Soft Output Decoding Algorithm for Turbo Codes Implementation in Mobile Wi-Max Environment

In the area of wireless communication system, researchers are concentrating on powerful forward error correction (FEC) coding techniques. A literature survey has shown that in the field of mobile Wi-Max environment Turbo code provides a coding gain close to Shannon limit. Since the performance of turbo codes depend on iterative decoding algorithms. Among various soft outputs decoding algorithms, Maximum A Posteriori (MAP) algorithm is used, which works on the principle of symbol estimation of the received signal. This paper presents logarithmic version of MAP decoding algorithm (Log-MAP). The author has taken efforts to modify the available Log MAP decoding algorithm in order to reduce the computational complexity. The results are presented for this new developed Max-Log-MAP decoding algorithm. Bit Error Rate (BER) performance and computational complexity of these algorithms are compared with reference to the standard defined by IEEE802.16e for mobile Wi-Max system.