Smart-CSMA with piggybacking and prioritized backoff timer scheduling mechanisms

In this work, we propose a novel medium access scheme that can provide a virtually collision-free environment for a high-speed WLAN in the infrastructure topology. The proposed scheme may be viewed as the merger of the standard PCF and DCF schemes. It can efficiently provide the quality-of-service support like the PCF scheme, while utilizing the flexible on-demand CSMA mechanism similar to the DCF scheme. In the proposed scheme, every station employs the standard CSMA mechanism with a slightly modified backoff procedure. A master station schedules backoff timers for every client station and it sends the backoff timer information together with the data or control frames destined to each given client station. A piggybacking frame exchange mechanism is provided to enhance throughput of the proposed system and a prioritized backoff-timer scheduling scheme is given to provide QoS support. Numerical results show that the proposed scheme significantly outperforms the standard IEEE 802.11 DCF and PCF schemes, and can effectively support prioritized traffic services. In addition, the performance is not susceptible to the number of active and inactive client stations in the network.