Enhanced turbo decoding algorithm for mimo ofdm system in wireless transmission

Abstract

Turbo coding has been adopted as a channel coding scheme for several 3G mobile systems and in 4G standards for high data rates Turbo decoder uses the following decoding algorithms Maximum A posteriori Probability MAP Logarithmic MAP LogMAP and Soft Output Viterbi Algorithm SOVA The MAP decoding algorithm is computationally intense and hence they cannot be implemented in real time systems So simplified and sub optimal algorithms like Log MAP and SOVA are used for practical implementation The computational intensity and unsuitability to chip design of Log MAP algorithm necessitated the development of its variant Max Log MAP MLMAP algorithm This work aims at improving the performance of MLMAP Turbo decoding algorithm This is due to the fact that both 3G 4G mobile communication standards considered LTE based Enhanced Turbo code as a promising channel coding scheme It employs scaled MLMAP algorithm with fixed scaling factor providing better error correction compared to other channel coding schemes but at the cost of increased complexity Also for many industrial control applications there is a need for developing a decoder with better BER performance because error correction is one of the key issues for such networks To address these obstacles modifications to conventional MLMAP algorithm has been proposed which provides better BER with reduced complexity In this work three algorithms Optimized Single Correction Factor Max Log MAP OSCF MLMAP Optimized Double Correction Factor Max Log MAP ODCF MLMAP and Reciprocal Data Max Log MAP RD-MLMAP to combat these drawbacks are proposed newline