Patent ID: 8578255

Claim:
A sequence estimator for re-estimating a transmitted signal from an existing estimate of the transmitted signal, the sequence estimator comprising: a) a plurality of decoding engines; b) control logic; and c) a memory; wherein: d) each decoding engine is arranged to re-estimate in series a plurality of sections of the transmitted signal; e) each decoding engine, in producing a new estimate of a given section of the transmitted signal, is arranged to perform on the existing estimate of the given section a type of maximum a posteriori probability (MAP) decoding in which state metrics of first and second types are calculated through the given section in opposing directions; f) the control logic is arranged to store into the memory the second type state metrics as produced by a first one decoding engine of said plurality of decoding engines for an end-point of a first one section of said plurality of sections; and g) the control logic is arranged to retrieve said second type state metrics stored in the memory and use them to initialize calculation of second type state metrics in a second one decoding engine of the plurality of decoding engines for a second one section of said plurality of sections, wherein initialization of the calculation of the second type state metrics for the second one section and production of the second type state metrics for the end-point of the first one section occur in one iteration of re-estimating the transmitted signal, further wherein initialization of calculation of first type state metrics for the first one section of said plurality of sections and production of the first type state metrics for an end-point of the second one section occur in different iterations of re-estimating the transmitted signal.