An Approach to Optimum Joint Beamforming Design in a MIMO-OFDM Multiuser System

This paper describes a multiuser scenario with several terminals acceding simultaneously to the same frequency channel. The objective is to design an optimal multiuser system that may be used as a comparative framework when evaluating other suboptimal solutions and to contribute to the already published works on this topic. The present work assumes that a centralized manager knows perfectly all the channel responses between all the terminals. According to this, the transmitters and receivers, using antenna arrays and leading to the so-called multiple-input-multiple-output (MIMO) channels, are designed in a joint beamforming approach, attempting to minimize the total transmit power subject to quality of service (QoS) constraints. Since this optimization problem is not convex, the use of the simulated annealing (SA) technique is proposed to find the optimum solution.