Beacon Schedule Persistence to Mitigate Beacon Loss in HomePlug AV Networks

Home networking is one of the most popular applications of power line communication (PLC) technologies. In the future, home networks will be required to simultaneously support both data and multimedia traffic. Unlike data, multimedia traffic requires guarantees on quality of service (QoS). The recently release HomePlug Standard, HomePlug AV (HPAV), uses a beacon based time division multiple access (TDEMA) technique for providing guaranteed QoS for multimedia streams. Since a station that misses a beacon will not know the TDMA allocation (or schedule) for that beacon period, it will not be able to transmit. Beacon reliability cannot always be guaranteed over PLC channels. To overcome occasional beacon loss, HPAV uses persistent beacon schedules. Persistent schedules are valid for multiple beacon periods, thus enabling a station to transmit even if it misses one or more beacons. In this paper we use a Markov chain based analysis to investigate the impact of beacon loss on systems with and without persistent beacon schedule. Results show that significant loss in efficiency, and in the level of guarantees on QoS, can occur when no schedule persistence is used. The analysis further shows that the use of persistent preview schedules can enable HPAV systems to tolerate up to 10% beacon loss probability with minimum impact to MAC efficiency and QoS guarantees