SIGNAL SEPARATION FOR A CDMA COMMUNICATIONS DEVICE AND ASSOCIATED METHODS

• US 20070200758A1
• Filed: 03/09/2007
• Published: 08/30/2007
• Est. Priority Date: 09/23/2004
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Goldberg, Steven
• Granted Patent: US 7,397,426 B2
• Time in Patent Office: Days
• US Class Current: 342/378
• CPC Class Codes: H04B 7/08 at the receiving station

Abstract

A method for operating a CDMA communications device includes receiving at an antenna array M different summations from a mixture of source signals provided by M signal sources, and providing the M different summations to a receiver assembly. The receiver assembly includes a first signal path and a second signal path parallel to the first signal path. In the first signal path, a mixing matrix including the M different summations of the M source signals is formed, and at least one source signal is separated from the mixing matrix. A determination is made if the separated source signal is an interferer source signal. In the second signal path, the M different summations are delayed corresponding to a delay introduced in the first signal path. The first signal path provides to a summer the separated source signal if the separated source signal is an interferer source signal, and the second signal path provides to the summer the M different summations after being delayed. The summer removes the interferer source signal if present from the M different summations after being delayed.

Claims

1. A code division multiple access (CDMA) communications device comprising:

an antenna array comprising N antenna elements for receiving at least M different summations from a mixture of source signals provided by M signal sources, the at least M different summations defining the mixture of source signals, where N<

M;

a receiver assembly connected to said antenna array for receiving the at least M different summations, said receiver assembly comprising

a first signal path comprising a

a signal separation processor for forming a mixing matrix comprising up to the at least M different summations of the M source signals, the mixing matrix having a rank equal to at least N, said signal separation processor for separating at least one source signal from the mixing matrix, and

a selector for determining if the at least one separated source signal is an interferer source signal,

a second signal path parallel to the first signal path for receiving the at least M different summations, the second signal path comprising a delay for delaying the at least M different summations corresponding to a delay introduced in the first signal path;

a summer connected to the first and second signal paths for respectively receiving from the first signal path at least one separated source signal if the separated source signal is an interferer source signal, and from the second signal path the at least M different summations after being delayed, said summer for removing the at least one interferer source signal if present from the at least M different summations after being delayed; and

a rake receiver coupled to said summer for receiving the at least M different summations without the at least one interferer source signal.

2. A communications device according to claim 1 wherein the at least one separated source signal comprises scrambling and spreading codes associated therewith;

and wherein said selector determines if the at least one separated source signal is an interferer source signal based on the scrambling code or spreading code being different from the scrambling and spreading codes associated with a desired source signal.

3. A communications device according to claim 1 wherein said selector determines if the at least one separated source signal is an interferer source signal based on having characteristics different from characteristics associated with a CDMA communications network.

4. A communications device according to claim 1 wherein said selector determines if the at least one separated source signal is an interferer source signal based on having characteristics similar to noise.

5. A communications device according to claim 1 wherein the first signal path further comprises an inverter connected between said selector and said summer for inverting the at least one separated source signal so that the same can be removed from the at least M different summations after being delayed in the second signal path.

6. A communications device according to claim 1 wherein if said selector determines that the at least one separated source signal is not an interferer source signal, then the first signal path provides a signal with zero amplitude to said summer.

7. A communications device according to claim 1 wherein said antenna array comprises a plurality of correlated antenna elements.

8. A communications device according to claim 7 wherein said plurality of correlated antenna elements comprise a plurality of active antenna elements so that said antenna array forms a phased array.

9. A communications device according to claim 7 wherein said plurality of correlated antenna elements comprise an active antenna element and a plurality of passive antenna elements so that said antenna array forms a switched beam antenna.

10. A communications device according to claim 7 wherein at least two of said correlated antenna elements have different polarizations.

11. A communications device according to claim 10 wherein the different polarizations are orthogonal to one another.

12. A communications device according to claim 1 wherein said antenna array forms at least two antenna patterns;

and further comprising a controller connected to said antenna array for selectively forming the at least two antenna patterns; and

wherein said signal separation processor is configured to

determine if the different summations of the at least two source signals are correlated or statistically independent, and if not, then

cooperate with said controller for forming different beams for receiving new different summations of the at least two source signals to replace the different summations of the at least two source signals that are not correlated or statistically independent.

