Patent ID: 7161975
Filing Date: 2007-01-09
Classification: H04B,H04L

Abstract:
1. A method for multi-user detection, comprising: receiving a complex input signal due to a superposition of waveforms encoding symbols in a constellation of fixed magnitude and variable phase, which symbols are transmitted respectively by a plurality of transmitters in a common frequency band; sampling the complex input signal at sampling intervals over the duration of an observation period to provide a sequence of complex samples; processing the sequence of complex samples to determine soft decision values corresponding to the symbols transmitted by the plurality of the transmitters in the observation period, while constraining the soft decision values to a circle in a complex plane; and projecting the soft decision values onto the constellation to estimate the transmitted symbols, wherein processing the sequence of complex samples comprises determining a phase angle of each of the soft decision values in the complex plane so as to minimize a cost function indicative of a difference between the soft decision values and the transmitted symbols.