Low-dimensional minimum leakage multiuser beamforming in a multicell system

In this paper, we have studied multiuser beamforming where beamforming and power allocation are carried out at each cell without cooperation between base stations in a time division duplexing (TDD)-based multicell system. At each base station that is equipped with an antenna array, multiple beams and transmission powers for downlink transmissions are optimized to minimize the interference leakage to other cells with signal-to-interference-plus-noise ratio (SINR) constraints for users in its cell. In order to reduce the computational complexity for beamforming at base stations, a low-dimensional beamforming approach has been proposed at the expense of degraded performance. Since an iterative algorithm is used to optimize beamforming vectors, the computational complexity can be significantly reduced if low-dimensional beamforming is employed for a large antenna array. Due to noncooperative and low-complexity beamforming, the proposed approach can be effectively employed when base stations have limited complexity and backhaul links do not exist or are limited.