Throughput Multiplexing Efficiency for MIMO Antenna Characterization

The antenna-channel effects on multiple-input-multiple-output (MIMO) throughput are characterized in terms of spatial multiplexing (SM) efficiency. In order to show the antenna effects explicitly, the SM efficiency of an MIMO system (with imperfect transmit antennas) is derived analytically at high signal-to-noise ratio (SNR) regime. It is shown that correlation and power imbalance affect the throughput adversely (as expected) and independently. Although derived for imperfect transmit antennas, the close-form SM efficiency formula turns out to be accurate for 2 x 2 MIMO systems with imperfect receive antennas as well. It is also shown that the derived SM efficiency formula even reasonably predicts the measured SM efficiency of a Long Term Evolution (LTE) system.