Regulating Queueing Delay in 802.11ac WLANs: Nonlinear Controller Analysis and Design
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In this paper we consider the analysis and design of a feedback controller to regulate queueing delay in a next generation edge transport architecture for 802.11ac WLANs. We begin by developing a simplified system model suited to control analysis and design, validated against both simulation and experimental measurements. Note that modelling of aggregation behaviour in WLANs is of course challenging in its own right. Using this model we develop a novel nonlinear control design inspired by the solution to an associated proportional fair optimisation problem. The controller compensates for plant nonlinearities and so can be used for the full envelope of operation. The robust stability of the closed-loop system is analysed and the selection of control design parameters discussed. We develop an implementation of the nonlinear control design and use this to present a performance evaluation using both simulations and experimental measurements.
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