Application Of LDPC Code In Underwater Communication

As for UWA communication is an important means of underwater communication, it became a research hotspot in recent year, the purpose of research is to enhance the UWA communication distance and transmission rate, lower BER etc, and the technical measures to be used are also constantly updated. Aiming at the UWA channel characteristic, this paper mainly focuses on the applications of LDPC code to UWA communication to improved the system frequency utilization or system reliability combining with spread spectrum UWA communication and multi-carrier spread spectrum UWA communication.Firstly, according to the researches on the characteristics of UWA channel and the influences on UWA communication, the paper establishes multi-path underwater acoustic channel model based on statistic theory. Secondly according to the hardware implementation complexity requirements, this paper presents a kind of method to construct the check-up matrix of QC-LDPC code which is lower triangle structure, this kind of LDPC code can realize linearly complexity with iterative coding, then aiming at the UWA communication demand, we improve the decoding initialization scheme, which can provide accurate decoding information to the iterative decoding algorithm. Again we apply LDPC code to spread spectrum UWA communication system, expound its system principle model and parameter selection, and carry on the simulation and analysis. Finally, it combines LDPC code and multi-carrier spread spectrum UWA communication system, discusses the system theory and multi-carrier parameter settings, and carries on the system simulation, gives the system reliability results under different code length, different modulation mode and compared with RS code.UWA communication develops rapidly, introducing the advanced LDPC code to UWA communication is a inevitable tendency, this paper combines it with spread spectrum UWA communication and multi-carries spread spectrum UWA communication successfully, then carries on simulation, achieves good effects, gives a reference for practical application.