Experiments on FPGA-Implemented Eigenbeam MIMO-OFDM With Transmit Antenna Selection

This paper describes the performance of eigenbeam multiple-input multiple-output (MIMO) with transmit antenna selection using orthogonal frequency-division multiplexing (OFDM), as measured in a testbed implemented using field-programmable gate arrays (FPGAs); it also targets the downlink performance improvement of wireless local area networks (LANs). For this verification, we employ a determinant-based simple transmit antenna selection approach based on the estimated instantaneous MIMO channel matrix. We show extensive experiments on the testbed to confirm the performance of eigenbeam MIMO-OFDM with transmit antenna selection in the three-select-two antenna case. First, the measured packet-error-rate (PER) performance confirms that the eigenbeam scheme with the three-select-two antenna-selection scheme provides a slight degradation in the required carrier-to-noise power ratio (CNR) that is approximately 0.2 dB from the eigenbeam-only scheme with three transmit antennas but with significantly lower computational complexity. Second, to determine the impact of Doppler frequency, both 5 Hz and 20 Hz, we focus on the required CNR performance degradation under various transmission intervals between the channel sounding packet and the data packet. It is experimentally confirmed that the eigenbeam scheme with transmit antenna selection offers improved robustness to MIMO channel fluctuation compared with the eigenbeam-only scheme.