A new MAC protocol with RCPC coded hybrid ARQ-II for CDMA networks

We propose and investigate a new type of multiple access protocol that combines the characteristics of PRMA, CDMA, and the hybrid ARQ error controlling and retransmission scheme to reduce the retransmissions and keep the frame error rate low when channel experiences heavy traffic. It is an adaptive optimization of the balance between the CDMA processing gain and FEC coding gain to obtain a better throughput. We use both the tagged user approach (TUA) and equilibrium point analysis (EPA) method to analyze performance of the protocol. Simulation shows that using hybrid ARQ-II with code combing in preamble minislot channel access protocol CDMA (PMCAP/CDMA) can significantly improve the delay performance in AWGN. Code limitation strategies can decrease the multiple access interference (MAI) level and frame error rate, which in turn improve the system performance when the background noise is very high.