A novel symbol-interleaved Serially Concatenated Overlapped Multiplexing system

Serially Concatenated Overlapped Code Division Multiplexing (SC-OVCDM) system was presented. In this system, for input of OVCDM can be arbitrary modulated symbol, Trellis-coded modulation (TCM) code is firstly employed as outer code, OVCDM code with short constraint length is inner code, a symbol interleaver serially concatenates them. We employ serially nonbinary iterative decoding in the receiver. Symbol-wise Extrinsic Information Transfer chart (EXIT) is used to analyze convergence property of SC-OVCDM system, based on EXIT we propose a search algorithm to look for optimal inner code. Performance of obtained SC-OVCDM system on the AWGN channel is simulated, and compared to three systems with same spectral efficiency including turbo code in Long Term Evolution. Simulation results show proposed search algorithm can accurately estimation cliff threshold of SC-OVCDM. At bit error rate level of 10^-5, SC-OVCDM system with short frame length can obtain 0.3 dB, 2.5 dB and 6 dB coding gain respectively.