The network construction model of broadcasting and TV should use the NGB demonstration network of the Ministry of Science and Technology and the General Administration of Radio and Television as the basic network model, and organically integrate the cable TV network, mobile multimedia TV (CMMB) network and traditional broadcasting and TV transmitting stations to establish national broadcasting with Chinese characteristics. The television network unifies the wireless network and the wired network, and integrates microwave and optical fiber to form a unified network structure. The terrestrial digital TV broadcast network is one of the most basic forms of digital broadcast TV transmission network, and is a necessary supplement to the cable network, providing users with TV programs and entertainment through wireless coverage. At the same time, the wireless TV network is universal, controllable, and invulnerable, and is regarded as a national security facility, making it the most direct and reliable government mouthpiece for mobilizing citizens in emergency situations. Utilize the current radio and television transmitter station and its large number of idle TV channel resources to achieve more application services to improve frequency efficiency and economic efficiency. Use existing wireless transmitter stations to carry out wireless digital TV coverage to avoid waste of resources for rebuilding stations. The broadcast operation unit uses the original TV channels to provide mobile reception and portable reception services for digital TV, and provides high-definition TV. While developing general digital TV services and data broadcasting, it gradually develops receiver positioning, timing reception and two-way Interactive services and personalized information to users, mobile Internet and communication services will greatly expand the business capabilities of wireless channels and the survivability of radio and television systems, and provide broader development opportunities for wireless television stations. Terrestrial digital TV has the characteristics of less investment and quick results, and can drive the development of related industries.
Technically, the DMB-TH terrestrial digital TV standard uses time-domain synchronous orthogonal frequency division multiplexing modulation technology filled with PN sequences, which effectively combines the transmission of signals in the time and frequency domains and transmits the payload in the frequency domain. Technology of high protection synchronous transmission technology and OFDM guard interval filling technology, insert strong power synchronous pilot OFDM modulation method, solve the effectiveness and reliability of the transmission system, improve the transmission system spectrum utilization efficiency and anti-noise interference performance . TDS-OFDM channel estimation technology improves the mobile reception performance of the system. Due to the defects of the European standard DVB-T single carrier 8VSB modulation technology and the American standard ATSC system error threshold difference, a new error correction codec (FEC) technology-LDPC was proposed, which successfully avoided foreign patent protection and obtained Better system error performance than ATSC. In response to the problems that other standards cannot support two-way interaction and Internet expansion, the DMB-TH terrestrial digital TV standard has made technical preparations for continuous development. DMB-TH ’s unique signal frame structure is designed to support the expansion of the Internet for the integration of multi-service broadcasting. Provide technical support to adapt to the integration of the three networks; provide technical support for digital, diversified and multimedia expansion of information. On the basis of the existing digital TV wireless broadcasting, it can further expand value-added services such as Internet services, multicast, on-demand, and paging, and even expand the integration, interaction, mobile, and portable of video, data, and voice. Based on the existing achievements in the digital video and audio industry, DMB-TH has designed a flexible interface solution that supports the internationally-available MPEG2-TS streaming data format and can support any type of video compression and data format. No matter what data format (MPEG-1, MPEG-2, China's AVS, MPEG-4, H.264, IP data, WindowsMedia9), as long as it is packaged into this format, it can be transmitted through the DMB-TH transmission system. Of course, it also includes source data streams in various display formats such as 16: 9. The DMB-TH system is an open and transparent data transmission system.
DMB-TH solves the problem of digital high-definition television transmission, and will bring new development space to high-speed information user access and mobile communication. These businesses mainly include:
(1) Further expand Internet applications; make the DMB-TH system a mobile network for the broadcast and television system.
(2) Add multicast, on-demand, and paging services.
(3) Expand the integrated and interactive application services of video, data, voice, etc .; expand the telecommunications business.
(4) Develop more portable CMMB mobile multimedia reception services, including mobile phones, PDAs, notebook computers, stylish portable audio-visual electronic equipment and other digital TV reception. Further develop receiver positioning services.
DMB-TH adopts a hierarchical multiframe structure that is different from existing digital TV technology standards and synchronized with natural time to support a single frequency network. The single-frequency network can not only better support mobile digital TV services, but also solve the problem of blind areas that cannot be covered by a single transmitter. The time-domain fast channel estimation technology used by DMB-TH can meet the needs of carrying out services on various high-speed carriers. It can normally receive high-definition digital TV signals on a carrier with a speed exceeding 200 km / h. DMB-TH can better support metropolitan and provincial single frequency networks: DMB-TH has a strict frame structure synchronized with absolute time. It is easier for the device to realize a single frequency network that transmits the same signal at the same frequency at the same time, saving wireless frequency resources. Support the single frequency network that supports mobile reception in a wider range of metropolitan and provincial areas.
Based on the performance of the DMB-TH system, it is realistic and feasible to establish the own wireless network of the broadcast and television system in the context of the triple play; 3G network resources are monopolized by the telecommunications industry, and it is impossible for the broadcast and television system to use the 3G network for mobile Network services and mobile services will play a decisive role in the development of future networks. Just like the transformation of fixed phones to mobile phones, future Internet services will also be the development trend. Wireless Internet will occupy a considerable number of Internet users, while 3G, 4G The network resources of the wireless Internet are unique to the telecommunications industry. If radio and television enter the wireless Internet industry to participate in the integration of the three networks, without their own network system structure, it will be a fool ’s dream. Therefore, the use of the rich frequency resources of the broadcast television system (TV channel 1- 68 channel frequency), expand the wireless Internet service on the basis of the DMB-TH system, realize the downlink upload bidirectional network expansion based on the existing DMB-TH system (Figure 1), and realize the mobile Internet network system. DMB-TH system has the ability to meet high-speed downlink, and its payload is shown in Table 1 below. The technical requirements fully meet the user's Internet access requirements. The two-way system can design L-band for uploading data and U-band for downloading data. According to the actual needs of downloading, the effective frequency band can be expanded by 2 * 8M. Its business includes not only mobile Internet, but also traditional TV can provide integrated service platforms such as video, voice, communication, and software QQ. User terminals include mobile phones, notebooks, computers, and televisions. The integration of the three networks allows you to watch TV, surf the internet and communicate on any network platform. Only this is the ultimate goal of the integration of the three networks. I hope my vision will be reality in the near future.
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