| The development of efficient medium access control (MAC) protocols, which provide both high throughput performance for data traffic and good quality of service (QoS) support for real-time traffic, is the current major focus in wireless medium access control (MAC) research. This dissertation focuses on the distributed contention-based MAC protocols based on the carrier sense multiple access (CSMA) scheme, targeted at improving throughput, maintaining a high degree of fairness for serving users, and providing QoS for real-time services. To provide all the required properties for MAC protocols in wireless networks, we propose an efficient contention resolution algorithm for wireless local area networks, namely the Fast Collision Resolution (FCR) algorithm. The MAC protocol with this new algorithm attempts to provide significantly high throughput performance for data services while maintaining the simplicity of implementation. The FCR algorithm is compared with the IEEE 802.11 MAC and is shown that higher throughput can be achieved. To provide fairness for serving users, the distributed self-clocked fair queueing (SCFQ) algorithm is modified and incorporated into the FCR algorithm with a maximum successive transmission limit controlled by the SCFQ algorithm, resulting in a new protocol called Fairly Scheduled FCR (FS-FCR). To provide the QoS support in the MAC layer, we apply the priority scheme based on service differentiations for real-time services in FCR algorithm and develop the new MAC protocol called Real-Time FCR (RT-FCR). Extensive simulation studies have been carried out to evaluate the FCR, the FS-FCR, and the RT-FCR and show that the FCR improves the throughput performance significantly, the FS-FCR provides a high degree of fairness while maintaining the high throughput performance of the FCR algorithm, and the RT-FCR supports the desired QoS for voice, video, and data services. |
