Low-Delay Proportional Fair Rate Allocation for 802.11ac WLAN Downlink

In this paper we consider a next generation edge architecture where traffic is routed via a proxy located close to the network edge (e.g. within a cloudlet). This creates freedom to implement new transport layer behaviour over the wireless path between proxy and clients. We use this freedom to develop a novel approach to achieving high rate, low latency communication on the downlink. This works by adjusting the send rates to clients so as to regulate the aggregation level of transmitted frames which in turn robustly regulates the queueing delay at the AP. We derive the low-delay proportional fair rate allocation in the presence of aggregation and using this consider primal-dual and PI controller approaches for achieving the low-delay proportional fair rate allocation. We find that the primal-dual approach is fragile in the sense that it is sensitive to modelling errors, and in contrast the PI controller approach is much more robust. We present numerical simulation results evaluating the performance.