Joint Rate Control and Scheduling for Providing Bounded Delay With High Efficiency in Multihop Wireless Networks

We consider the problem of supporting traffic with elastic bandwidth requirements and average end-to-end delay constraints in multihop wireless networks, with focus on source rates and link data rates as the key resource allocation decisions. The network utility maximization-based approaches to support delay-sensitive traffic have been predominantly based on either reducing link utilization, or approximation of links as M/D/1 queues, which lead to inefficient link utilization under optimal resource allocation, and mostly to unpredictable transient behavior of packet delays. On the contrary, we present an alternative formulation where the delay constraint is omitted and sources' utility functions are multiplied by a weight factor. The alternative optimization problem is solved by a scheduling algorithm incorporating a duality-based rate control algorithm at its inner layer, where link prices correlate with their average queueing delays. We then present an alternative strategy where the utility weight of each source is adjusted to ensure its desired optimal path prices, and hence the desired average path delays. Since the proposed strategy is based on solving a concave optimization problem for the elastic traffic, it leads to maximal utilization of the network capacity. The proposed approach is then realized by a scheduling algorithm that runs jointly with an integral controller whereby each source independently regulates the queueing delay on its paths at the desired level, using its utility weight factor as the control variable. The proposed algorithms are shown, using theoretical analysis and simulation, to achieve asymptotic regulation of end-to-end delay with good performance.