Kabushiki Kaisha Toshiba

Mong Suan Yee

Robert Jan Piechocki

Cheran Malsri Vithanage

Christophe Andrieu

This invention generally relates to methods, apparatus and computer program code for decoding signals, and more particularly to trellis-based decoding using a variant of a BCJR procedure. The invention includes a trellis decoder for decoding symbols of a received signal, the symbol including a sequence defined by transitions between states of a trellis, the trellis decoder including: means for performing a forward recursion through the trellis to determine a first set of probabilities (&#x3b1;(X)) each defining a probability of a said trellis state (X) responsive to one or more current or earlier received signal values (y); means for providing a second set of (&#x3b2;(X)) probabilities each defining a probability of one or more received signal values (y) given an earlier the trellis state (X); means to decode the received signal to determine probabilities (p(b|y)) for symbols of a corresponding transmitted sequence of symbols from the first and second sets of probabilities; and where the decoder further includes: means to select states for determining the first set of probabilities responsive to one or more received signal values later than a the trellis state defining a probability in said first set.

Signal decoding methods and apparatus

A method of decoding a transmitted string of symbols received as a received signal. The method includes searching for a candidate string of symbols, by searching for candidate symbols within a region of a multi-dimensional lattice, and decoding the transmitted string of symbols by selecting a candidate string of symbols. The candidate string of symbols includes a string of candidate symbols. The searching for the candidate symbols includes selecting a candidate value for one of the transmitted symbols, and testing whether a part of the multi-dimensional lattice defined by the selected candidate value is within a bounding distance from the received signal. The searching for the candidate symbols is stopped after a limiting number of performances of the testing. The decoding includes providing a linear estimate of the transmitted string of symbols when the searching for the candidate string of symbols fails to locate the candidate string of symbols.

The invention relates to apparatus, methods and computer program code for equalisation. A soft-in-soft-out (SISO) equaliser for use in a receiver for receiving data from a transmitter configured to transmit data from a plurality of transmit antennas simultaneously is described. The equaliser comprises at least one received signal input for inputting a received signal; a plurality of likelihood value inputs, one for each transmit antenna, for inputting a plurality of decoded signal likelihood values from a SISO decoder; a processor configured to determine from said plurality of signal likelihood values an estimated mean and covariance value for a signal from each of said transmit antennas; an expected signal determiner coupled to said processor to determine an expected received signal value using said mean values; a subtractor coupled to said received signal input to subtract said expected received signal value from said received signal to provide a compensated signal; a filter coupled to said subtractor to filter said compensated signal to provide a plurality of estimated transmitted signal values, one for each said transmit antenna; a filter coefficient determiner coupled to said processor to determine coefficients of said filter using said covariance values; and an output stage coupled to said filter to output a plurality of transmitted signal likelihood values, one for each said transmit antenna, for input to said SISO decoder.

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Bristol, United Kingdom

Mong Suan Yee