Patent ID: 6317466
Filing Date: 2001-11-13
Classification: H01Q,H04B,H04L

Abstract:
A communications system comprising a transmitter having k antennas, said transmitter responsive to receipt of an m-dimensional transmit symbol vector from a source, transmits the symbol vector over m of the k antennas using a predetermined modulation technique, in which components of said transmit symbol vector comprise QAM symbols, where k.gtoreq.m>1,a receiver having n antennas for receiving signals from said transmitter as n-dimensional received signal vectors, where n.gtoreq.m, each of said received signal vectors comprising a linear combination of symbols from said transmitter and additive noise, wherein said receiver further comprises a detection processor that processes the n-dimensional received signal vector to form an estimate of the m-dimensional transmit symbol vector, the detection processor further comprisesa processor that (a) determines a preferred permutation of integers 1, 2, . . . m, which define an order in which said m components of said transmit symbol vector are estimated, and in which the preferred permutation is a function of the signal-to-noise ratios of the m components determined such that the component having a predetermined signal-to-noise ratio among the m components is placed first in the permutation and then subtracted from the m components, the component having a predetermined signal-to-noise ratio among the remaining ones of the components is placed second in the permutation and then subtracted from the remaining components, and so on, and (b) in the order defined by said preferred permutation then estimates the (i)-th ordered component of the transmit symbol vector by nulling out from the received signal vector contributions due to transmit symbol vector components (i+1), (i+2), . . . (m) which have not yet been estimated, and canceling out from the received signal vector contributions due to transmit symbol vector components (1), (2), . . . (i-1) which have already been estimated, where (i) denotes the ith element of the preferred permutation.