Turbo codes play a very key role in making digital communications systems very efficient & at the same time very reliable. Turbo codes belong to powerful class of forward error correcting codes. They come very close to approaching the Shannon capacity limit on maximum achievable data transfer rate over a noisy channel. In turbo Codes iterative decoding mechanism is used. In matter of channel coding, upto the invention of turbo codes, 3.0 dB stood between what the theory promised and what real time systems were offering. In order to ensure the efficiency of the data transmission with high speed, we must ensure the excellent performance of decoding. There are two algorithms for decoding Turbo Codes Soft-output Viterbi algorithm and logarithmic-maximum a posteriori turbo decoding algorithm. Log Map algorithm is the extension of MAP algorithm operating in Log domain. MAP algorithm is very efficient but posses many difficulties because of necessity of non linear functions and high number of additions and multiplications. In this paper we focus on Bit Error Rate & Frame Error Rate performance of Turbo Codes in AWGN channel using code rate of ½ and BPSK modulation technique. Decoding is perfomed by using Log Map algorithm that avoids the approximation in Max Log Map algorithm. Simulation results are provided below which show that as SNR increases Bit & Frame Error rate decreases.
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