Performance Analysis Of A Novel Ldpc-Turbo Hybrid Structure Code In Atmospheric Optical Communication

Atmospheric optical communication, having high confidentiality, wide bandwith and high capacity, can overcome geographic limitations and may successfully solve the last kilometer problem, comparing to optical fiber communication.Beams in atmospheric optical communication may be affected by atmospheric turbulence resulting in decline in the quality of communication. During the transmission, beams may generate atmospheric turbulence, the detection signal intensity of the optical receiver may change dramatically, and the light spot may flicker, resulting in high error rate seriously affecting the performance of the atmospheric optical communication. So it is necessary to design a channel coding technique with high error correction capability in atmospheric optical communication that can effectively avoid the light intensity fluctuation.In this paper, we analyzed a new novel LDPC-Turbo hybrid structure code in atmospheric optical communication. Study of the turbulence in atmospheric optical communication. Channel modeling for both strong turbulence and weak atmospheric turbulence. Simulation analysis of performance of Turbo, LDPC, RS and PCGC in atmospheric optical communication system.Designed a new novel LDPC-Turbo hybrid structure code suitable for atmospheric optical communication. Elaborated the design ideas and proposed the encoding and decoding method. Simulated the error correction capability,the time complexity and space complexity of the new code. Simulation results show its excellent performance and a low decoding complexity. Then analyzed the advantages and disadvantages of the new hybrid structure code concretely.Designed the simulation system of the new novel LDPC-Turbo hybrid structure code applied in atmospheric optical communication. Simulation analysis of performance of new novel LDPC-Turbo hybrid structure code, RSC-Turbo hybrid structure code, PCGC and SCGC in the atmospheric optical communication system.And then analyzed the influence of code length, bit rate, the number of iterations and interleaving depth to the error correction capability, complexity and the capability of inhibiting light intensity fluctuation of the system with new novel LDPC-Turbo hybrid structure code in both strong turbulence and weak turbulence. Simulation results verify the effectiveness of the new code inhibiting light intensity fluctuation and its high error correction capability as well. The results also guide us to select proper codeword parameters in different scenarios design the optimal LDPC-Turbo hybrid structure code.Applied the new novel LDPC-Turbo hybrid structure code in3x2.5Gb/s WDM atmospheric optical communication system. Proposed a joint error correction WDM atmospheric optical system. Simulated and analyzed the BER performance of the system. Results show that, compared to3×2.5Gb/s WDM having three independent code, the joint system is suitable for extra long distance optical communication systems with stronger error correnction capability, but smaller capacity of transmit information. Designed a multi-stage joint error correction WDM atmospheric optical communication system. The new system has higher information capacity, and the multiple transmission paths in the system can effectively inhibit light intensity fluctuation.