METHOD AND SCHEME FOR SPACE-TIME CODED COCHANNEL INTERFERENCE CANCELLATION

• US 20090175366A1
• Filed: 09/30/2005
• Published: 07/09/2009
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Choi, Yang-seok, Maltsev, Alexander, Khoryaev, Alexey, Maslennikov, Roman, Li, Qinghua, Pestretsov, Vladimir
• Granted Patent: US 8,064,532 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• 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
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0631 Receiver arrangements

Abstract

An apparatus, system, and method for space-time cochannel interference cancellation are described. The apparatus may include a time stacking module to stack consecutive subcarrier signals for a period of time equal to several symbols and a space-time subcarrier beamformer module to perform space-time subcarrier beamforming by applying space-time beamformer weights to stacked symbols on one or more subcarriers. The space-time beamformer weights may be calculated based on spatial and time correlation properties of one or more interference signals. Other embodiments are described and claimed.

Claims

1. An apparatus, comprising:

a node to perform space-time cochannel interference cancellation for a multicarrier communications system, said node comprising;

a time stacking module to stack consecutive subcarrier signals for a period of time equal to several symbols, said time stacking module to use both spatial and time correlation properties of at least one of useful signals and interference signals; and

a space-time subcarrier beamformer module to perform space-time subcarrier beamforming by applying space-time beamformer weights to stacked symbols on one or more subcarriers, said space-time beamformer weights calculated based on spatial and time correlation properties of one or more interference signals.

2. The apparatus of claim 1, wherein said space-time beamforming weights are received by said space-time subcarrier beamformer module from a beamforming weights calculator module.

3. The apparatus of claim 2, wherein said node comprises a transmitter node and said space-time beamformer weights comprise transmit space-time beamformer weights received through a feedback channel from a receiver node comprising said beamforming weights calculator module.

4. The apparatus of claim 2, wherein said node comprises a receiver node including said beamforming weights calculator module, and said space-time beamformer weights comprise receive space-time beamformer weights.

5. The apparatus of claim 2, wherein said beamforming weights calculator module is to perform joint space-time beamforming optimization for both a transmit space-time subcarrier beamformer module and a receive space-time subcarrier beamformer module.

6. The apparatus of claim 2, wherein said beamforming weights calculator module is to calculate said space-time beamformer weights based on channel estimates and interference and noise estimates.

7. The apparatus of claim 6, wherein said interference and noise estimates comprise interference and noise space-time correlation matrix estimates.

8. The apparatus of claim 1, further comprising a space-time correlation matrix estimator to extract interference and noise signals and to calculate interference and noise space-time correlation matrix estimates for at least one of each subcarrier and each set of adjacent subcarriers, said space-time beamformer weights based on said interference and noise space-time correlation matrix estimates.

9. The apparatus of claim 1, wherein said symbols comprise orthogonal frequency division multiplexing symbols, and said cochannel interference comprises spatially and time correlated interference.

10. The apparatus of claim 1, wherein said multicarrier communications system comprises at least one of an open loop communications system and a closed loop communications system, and said node is to perform said space-time cochannel interference cancellation without additional antenna elements required by spatial only cochannel interference cancellation.

11. A system, comprising:

at least one antenna; and

a node to couple to said at least one antenna over a multicarrier communication channel and to perform space-time cochannel interference cancellation, said node comprising;

a time stacking module to stack consecutive subcarrier signals for a period of time equal to several symbols; and

a space-time subcarrier beamformer module to perform space-time subcarrier beamforming by applying space-time beamformer weights to stacked symbols on one or more subcarriers, said space-time beamformer weights calculated based on spatial and time correlation properties of one or more interference signals.

12. The system of claim 11, wherein said space-time beamforming weights are received by said space-time subcarrier beamformer module from a beamforming weights calculator module.

13. The system of claim 12, wherein said node comprises a transmitter node and said space-time beamformer weights comprise transmit space-time beamformer weights received through a feedback channel from a receiver node comprising said beamforming weights calculator module.

14. The system of claim 12, wherein said node comprises a receiver node including said beamforming weights calculator module, and said space-time beamformer weights comprise receive space-time beamformer weights.

15. The system of claim 12, wherein said beamforming weights calculator module is to perform joint space-time beamforming optimization for both a transmit space-time subcarrier beamformer module and a receive space-time subcarrier beamformer module.

16. The system of claim 12, wherein said beamforming weights calculator module is to calculate said space-time beamformer weights based on channel estimates and interference and noise estimates.

17. The system of claim 16, wherein said interference and noise estimates comprise interference and noise space-time correlation matrix estimates.

18. The system of claim 11, further comprising a space-time correlation matrix estimator to extract interference and noise signals and to calculate interference and noise space-time correlation matrix estimates for each subcarrier, said space-time beamformer weights based on said interference and noise space-time correlation matrix estimates.

19. The system of claim 11, wherein said symbols comprise orthogonal frequency division multiplexing symbols, and said cochannel interference comprises spatially and time correlated interference.

20. The system of claim 11, wherein said multicarrier communication channel comprises a multiple-input multiple-output channel and said node is to perform said space-time cochannel interference cancellation without additional antenna elements required by spatial only cochannel interference cancellation.

21. A method to perform space-time cochannel interference cancellation, comprising:

stacking consecutive subcarrier signals for a period of time equal to several symbols;

calculating space-time beamformer weights based on spatial and time correlation properties of one or more interference signals; and

applying said space-time beamformer weights to stacked symbols on one or more subcarriers.

22. The method of claim 21, further comprising:

extracting interference and noise signals; and

calculating interference and noise space-time correlation matrix estimates for at least one of each subcarrier and each set of adjacent subcarriers.

23. The method of claim 22, further comprising calculating said space-time beamformer weights based on said interference and noise space-time correlation matrix estimates.

24. The method of claim 22, further comprising calculating said space-time beamformer weights based on channel estimates.

25. The method of claim 21, further comprising providing subcarrier beamformers with corresponding space-time beamformer weights.

26. The method of claim 25, further comprising performing joint space-time beamforming optimization for both transmit space-time beamformers and receive space-time subcarrier beamformers.

27. The method of claim 25, further comprising providing receive subcarrier beamformers with receive space-time beamformer weights.

28. The method of claim 25, further comprising providing transmit subcarrier beamformers with transmit space-time beamformer weights.

29. The method of claim 21, wherein said symbols comprise orthogonal frequency division multiplexing symbols, and said cochannel interference comprises Alamouti space-time interference.

30. The method of claim 21, wherein said multicarrier communication channel comprises a multiple-input multiple-output channel and said space-time cochannel interference cancellation is performed without additional antenna elements required by spatial only cochannel interference cancellation.

31. An apparatus, comprising:

a receiver node to perform calculation of space-time beamforming weights that can be applied to cancel space-time coded cochannel interference, said receiver node comprising;

a minimum mean square error filter module to filter desired signals from interfering signals based on an estimated channel matrix for said desired signals and an estimated channel matrix for said interfering signals by treating said multicarrier communication channel as approximately quasi-static across received symbols.

32. The apparatus of claim 31, wherein said calculation provides computational savings for calculation of beamformer weights applied to cancel space-time interference and to detect useful space-time coded signals.

33. The apparatus of claim 31, wherein said minimum mean square error filter is to calculate beamformer weights comprising inversion of a reduced size matrix resulting in computational savings.

34. The apparatus of claim 31, wherein said receiver node receives interfering signals from a space-time block code interfering transmitter node.

35. The apparatus of claim 31, wherein said receiver node receives interfering signals from a single-antenna interfering transmitter node.