A near-optimum MAC protocol based on the distributed queueing random access protocol (DQRAP) for a CDMA mobile communication system

This paper presents and analyzes a new near-optimum medium access control ( MAC) protocol. The proposed access scheme is suitable for a CDMA mobile com munication environment, and keeps under control and upper bounded the numbe r of simultaneous transmissions. It has a delay performance approaching tha t of an ideal optimum M/M/K system, where K is the number of spreading code s being used (maximum number of simultaneous transmissions). The protocol i s a free random access protocol when the traffic load is light, and switche s smoothly and automatically to a reservation protocol when traffic load be comes heavier. It is based on distributed queues and a collision resolution algorithm. Moreover, a physical receiver structure is proposed and analyze d in order to preserve the robustness of the protocol in a wireless link. T he results obtained show that the protocol outperforms other well known med ium access protocols in terms of stability and delay, even when taking into account the loss caused by channel propagation conditions.