Optimation of simplified serial concatenated overlapped code division multiplexing system

摘要

A simplified serial concatenated overlapped code division multiplexing (SC-OVCDM) system is proposed in this paper, in this scheme, inner overlapped code division multiplexing (OVCDM) code matrix is simplified into multiplexing matrix with constraint length 1, which can obtain two benefits. Firstly, system complexity has significant reduction. Moreover, the output constellation diagram distribution is close to the Gaussian distribution and can obtain better BER performance. Secondly, higher spectral efficiency greater than 4 bit/s/Hz can be achieved for its low complexity. Coded simplified SC-OVCDM system is studied at the first time, BCH (Bose, Ray-Chaudhuri and Hocquenghem) code correcting multiple errors is selected as error correcting code through error histogram analysis, simulations show shorten BCH codes which code rate is close to 1 can effectively eliminate high error floor and reduce loss of spectral efficiency. Proposed system performance needs joint optimisation of encoders, signal sets and multiplexing matrix. Novel multipexing matrices are given for systems that spectral efficiency equals to and greater than 4bit/s/Hz. Simulation results show the effectiveness of the optimal new scheme in AWGN channel.