Comparitive study of turbo decoding techniques

This paper presents an overview of the novel class of channel codes referred to as turbo codes, which have been shown to be capable of performing the decoding close to the Shannon limit. First, a brief discussion on turbo encoding is given, and then move to describe the form of the iterative decoder most commonly used to decode turbo codes. Various decoding algorithms that can be used in an iterative decoder are discussed, and an example of the operation of such a decoder using the so-called Soft Output Viterbi Algorithm (SOVA) is given. Lastly, the effect of a range of system parameters is investigated in a systematic fashion, in order to gauge their performance ramifications.