Fast Optimal Antenna Selection for Massive MIMO

This paper investigates the optimal antenna selection problem for very large-scale multiple-input multiple-output (MIMO) systems. The problem is NP-hard, and solving it optimally requires exponential computation time, which limits its application in very large MIMO systems. In order to develop a feasible optimal method and help evaluate the performance gap of low-complexity algorithms in the scenarios of our interests, we start by proposing a new objective function, which reformulates the original problem into a shortest path finding. By combining the best-first search strategy, we further develop an efficient pruning algorithm, namely BFS-AS, for finding the optimal antenna combination. Our simulation results show that the proposed BFS-AS not only achieves the exact optimal performance, but also has a fixed space complexity and a much lower average time complexity with comparison to the existing optimal performance achieving approaches.