Performance Comparison of Channel Coding Methods for Optical Satellite Data Relay System

The demand for high-capacity satellite communications has continuously increased, owing to the need to enhance the performance of sensors on earth observation satellites. One of the challenges is to realize a high-capacity return link from user satellites to ground stations. The Japan Aerospace Exploration Agency (JAXA) developed an optical intersatellite communication system "LUCAS" in 2020. JAXA aims to demonstrate a 1.8 Gbps data relay between a user satellite in low earth orbit and a ground station. Currently, the realization of a next-generation optical data relay system capable of even higher-speed communications is being studied. However, a detailed performance comparison of channel coding methods for optical data relay systems has not been conducted to enable high-speed communication within the limits of realistic computation power for installation in data relay satellites using optical intersatellite communication. Therefore, in this paper, we conduct numerical simulations to evaluate the characteristics of communication channel coding technologies, such as polar, low-density parity check codes, and Digital Video Broadcasting- Satellite-Second Generation (DVB-S2) channel codes, when applied to optical data relay satellite systems. The results of the simulations indicate that the performance of DVB-S2 codes is relatively good. Furthermore, a simple log-likelihood ratio correction method for DVB-S2 is proposed and shown to be effective.