# US 7,609,794 B2 · Reduced complexity sliding window based equalizer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,794 B2 - Document ID: US7609794B2 - Status: Granted - Kind: B2 - Application number: 12/191,702 - Filed: 2008-08-14 - Published: 2008-12-04 - Granted: 2009-10-27 - Earliest claimed: 2003-03-03 - Assignees: InterDigital Technology Corporation - Inventors: Alexander Reznik; Rui Yang; Bin Li; Ariela Zeira - Web page: https://patentgrep.com/patent/US7609794B2 ## CPC - H04L 25/0242: {using matrix methods} - H04B 1/71052: {using decorrelation matrix} - H04L 25/03057: {with a recursive structure (H04L25/03031 takes precedence)} - H04L 25/03292: {with channel estimation circuitry} - H04L 25/0212: {of impulse response} - H04L 2025/03426: {transmission using multiple-input and multiple-output channels} - H04L 2025/03509: {fractionally spaced (H04L2025/03515 takes precedence)} - H04L 2025/03605: {Block algorithms} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04B: TRANSMISSION ## 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 ### Claim 1 A wireless transmit/receive unit (WTRU) comprising: a processor 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 2) 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. ### Claim 4 (depends on 3) 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. ### Claim 5 (depends on 3) 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. ### Claim 6 (depends on 1) 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. ### Claim 7 (depends on 1) 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. ### Claim 8 (depends on 1) 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. ### Claim 9 (depends on 1) 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. ### Claim 10 (depends on 1) 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. ### Claim 11 (depends on 1) 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. ### Claim 12 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. ### Claim 13 (depends on 12) The WTRU of claim 12 wherein the processing circuit is configured to use a sliding window based approach that uses an exact solution. ### Claim 14 (depends on 12) The WTRU of claim 12 wherein the processing circuit is configured to use a sliding window based approach that assumes that noise between each receive antenna is uncorrelated. ### Claim 15 (depends on 12) The WTRU of claim 12 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. ### Claim 16 (depends on 12) The WTRU of claim 12 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.