Abstract:

Low density parity check codes are used to multiple access channels and the user-specific check matrices are used as the unique characteristics. A simplified algorithm is adopted to update the output message of multiple access channel factor nodes. Density evolution algorithm with Gaussian approximations is designed for the message propagation process of multi-user low density parity check codes. Based on the Gaussian approximation algorithm, the degree sequences for irregular low density parity check codes are optimized by using differential evolution algorithm. Analysis and simulation results show that the designed low density parity check codes have good performance on multiple access channel.

Key words: low density parity check codes, multiple access channel, Gaussian approximation, density evolution；differential evolution