Abstract :
The number of competing stations has great influence on the performance of IEEE 802.11 MAC protocol based on the distributed coordination function (DCF), which utilizes Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). Some researchers try to use performance modeling to analyze and optimize the protocol, but the strict assumptions of the modeling often lead to research results that could not be adaptive to the dynamic change of competing station number, which is extremely prevalent in today´s IEEE 802.11 networks. Some other researchers try to use filters, based on accurate measurement, to estimate the number of competing stations, and improve system performance by dynamically tuning the protocol parameters. However, such mechanisms are too complex to apply in real environment. Base on our discovery, we propose a simple adaptive optimization mechanism, DOOR (Dynamic Optimization on Range), for the IEEE 802.11 DCF, which is based on the subrange of competing station number. The reason, principle and method for partitioning subranges are introduced. Moreover, the detailed system model and performance evaluation for the new mechanism are given. The elaborate numerical results show that this mechanism could achieve much higher throughput and shorter delay than the standard IEEE 802.11 DCF in almost all the different competing stations numbers.
