Joint base station clustering and beamformer design for partial coordinated transmission using statistical channel state information

In this paper we consider the problem of partial coordinated transmission in the downlink of a wireless heterogeneous network (HetNet). The partial coordination is crucial in trading off system performance with backhaul overhead, and it is achieved through jointly optimizing the base station (BS) clustering and the downlink beamformers. Unlike many existing works, we focus on the practical scenario where the channel state information (CSI) is imperfect/incomplete at the transmitter. Mathematically, we formulate the problem into a penalized stochastic optimization problem, and propose an algorithm that converges almost surely to its stationary solution set. Interestingly, our method does not require any additional computational complexity or memory compared to the existing algorithms using perfect CSI. Effectiveness of our method is validated through numerical experiments.