Joint Optimization over Transmit Power, Port Selection and Beam Coefficients in a Multi-cell Multi-user Distributed Antenna System

In this paper, the problem under consideration is to maximize the minimum signal-to-interference-plus-noise ratio (SINR) of user terminals (UTs) in a multi-cell multiuser distributed antenna system (DAS). Based on the Block Coordinate Decent (BCD) method, we propose the strategy of alternatively optimizing over the blocks variables representing the transmit power, the port selection and the beam coefficients. In each iteration, we optimize one block variable at a time and fix the other two, which makes the related subproblem easier and reduces the computational complexity. Because all the subproblems are actually NP-hard., we propose an approximation algorithm based on Semidefinite Relaxation (SDR) and Gaussian randomization. In our paper, we first take all the blocks into consideration to optimize successively in the literature. Simulation result shows that the performance of the proposed method is superior than other known methods in the literature.