

7. A method according to claim 6 wherein if the rank of 2kN is less than the minimum rank associated with the initial mixing matrix, then a rank deficient flag is set in the processor.

8. A method according to claim 4 wherein the signal splitter comprises in-phase (I) and quadrature (Q) modules for separating each one of the N different summations of the source signals into I and Q component sets, the additional mixing matrix comprising 2N different summations of the source signals so that a rank of 2N is provided.

9. A method according to claim 1 wherein if the rank of the additional mixing matrix is greater than the minimum rank associated with the initial mixing matrix, then modifying the source signals so that the rank of the additional mixing matrix is decreased.

10. A method according to claim 9 wherein the modifying comprises not including at least one of the N different summations of the source signals when forming the additional mixing matrix.

11. A method according to claim 1 wherein the N antenna elements comprise N active antenna elements so that the antenna array forms a phased array.

12. A method according to claim 1 wherein the N antenna elements comprise N active antenna elements, with at least two of the active antenna elements having different polarizations.

13. A method according to claim 1 wherein the N antenna elements comprise at least one active antenna element, and up to N−

1 passive antenna elements so that the antenna array forms a switched beam antenna.

14. A method according to claim 1 wherein the processing for separating desired source signals from the additional mixing matrix is based on at least one of principal component analysis (PCA) and independent component analysis (ICA).

15. A method according to claim 1 wherein the processing for separating desired source signals from the additional mixing matrix is based on single value decomposition (SVD).

16. A method according to claim 1 further comprising determining if the N different summations of the source signals are stationary relative to the communications device;

and wherein the processing for separating desired source signals from the additional mixing matrix is based on a stationary processing procedure if the received signals are stationary, or a non-stationary processing procedure if the received signals are not stationary.

17. A method according to claim 16 wherein the processing for separating the desired source signals from the additional mixing matrix is based on principal component analysis (PCA) if the source signals are stationary, or non-stationary PCA if the source signals are not stationary.

18. A method according to claim 1 wherein the type of processing used for separating the at least one desired source signal from the initial mixing matrix is used for separating the at least one desired source signal from the additional mixing matrix, the type of processing comprising at least one of principal component analysis (PCA), non-stationary PCA and independent component analysis (PCA).

19. A method according to claim 1 further comprising:

determining a bit error rate in the at least one desired source signal after the decoding of the initial mixing matrix; and

providing feedback via the transceiver to a transmitter transmitting the at least one desired source signal for adjusting the encoding of the at least one desired source signal at the transmitter.

20. A communications device comprising:

an antenna array for receiving source signals, said antenna array comprising N antenna elements for receiving N different summations of the source signals;

a transceiver coupled to said antenna array for receiving the N different summations of the source signals; and

a processor coupled to said transceiver for evaluating the N different summations of the source signals by

forming an initial mixing matrix comprising the N different summations of the source signals, the initial mixing matrix having a rank equal to or less than N,

separating at least one desired source signal from the initial mixing matrix,

decoding the at least one desired source signal after the separating,

determining a minimum rank of the initial mixing matrix necessary for the at least one desired source signal to be useable after the decoding; and

said processor forming an additional mixing matrix comprising the N different summations of the source signals, and if the rank of the additional mixing matrix is less than the minimum rank associated with the initial mixing matrix, then modifying the source signals so that the rank of the additional mixing matrix is increased.

21. A communications device according to claim 20 wherein the N different summations of the source signals used for the additional mixing matrix are the same as the N different summations of the source signals used for the initial mixing matrix, except time delayed.

22. A communications device according to claim 20 wherein the N different summations of the source signals used for the additional mixing matrix are different than the N different summations of the source signals used for the initial mixing matrix.

23. A communications device according to claim 20 further comprises a signal splitter between said antenna array and said transceiver;

and wherein the modifying comprises splitting the source signals so that the rank of the additional mixing matrix is increased.

24. A communications device according to claim 23 wherein said signal splitter comprises a code despreader for decoding the N different summations of the source signals, each one of the N different summations including k codes for providing k different summations of the source signals associated therewith, the additional mixing matrix comprising kN different summations of the source signals so that a rank of kN is provided.

25. A communications device according to claim 24 wherein said signal splitter further comprises in-phase (I) and quadrature (Q) modules downstream from said code despreader, and if the rank of kN is less than the minimum rank associated with the initial mixing matrix, then said I and Q modules separate each one of the kN different summations of the source signals into I and Q component sets so that a rank of 2kN is provided.

26. A communications device according to claim 25 wherein if the rank of 2kN is less than the minimum rank associated with the initial mixing matrix, then a rank deficient flag is set in said processor.

27. A communications device according to claim 23 wherein said signal splitter comprises in-phase (I) and quadrature (Q) modules for separating each one of the N different summations of the source signals into I and Q component sets, the additional mixing matrix comprising 2N different summations of the source signals so that a rank of 2N is provided.

28. A communications device according to claim 20 wherein if the rank of the additional mixing matrix is greater than the minimum rank associated with the initial mixing matrix, then the source signals are modified so that the rank of the additional mixing matrix is decreased.

29. A communications device according to claim 28 wherein the modifying comprises not including at least one of the N different summations of the source signals when forming the additional mixing matrix.

30. A communications device according to claim 20 wherein the N antenna elements comprise N active antenna elements so that said antenna array forms a phased array.

31. A communications device according to claim 20 wherein the N antenna elements comprise N active antenna elements, with at least 2 of the antenna elements having different polarizations.

32. A communications device according to claim 20 wherein the N antenna elements comprise at least one active antenna element, and up to N−

1 passive antenna elements so that said antenna array forms a switched beam antenna.

33. A communications device according to claim 20 wherein the processing performed by said processor for separating desired source signals from the additional mixing matrix is based on at least one of principal component analysis (PCA) and independent component analysis (ICA).

34. A communications device according to claim 20 wherein the processing performed by said processor for separating desired source signals from the additional mixing matrix is based on single value decomposition (SVD).

35. A communications device according to claim 20 wherein said processor further determines if the N different summations of the source signals are stationary relative to said transceiver;

and wherein the processing for separating desired source signals from the additional mixing matrix is based on a stationary processing procedure if the received signals are stationary, or a non-stationary processing procedure if the received signals are not stationary.

36. A communications device according to claim 35 wherein the processing performed by said processor for separating desired source signals from the additional mixing matrix is based principal component analysis (PCA) if the source signals are stationary, or non-stationary PCA if the source signals are not stationary.

37. A communications device according to claim 20 wherein the type of processing used by said processor for separating the at least one desired source signal from the initial mixing matrix is used for separating the at least one desired source signal from the additional mixing matrix, the type of processing comprising at least one of principal component analysis (PCA), non-stationary PCA and independent component analysis (PCA).

38. A communications device according to claim 20 wherein said processor determines a bit error rate in the at least one desired source signal after the decoding of the initial mixing matrix, and provides feedback via said transceiver to a transmitter transmitting the at least one desired source signal for adjusting the encoding of the at least one desired source signal at the transmitter.