8K Terrestrial Transmission Field Tests Using Dual-Polarized MIMO and Higher-Order Modulation OFDM

Japan Broadcasting Corporation (NHK) is conducting research on the next-generation of digital terrestrial broadcasting that will enable ultrahigh definition television such as 8K. Multiple-input multiple-output (MIMO) technology should be able to expand the single-input single-output channel capacity. $2 {\times }2$ MIMO is adopted in ATSC3.0 as an optional method. In order to construct a next-generation terrestrial network using MIMO technology and to ensure an adequate link budget especially as regards the MIMO propagation parameters, two experimental stations have been installed in Hitoyoshi city, Kumamoto, Japan. This system is an extension of the conventional DTV system in Japan, called ISDB-T. NHK conducted $2 {\times }2$ MIMO field tests using one station and $4 {\times }2$ MIMO field tests using two stations composing a single frequency network (SFN). For the $4 {\times }2$ MIMO test, an advanced SFN using space time coding was developed. The $2 {\times }2$ MIMO field tests involved terrestrial 8K transmissions (91 Mb/s) over a single UHF band channel (6 MHz bandwidth). The degradation of required carrier to noise ratio compared to laboratory measurements in dual-polarized MIMO propagation was under 3 dB even in non-line-of-sight conditions. The $4 {\times }2$ MIMO field tests indicated that the required received power of the SFN was up to 3 dB better than that of the conventional SFN.