13. A communications device according to claim 1 wherein said antenna array comprises at least one antenna element;

and further comprising;

a respective in-phase and quadrature module connected downstream to each antenna element for separating a respective different summation into an in-phase and quadrature component set with each in-phase and quadrature component set providing two inputs into said signal separation processor.

14. A communications device according to claim 1 wherein said antenna array forms at least one initial antenna pattern for receiving one of the different summations;

and further comprising an elevation controller for selectively changing an elevation of the at least one initial antenna pattern for forming at least one additional antenna pattern so that the second different summation is received thereby.

15. A method for operating a code division multiple access (CDMA) communications device comprising an antenna array comprising N antenna elements, and a receiver assembly connected thereto, the method comprising:

receiving at the antenna array at least M different summations from a mixture of source signals provided by M signal sources, the at least M different summations defining the mixture of source signals, where N<

M;

providing the at least M different summations to the receiver assembly, the receiver assembly comprising a first signal path and a second signal path parallel to the first signal path, and performing the following within the first and second signal paths

in the first signal path, forming a mixing matrix comprising up to the at least M different summations of the M source signals, the mixing matrix having a rank equal to at least N, separating at least one source signal from the mixing matrix, and determining if the at least one separated source signal is an interferer source signal, and

in the second signal path, delaying the at least M different summations corresponding to a delay introduced in the first signal path;

providing to a summer from the first signal path the at least one separated source signal if the separated source signal is an interferer source signal, and from the second signal path the at least M different summations after being delayed, the summer for removing the at least one interferer source signal if present from the at least M different summations after being delayed; and

providing the at least M different summations without the at least one interferer source signal to a rake receiver.

16. A method according to claim 15 wherein the at least one separated source signal comprises scrambling and spreading codes associated therewith;

and wherein the selector determines if the at least one separated source signal is an interferer source signal based on the scrambling code or spreading code being different from the scrambling and spreading codes associated with a desired source signal.

17. A method according to claim 15 wherein the selector determines if the at least one separated source signal is an interferer source signal based on having characteristics different from characteristics associated with a CDMA communications network.

18. A method according to claim 15 wherein the selector determines if the at least one separated source signal is an interferer source signal based on having characteristics similar to noise.

19. A method according to claim 15 wherein the first signal path comprises a signal separation processor for forming the mixing matrix and for separating at least one source signal from the mixing matrix, and a selector connected to the signal separation processor for determining if the at least one separated source signal is an interferer source signal, and further comprising an inverter connected between the selector and the summer for inverting the at least one separated source signal so that the same can be removed from the at least M different summations after being delayed in the second signal path.

20. A method according to claim 19 wherein if the selector determines that the at least one separated source signal is not an interferer source signal, then the first signal path provides a signal with zero amplitude to the summer.

21. A method according to claim 15 wherein the antenna array comprises a plurality of correlated antenna elements.

22. A method according to claim 21 wherein the plurality of correlated antenna elements comprise a plurality of active antenna elements so that the antenna array forms a phased array.

23. A method according to claim 21 wherein the plurality of correlated antenna elements comprise an active antenna element and a plurality of passive antenna elements so that the antenna array forms a switched beam antenna.

24. A method according to claim 21 wherein at least two of the correlated antenna elements have different polarizations.

25. A method according to claim 24 wherein the different polarizations are orthogonal to one another.

26. A method according to claim 15 wherein the antenna array forms at least two antenna patterns;

and further comprising a controller connected to the antenna array for selectively forming the at least two antenna patterns; and

wherein the signal separation processor is configured to

determine if the different summations of the at least two source signals are correlated or statistically independent, and if not, then

cooperate with the controller for forming different beams for receiving new different summations of the at least two source signals to replace the different summations of the at least two source signals that are not correlated or statistically independent.

27. A method according to claim 15 wherein the antenna array comprises at least one antenna element;

and further comprising;

a respective in-phase and quadrature module connected downstream to each antenna element for separating a respective different summation into an in-phase and quadrature component set, with each in-phase and quadrature component set providing two inputs into the signal separation processor.

28. A method according to claim 15 wherein the antenna array forms at least one initial antenna pattern for receiving one of the different summations;

and further comprising an elevation controller for selectively changing an elevation of the at least one initial antenna pattern for forming at least one additional antenna pattern so that the second different summation is received thereby.