A spatial slotted-Aloha protocol in wireless networks for group communications

In a large-scale group communication networks, we propose a slotted-Aloha-based access control (SA-AC) scheme with the optimal transmission probability (TP) using the stochastic geometry. Since the performance of SA-AC scheme depends on the TP of the members in a group, the analytical model presents a joint view for the downlink (DL) and the uplink (UL) with TP of the members in a group. We present simple and closed form expressions for the DL and UL joint probability by using Poisson point process (PPP). Furthermore, we analyze the dynamic TP and the optimal TP to maximize the DL/UL joint probability, for which the inclusion of a member and the transmission of the member is determined by the DL and UL thresholds. Since the requirement of the DL/UL joint probability varies with the type of services, the optimal TP has to be determined for an efficient group communication service. The performance of the SA-AC scheme with the optimal TP is demonstrated, and it is shown to be superior over the other schemes.