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Mathematical Implementation of MAX LOG MAP Algorithm for Low Power Applications in Turbo Decoders

P.Maniraj Kumar, Dr.S.Sutha, V.Krishna Mourthy

In Turbo decoding the design of Log MAP algorithm is more complicated with the exponential sum. In this paper a mathematical model is designed with a jacobian logarithm which consists of a max function along with the exponential correction function. The complexity of the jacobian logarithm is also reduced by the Max Log Map algorithm by eliminating the correction term. Multistep Log Map algorithm is used to approximate the correction function. A Dual Mode (SB/DB) procedure is used to compute the log likelihood ratio in order to increase the speed of the computation. The performance of this algorithm is similar to the Log Map algorithm. This method will be incorporated into VLSI technology to design a High Speed MAP Decoder (15% to 25 % as in existing) with less area Utilization (8% as in existing) and low Power (74.95mW)