QoS-driven power control in fading multiple-access channels with random arrivals

Power control policies in the fading multiple-access channels (MAC) with quality of service (QoS) constraints and random arrivals are studied. Perfect channel side information (CSI) is assumed to be available at both the transmitters and the receiver. Two types of Markovian sources, namely discrete Markov source and Markov fluid source, are considered. The maximum average arrival rates that can be supported in the fading multiple-access channel under QoS constraints are identified by incorporating the effective capacity of time-varying wireless transmission channels and effective bandwidth of random arrivals. The average throughput region is shown to be convex. Power control policies that maximize the weighted summation of the average arrival rates are characterized in the two-user case. Specifically, given the decoding order strategy, the conditions that the optimal power control policies must satisfy are determined, and an algorithm for the optimal power control policies is proposed for different source arrival models.