Research On Enhancing Techniques For SC-FDE System Over Maritime Multipath Channel

With the economic globalization, great developments have been made in the field of maritime ship communications. The communication distance of maritime communications network is extended greatly. In view of the status of the maritime ship communications, finding a remote transmission system over sea is in an urgent need. Concerned on the characteristics of maritime multipath channel, a enhancing techniques for SC-FDE system over maritime multipath channel is researched in this paper. A novel adaptive CP algorithm and the sparse multipath channel estimation based on compressed sensing (CS) are proposed in this paper. Finally, the adaptability of SC-FDE system over maritime multipath channel is enhanced.Firstly, this paper introduces a theoretical maritime multipath channel model suitable for different sea states. The performance of SC-FDE system and OFDM system over the maritime multipath channel is compared by simulation. Simulation results show that the SC-FDE system has good anti-multipath ability and can satisfy the need of maritime ship communications.Secondly, the CP- adaptive technique of SC-FDE system is introduced. According to the influence of the diffuse reflection and time delay of the maritime multipath channel, a novel CP- adaptive algorithm is proposed. Furthermore, SC-FDE system model with length-adaptive CP over maritime multipath channels is estimated in this section. The comparison between the adaptive system and non-adaptive system is made by simulation. Simulation results demonstrate that the adaptive system is more effective for combating multipath fading over sea without sacrificing BER performance.Finally, this paper proposes a method for sparse channel estimation based on compressed sensing for SC-FDE system over maritime multipath channel. The Zadoff-Chu sequence as the pilot sequence is proposed to form a circulant Toeplitz observation matrix, and a T-SAMP based on Sparsity Adaptive Matching Pursuit algorithm is proposed for signal recovery. The NMSE (Normalized Mean Square Error) and BER(Bit Error Rate) of T-SAMP, OMP (Orthogonal Matching Pursuit), and LS(Least Squares) algorithms are compared by simulation. The simulation results demonstrate that T-SAMP algorithm is more practical than OMP algorithm because of its capability of signal reconstruction without prior information of the sparsity. Furthermore, the T-SAMP algorithm achieves better performance than the traditional LS algorithm with reduced length of pilot sequence.