Sangchul Moon

MIMO for ATSC 3.0

This paper provides an overview of the optional multiple-input multiple-output (MIMO) antenna scheme adopted in ATSC 3.0 to improve robustness or increase capacity via additional spatial diversity and multiplexing by sending two data streams in a single radio frequency channel. Although it is not directly specified, it is expected in practice to use cross-polarized 2×2 MIMO (i.e., horizontal and vertical polarization) to retain multiplexing capabilities in line-of-sight conditions. MIMO allows overcoming the channel capacity limit of single antenna wireless communications in a given channel bandwidth without any increase in the total transmission power. But in the U.S. MIMO can actually provide a larger comparative gain because it would be allowed to increase the total transmit power, by transmitting the nominal transmit power in each polarization. Hence, in addition to the MIMO gains (array, diversity, and spatial multiplexing), MIMO could exploit an additional 3 dB power gain. The MIMO scheme adopted in ATSC 3.0 re-uses the single-input single-output antenna baseline constellations, and hence it introduces the use of MIMO with non-uniform constellations.

Enhanced spatial multiplexing for rate-2 MIMO of DVB-NGH system

The demand for high bit-rate service transmission is increasing for digital terrestrial broadcasting just like other transmission technologies. Multiple-input multiple-output (MIMO) transmission is one of the most promising techniques to fulfill this demand for high transmission rates. This paper introduces enhanced spatial multiplexing (eSM) scheme adopted as technical baseline for the DVB next generation handheld (DVB-NGH) system. Most technical challenges for MIMO transmission in broadcasting comes from the rate-2 spatial multiplexing performance degradation in high correlation channel condition, which frequently happens in broadcasting owing to the line-of-sight (LOS) channel conditions. The proposed eSM exploits a pre-coding matrix optimized to overcome this condition. When combined with phase hopping to avoid specific harmful condition, eSM minimizes the performance loss under high correlation channels whilst keeping maximum multiplexing gain over rich scattering channels.

Transmit diversity based on subcarrier diversity for OFDM broadcasting systems

This paper investigates the utilization of subcarrier diversity (SD) in modern broadcasting systems to achieve transmit diversity. SD takes advantage of orthogonal frequency-division multiplexing (OFDM) and robust forward error correction (FEC) to exploit the space diversity of multiple transmit antennas. In particular, we focus on a variant of SD that we call transmit antenna switching (TxAS) in which each antenna transmits only in one contiguous portion of the spectrum. This way, it is possible to achieve a higher diversity than single transmit antenna configurations with no significant increase in terms of complexity or pilot density. As a result, the utilization of TxAS can outperform more complex space-frequency block codes (SFBC) like Alamouti if the transmission of pilots is taken into account. We evaluate the performance of the proposed technique by means of physical layer simulations in the context of DVB-NGH (Digital Video Broadcasting - Next Generation Handheld), the future broadcasting DVB system for the provision of mobile services to handheld devices.