Downlink Scheduling of Heterogeneous Traffic

Next generation wireless cellular networks will support a variety of quality-of-service (QoS) sensitive applications like streaming multimedia and high-speed data for downlink users. Channel and QoS aware downlink packet scheduling policies are going to play a key role in efficiently utilizing system resources and enhancing QoS experienced by end users. Schedulers specifically designed to support non-real-time delay tolerant services perform poorly for real-time delay sensitive services, and vice-versa. Scheduler design for supporting a heterogeneous mixture of real-time and non-real-time traffic is a relatively less studied problem. We propose a "quasi-stationary" approach to scheduling of hetergeneous traffic, which involves solving a stationary infinite horizon stochastic shortest-path problem at each scheduling instant. We thoroughly characterize the structural properties of the optimal control associated with the stationary problem, and leverage the intuition thus gained to construct a low-complexity heuristic scheduling policy. We demonstrate the efficacy of the proposed scheduler over benchmark schedulers like the exponential rule via link-level simulations.