Adaptive Contention Window Mechanism for Enhancing Throughput in HomePlug AV Networks

HomePlug AV (HPAV) is the standard for distribution of Audio/Video content as well as data within the home by using the power line. It uses a hybrid access mechanism that combines TDMA with CSMA/CA for MAC technology. The CSMA/CA protocol in HPAV has two main control knobs that can be used for access control: contention window (CW) size and deferral counter (DC). In this paper, we extensively investigate the impacts of CW and DC on performance through simulations, and propose an adaptive mechanism that adjusts the CW size to enhance the throughput in HPAV MAC. We find that the CW size is more influential on performance compared to the DC. Therefore, to make the network control easier, our proposal uses a default value of DC and adjusts the CW size. Our scheme simply increases the CW size if the network is too busy and decreases it if too idle. We compare the performance of our proposal with those of the standard and other competitive schemes in terms of throughput and fairness. Our simulation and analysis results show that our adaptive CW mechanism performs very well under various scenarios.