Patent ID: 6442193
Filing Date: 2002-08-27
Classification: H04B

Abstract:
A spread spectrum communication device for use in a direct sequence spread spectrum, code division multiple access system, wherein a symbol is spread by a pseudo-noise reference sequence with a chip rate which is substantially greater than a symbol rate of said symbol, so as to form a spread spectrum signal, said spread spectrum signal being modulated onto a carrier and being transmitted over an air interface tending to produce multipath components of said modulated spread spectrum signal, said spread spectrum communication device comprising:a receiver front-end means for receiving said modulated spread spectrum signal; a carrier demodulation means for demodulating said received modulated spread spectrum signal; a sampling means for obtaining samples from said demodulated spread spectrum signal, said sampling means having a sampling rate exceeding said chip rate; a channel estimator for estimating from said samples, with a sub-chip resolution, channel characteristics of said multipath components, and for determining local maximums in said channels characteristics, and, within a chip period, sample locations corresponding to said local maximums; a rake receiver, said rake receiver being coupled to said channel estimator, receiving said samples, and comprising a plurality of receiver branches, each of said receiver branches comprising: a down-sampler for sampling down said samples, on the basis of said determined sample locations, and a correlation means for correlating said down-sampled samples with a locally generated pseudo-noise reference sequence so as to generate correlation values; said rake receiver further comprising:combining means for diversity combining said correlation values; and, said spread spectrum communication device further comprising:decision means for deciding about a received symbol value, on the basis of said diversity combined correlation values.