Scheduling and Control of Mobile Communications Networks with Randomly Time Varying Channels by Stability Methods

摘要

Consider a communications network consisting of mobiles, some of which can serve as a receiver and/or transmitter in a multihop path. There are random external data processes, each destined for some destinations. At each mobile the data is queued according to the source-destination pair until transmitted. The capacities of the connecting channels are randomly varying. Time is divided into small scheduling intervals. At the beginning of the intervals, the channels are estimated via pilot signals and this information is used for the scheduling decisions during the interval, concerning the allocation of transmission power and/or time, bandwidth, and perhaps antennas, to the various queues in a queue and channel-state dependent way, to assure stability. Lost packets might or might not have to be retransmitted. General networks are covered, conditions used in previous works are weakened, and the distributions of the input file lengths can be heavy tailed. The resulting controls are readily implementable. The choice of Liapunov function allows a range of trade-offs between current rates and queue lengths, under very weak conditions. Because of the non-Markovian nature of the problem, we use the perturbed Stochastic Liapunov function method, which is designed for such problems. Extensions concerning acknowledgments, multicasting, non-unique routes, and others, are available.