Virtual Channel Optimization for Overloaded MIMO Systems

In this brief, we present a virtual channel (VC) optimization approach for overloaded multiple-input multiple-output (MIMO) systems. With this approach, a VC vector is generated at the transmitter, which is combined with the actual wireless channel matrix to form the overall transmission channel matrix. Through VC optimization, the overall transmission channels can be properly adjusted in favor of the signal detection, leading to an improved performance. Moreover, we investigate the overloaded MIMO system in which the number of receive antennas equals the number of transmit antennas. By using superposition VC method, this overloaded MIMO system allows more number of data streams to be transmitted than the number of transmit antennas. The methods for obtaining the optimal VC vector are presented. Simulation results illustrate the effectiveness of the proposed approaches.