Research on Degree Distribution Optimization of LT Codes

Abstract

LT code, as a channel coding scheme with good adaptability to the channel, has a stable performance in data transmission of underwater acoustic communication. In the case of large decoding overhead, the LT code can reach the ideal bit error rate(BER), but when the length of the encoded data is short, its coding and decoding performance is not ideal. LT code was applied to underwater acoustic communication by combining with orthogonal frequency division multiplexing (OFDM), and a LT-OFDM system was constructed. To improve the performance of LT code in the case of short code length, a method for degree distribution optimization was proposed on the objective of minimizing BER and minimizing average coding degree. Simulation and sea trial results show that under the same BER this method can optimize the system, transform 7%-22% conversion, and reduce the complexity of coding and decoding.