Performance Evaluation of Asymmetric Turbo Codes Using Log-MAP Decoding Technique

In this paper, the performance evaluation of an asymmetric turbo code for different codec parameters have been done. The asymmetric turbo codes performances are compared with symmetric counter part of the turbo code. With proper selection of weight configuration, the turbo code can show better results in both water fall region as well as error floor region simultaneously. So, in some cases asymmetric turbo code's performance is more nearer to Shannon limit than symmetric one. This paper includes the effect of different codec parameters (like no. of iteration, frame size, code-rate, and generator polynomial Structure & constraint length etc) on asymmetric turbo code and also explains its performance in comparison with symmetric turbo code. Although, the asymmetric turbo code of all combinations don't show better performance always. Here, we have evaluated the bit error rate (BER) performance using sub-optimal Log-MAP (Logarithmic Maximum-A-Posteriori) decoding algorithm under Additive White Noise (AWGN) channel. The simulation model was developed for AWGN case using MATLAB.