Complexity Reduced Log-MAP Algorithm for the Turbo Decoding

Due to the high complexity of the log-MAP algorithm, many modifications and simplifications were proposed to simplify the VLSI implementation of turbo decoding. A new way to reduce the complexity of the log-MAP algorithm is presented. It takes place of log and exp operation with look-up table without considering the channel state information, which make the decoding process more easily and faster. In some communication system, it is hard or impossible to estimate the channel state information. It allows for efficient ASIC implementation and almost has the same performance as the log-MAP algorithm. The simulation results show that the presented algorithm has a good performance in all circumstance.