Optimization-Theoretic Analysis of Stability-Optimal Transmission Policy for Multiple-Antenna Multiple-Access Channel

The philosophy of scheduler design in modern wireless data networks exposes the tendency towards layer-spanning optimization (cross-layer design). An important particular goal of joint design of the physical and (data) link layer appears to be the achievement of the entire stability region of the network. In this work, we provide the optimization-theoretic analysis of the corresponding policy, referred to as stability-optimal policy, in the multiple-antenna multiple-access channel. We characterize some useful features of the policy. In particular, we state the conditions for optimality of link subset transmission and expose essential differences to the established scheduling approaches, such as sum-rate maximization. This further allows for the statement of necessary and sufficient conditions for the overall stability optimality of successive interference cancellation order. Finally, we present the approach of splitting of the multilink stability problem into the set of single-link optimization problems. We propose a corresponding iterative optimization method, which is an extension of the known concept of iterative waterfilling from