Interference cancellation in a spread spectrum communication system
First Claim
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1. A method implemented in a wireless transmit receive unit (WTRU) comprising, the method comprising:
- receiving a plurality of combined signals over a shared spectrum at a carrier frequency;
demodulating the plurality of combined signals to a baseband frequency;
converting the plurality of combined signals to digital samples;
filtering a plurality of pilot signals from the plurality of combined signals;
despreading the digital samples with delayed versions of the pilot signals to produce a window of despread pilot code window samples, wherein the window has evenly time spaced samples;
determining a weight for each despread pilot code window sample using a minimum mean square error algorithm;
processing each of the plurality of combined signals with the determined weights to produce weighted received signal; and
despreading the weighted received signal to recover data of the plurality of combined signals.
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Abstract
A code division multiple access communication system transmits a pilot and traffic signal over a shared spectrum. The pilot and traffic signal have an associated code and are received over the shared spectrum. The received signals are sampled and the samples are delayed to produce a window. A weighted value for each despread pilot code window sample is determined using an adaptive algorithm. Each window sample is despread with a traffic code. Each despread traffic code window sample is weighted according to a weight corresponding to its respective pilot code sample.
66 Citations
7 Claims
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1. A method implemented in a wireless transmit receive unit (WTRU) comprising, the method comprising:
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receiving a plurality of combined signals over a shared spectrum at a carrier frequency; demodulating the plurality of combined signals to a baseband frequency; converting the plurality of combined signals to digital samples; filtering a plurality of pilot signals from the plurality of combined signals; despreading the digital samples with delayed versions of the pilot signals to produce a window of despread pilot code window samples, wherein the window has evenly time spaced samples; determining a weight for each despread pilot code window sample using a minimum mean square error algorithm; processing each of the plurality of combined signals with the determined weights to produce weighted received signal; and despreading the weighted received signal to recover data of the plurality of combined signals. - View Dependent Claims (2, 3)
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4. A method, implemented in a base station, the method comprising:
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receiving a plurality of combined signals over a shared spectrum at a carrier frequency; demodulating the plurality of combined signals to a baseband frequency; converting the plurality of combined signals to digital samples; filtering a plurality of pilot signals from the plurality of combined signals; despreading the digital samples with delayed versions of the pilot signals to produce a window of despread pilot code window samples, wherein the window has evenly time spaced samples; determining a weight for each despread pilot code window sample using a minimum mean square error algorithm; processing the plurality of combined signals with the determined weights to produce a weighted received signal; and despreading the weighted received signal to recover data of the plurality of combined signals. - View Dependent Claims (5, 6)
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7. A method, implemented in a wireless transmit receive unit (WTRU), the method comprising:
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producing a data signal; producing, by a plurality of mixers, a plurality of spread data signals, wherein each mixer is configured to mix the data signal with a different pseudo random chip code sequence to produce a different spread data signal; producing, by a plurality of pilot signal generators, a plurality of spread pilot signals, wherein each pilot signal is spread with a different pseudo random chip code sequence and each pilot signal generator is associated with a different spread data signal; producing, by a plurality of combiners, a plurality of combined signals, wherein each combined signal is produced as a result of combining one of the pilot signals with one of the spread data signals; modulating the combined signals to a carrier frequency; and radiating, by a plurality of antennas, the plurality of combined signals over a shared spectrum at the carrier frequency, wherein each antenna is associated with a different modulated combined signal.
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Specification