Optimal scheduling for high speed uplink packet access - a cross-layer approach

With the increasing proliferation of new services requiring low-delay and/or high-rate uplinks, such as image/video-upload high-rate streaming, there is an associated need for flexible and fair uplink scheduling. Especially, the design of a high speed uplink packet access (HSUPA) radio link scheme for future use mirrors this need. Recently, a number of uplink and downlink scheduling schemes based on combined optimization of the physical layer and the data link layer (so called cross-layer design), were presented (Boche, H. et al., 2003; Neely, M.J. et al., 2003). We extend recent works to the case of arbitrary fading channels. We concentrate on the stability of the queue system as an objective for scheduling and utilize the drift technique for the design of scheduling policies under fading. We propose a simple spatial scheduling policy achieving the largest possible stability region equal to the ergodic capacity region of the multiple access channel (MAC). We show its efficiency and ease of its implementation. Finally, we state several bounds and asymptotics describing the behaviour of the queue system under the optimal policy.