On the parallel MAP algorithm

The MAP algorithm used In Turbo decoders is very parallelizable. This property can be used to speed them up. The speedup Is attained at the expense of increased complexity and processing hardware. The increase in processing hardware is linear with the speedup but the increase in complexity of the parallel implementation compared to the traditional implementation is extremely small and this is the main observation of this paper. We discuss the parallel iniplementation of the MAP algorithm, the increase in complexity and memory and contrast the behaviour with that of the Viterbi algorithm. The results given here also suggest a change in design methodology of the sliding window implementation of Turbo decoders.