Abstract: This paper describes the design of an asynchronous Viterbi decoder having a convolutional encoder with constraint length K=3 and a code rate ½. Viterbi decoders are used to decode convolutional codes. Using Viterbi algorithm Viterbi decoder decodes a bit stream that has been encoded using convolutional encoder. The soft decision output is used for convolutional encoder. In this paper we have used Hybrid Register Exchange Method (HREM) which is the combination of Trace Back Method (TBM) and Register Exchange Method (REM) for decoding the bit stream. HREM is having an advantage over TBM and REM that it reduces the switching activity due to which power can be reduced. The choice of asynchronous design was predicted due to its power advantage. Asynchronous designs are inherently data driven and are active only when doing useful work, enabling considerable savings in power and better reliability. The main aim of proposed method is to reduce power consumption.

Keywords: Convolutional encoder, Viterbi Algorithm, Viterbi decoder, asynchronous Viterbi decoder, power consumption, hybrid register exchange method, soft output decision.