A Modem Link Strategy for Optimization of LEO Satellite Throughput

This paper presents a means for optimizing the data throughput for low earth orbit (LEO) satellites by implementing a mission specific error control strategy. Due to limited connectivity and very limited overflight time exposure offered by LEO satellites, it is imperative to volumetrically optimize the data throughput. With power limitations on the space segment and remote groundstations, hardware utilization efficiency need to be optimized to reduce power consumption. Most protocols focus on correcting congestion related link errors, but with beam shaping introduced for satellite communication, error control strategies optimized for correcting link related bit errors need to be investigated and implemented. Low density parity check (LDPC) codes have been shown to achieve error performance near the Shannon limit, and with its sparse matrix property, decoding complexity is very low. Using a special class of LDPC codes, called quasi-cyclic (QC) LDPC codes the encoding complexity is also dramatically reduced. With iterative decoding, LDPC codes show large coding gains with low processing power requirements. With its advantages in parallel processing an field-programmable gate array (FPGA) will be used to implement the error control coding (ECC).