A Model of Turbo Code Based on OFDM-CDMA

A model of turbo code based on OFDM-CDMA (orthogonal frequency division multiplexing and code division multiple access) is proposed in this paper. The model consists of three parts, channel code, extending frequency and the modulation of the multicarrier, which has prominent advantages that making full use of the frequency spectrum, overcoming ISI (inter symbol interference), high reliability and good capability of overcoming multipath fading. Log-map and Sova algorithms are adopted to decode here, and simulated by MATLAB. The results of the simulation show that when decoded with log-map algorithm, the BER (bit error rate) performance of turbo code under this model is improved about 0.3 dB than which without adopting this model; When decoded with Sova algorithm, the BER performance of Turbo code under this model is improved about 0.1 dB than which without adopting this model. The calculation of log-map algorithm is obviously more complex than Sova algorithm. The simulation results show that the proposed model has favorable decoding performance, and is suitable for further researching