Joint optimization of HD video coding rates and unicast flow control for IEEE 802.11ad relaying

This paper proposes a joint optimization framework for minimizing high-definition (HD) video coding rates and selecting optimal relay nodes in 60 GHz millimeter-wave (mmWave) IEEE 802.11ad very high throughput (VHT) wireless systems. While IEEE 802.11ad VHT aims to support uncompressed HD video wireless transmission, its major limitation is the extremely high attenuation even in line-of-sight situations, which leads to a short admissible distance between transmitter and receivers and/or the necessity to compress video. To deal with this problem, the IEEE 802.11ad VHT draft standard defines efficient relaying protocols to extend the network coverage. When multiple source-destination pairs and multiple relays are present, a key question is which relay should help in the forwarding of which source flow. This selection should be done in such a way that the average video quality of the streams, which is related to the throughput in a nonlinear way, is maximized. We solve this problem by an integer programming framework that selects optimal relay nodes, their cooperation modes (i.e., amplify-and-forward, decode-and-forward, or non-cooperation), and the video coding (compression) rates which can maximize transmission quality.