Woosuk Ko

Physical Layer Time Interleaving for the ATSC 3.0 System

This paper presents optimized time interleaving which has been adopted for the Advanced Television System Committee 3.0 system as a physical layer tool to mitigate the effects of burst errors. The adopted time interleaver (TI) is very flexible and can have different configurations according to the number of physical layer pipes (PLPs) and service type, i.e., fixed, portable, and mobile. Notably, for single-PLP mode a sheer convolutional TI (CTI) is used, whereas for the multiple-PLP mode a hybrid TI (HTI) composed of cell interleaver, twisted block interleaver, and a convolutional delay-line is used. Optionally, the CTI and the HTI can be used in conjunction with extended time interleaving and a cell interleaver (only for HTI) to further improve robustness over long burst error lengths at the expense of latency.

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.