# US 8,542,772 B2 · Multi-user detection using equalization and successive interference cancellation

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- Number: US 8,542,772 B2
- Document ID: US8542772B2
- Status: Granted
- Kind: B2
- Application number: 13/588,023
- Filed: 2012-08-17
- Published: 2012-12-13
- Granted: 2013-09-24
- Earliest claimed: 2003-03-03
- Assignees: InterDigital Technologies Corporation
- Applicants: Ariela Zeira
- Inventors: Ariela Zeira
- Web page: https://patentgrep.com/patent/US8542772B2

## CPC

- H04B 1/123: {using adaptive balancing or compensation means (adaptive filter circuits and algorithms H03H)}
- H04B 1/7105: Joint detection techniques, e.g. linear detectors
- H04B 1/71072: {Successive interference cancellation}
- H04L 25/03006: {Arrangements for removing intersymbol interference}
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A method and apparatus for multi-user detection is disclosed. A signal is received in a shared spectrum, and samples of the received signals are produced as a received vector. The received vector is segmented into vector segments. Each segment has a portion that overlaps with another segment and the overlapping portion includes at least one chip less than twice a channel impulse response length. For each vector segment, symbols are successively determined for communications by determining symbols for a communication in the communications, ordering the communications by received power and removing a contribution of the communication from the vector segment. The determining of symbols includes equalizing an input vector corresponding to a segment of the received vector using fast Fourier transform. The determined symbols are assembled into a data vector for each communication in the communications.

## Claims

### Claim 1

A method for wireless communication, the method comprising:
receiving a signal in a shared spectrum;
producing samples of the received signal as a received vector;
segmenting the received vector into a plurality of vector segments, wherein each segment has a portion that overlaps with another segment and the overlapping portion includes at least one chip less than twice a channel impulse response length;
for each vector segment, successively determining symbols for a plurality of communications by determining symbols for a communication in the plurality of communications, ordering the communications by received power and removing a contribution of the communication from the vector segment, wherein the determining of symbols includes equalizing an input vector corresponding to a segment of the received vector using fast Fourier transform; and
assembling the determined symbols into a data vector for each communication in the plurality of communications.

### Claim 2 (depends on 1)

The method of claim 1 wherein the determining symbols for a communication further includes despreading the equalized vector segment and making a hard decision on the despread equalized vector segment.

### Claim 3 (depends on 1)

The method of claim 1, wherein removing a contribution of the communication includes subtracting the determined symbols from the vector segment.

### Claim 4 (depends on 1)

The method of claim 1, wherein successively determining symbols for a plurality of communications includes determining symbols for a communication of interest.

### Claim 5 (depends on 2)

The method of claim 2, wherein despreading the equalized vector segment includes applying a code associated with the communication to produce a despread equalized vector segment including a plurality of soft symbols.

### Claim 6

A wireless transmit/receive unit (WTRU) comprising:
an antenna configured to receive a signal in a shared spectrum;
a sampling device configured to produce samples of the received signal as a received vector;
a segmentation device configured to segment the received vector into a plurality of vector segments, wherein each segment has a portion overlapping with another segment and the overlapping portion includes at least one chip less than twice a channel impulse response length;
a equalization and successive interference canceller configured to successively determine for each vector segment symbols for a plurality of communications by determining symbols for a communication in the plurality of communications, ordering the communications by received power and removing a contribution of the communication from the vector segment, wherein the equalization and successive interference canceller is configured to determine the symbols by equalizing an input vector corresponding to a segment of the received vector using fast Fourier transform; and
a segment reassembly device configured to assemble the determined symbols into a data vector for each communication in the plurality of communications.

### Claim 7 (depends on 6)

The WTRU of claim 6, wherein the equalization and successive interference canceller further includes a despreader configured to despread the equalized vector segment and a hard decision device configured to make hard decisions on the despread equalized vector segment.

### Claim 8 (depends on 6)

The WTRU of claim 6, wherein the equalization and successive interference canceller is configured to remove a contribution of the communication from the vector segment by subtracting the determine symbols from the vector segment.

### Claim 9 (depends on 6)

The WTRU of claim 6, wherein the equalization and successive interference canceller is configured to determining symbols for a communication of interest.

### Claim 10 (depends on 7)

The WTRU of claim 7, wherein the despreader is configured to produce a despread equalized vector segment including a plurality of soft symbols by apply a code associated with the communication to the equalized vector segment.