Blind signal separation using spreading codes

• US 7,116,271 B2
• Filed: 09/22/2005
• Issued: 10/03/2006
• 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: Kostanic, Ivica, Goldberg, Steven J.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H.
• Application Number:
  US11/232,610
• Publication Number:
  US 20060066480A1
• Time in Patent Office: 376 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: H04B 7/08 at the receiving station
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 1/065 by means of convolutional encoding

Abstract

A communications device for separating source signals provided by M signal sources includes an antenna array comprising N antenna elements for receiving at least N different summations of the M source signals. A code despreader is connected to the N antenna elements for decoding the at least N different summations of the M source signals. Each one of the N different summations includes k codes for providing k different summations of the M source signals associated therewith. A blind signal separation processor forms a mixing matrix comprising at least kN different summations of the M source signals, and separates desired source signals from the mixing matrix. The mixing matrix has a rank equal up to kN.

Claims

1. A communications device for separating source signals provided by M signal sources, the communications device comprising:

an antenna array comprising N antenna elements for receiving at least N different summations of the M source signals;

a code despreader connected to said N antenna elements for decoding the at least N different summations of the M source signals, each one of the N different summations including k codes for providing k different summations of the M source signals associated therewith;

a receiver assembly connected to said code despreader for receiving at least kN different summations of the M source signals; and

a blind signal separation processor connected to said receiver assembly for forming a mixing matrix comprising the at least kN different summations of the M source signals, the mixing matrix having a rank equal up to kN, said blind signal separation processor for separating desired source signals from the mixing matrix.

2. A communications device according to claim 1 wherein kN=M.

3. A communications device according to claim 1 wherein the rank of the mixing matrix is K, where K<

kN, and said blind signal separation processor separating K of the M source signals from the mixing matrix.

4. A communications device according to claim 1 wherein kN>

M.

5. A communications device according to claim 1 wherein said N antenna elements comprise N correlated antenna elements.

6. A communications device according to claim 5 wherein said N correlated antenna elements comprise N active antenna elements so that said antenna array forms a phased array.

7. A communications device according to claim 5 wherein said N correlated 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.

8. A communications device according to claim 1 wherein at least two of said N antenna elements are correlated and have different polarizations.

9. A communications device according to claim 8 wherein the different polarizations are orthogonal to one another.

10. A communications device according to claim 1 further comprising an elevation controller for selectively changing an elevation of at least one of the N antenna beams for generating at least one additional antenna beam so that at least one additional different summation of the M source signals is received thereby;

wherein said decoder decodes the at least one additional different summation of the M source signals, each additional different summation including k codes for providing k different summations of the M source signals associated therewith;

wherein said receiver assembly also receives the at least one additional kN different summations of the M source signals using the at least one additional antenna beam; and

wherein said blind signal separation processor forms the mixing matrix to include the at least one additional kN different summations of the M source signals.

11. A communications device according to claim 10 wherein said elevation controller selectively changes the elevation of the N antenna patterns so that N additional antenna patterns are generated for receiving N additional different summations of the M source signals, with the rank of the mixing matrix now being equal to 2 kN.

12. A communications device according to claim 10 wherein said elevation controller is segmented into P regions relative to said N antenna elements, each region being independently controlled for changing the elevation of the N antenna patterns so that N additional antenna patterns are generated for receiving N additional different summations of the M source signals, with the rank of the mixing matrix now being equal to 2 kPN.

13. A communications device according to claim 10 wherein said antenna array comprises a ground plane;

and wherein said N antenna elements comprise;

an active antenna element adjacent said ground plane;

a plurality of passive antenna elements adjacent said ground plane, each passive antenna element comprising

an upper half and a corresponding lower half,

an upper variable reactive load connecting said upper half to said ground plane for changing an antenna pattern in azimuth;

said elevation controller comprising a respective lower variable reactive load for each passive antenna element for connecting said lower half to said ground plane, the N antenna patterns being moved in elevation by adjusting at least one of the lower variable reactive loads.

14. A communications device according to claim 10 wherein said antenna array comprises a ground plane adjacent said N antenna elements;

and wherein said elevation controller comprises a controllable RF choke coupled to said ground plane, the N antenna beams being moved in elevation by controlling said RF choke.

