Second-Order Memory Based LT Encoder Design
Luyao Shang, Erik S. Perrins · 2016
Increasing communication reliability and decreasing latency is an increasing demand in wireless multihop networks. In this regards, fountain codes have been widely adopted in cooperative transmissions. The Luby transform (LT) code is considered as a fundamental fountain code that is used to improve the performance of the fountain code family. Previous work on LT code design has focused mainly on the degree distribution of the output symbols, leaving the input symbols as being Poisson distributed. It has been proved that by introducing memory to the encoder, the degree distribution of the input symbols can be designed to improve the code performance. However, existing work focuses only on first- order memory based LT encoders (MBLTEs); the performance with higher memory orders is not investigated. Therefore, in this paper we study the second-order MBLTE with the belief propagation (BP) decoder over the binary erasure channel (BEC) and show that it outperforms the first-order MBLTE in terms of the decoder convergence speed, the bit error rate (BER) and the error floor.