Soft OSD-Sliding Window Decoding for Staircase LDPC Codes in Deep Space Communications

In this paper, we propose a soft ordered statistic decoder (SOSD) sliding window decoding (SWD) algorithm for staircase low density parity check (LDPC) codes in deep space optical communications. First, according to the relative position variation of Earth-to-Mars during a conjunction cycle, we model a related optical channel model by calculating the scintillation index in the Gamma-Gamma distribution, which divide three states due to the Sun-Earth-Mars (SEM) angle. Then, we propose the SOSD-SWD algorithm for the rate-adaptive staircase LDPC codes for the channel model, which can approach to 10
⁻⁴
bit error rate (BER) under the three channel states with adjustable decoding parameters. Simulation results validate the impact of different parameters of the SOSD-SWD algorithm, and shed light to tradeoff the achievable BER and complexities under different channel conditions, and the proposed SOSD-SWD algorithm can achieve lower BER than the related SWD algorithms for staircase LDPC codes.