[Paper] A Study on Low-Latency Channel for Advanced ISDB-T

抄録

We are currently developing the advanced Integrated Services Digital Broadcasting-Terrestrial (advanced ISDB-T) system for the next generation of digital terrestrial television broadcasting (DTTB). In advanced ISDB-T, subcarriers for auxiliary data transmissions are randomly placed in each segment, as is done in the Auxiliary Channel (AC) of ISDB-T. The transmission scheme using these subcarriers is named Low-Latency Channel (LLch). Since differential binary shift keying (DBPSK) is used for the subcarrier modulation scheme, LLch transmissions are expected to be robust. Furthermore, LLch data can be transmitted speedy because they do not have time interleaving and can be demodulated without a channel estimation by using the pilot signal. This paper reports a study of earthquake early warning (EEW) transmission for the next generation of DTTB with using LLch. Here, a new low-density parity-check (LDPC) code was designed in accordance with the EEW specification. The LDPC codewords are modulated with DBPSK and transmitted on the LLch subcarriers. The transmission performance of LLch was evaluated in a computer simulation. Furthermore, the feasibility of LLch transmission was verified in a laboratory experiment with a prototype modulator and demodulator.