Field Experiments on MIMO Multiplexing with Peak Frequency Efficiency of 50 Bit/Second/Hz Using MLD Based Signal Detection for OFDM High-Speed Packet Access

This paper presents indoor and field experimental results on extremely high-speed packet transmissions of 4.92 Gbps in a 100 -MHz channel bandwidth, i.e., the frequency efficiency of approximately 50 bit/second/Hz, in the downlink OFDM radio access. The required received signal-to-noise power ratio (SNR) is less than 30dB, which is almost the upper limit in cellular environments near a cell site even with a light channel load, with the aim of application to future universal broadband packet radio access. We apply 12-by-12 MIMO multiplexing using the maximum likelihood detection employing QR decomposition and the M-algorithm (QRM-MLD) with adaptive selection of the surviving symbol replica candidates (ASESS),64QAM data modulation, and Turbo coding with the coding rate of R = 8/9 to achieve an extremely high frequency efficiency level. In the field experiments conducted in the Yokosuka Research Park (YRP) district of Yokosuka city, we show that the measured throughput of 4.92 Gbps is achieved at the average received SNR per receiver antenna of approximately 28.0 and 28.5 dB when the respective receiver antenna separation is 40 cm (6.2lambda) and 10 cm (1.5lambda) and the transmitter antenna separation is 70 cm (10.9lambda) at the average speed of 10 km/h under non-line-of-sight (NLOS) conditions.