Joint power control, beamforming and BS assignment for optimal SIR assignment

This paper considers the open problem of joint power control, beamforming, and base station assignment to achieve an optimal SIR assignment in uplink cellular networks. The adaptive beamforming and adaptive base station assignment strategies in addition to power control will broaden the feasible SIR region. The problem is challenging, since the feasible SIR region is the union of regions from all possible combinations of beamformer and base station assignment, which is generally not log-convex. By using concave interference function property, the Pareto boundary of the feasible SIR region of joint power control, beamforming, and base station assignment is characterized. Since the optimal SIR assignment solution must lie on the Pareto boundary of the feasible SIR region to achieve the highest possible efficiency, the optimization problem can be reduced to the optimization along the Pareto optimal boundary. Thus instead of searching the operating point over the whole feasible SIR region, a distributed greedy algorithm that searches a possible optimal solution on the Pareto boundary is developed. From the simulation, we show that the performance gain obtained from joint power control, beamforming, and base station assignment is quite significant.