User Selection and Resource Allocation for Multi-User MIMO-OFDM Systems with Downlink Beamforming

In this paper, a multi-user MIMO-OFDM system with downlink beamforming technique is considered. We aim at minimizing the total transmission power while fulfilling each user's data rate and bit error rate (BER) requirement. This problem is formulated as a linear optimization problem in our paper. Since the optimal solution obtained from integer programming (IP) approach can hardly be implemented due to its high computational complexity, we present a heuristic user selection and resource allocation algorithm. Simulation results show that compared with existing SDMA-OFDM systems with or without resource allocation, our algorithm achieves significant performance improvement. The performance of the proposed heuristic algorithm is very close to that of the optimal solution.