Functional Optimization Models for Active Queue Management

Active Queue Management (AQM) is an important problem in networking. In this paper, we propose a general functional optimization model for designing AQM schemes. Unlike the previous static function optimization models based on the artificial notion of utility function, the proposed dynamic functional optimization formulation allows us to directly characterize the desirable system behavior of AQM and design AQM schemes to optimally control the dynamic behavior of the system. Such a formulation also allows adaptive control which enables the AQM scheme to continuously adapt to dynamic changes of networking conditions. In this paper, we present the Pontryagin minimum principle, a necessary condition, for the functional optimization model of AQM with TCP AIMD congestion control. As an example, we investigate a queuing stability criteria and apply the necessary conditions to optimize the functional model.