Improving WLANs through a Hybrid MAC Access Protocol with a Natural Index

The MAC protocol is important in LAN, especially in wireless LAN because of limited bandwidth. A great deal of research has been carried out and some of proposed schemes are effective. Specifically, considerable effort has been devoted to improving the IEEE 802.11 standard which is utilized widely and it seems that we cannot expect to enhance the throughput dramatically than improved proposals ether for DCF or PCF. In the meantime, besides throughput, there are some other issues for DCF such as fairness and QoS support. However, except for several hybrid protocols, most proposals were either based on contention mode or schedule mode and neither of the two modes has possessed the good characters of the other. In this paper, we propose a new hybrid MAC scheme used for distributed system (with no control node) that dynamically adapts to traffic changes without degradation of delay in the case of low traffic load and achieves high throughput which is close to transmission capacity in saturated case. We carried out simulations focusing on throughput and delay. Through an analysis of simulation results, we show that our scheme can greatly improve the throughput with low delay.