Interference mitigation via power control under the one-power-zone constraint

Complexity and hardware constraints are two essential considerations in applying interference mitigation techniques to practical wireless systems. This paper considers a practical wireless backhaul network composed of several access nodes (AN), each serving several remote terminals (RT), and where the transmit frame structure at each AN is comprised of multiple zones, with different RTs scheduled on different zones. The objective of this paper is to design power control strategies to mitigation inter-AN interference in the downlink. Unlike prior studies, this paper adopts a practical constraint whereby every AN maintains the same power level across the different zones within one transmitted frame. The main advantage of imposing this new constraint, called the one-power-zone (OPZ) constraint in this paper, is that for a class of scheduling policies under which the number of zones assigned to each RT is fixed, the power optimization and the scheduling subproblems are decoupled under the OPZ constraint. This allows the design of efficient power control methods independent of scheduling. Further, it also simplifies the design of radio-frequency (RF) front-end. The main contribution of this paper is a set of efficient algorithms to solve this constrained power control problem based on an iterative function evaluation technique. The proposed algorithms have low computational complexity, and can be implemented in a distributed fashion. Some of these algorithms can be further implemented asynchronously at each AN.