Pattern diversity to support a MIMO receiver and associated methods

• US 7,627,052 B2
• Filed: 01/05/2006
• Issued: 12/01/2009
• 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.
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US11/326,042
• Publication Number:
  US 20060198343A1
• Time in Patent Office: 1,426 Days
• Field of Search: 375/267, 375/141, 375/144, 375/148, 375/219, 375/220, 375/299, 375/349
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0413 MIMO systems
• 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: H04W 88/02 Terminal devices

Abstract

A MIMO communications system includes a transmitter, and a transmit antenna array connected to the transmitter and having M antenna elements for transmitting M source signals. A receive antenna array is connected to a receiver and has N antenna elements for receiving at least M different summations of the M source signals, with N being less than M. A signal separation processor is connected to the receiver for forming a mixing matrix that includes the at least M different summations of the M source signals so that the mixing matrix has a rank equal to at least M. The signal separation processor separates desired source signals from the mixing matrix.

Claims

1. A multiple-input multiple-output (MIMO) communications system comprising:

a transmitter configured to transmit M source signals;

a transmit antenna array connected to said transmitter and comprising M antenna elements for transmitting the M source signals;

a receive antenna array comprising N antenna elements for receiving at least M different summations of the M source signals, with N being less than M;

a receiver connected to said receive antenna array and configured to receive the at least M different summations of the M source signals; and

a signal separation processor connected to said receiver for forming a mixing matrix comprising the at least M different summations of the M source signals so that the mixing matrix has a rank equal to at least M;

said signal separation processor for separating desired source signals from the mixing matrix based on a knowledge based processing signal extraction process, with the knowledge based signal separation process separating the desired source signals from the mixing matrix based on at least one of a zero forcing (ZF) process, and a minimum mean squared estimation (MMSE) process.

2. A MIMO communications system according to claim 1 wherein L interferer source signals exist and interfere with separation of the desired source signals from the mixing matrix, with L being greater than 1;

wherein said mixing matrix also increase its rank by L sums in addition to the M different summations of the M source signals so that the mixing matrix has a rank equal to at least M+L.

3. A MIMO communications system according to claim 1 wherein said receive antenna array comprises N correlated antenna elements for forming a phased array.

4. A MIMO communications system according to claim 1 wherein said receive antenna array comprises N correlated antenna elements, said N correlated antenna elements comprising at least one active antenna element and up to N−

1 passive antenna elements for forming a switched beam antenna.

5. A MIMO communications system according to claim 1 wherein each summation of the M source signals is linear.

6. A MIMO communications system according to claim 1 wherein said receive antenna array comprises N correlated antenna elements, and wherein at least two of said N correlated antenna elements have different polarizations.

7. A MIMO communications system according to claim 6 wherein the different polarizations are orthogonal to one another.

8. A MINO communications system according to claim 1 wherein said receive antenna array generates N initial antenna patterns for receiving at least N different summations of the M source signals;

and further comprising an elevation controller connected to said receive antenna array for selectively changing an elevation of at least one of the N initial antenna patterns so that at least one additional different antenna pattern is generated for receiving at least one additional summation of the N source signals; and

wherein the mixing matrix further comprises the at least one additional different summation of the M source signals, the mixing matrix having a rank equal to N plus the number of additional different summations of the M source signals received using the additional antenna patterns, with a resulting rank at least being equal to M.

9. A MIMO communications system according to claim 1 wherein said receive antenna array generates at least N antenna beams for receiving at least N different summations of the M source signals, with N and M being greater than 2;

and further comprising a controller connected to said receive antenna array for selectively forming the at least N antenna beams;

said 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 so that the rank is at least equal to M.

10. A MIMO communications system according to claim 1 further comprising a code despreader connected to said N antenna elements for decoding 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;

wherein said receiver is connected to said despreader for receiving at least KN different summations of the M source signals; and

wherein said signal separation processor forms the mixing matrix comprising the at least kN different summations of the M source signals, with a resulting rank at least being equal to M.

11. A MINO communications system according to claim 1 further comprising respective in-phase and quadrature module connected downstream to each antenna element in said receive antenna array for separating each one of the M different summations of the M source signals received thereby into an in-phase and quadrature component set;

and wherein said signal separation processor forms the mixing matrix comprising at least 2N different summations of the M source signals, with each in-phase and quadrature component set providing 2 inputs into the mixing matrix, with a resulting rank at least being equal 2N, where 2N is at least equal to M.

12. A MIMO communications system according to claim 1 wherein said signal separation processor separates the desired source signals from the mixing matrix based on a combination of a knowledge based signal extraction process and a blind signal separation process.

13. A MIMO communications system according to claim 1 wherein each summation of the N source signals is linear.

14. A MIMO communications system according to claim 1 wherein said receive antenna array comprises N correlated antenna elements, and wherein at least two of said N correlated antenna elements have different polarizations.

15. A method for operating a multiple-input multiple-output (MIMO) communications system comprising:

operating a transmitter configured to transmit M source signals;

transmitting the M source signals from a transmit antenna array connected to a transmitter, the transmit antenna array comprising M antenna elements;

receiving at a receive antenna array at least M different summations of the M source signals, with N being less than M, the receive antenna array comprising N antenna elements; and

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

processing by a signal separation processor connected to the receiver the at least M different summations of the M source signals, the processing comprising

forming a mixing matrix comprising the at least M different summations of the M source signals so that the mixing matrix has a rank equal to at least M, and

separating desired source signals from the mixing matrix based on a knowledge based processing signal extraction process, with the knowledge based signal separation process separating the desired source signals from the mixing matrix based on at least one of a zero forcing (ZF) process, and a minimum mean squared estimation (MMSE) process.

