Abstract: A symbol based communications system involves symbol detection at a receiver in the system. The symbol detection involves determining a set of symbols likely to be present on a sequence of received data. A symbol detector provided to fulfil this role includes means for performing a forward backward recursion means on the basis of a reduced set of active states, to determine state probabilities in a hidden Markov model state trellis. The symbol detector further comprises forward message determination means operable to determine a reduced set of forward messages associated with a set of the available states for performance of the reduced state forward recursion, and backward message determination means operable, independently of the forward message determination means, to determine a reduced set of backward messages associated with a backward message determination means for performance of the reduced state backward recursion.

Abstract: 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.

Abstract: This invention is generally concerned with methods, apparatus and processor control code for decoding signals, in particular by means of sphere decoding. A sphere decoder configured to search for one or more strings of symbols less than a search bound from an input signal by establishing a value for each symbol in turn of a candidate said string by postulating values for each said symbol in turn of said candidate string and determining whether a said postulated symbol value results in a distance metric dependent upon said search bound being satisfied, each said symbol of a said candidate string for which values are postulated defining a level of said search. The sphere decoder includes a data structure configured to define, for each level of said search, a set of symbol values from which said postulated values are selected, said sets of symbol values being different at different levels of said search.

Abstract: This invention relates to apparatus, methods and computer program code for transmission and reception in communication systems in which a receiver receives signals from a plurality of transmit antennas associated with a single transmitter. In particular this is related to MIMO (multiple input multiple output) and MISO (multiple input single output) channel based wireless systems. The present invention provides a method of transmitting a data sequence in a wireless communications system comprising: transmitting said data sequence from a first antenna; interleaving the data sequence; transmitting at least a part of the interleaved sequence from a second antenna spaced apart from the first antenna, the part of the interleaved sequence transmitted simultaneously with a part of the data sequence transmitted from the first antenna.

Abstract: This invention is generally concerned with methods, apparatus and processor control code for a signal decoding, in particular by employing a plurality of maximum likelihood hard detectors such as sphere decoders. A decoder for decoding a received signal, said received signal being provided by a transmitted signal comprising a string of symbols sent over a channel, each said symbol comprising one or more bits, said decoder comprising: a plurality of maximum likelihood decoders each configured to determine a minimum bit-dependent distance metric for a string of symbols in which a bit has a defined value, said distance metric being dependent upon a distance of said received signal from an estimated received signal determined from said string and a response of said channel; and a bit likelihood estimator coupled to each of said maximum likelihood estimators and configured to determine a bit likelihood value for each bit of said string dependent upon said minimum distance metrics.

Abstract: This invention is generally concerned with methods, apparatus and processor control code for decoding signals, in particular by means of sphere decoding.