GEN01-6: Allocation Requirements for Supporting Latency Bound Traffic in HomePlug AV Networks

Impulse noise sources such as dimmers, halogen lamps etc., are quite common in power line networks. Hence, high-speed power line communications systems should be designed to deal effectively with them. HomePlug AV uses aggressive channel adaptation at the physical layer and efficient retransmissions at the MAC layer to deal with impulse noise. This approach can lead to very high probability (up to 20%) of Forward Error Correction (FEC) block errors under some channel conditions. HomePlug AV also has large transmission overhead to ensure reliable communication over the powerline. Transmission overhead can negatively impact the MAC efficiency on channels with high FEC Block Error Rate (BLER) due the need for a large number of retransmissions to successfully deliver packets. This paper studies the complex interaction between FEC block errors, transmission overhead, Quality of Service (QoS) requirements of a multimedia stream and its TDMA allocation requirements. Our results show that, to support low latency applications at high BLERs, the average allocation size has to be increased by one or more transmission overheads. Further, the increase in average allocation is not a strong function of application data rate. Hence, low data rate applications can suffer significant loss in efficiency at high BLERs. Our results also show that using a fixed size TDMA allocation can lead to poor utilization when the latency requirements of the application are less than four beacon periods. These results indicate that channel adaptation in HPAV should take into consideration the application QoS requirements to optimize the overall system capacity.