Patent ID: 7970077
Filing Date: 2011-06-28
Classification: H04L

Abstract:
1. A method of estimating a symbol that has been transmitted into a channel connecting a modulator for producing modulation symbols and an equaliser, wherein a channel estimate describes said channel and the method comprises: a. calculating a metric for each of a number of hypotheses of a sequence commencing with the symbol under estimation followed by a number of subsequently transmitted symbols, each symbol in the sequence occupying a respective node of the sequence; and b. deeming the symbol at the beginning of the hypothesis that has the best metric to be the symbol under estimation; wherein calculating a metric for a given hypothesis comprises: c. calculating a discrepancy metric at each node of the given hypothesis; and d. combining the discrepancy metrics of nodes in the given hypothesis to produce the metric; and wherein a discrepancy metric for a given node of a given hypothesis is an assessment of the difference between: e. a sample received from said channel at a time point corresponding to said given node; f. and a sample that would be received at that time point if said channel estimate were acting on a model signal comprising the symbols of the given hypothesis up to the given node preceded by any estimates of symbols transmitted into the channel immediately prior to said time point as may be required to fill the estimated channel.