Experiments on peak spectral efficiency of 50 bps/Hz with 12-by-12 MIMO multiplexing for future broadband packet radio access

This paper presents field experimental results of peak frequency efficiency of approximately 50 bps/Hz, i.e., 4.9 Gbps packet transmission in a 100-MHz channel bandwidth, using 12-by-12 MIMO-OFDM focusing on the influence of fading correlation between the transmitter and receiver antennas using vertically polarized antennas. Maximum likelihood detection (MLD)-based signal detection was employed to achieve such high frequency efficiency with the required received signal-to-noise power ratio (SNR) of less than 30 dB. From the field experimental results under non-line-of- sight conditions, we show that the required average received SNR to achieve the throughput of 4.9 Gbps is degraded by less than 0.5 dB when the receiver antenna separation is reduced from 40 cm (6.2¿) to 10 cm (1.5¿), while it is degraded by approximately 1.5 dB when the transmitter antenna separation is decreased from 70 cm (10.9¿) to 20 cm (3.1¿). Furthermore, we clarify that the required minimum antenna separations of the base station transmitter and mobile station receiver are 20 cm and 10 cm, respectively, in order to achieve the peak throughput of 4.9 Gbps at the average received SNR of less than 30 dB in a field environment.