Two Alternative Schemes to EY-NPMA for Medium Access in High Bitrate Wireless LANs

The growing penetration of WLANs in the market, as well as the wider spectrum of applications that these kinds of networks are called to support, demands the introduction of new methods for efficient medium access. Today, the two dominating paradigms in medium access control are those of dynamic assignment and contention based ones. EY-NPMA is a contention based scheme that exhibits very low collision rates, while being quality of service aware. In this paper, we propose a solution to the highly criticised drawback of the EY-NPMA protocol – the increased overhead. Towards this end, we propose and evaluate the performance of two medium access schemes that are based on EY-NPMA and compare them to the base protocol. The theoretical analysis of the proposed schemes shows that they make better utilization of the common medium. It also allows us to determine the optimal working parameters for each one. Furthermore, extended simulation trials validate these results and confirm the good characteristics of the proposed protocols.