subject: Mobile TV-CMMB system technology of-CMMB, multimedia, mobile TV - broadcast industry [print this page] Mobile TV-CMMB system technology of-CMMB, multimedia, mobile TV - broadcast industry
Mobile TV Is the integration of mobile communications and radio and television features of the new business. With high-speed mobile communication network to network evolution, the first mobile TV to Streaming Media Forms, through radio and television coverage to provide real-time mobile multimedia broadcasting service to become the fastest growing of contemporary information science one of the hot areas. To achieve mobile multimedia broadcasting ( CMMB ) And mobile TV applications in technology must address three main points: First, high compression source coding; Second, high reliability, strong anti-jamming channel processing technology, high spectrum efficiency, digital modulation techniques; Third, high integration, small size, light weight, low power consumption of mobile phone chips. CMMB technology to support independent innovation, to adapt the terminal to receive low power, low bit rate requirements, have good mobile reception performance, with a new business is different from traditional television broadcasting properties, can provide high quality services to mobile populations.
1 System Features Radio System proposed in 2006 based on independent intellectual property rights of China Mobile Multimedia Broadcasting (CMMB: ChinaMobileMultimediaBr0ADCasting) system is characterized by a "one world" of the technical system, namely the use of high-power S-band Satellite Through the broadcast channel and sub-letters Road to achieve national coverage 100% of land mobile multimedia broadcasting signal coverage, using s-band surface added to the network of S-band satellite coverage shadow signal transmitted coverage, using U-band terrestrial network coverage to the urban population is highly concentrated and effective coverage; use of wireless mobile communication networks is to achieve interactive return path, forming a one-way broadcast and two-way interaction between the combination of central and local seamless coverage system combined as shown in Figure l.
CMMB system Its main technical characteristics can be summarized as:
1) applies to 30Mg ~ 3000Hg frequency range, to support two 8Hg and 2Mg Broadband , Application flexibility;
2) using a highly structured, low complexity implementation of advanced technologies of channel coding with low density parity check codes (Lopc), to reduce the signal receiving threshold.
3) frame structure based on time slots and orthogonal frequency division multiplexing (OFDM) modulation, for the terminal to provide a good mechanism for power saving.
4) use of logical channel technology, flexible configuration, suitable for real-time radio and television facilities, data broadcasting and other services.
5) with control parameters and the separation of business data transmission method, will be supporting business critical information and channel scheduling control information placed in a dedicated transmission channel, the high rate of protection can be well adapted to harsh environment of wireless transmission.
6) by Beacon, the complex and volatile wireless channel to achieve rapid synchronization.
With other existing mobile multimedia broadcasting technology comparison, CMMB this "one world" technology is a natural system-level advantages. We know now a kind of mobile media broadcasting technology is already Digital Terrestrial Television / Audio broadcasting transmission based on the improvement of development from, for example, DVB? T based on the development of DVB-H And the DVB came to change the basis of T-DMB, TMMB so.
