Orthogonalized Spatial Multiplexing for MIMO systems

In this paper, we propose a new spatial multiplexing scheme for transmission over flat-fading multiple-input multipleoutput (MIMO) channels, which allows a simple maximum-likelihood decoding at the receiver with small feedback information. We begin with a real-valued representation of the complexvalued system model and show that we can achieve orthogonality between transmitted signals by applying a proper rotation to transmitted symbols. Based on the minimum Euclidean distance between received vectors, we also present a simple antenna selection metric for the proposed spatial multiplexing systems. Simulation results demonstrate that our spatial multiplexing system per-forms close to the optimum closed loop system with much reduced complexity and feedback overhead.