Experimental Evaluation of Eigenbeam MIMO-OFDM Implemented in FPGA for Wireless LAN

This paper describes the experimental performance of eigenbeam multi-input multi-output with orthogonal frequency division multiplexing (MIMO-OFDM) systems as measured in a testbed implemented with field programmable gate arrays (FPGA). The testbed offers 1/5-scale real time signal processing. Extensive experiments on the testbed confirm the basic operation and performance of eigenbeam MIMO-OFDM with 16QAM. From the PER performance, we confirm that the eigenbeam scheme with permutation matrix and three transmit antennas (M_t = 3) drastically improves the required carrier-to-noise power ratio (CNR) by approximately 5.6 dB over the scheme without eigenbeam with M_t = 2. Furthermore, to determine the impact of Doppler frequency, we focus on the transmission interval between the MIMO channel estimation and data transmission. To suppress the required CNR degradation to within 1.5 dB, it is found that the eigenbeam scheme with permutation matrix and M_t= 3 permits a transmission interval of approximately 15.5 ms when f_d = 5 Hz