AMBIGUITY RESOLUTION IN DIRECT SEQUENCE SPREAD SPECTRUM MODULATION SYSTEMS

摘要

Coherent demodulation of phase shift keyed direct sequence spread spectrum generally needs a strong pilot to provide channel estimates and to avoid phase ambiguities. This invention relates to a novel approach in which the pilot takes the form a few known chips in every bit and in which the channel is estimated primarily by decision directed removal of the modulation and the pilot chips serve to resolve the 180 degree phase ambiguity.