We are researching satellite transmission technologies and multiplexing technologies for 8K Super Hi-Vision (SHV) satellite broadcasting.
■ Transmission systems for satellite broadcasting
For ultra-high-definition television broadcasting in the 12-GHz band, we increased the symbol rate of the satellite transmission scheme by reducing the roll-off factor and using 16 Amplitude and Phase Shift Keying (APSK). These improvements are part of the ARIB standard, “Transmission system for advanced wide band digital satellite broadcasting” that is under examination by the Information and Communications Council.
We prototyped a transmitter and receiver with a roll-off factor as small as 0.01 and helped to perform the verification tests of their transmission scheme at ARIB. The tests led to ARIB adopting a roll-off factor of 0.03 and symbol rate of 33.7561 Mbaud. We also submitted to ARIB a scheme for 100-Mbps transmissions over a single channel of the satellite transponder that uses 16 APSK and a coding rate of 7/9 (an error-correcting code parameter).
We conducted transmission tests using the N-SAT-110 and BSAT-3a broadcasting satellites and verified the feasibility of this scheme (Figure 1)(1). The test results were incorporated in a report issued by the broadcasting system committee of the Information and Communications Council. As part of our ARIB related activities, we also studied on-premises cable distribution of ultra-high resolution television satellite broadcasting.
Part of this research was conducted as part of a government-commissioned project of the Ministry of Internal Affairs and Communications titled, “The research and development project for the expansion of radio spectrum resources”.
We also worked on improving the multi-level coded modulation for 8 Phase Shift Keying (PSK). We devised a hybrid set partitioning method, which adjusts the error-correcting capability of each bit by interchanging bits allotted to 8PSK symbols and showed that it could outperform the normal 8PSK system in advanced wide-band digital satellite broadcasting (with a coding rate of 3/4).
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Figure 1. Required C/N vs. information bit rate in the ARIB satellite transmission test |
■ Media transport scheme for multiple delivery channels
We are researching a media transport scheme using multiple delivery channels without needing to pay attention to the sort of network (broadcasting and broadband) the channels belong to. This scheme is also intended to accommodate the diversifying terminal environment and channels of viewers.
Synchronized presentation of program components transmitted through multiple channels has been difficult for conventional media transport schemes such as MPEG-2 Transport Stream (TS), which assumes a single channel, and Real-time Transport Protocol (RTP), which does not support multiplexed transmission of program components and signaling information. In contrast, a multiplexing technology called Moving Picture Experts Group Media Transport (MMT) can easily combine high-resolution video transmitted by broadcasting with other program components transmitted over broadband networks.
We presented the results of our study on a next-generation broadcasting system using MMT at international conferences(2) and demonstrated the effectiveness of MMT as a multiplexing technology for SHV satellite broadcasting.
We conducted a study on migrating the signaling information used for current broadcasting systems to MMT. The results were incorporated in a report issued by the broadcasting system committee of the Information and Communications Council.
We also worked on international standardization of our research results. Part of our proposal was incorporated in the ISO/IEC 23008-1 international standard on MMT.
■ Advanced satellite broadcasting system
We studied a micro-strip antenna for feeding power to right- and left-hand circularly polarized receiving antennas for 12-GHz satellite broadcasting. Computer simulations showed that a cross polarization discrimination (XPD) level of over 25 dB could be obtained by using sequentially rotated four-element arrays.
We are developing engineering models of the transponder and antenna for a 21-GHz-band broadcasting satellite. We prototyped a wideband band pass filter (BPF) and high-power traveling wave tube (TWT) for the 21-GHz band and conducted thermal tests on them(3). We also fabricated a partial prototype of the beam forming network consisting of a 21-GHz array-fed imaging reflector antenna and a prototype of a 32-element horn array and evaluated its electrical characteristics. We also analyzed the surface distortion caused by temperature fluctuations of the reflecting mirror. This research was conducted as part of a government-sponsored project of the Ministry of Internal Affairs and Communications, titled “Research & development of efficient use of frequency resource for next-generation satellite broadcasting system”.
To reduce waveguide loss in the array feeding unit, we studied a thermal transportation method that could deal with the case in which the TWT and output filter are close to each other. We conducted a thermal vacuum experiment on the TWT and filter using a thermal dummy and found that heat transfer to the satellite bus could be improved by using solid-state materials for the thermal filter inserted between the heat-generating part and the onboard equipment panels. This research was conducted in cooperation with the Japan Aerospace Exploration Agency.
[References]
(1) Y. Suzuki, K. Tsuchida, Y. Matsusaki, A. Hashimoto, S. Tanaka, T. Ikeda, N. Okumura: “ARIB Evaluation Tests of Transmission System for Ultra High Definition Television Satellite Broadcasting,” ITE Technical Report, Vol. 38, No. 14, pp.33-38, (2014) (in Japanese)
(2) S. Aoki, K. Otsuki, H. Hamada: “Effective Usage of MMT in Broadcasting Systems,” IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, mm13-11(2013)
(3) M. Kamei, Y. Matsusaki, M. Nagasaka, S. Nakazawa, S. Tanaka, T. Ikeda: “Developments of Wideband BPF for Output Filter of 21GHz-band Broadcasting Satellite,” IEICE General Conference, B-3-15 (2014)
