Efficient multiple input multiple output system for multi-path fading channels

• US 20030125090A1
• Filed: 11/27/2002
• Published: 07/03/2003
• Est. Priority Date: 11/29/2001
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Zeira, Ariela
• Granted Patent: US 7,170,926 B2
• Time in Patent Office: Days
• US Class Current: 455/562.1
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04L 2025/03375 Passband transmission
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0242 using matrix methods

Abstract

Data is transferred in a wireless communication system, such as a wireless spread spectrum communication system. Data is encoded to produce a plurality of data streams. For each of a plurality of transmitting antennas, the data streams are used to produce a vector for transmission. Each transmission vector is transmitted by its transmitting antenna through a wireless air interface experiencing multipath. Multipath components from each transmitted transmission vector are received by a plurality of receiving antennas. The received multiplath components are equalized to recover the transmission vectors. The data is recovered from the recovered transmission vectors.

Claims

1. A method for recovering data transmitted from a plurality of transmitting antennas and received by a plurality of receiving antennas, the method comprising:

receiving a signal at each of the receiving antennas;

sampling each received antenna signal to produce a combined received signal;

estimating a overall channel response comprising a channel response for each transmitting and receiving antenna combination;

processing a block-column of the overall channel response to produce a diagonal matrix;

processing the combined received signal to effectively take a block-Fourier transform of the combined received signal;

using the diagonal matrix and the effective block-Fourier transform of the combined received signal to produce a Fourier transform of a spread data vector;

processing the Fourier transform of the spread data vector to produce the spread data vector; and

despreading the spread data vector to recover the transmitted data.

2. The method of claim 1 wherein the processing of the block-column of the overall channel response matrix comprises taking a block-Fourier transform of the block-column.

3. The method of claim 1 wherein the processing the combined received signal comprises taking a plurality of non-block discrete Fourier transforms.

4. The method of claim 1 wherein the using the diagonal matrix and the effective block-Fourier transform of the combined received signal uses Cholesky decomposition.

5. The method of claim 1 wherein the using the diagonal matrix and the effective block Fourier transform of the combined received signal uses a matrix inversion of blocks of the diagonal matrix.

6. The method of claim 1 wherein the processing of the Fourier transform of the spread data vector comprises taking a block inverse Fourier transform of the Fourier transform of the spread data vector.

7. A method for recovering data transmitted from a plurality of transmitting antennas and received by a plurality of receiving antennas, the method comprising:

receiving a signal at each of the receiving antennas;

sampling each received antenna signal to produce a combined received signal;

estimating a overall channel response comprising a channel response for each transmitting and receiving antenna combination;

producing a cross channel correlation matrix using the overall channel response;

processing a block-column of the cross channel correlation matrix to produce a cross correlation diagonal matrix;

processing a block-column of the overall channel response matrix to produce a channel response diagonal matrix;

processing the combined received signal to effectively take a block-Fourier transform of the combined received signal;

combining the channel response diagonal matrix and the effective block-Fourier transform of the combined received signal to produce a combined result;

using the cross correlation diagonal matrix and the combined result to produce a Fourier transform of a spread data vector;

processing the Fourier transform of the spread data vector to produce the spread data vector; and

despreading the spread data vector to recover the transmitted data.

8. The method of claim 7 wherein the producing the cross correlation matrix comprises multiplying the overall channel response with a conjugate transpose of the overall channel response.

9. The method of claim 7 wherein the processing the block-column of the cross channel correlation matrix comprises taking a block-Fourier transform of the cross channel correlation matrix block-column.

10. The method of claim 7 wherein the processing the combined received signal comprises taking a plurality of non-block discrete Fourier transforms.

11. The method of claim 7 wherein the processing the block-column of the overall channel response comprises taking a block-Fourier transform of the over channel response block column.

12. The method of claim 7 wherein the combining of the channel response diagonal matrix and the effective block-Fourier transform of the combined received signal is by multiplying.

13. The method of claim 7 wherein the using the cross correlation diagonal matrix and the combined result uses Cholesky decomposition.

14. The method of claim 7 wherein the processing of the Fourier transform of the spread data vector comprises taking a block inverse Fourier transform of the Fourier transform of the spread data vector.

15. A user equipment comprising:

means for receiving a signal at each of a plurality of receiving antennas, each of the received signals including signals transmitted from a plurality of antennas at a single site;

means for sampling each received antenna signal to produce a combined received signal;

means for estimating a overall channel response comprising a channel response for each transmitting and receiving antenna combination;

means for processing a block-column of the overall channel response to produce a diagonal matrix;

means for processing the combined received signal to effectively take a block-Fourier transform of the combined received signal;

means for using the diagonal matrix and the effective block-Fourier transform of the combined received signal to produce a Fourier transform of a spread data vector;

means for processing the Fourier transform of the spread data vector to produce the spread data vector; and

means for despreading the spread data vector to recover the transmitted data.

16. The user equipment of claim 15 wherein the means for processing of the block-column of the overall channel response matrix takes a block-Fourier transform of the block-column.

17. The user equipment of claim 15 wherein the means for processing the combined received signal takes a plurality of non-block discrete Fourier transforms.

18. The user equipment of claim 15 wherein the means for using the diagonal matrix and the effective block-Fourier transform of the combined received signal uses Cholesky decomposition.

19. The user equipment of claim 15 wherein the means for using the diagonal matrix and the effective block Fourier transform of the combined received signal uses a matrix inversion of blocks of the diagonal matrix.

