The symbol-by-symbol maximum a posteriori (MAP) known also as BCJR algorithm is described. The logarithmic versions of the MAP algorithm, namely, Log-MAP and Max-Log-MAP decoding algorithms along with a new Simplified-Log-MAP algorithm, are presented here. Their bit error rate performance and computational complexity of these algorithms are compared. A new hardware architecture for implementing the MAP-based decoding algorithms suitable for chip design is also presented here.
Hamid R. Sadjadpour,
"Maximum a posteriori decoding algorithms for turbo codes", Proc. SPIE 4045, Digital Wireless Communication II, (26 July 2000); doi: 10.1117/12.394081; https://doi.org/10.1117/12.394081