REDUCED COMPLEXITY SLIDING WINDOW BASED EQUALIZER

• US 20080298523A1
• Filed: 08/14/2008
• Published: 12/04/2008
• Est. Priority Date: 03/03/2003
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Yang, Rui, Reznik, Alexander, Zeira, Ariela, Li, Bin
• Granted Patent: US 7,609,794 B2
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H04B 1/71052 using decorrelation matrix
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03509 fractionally spaced H04L2025/03515 takes precedence
• CPC Class Codes: H04L 2025/03605 Block algorithms
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 25/0242 using matrix methods
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/03292 with channel estimation circuitry

Abstract

Data estimation is performed in a wireless communication system using both oversampling and multiple reception antennas. A receive vector is produced for each antenna at a sampling interval which is a multiple of the chip rate of the received signal. A channel response matrix is produced for each antenna at a preferred multiple of the sampling rate. Each receive vector is processed using a sliding window based approach, where a plurality of successive windows are processed. For each window, a combined circulant channel response matrix is produced using the channel response matrices. Using the combined circulant channel response matrix and a combined received vector comprising each received vector in a discrete Fourier transform based approach to estimate a data vector corresponding to that window; and combining the data vector estimated in each window to form a combined data vector.

Claims

1. A wireless transmit/receive unit (WTRU) comprising:

a processor component configured to process a received vector using a sliding window based approach;

the processor configured to process windows of response matrix values to produce an estimated data vector such that for each window;

a non-Toeplitz channel response matrix is transformed into a Toeplitz matrix;

the Toeplitz matrix is transformed into a circulant channel response matrix; and

the circulant channel response matrix is used in a discrete Fourier transform based approach to estimate a data vector corresponding to the window; and

a summer, configured to combine the data vector estimated in each window to form a combined data vector.

2. The WTRU of claim 1 wherein the processor is configured to process a received vector that is produced by sampling at a multiple of a signal chip rate.

3. The WTRU of claim 2 further comprising:

a root-raised cosine filter configured to apply a root-raised cosine filter to the received vector for input to the processor.

4. The WTRU of claim 3 wherein the processor is configured to ignore a correlation between noise associated with each multiple of the chip rate samples.

5. The WTRU of claim 3 wherein the processor is configured to use the received vector and a channel response matrix arranged in a natural order, the natural order being an order that elements of the received vector and channel response matrix were actually received, such that the arranged channel response matrix is a block-Toeplitz matrix.

6. The WTRU of claim 1 where the received vector comprises received samples from multiple receiving antennas at a multiple of a signal chip rate wherein the processor is configured to assume that noise is uncorrelated for each multiple of the chip rate samples and across the multiple antennas in processing the received vector.

7. The WTRU of claim 1 where the received vector comprises received samples from multiple receiving antennas at a multiple of the chip rate wherein the processor is configured to assume that noise is uncorrelated for each multiple of the chip rate samples and correlated across the multiple antennas in processing the received vector.

8. The WTRU of claim 1 where the received vector comprises received samples from multiple receiving antennas at a multiple of the chip rate wherein the processor is configured to assume that noise is correlated for each multiple of the chip rate samples and uncorrelated across the multiple antennas in processing the received vector.

9. The WTRU of claim 1 where the received vector comprises received samples from multiple receiving antennas at a multiple of the chip rate wherein the processor is configured to assume that noise is correlated for each multiple of the chip rate samples and correlated across the multiple antennas in processing the received vector.

10. The WTRU of claim 1 wherein the processor includes:

a pulse shaping filter configured to process received signals; and

a noise vector cross correlation component configured to multiply a discrete Fourier transform of the pulse shaping filter by a measured noise variance to produce a discrete Fourier transform of the noise vector cross correlation.

11. The WTRU of claim 1 wherein the processor includes:

a pulse shaping filter configured to process received signals; and

a noise vector cross correlation component configured to multiply a discrete Fourier transform of an ideal pulse shape by a measured noise variance to produce a discrete Fourier transform of the noise vector cross correlation.

12. A wireless transmit/receive unit (WTRU) comprising:

a channel estimation device configured to produce past, center and future channel estimate matrices using a received vector;

a noise auto-correlation correction device configured to determine a noise auto-correlation correction factor using the future and past channel estimate matrix;

a noise auto-correlation device configured to determine a noise auto-correlation factor using the received vector;

a summer configured to sum the noise auto-correlation correction factor and the noise auto-correlation factor; and

a minimum mean square error (MMSE) device configured to estimate a center portion of the data using the sum of the noise auto-correlation correction factor and the noise auto-correlation factor, the received vector, and the center channel estimate matrix.

13. The WTRU of claim 12 further comprising:

a past input correction device for producing a past correction factor using the past channel estimate matrix and a past determined portion of a data vector;

a subtractor for subtracting the past correction factor from the received vector producing a modified received vector; and

wherein the MMSE device is configured to determine a received data vector center portion using the modified received vector.

14. A wireless transmit/receive unit (WTRU) comprising:

a plurality of receive antennas;

a sampling device configured to sample wireless signals received on each antenna at a multiple of a signal chip rate and to produce a received vector at the sampling rate for each receive antenna;

a processing circuit configured to produce a channel response matrix for each antenna;

the processing circuit configured to process each received vector using a sliding window based approach, where a plurality of successive windows are processed;

the processing circuit configured to process each window of the plurality of windows;

to produce a combined circulant channel response matrix using the channel response matrices; and

to use the combined circulant channel response matrix and a combined received vector comprising each received vector in a discrete Fourier transform based approach for estimating a data vector corresponding to that window; and

the processing circuit configured to combine the data vector estimated in each window to form a combined data vector.

15. The WTRU of claim 14 wherein the processing circuit is configured to use a sliding window based approach that uses an exact solution.

16. The WTRU of claim 14 wherein the processing circuit is configured to use a sliding window based approach that assumes that noise between each receive antenna is uncorrelated.

17. The WTRU of claim 14 wherein the processing circuit is configured to use a sliding window based approach that assumes that noise between multiples of the chip rate does not have a temporal correlation.

18. The WTRU of claim 14 wherein the processing circuit is configured to use a sliding window based approach that assumes no correlation of noise between any of the combinations of the multiple of the chip rate and receive antenna exists.