Overloaded MIMO Spatial Multiplexing Independent of Antenna Settings

This paper proposes overloaded MIMO spatial multiplexing that is able to increase the number of spatially multiplexed signal streams despite of the number of antennas on a terminal and that on a receiver. We propose extension of the channel matrix for the increase in the number of the signal streams. We apply QR-decomposition based on the equal gain transform to the extended channel matrix, which is employed to achieve superior transmission performance despite of the increase in the number of the spatially multiplexed streams. The transmission performance of the proposed multiplexing is evaluated by computer simulation. The simulation reveals that the proposed multiplexing can implement 6 stream-spatial multiplexing in a 2 × 2 MIMO system, i.e., the overloading ratio of 3.0. The diversity order of 2 is attained in the MIMO system, despite of the high overloading ratio of 3.0.