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Mobile TV service is the mobile end users with operating systems and intelligent video capabilities to mobile devices in the form of channels or channel form to receive broadcast digital audio and video content business.
Way to achieve mobile TV services are mainly two kinds: the first is the use of cellular mobile networks, China Mobile and China Unicom has launched such a mobile TV service; the second is the use of terrestrial or satellite digital broadcasting, with digital mobile TV receiver module to receive digital TV signals directly, which is currently the most promising way to achieve.
Mobile TV business as a new multimedia service caused widespread concern in the industry, the current international research on this business is very warm, the related technology has more than 10 species can be summarized into the following 4 types:
Mobile Network Technology: such technology is the mobile communication network through improved to provide users with downlink broadcast channel, where the band mobile communication systems. Typical technologies include multimedia broadcast and multicast service (MBMS), broadcast and multicast service (BCMCS) and so on.
Based on terrestrial digital broadcasting Network Technology: Realization of such major terrestrial digital broadcasting for television, radio and television frequencies to use. Some of the terrestrial digital broadcast television technology improvements based on a mobile TV technology, such as DVB-H, MediaFLO, etc.; while others are only for the current terrestrial digital broadcast television system, including the Korean T-DMB, Japan's ISDB-T, Tsinghua University DMB-T and Shanghai Jiaotong University ADTB-T and so on.
Satellite-based implementation techniques: this type of technology, mainly through satellite downlink, the typical technology including S-DMB in Europe and Japan, South Korea S-DMB and so on.
Implementation techniques based on application layer: The Open Mobile Alliance broadcasting group OMABCAST represented, mainly from the application layer to define the implementation of mobile TV services.
This article describes the DVB-H and two typical Korean T-DMB terrestrial digital broadcast television technology, and discuss the launch of mobile TV business is facing major problems.
1 DVB-H standard 1.1 DVB-H network architecture DVB-H is to use digital terrestrial mobile TV content networks down, use of mobile cellular networks-on-demand, user authorization, billing, customer service and interactive return, the network architecture (Figure 1), including figures terrestrial networks and mobile cellular networks.
Figure 1 1.2 DVB-H Key Technologies DVB Standard DVB project group first by the early 90s in the 20th century made the digital television terrestrial broadcasting DVB-T is 90 in the mid-20th century development, and in February 1997 the European Telecommunications Standards Institute (ETSI) recognition of the European digital TV terrestrial broadcasting standards. Currently there are 59 countries and regions, DVB-T standard used, in addition to European countries, there are Australia, New Zealand, Brazil, Singapore and other countries. Judging from the overall application, DVB-T technology is very mature.
DVB-H based DVB-T, fully backward compatible and can share business and MPEG-2 DVB-T multiplexer, its technical specification is primarily the implementation of the DVB project group. DVB-H standard has been ratified in 2004 by the ETSI of Europe's mobile TV standard, currently in place have been established in more than 20 DVB-H network, and has launched commercial operation of test. Using the DVB-H technology to mobile handheld devices (including cell phone) also send multiple television channels, radio channels and video channels. DVB-H time slicing through the receiving equipment to reduce power consumption, by increasing the cell ID to support the rapid signal scan and frequency switching, and enhance the mobile environment, received signal strength, to achieve the indoor, outdoor, walking and moving environment and other support. DVB-T in terms of relative
, DVB-H adds the following technologies: (1) the introduction of time slice, lower power consumption
Order to reduce the power consumption of the receiver, DVB-H used to send data in bursts: ie a business in a time period (eg 200ms), the individual occupying the full bandwidth of the system to send data, then send the next one kind of business, business to send all finished (eg after 4s), and then re-send the first business. Receiver only needs the time period specified in the received signal, other times you can turn off. Each time the data transfer rate is high, so every time can be a very short duration, most of the time the receiver can be in sleep or off state, so the receiver can reduce the power consumption, the largest savings of 90% power consumption.
(2) the introduction of 4K mode, mobile performance support in raising the same time achieve greater coverage
4K mode download wave number is 3409, each sub-carrier modulation methods are QPSK, 16QAM, 64QAM 3 .
(3) the introduction of Multi-Protocol Encapsulation – Forward Error Correction (MPE-FEC), IP-based business services, enhanced anti-jamming capability
MPE-FEC IP data packet in an increase of RS error correction code. Arrangements MPE-FEC frame is a 255 matrix, the rows from a change to a fixed value, the maximum is 1024, the maximum MPE-FEC frame occupy 2 Mbps.
DVB-H standard has the following advantages:
Reduce terminal power consumption: Based on the IP data packet, the receiver generally open throughout the transmission time of 10%.
Seamless switching: Using a receiver can be done to ensure continuity of service.
Improve reception for mobile and portable support: MPE-FEC enhanced weak signal reception, an increase of anti-jamming capability to support mobile high-speed data transfer.
High capacity: 8 MB bandwidth to transmit more than 40 to 50 TV channels.
Flexibility: In the medium to large single-frequency network through a single antenna within the mobile receiver, can achieve a lot of flexibility in the capacity of choice and cellular size.
And DVB-T system compatibility: DVB-H and DVB-T based on the same DVB-H standard physical technology solutions mainly IP data broadcasting (IPDC), a mobile network user authentication to complete . In addition, the mobile TV business, billing, bill processing, customer service, customer management, and video-on-demand, download, web browsing and other services, also through the mobile networks to achieve. IPDC solution also provides a standard Simple Network Management Protocol (SNMP) network management interface, operators can interconnect the existing network management system.
IPDC achieve user authentication process is: mobile end users in the form of a short message to the core application systems IPDC watch programs sent the request, the nuclear
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