15. A communications device according to claim 1 wherein said antenna array forms at least N antenna beams;

and further comprising a controller connected to said antenna array for selectively forming the at least N antenna beams, with N and M being greater than 2; and

wherein said blind signal separation processor also

determining if the different summations of the M source signals are correlated or statistically independent, and if not, then

cooperating with said controller for forming different beams for receiving new different summations of the M source signals to replace the different summations of the M source signals that are not correlated or statistically independent in the mixing matrix.

16. A communications device according to claim 15 wherein said receiver assembly comprises N rake receivers, each rake receiver comprising P fingers for generating P different multipath components for each one of the N different summations of the M source signals received by the respective antenna element connected thereto;

and wherein said blind signal separation processor is connected to said N rake receivers for forming the mixing matrix, the mixing matrix comprising up to at least kPN different multipath components of the at least N different summations of the M source signals, and the mixing matrix having a rank equal up to kPN.

17. A communications device according to claim 1 wherein said blind signal separation processor separates the desired source signals from the mixing matrix based on at least one of principal component analysis (PCA), independent component analysis (ICA), and single value decomposition (SVD).

18. A method for operating a communications device for separating source signals provided by M signal sources, the communications device comprising an antenna array, a code decoder connected to the antenna array, a receiver assembly connected to the code decoder, and a blind signal separation processor connected to the receiver assembly, the method comprising:

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

decoding by the decoder the at least N different summations of the M source signals, each one of the N different summations including k codes for providing k different summations of the M source signals associated therewith;

providing the at least kN different summations of the M source signals to the receiver assembly; and

processing by the blind signal separation processor the at least kN different summations of the M source signals, the processing comprising

forming a mixing matrix comprising the at least kN different summations of the M source signals, the mixing matrix having a rank equal up to kN, and

separating desired source signals from the mixing matrix.

19. A method according to claim 18 wherein kN=M.

20. A method according to claim 18 wherein the rank of the mixing matrix is K, where K<

kN, and the blind signal separation processor separating K of the M source signals from the mixing matrix.

21. A method according to claim 18 wherein kN>

M.

22. A method according to claim 18 wherein the N antenna elements comprise N correlated antenna elements.

23. A method according to claim 22 wherein the N correlated antenna elements comprise N active antenna elements so that the antenna array forms a phased array.

24. A method according to claim 22 wherein the N correlated 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.

25. A method according to claim 18 wherein at least two of the N antenna elements are correlated and have different polarizations.

26. A method according to claim 18 wherein the communications device further comprises an elevation controller for selectively changing an elevation of at least one of the N antenna beams for generating at least one additional antenna beam so that at least one additional different summation of the M source signals is received thereby;

wherein the decoder decodes the at least one additional different summation of the M source signals, each additional different summation including k codes for providing k different summations of the M source signals associated therewith;

wherein the receiver assembly also receives the at least one additional kN different summations of the M source signals using the at least one additional antenna beam; and

wherein the blind signal separation processor forms the mixing matrix to include the at least one additional kN different summations of the M source signals.

27. A method according to claim 26 wherein the elevation controller selectively changes the elevation of the N antenna patterns so that N additional antenna patterns are generated for receiving N additional different summations of the M source signals, with the rank of the mixing matrix now being equal to 2 kN.

28. A method according to claim 18 wherein the antenna array forms at least N antenna beams;

the communications device further comprising a controller connected to the antenna array for selectively forming the at least N antenna beams, with N and M being greater than 2; and

wherein the blind signal separation processor also

determining if the different summations of the M source signals are correlated or statistically independent, and if not, then

cooperating with the controller for forming different beams for receiving new different summations of the M source signals to replace the different summations of the M source signals that are not correlated or statistically independent in the mixing matrix.

29. A method according to claim 28 wherein the receiver assembly comprises N rake receivers, each rake receiver comprising P fingers for generating P different multipath components for each one of the N different summations of the M source signals received by the respective antenna element connected thereto;

and wherein the blind signal separation processor is connected to the N rake receivers for forming the mixing matrix, the mixing matrix comprising up to at least kPN different multipath components of the at least N different summations of the M source signals, and the mixing matrix having a rank equal up to kPN.

30. A method according to claim 18 wherein the blind signal separation processor separates the desired source signals from the mixing matrix based on at least one of principal component analysis (PCA), independent component analysis (ICA), and single value decomposition (SVD).