Power Allocation and Multiuser Scheduling with Outage Capacity Constraints

This paper studies the joint scheduling and power allocation problem for a multiuser downlink system in Rayleigh K-block fading channels. The optimization is performed subject to individual outage capacity constraints, and our goal is to find the optimal number of allocated blocks {n_j} and the transmit power {Q_j} for each user in minimizing the aggregate transmit power given only the channel statistics at the transmitter (CST). Our technique is based on constraining the upper bound of the outage probability for each user, and a relaxation on the number of allocated blocks. We shall show that the relaxed problem is convex and thus can be solved optimally in the global sense. The optimal number of users´ allocated blocks is found by rounding the solution from the relaxed problem while the power allocation comes directly from activating the constraints to minimize the overall power