Abstract: A switchable-output encoder for encoding an input data sequence into an error protection encoded output sequence is switchable between two encoding modes. The encoder modes comprise a relatively complex mode suitable for a relatively high noise level channel and a relatively simple mode suitable for a relatively low noise level channel. A corresponding decoder is also discussed.

Abstract: A decoder, for decoding a data sequence received from a noisy channel into an estimate of an input sequence, comprises a soft-decision decoder combined with a soft-input calculator. The decoder and calculator are interconnected, and jointly converge on an output which is an estimate of a transmitted sequence.

Abstract: A coset analyzer is used for analyzing time-varying error correction codes in data communications. The time-varying error correction code has cosets, and each coset has a coset leader and a syndrome. The analyzer comprises a coset representation unit for representing a coset of the code as a time-varying error trellis and an error trellis searcher for searching the error trellis. Each member of the coset corresponds to a path through the error trellis. A lossless data sequence compressor and decompressor are also discussed.

Abstract: A decoding device for receiving a data stream from a data source over a noisy channel, the data being arranged in variable length packets using unequal encoding levels for different parts of the data stream, the decoder having a feedback transmitter for sending feedback data via a feedback channel to said data source to indicate a level of quality of data receipt at said decoder, thereby to provide adaptive error correction and concealment in a data stream transferred over said channel.

Abstract: A system for streaming data and corresponding protective parity bits in packets over a channel, the system comprising a recursive systematic convolutional encoder at a sending end for producing said corresponding protective parity bits and a recursive systematic convolutional decoder at a receiving end for reconstructing data lost in the channel, and a data interleaver at a sending end for interleaving data for said recursive systematic convolutional encoder according to a uniformity criterion to form parity bits therefrom, and a parity bit distributor operable to distribute said parity bits over said packets differentially from corresponding data. The system is useful in enabling real time multimedia data distribution over cellular networks.

Abstract: A method of discriminating between equally probable trellis paths surviving in a trellis decoder to select a single output path. The method comprises: windowing over the trellis decoder to view said surviving paths in successive windows, identifying a predetermined feature in the paths as they appear in the successive windows, and eliminating surviving paths having the predetermined feature to leave a single surviving path to form the single output path.

Abstract: A turbo block codes decoder for decoding turbo block codes presented in a matrix form and having at least two dimensions is provided. The turbo block codes decoder including: (a) a first decoder for soft decoding individual first block codes along a first dimension of the matrix for generating first codewords in the first dimension of the matrix; (b) a reliability measure calculator for calculating reliability measures of the first codewords in the first dimension of the matrix, thereby forming soft valued vectors along a second dimension of the matrix; and (c) a second decoder for soft decoding individual vectors of the soft valued vectors along the second dimension of the matrix, for generating second codewords in the second dimension of the matrix, the second codewords being a decoded output of the turbo block codes decoder.

Abstract: An apparatus for blind transport format detection of a received turbo coded data signal is provided. The apparatus includes (a) a syndrome vector generator for generating syndrome vectors for each of at least two constituent codes of a first candidate turbo code; and (b) an error rate estimator for estimating an error rate of a received turbo coded data signal based on said syndrome vectors of at least one constituent code of the at least two constituent codes.