Performance of a spread slotted CDMA/ALOHA with hybrid ARQ system with variations on the FEC code capabilities

In the present paper we investigate the effect of changing the error correcting and detecting capability of the FEC code used on the Spread Slotted ALOHA(SSA) protocol with Hybrid-ARQ when the channel experiences different traffic conditions. The main feature of our proposed systems is the utilization of a CDMA m-sequence coding for the SSA together with a Type I Hybrid ARQ system. The ARQ system utilized was a Selective Repeat ARQ system together with BCH code intended to perform error detection and correction. The system performance was evaluated according to different amount of error correcting (ECC) and detecting (EDC) capability of the BCH code on an environment with noise (AWGN) and co-channel interference from other users trying to access the hub. Starting from only error detection and no-correction capability we changed the balance of these two quantities to obtain a better throughput.