Patent ID: 6249518
Filing Date: 2001-06-19
Classification: H04B,H04L

Abstract:
In a demodulator that takes as input a series of received signals from a single antenna receiver system within a time division multiple access (TDMA) time slot, each received signal comprising an information component and an interference component, both components comprising a signal and a fading coefficient, the TDMA time slot comprising a training period when the information signals are known at the processor and a data period when the information signals are not known, a method of reducing interference during demodulation comprising the steps of:inputting to the processor, during the training period, a plurality of training received signals and a plurality of known information signals that correspond to the training received signals;estimating an information fading coefficient by processing the training received signals and the known information signals and deriving estimates of a plurality of information components corresponding to the training received signals;estimating a plurality of interference components corresponding to the training received signals by processing the training received signals and the estimates of the information components;inputting to the processor, during the data period, a first received signal;correlating the first received signal with the estimates of the information and interference components to generate an estimate of a first information signal corresponding to the first received signal;wherein each information signal and interference signal within the series of received signals is modulated according to a given information modulation scheme and a given interference modulation scheme respectively;wherein the generation of the estimate for the first information signal comprises;correlating the estimate of one of the plurality of information components and all possible information reference signals, each information reference signal being one of the closed set of all possible information signals recognized by the given information digital modulation scheme, to generate a plurality of information correlations;correlating the estimate of one of the plurality of interference components and all possible interference reference signals, each interference reference signal being one of the closed set of all possible interference signals recognized by the given interference digital modulation scheme, to generate a plurality of interference correlations;correlating the plurality of information correlations, the plurality of interference correlations, and the first received signal to generate a plurality of decision variables; andcomparing the plurality of decision variables to generate an estimate of the second information signal.