Joint Base Station Clustering and Beamformer Design for Partial Coordinated Transmission in Heterogeneous Networks

TLDR

Interference management in multicell MIMO heterogeneous networks is challenged by many distributed micro/pico base stations that can potentially be coordinated for joint transmission. The study aims to reduce coordination overhead by serving each user with only a small number of potentially overlapping base stations through user‑centric clustering. To achieve this, the authors formulate the joint clustering and beamformer design as a sparse optimization problem and solve it with an efficient iterative group LASSO algorithm. The algorithm jointly performs clustering and beamforming, allows cluster size control via a single penalty parameter, converges to a stationary solution, and shows superior performance in extensive simulations.

Abstract

We consider the interference management problem in a multicell MIMO heterogeneous network. Within each cell there is a large number of distributed micro/pico base stations (BSs) that can be potentially coordinated for joint transmission. To reduce coordination overhead, we consider user-centric BS clustering so that each user is served by only a small number of (potentially overlapping) BSs. Thus, given the channel state information, our objective is to jointly design the BS clustering and the linear beamformers for all BSs in the network. In this paper, we formulate this problem from a {sparse optimization} perspective, and propose an efficient algorithm that is based on iteratively solving a sequence of group LASSO problems. A novel feature of the proposed algorithm is that it performs BS clustering and beamformer design jointly rather than separately as is done in the existing approaches for partial coordinated transmission. Moreover, the cluster size can be controlled by adjusting a single penalty parameter in the nonsmooth regularized utility function. The convergence of the proposed algorithm (to a stationary solution) is guaranteed, and its effectiveness is demonstrated via extensive simulation.