Turbo code and star 16-QAM for DS/SSMA communications

In this paper, we propose a turbo coding scheme for spread spectrum with bandwidth efficiency. The scheme has a good performance on Gaussian channels and Rayleigh fading channels. We also show that the turbo code is powerful in multi-user environments. In our research, the turbo coded direct-sequence spread spectrum multiple access (DS/SSMA) system with differentially encoded star 16-QAM modulation is investigated in both aspects of error control performance and bandwidth efficiency. The results show that the coding system has a good error performance and spectral efficiency of 2 bits/s/Hz with star 16-QAM.