A delay and throughput study of adaptive contention window based HomePlug MAC with prioritized traffic classes

Abstract

Power Line Communication (PLC) has become an integral part of home area networks (HANs) with increasing deployment of intelligent and connected devices. The advent of smart devices creates a heterogeneous type of network with a variety of throughput and delay sensitive applications that must coexist in the HAN. Meeting the quality of service (QoS) for various applications requires high MAC throughput, low channel access delay and prioritized channel access for certain types of data. The Medium Access Control (MAC) protocol for PLC, defined in HomePlug and IEEE 1901, exhibits significant degradation in MAC throughput and increasing channel access delay when the number of users increases. PLC MAC layer issues have received relatively modest attention of researchers compared with physical layer problems and as a result relatively little improvement in MAC throughput and delay performance has been reported over the standard IEEE 1901 protocol. This paper studies an adaptive contention window PLC MAC protocol with a view to assessing access delay performance of this modified protocol, with the throughput and prioritized traffic classes. In the adaptive protocol, each node observes the channel status and adaptively finds the optimum contention window size. Results demonstrate a significant improvement in both MAC efficiency and access delay for the highest priority class in the presence of lower priority classes. Whereas the MAC efficiency drops down to 10% in standard protocols, the proposed adaptive MAC protocol retains its efficiency at about 81% for up to 100 users. Also, the channel access delay is for the modified protocol is maintained under 200 ms for 100 users compared to more than 1000 ms for the standard HomePlug MAC.