16. A method according to claim 15 wherein L interferer source signals exist and interfere with separation of the desired source signals from the mixing matrix, with L being greater than 1;

further comprising L additional sums in addition to the at least M different summations of the M source signals so that mixing matrix has a rank equal to at least M+L.

17. A method according to claim 15 wherein the receive antenna array comprises N correlated antenna elements for forming a phased array.

18. A method according to claim 15 wherein the receive antenna array comprises N correlated antenna elements, the N correlated antenna elements comprising at least one active antenna element and up to N−

1 passive antenna elements for forming a switched beam antenna.

19. A method according to claim 15 wherein the receive antenna array comprises N correlated antenna elements, and wherein at least two of the N correlated antenna elements have different polarizations.

20. A method according to claim 15 wherein the receive antenna array generates N initial antenna patterns for receiving at least N different summations of the M source signals;

and further comprising an elevation controller connected to the receive antenna array for selectively changing an elevation of at least one of the N initial antenna patterns so that at least one additional different antenna pattern is generated for receiving at least one additional summation of the M source signals; and

wherein the mixing matrix further comprises the at least one additional different summation of the M source signals, the mixing matrix having a rank equal to N plus the number of additional different summations of the M source signals received using the additional antenna patterns, with a resulting rank at least being equal to M.

21. A method according to claim 15 wherein the receive antenna array generates at least N antenna beams for receiving at least N different summations of the M source signals, with N and M being greater than 2;

and further comprising a controller connected to the receive antenna array for selectively forming the at least N antenna beams;

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 so that the rank is at least equal to M.

22. A method according to claim 15 further comprising a code despreader connected to the N antenna elements for decoding the at least N different summations of the N source signals, each one of the N different summations including k codes for providing k different summations;

wherein the receiver is connected to the despreader for receiving at least kN different summations of the N source signals; and

wherein the blind signal separation processor forms the mixing matrix comprising the at least kN different summations of the M source signals, with a resulting rank at least being equal to M.

23. A method according to claim 15 further comprising a respective in-phase and quadrature module connected downstream to each antenna element in the receive antenna array for separating each one of the M different summations of the M source signals received thereby into an in-phase and quadrature component set;

and wherein the blind signal separation processor forms the mixing matrix comprising at least 2N different summations of the M source signals, with each in-phase and quadrature component set providing 2 inputs into the mixing matrix, with a resulting rank at least being equal 2N, where 2N is at least equal to M.

24. A method according to claim 15 wherein separating the desired source signals from the mixing matrix is based on at least one of a knowledge based signal extraction process and a blind signal separation process.

25. A multiple-input multiple-output (MIMO) communications system comprising:

a transmitter configured to transmit M source signals;

a transmit antenna array connected to said transmitter and comprising M antenna elements for transmitting the M source signals;

a receive antenna array comprising N antenna elements for receiving at least M different summations of the M source signals, with N being less than M;

a receiver connected to said receive antenna array and configured to receive the at least M different summations of the M source signals; and

a signal separation processor connected to said receiver for forming a mixing matrix comprising the at least M different summations of the M source signals so that the mixing matrix has a rank equal to at least M;

said signal separation processor comprising a blind signal separation processor for separating desired source signals from the mixing matrix, wherein separating the desired source signals from the mixing matrix is based on at least one of principal component analysis (PCA), independent component analysis (ICA), and single value decomposition (SVD).

26. A MIMO communications system according to claim 25 wherein said receive antenna array comprises N correlated antenna elements for forming a phased array.

27. A MIMO communications system according to claim 25 wherein said receive antenna array comprises N correlated antenna elements, said N correlated antenna elements comprising at least one active antenna element and up to N−

1 passive antenna elements for forming a switched beam antenna.

28. A method for operating a multiple-input multiple-output (MIMO) communications system comprising:

operating a transmitter configured to transmit M source signals;

transmitting the M source signals from a transmit antenna array connected to a transmitter, the transmit antenna array comprising M antenna elements;

receiving at a receive antenna array at least M different summations of the M source signals, with N being less than M, the receive antenna array comprising N antenna elements; and

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

processing by a blind signal separation processor connected to the receiver the at least M different summations of the M source signals, the processing comprising

forming a mixing matrix comprising the at least M different summations of the M source signals so that the mixing matrix has a rank equal to at least M, and

separating desired source signals from the mixing matrix, wherein separating the desired source signals from the mixing matrix is based on at least one of principal component analysis (ECA), independent component analysis (ICA), and single value decomposition (SVD)

29. A method according to claim 28 wherein L interferer source signals exist and interfere with separation of the desired source signals from the mixing matrix, with L being greater than 1;

further comprising L additional sums in addition to the at least N different summations of the N source signals so that mixing matrix has a rank equal to at least M+L.

30. A method according to claim 28 wherein the receive antenna array comprises N correlated antenna elements for forming a phased array.

31. A method according to claim 28 wherein the receive antenna array comprises N correlated antenna elements, the N correlated antenna elements comprising at least one active antenna element and up to N−

1 passive antenna elements for forming a switched beam antenna.