MIMO Performance Evaluation for Airborne Wireless Communication Systems

This paper presents a characterization of the practical performance gains of a multiple-input/multiple-output (MIMO) system with respect to a traditional single-input/single-output (SISO) system in an air-to-ground environment. Analysis of these performance gains is based on actual data throughput and channel-state measurements of an airborne 4x4 MIMO-enabled orthogonal frequency division multiplexing (OFDM) system. Practical realization of these performance gains with a coded-OFDM wideband system was accomplished through airborne field trials across multiple flight profiles. We show through experimental validation that average MIMO throughput gains in excess of 2x can be achieved relative to a SISO system. These field trials also indicate that MIMO processing can deliver a 1.6x increase in the range of the link. Additionally, if channel-state information (CSI) is available at the transmitter - which enables MIMO eigen beamforming - the average throughput gain can be further increased to 4.5x and the link range can be increased by as much as 3.6x. It is also shown that for a 4x4 MIMO system to deliver the same throughput performance as a conventional SISO system in an air-to-ground environment, a relative TX power savings of up to 21 dB can be realized.