20. The user equipment of claim 15 wherein the means for processing of the Fourier transform of the spread data vector takes a block inverse Fourier transform of the Fourier transform of the spread data vector.

21. A user equipment comprising:

means for receiving a signal at each of a plurality of receiving antennas, each of the received signals including signals transmitted from a plurality of antennas at a single site;

means for sampling each received antenna signal to produce a combined received signal;

means for estimating a overall channel response comprising a channel response for each transmitting and receiving antenna combination;

means for producing a cross channel correlation matrix using the overall channel response;

means for processing a block-column of the cross channel correlation matrix to produce a cross correlation diagonal matrix;

means for processing a block-column of the overall channel response matrix to produce a channel response diagonal matrix;

means for processing the combined received signal to effectively take a block-Fourier transform of the combined received signal;

means for combining the channel response diagonal matrix and the effective block-Fourier transform of the combined received signal to produce a combined result;

means for using the cross correlation diagonal matrix and the combined result to produce a Fourier transform of a spread data vector;

means for processing the Fourier transform of the spread data vector to produce the spread data vector; and

means for despreading the spread data vector to recover the transmitted data.

22. The user equipment of claim 21 wherein the means for producing the cross correlation matrix multiplies the overall channel response with a conjugate transpose of the overall channel response.

23. The user equipment of claim 21 wherein the means for processing the block-column of the cross channel correlation matrix takes a block-Fourier transform of the cross channel correlation matrix block-column.

24. The user equipment of claim 21 wherein the processing the means for combined received signal takes a plurality of non-block discrete Fourier transforms.

25. The user equipment of claim 21 wherein the means for processing the block-column of the overall channel response takes a block-Fourier transform of the over channel response block column.

26. The user equipment of claim 21 wherein the means for combining of the channel response diagonal matrix and the effective block-Fourier transform of the combined received signal is performed by multiplying.

27. The user equipment of claim 21 wherein the means for using the cross correlation diagonal matrix and the combined result uses Cholesky decomposition.

28. The user equipment of claim 21 wherein the means for processing of the Fourier transform of the spread data vector takes a block inverse Fourier transform of the Fourier transform of the spread data vector.

29. A user equipment comprising:

a plurality of receiving antennas for receiving signals from a plurality of transmitting antennas at a single site;

a plurality of sampling devices for sampling a received version of the received signals as received by each of the plurality of receiving antennas to produce a combined received signal;

a channel estimation device for determining a channel response for each receiving and transmitting antenna combination and producing an overall channel response;

a MIMO channel equalization device for processing the combined received signal and the overall channel response using a block-Fourier transform based algorithm to produce a spread data vector; and

a despreading device for despreading the spread data vector to recover data of the received signals.

30. The user equipment of claim 29 further comprising a spread vector reordering device for reordering the spread data vector so that chips of transmitted by each transmitting antenna are grouped together.

31. The user equipment of claim 29 further comprising a despread data stream decoder for decoding data recovered by the depreading device.

32. The user equipment of claim 29 wherein the MIMO channel equalization device comprises:

a block-Fourier transform device for processing a block-column of the overall channel response to produce a diagonal matrix;

a block Fourier transform device for processing the combined received signal to take a block-Fourier transform of the combined received signal; and

a processing device for using the diagonal matrix and the block-Fourier transform of the combined received signal to produce a Fourier transform of the spread data vector; and

an inverse block-Fourier transform device for taking an inverse block Fourier transform of the Fourier transform of the spread data vector.

33. The user equipment of claim 29 wherein the MIMO channel equalization device comprises:

a cross channel correlation determining device for producing a cross channel correlation matrix using the overall channel response;

a block-Fourier transform device for processing a block-column of the cross channel correlation matrix to produce a cross correlation diagonal matrix;

a block-Fourier transform device for processing a block-column of the overall channel response matrix to produce a channel response diagonal matrix;

a block-Fourier transform device for processing the combined received signal to take a block-Fourier transform of the combined received signal;

a combining device for combining the channel response diagonal matrix and the block-Fourier transform of the combined received signal to produce a combined result;

a processing device for using the cross correlation diagonal matrix and the combined result to produce a Fourier transform of the spread data vector; and

a block-inverse Fourier transform device for processing the Fourier transform of the spread data vector to produce the spread data vector.

34. A method for transferring data in a wireless spread spectrum communication system, the method comprising:

providing a plurality of transmitting antennas;

encoding data to produce a plurality of data streams for each of the plurality of codes;

spreading the plurality of data streams with the plurality of spreading codes;

for each transmitting antenna, combining one of the spread data streams of each code together to produce a spread data vector;

each transmitting antenna transmitting its spread data vector;

receiving the transmitted spread data vectors by each of a plurality of receiving antennas as a received version; and

recovering the data using the received versions.

35. The method of claim 34 wherein the recovering the data uses a fast Fourier transform based alogorithm.

36. The method of claim 34 wherein the recovering the data uses a Cholesky decomposition.

37. The method of claim 34 wherein the recovering the data uses an approximate Cholesky decomposition.

38. A method for transferring data in a wireless communication system, the method comprising:

providing a plurality of transmitting antennas;

encoding data to produce a plurality of data streams;

for each transmitting antenna, using the data streams to produce a vector for transmission;

transmitting each transmission vector by its transmitting antenna through a wireless air interface experiencing multipath;

receiving multipath components from each transmitted transmission vector by a plurality of receiving antennas;

equalizing the received multiplath components to recover the transmission vectors; and

recovering data from the recovered transmission vectors.