Performance Improvements with a P-Persistent Enhanced DCF for WLANs

This paper focuses on the design and performance evaluation of a p-persistent transmission control protocol that can enhance the IEEE 802.11 DCF MAC, called P-IEEE 802.11 DCF. Unlike the so-called p-persistent IEEE 802.11, which is a variant of p-persistent CSMA and is not compliant with IEEE 802.11 DCF control scheme, our proposed protocol truly exploits the p-persistent transmission over the standard IEEE 802.11 MAC scheme. In WLANs, our protocol can greatly enhance the throughput by setting the optimal transmission probability in each back-off stage in DCF according to the throughput calculation results. When the number of active nodes varies, an intelligent scheme can adaptively adjust its transmission probability to achieve the maximal throughput during the run time. The key characteristics of our protocol are its simplicity, in compliance with the standard IEEE 802.11, complete distribution, and no requirement of handshaking extra messages among network hosts. Analysis and simulation results show the effectiveness of the p-persistent protocol in achieving the maximal throughput, and in improving the frame delay and short-term fairness.