CSMA with priority reservation by interruptions for efficiency improvement and QoS support

Ethernet has been the most important local area network (LAN) technology for low cost and popular deployment. However, its medium access control (MAC) protocol, CSMA/CD, is inefficient and can´t support multiple services with different quality-of-service (QoS) requirements. It severely restricts network carriers to provide new Internet services based on Ethernet networks. An enhancement on CSMA/CD protocol, coined CSMA with priority reservations by interruptions (CSMA/PRI), is proposed in this paper. The proposed protocol uses a hierarchical reservation approach to improve the efficiency of Ethernet networks and guarantee the QoS for different services. In order to meet the increasing need for providing real-time services over Ethernet, our enhancement firstly reserves network resources for real-time traffic and uses different collision resolution algorithms for different types of traffic. The performance of our proposed enhancement is seriously studied under realistic traffic scenarios and is compared with CSMA/CD and CSMA with reservations by interruptions (CSMA/RI). The theoretical analyses show that CSMA/PRI offers much shorter delay and higher channel utilization than CSMA/CD and CSMA/RI.