Fair Scheduling and Admission Control for Shared-Channel Wireless Packet Networks

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Abstract for the web page http://tesla.csl.uiuc.edu/~srikant/~wireless.html Fair scheduling of delay and rate-sensitive packet flows over a wireless channel is not addressed effectively by most contemporary wireline fair scheduling algorithms because of two unique characteristics of wireless media: (a) bursty channel errors, and (b) location-dependent channel capacity and errors. Besides, in packet cellular networks, the base station typically performs the task of packet scheduling for both downlink and uplink flows in a cell; however a base station has only a limited knowledge of the arrival processes of uplink flows. Fair scheduling is closely connected to admission control and channel measurements since these are used to allocate a fraction of the channel's capacity to each flow based or its Quality-of-Service (QoS) requirements. In this proposal, we will study the problem of admission control and scheduling together. Most previous work has addressed these two problems separately in the context of wireline networks, but such an approach is not applicable to wireless networks. On-line measurements will be used along with admission control, scheduling and rate adaption to provide good QoS performance. We plan to use on-line measurements to estimate the parameters of simple stochastic processes (such as on-off Markov models) describing the channel state. Off-line measurements would be used to validate and refine our prediction algorithm as well as to develop a simple model for the channel which can used by the on-line measurement algorithm. We will also study the impact of fair wireless packet scheduling on medium access and develop an effective MAC protocol to support simple rate and delay guarantees. Finally, using existing testbeds, we will evaluate the algorithms that result from this research project.