Iterative decodable block codes for high-speed free space optical communication

This paper investigates the performance of high-rate block codes in log-normal fading atmospheric channel based on the discussion of channel characteristics. Several block codes are under study, especially two kinds of iterative decoding codes with high code rate and low encoder/decoder complexity: hamming-based TPC codes and block circulant based LDPC codes. The code types selection and iterative decoding algorithms for the two codes are discussed. The performance of several codes under different turbulence strength are also reported. Both TPC and LDPC codes can achieve impressive coding gain based on theoretical analysis and extensive computer simulation. In term of superior property in coding gain, error floor effect and hardware implementation, we recommend TPCs as FEC scheme for FSO system.