China Multimedia Mobile Broadcasting
Chinese mobile TV standard using satellite and terrestrial repeaters.
CMMB, or China Multimedia Mobile Broadcasting, is a standard for mobile TV and multimedia services, created by China’s State Administration of Radio, Film, and Television (SARFT). It relies on the Satellite and Terrestrial Interactive Multiservice Infrastructure (STiMi), a system developed by TiMiTech—a company spun off from the Chinese Academy of Broadcasting Science. First announced in October 2006, the standard is often compared to Europe’s DVB-SH, which also delivers digital video to handheld devices via satellites and ground-based repeaters.
The standard uses the S-band (2635–2660 MHz) for satellite and gap-filler terrestrial broadcasts, plus the UHF band (470–862 MHz) for additional terrestrial signals. It occupies a 25 MHz bandwidth, carrying 25 video channels, 30 radio channels, and some data channels. Channel bandwidth can be set to either 2 or 8 MHz, depending on the desired data rate. Several companies produce chips that support CMMB; Innofidei released the first such solution on March 28, 2007. Other manufacturers, like Unique Broadband Systems, quickly followed with hardware platforms that handle CMMB alongside other standards such as DTMB.
As of June 2, 2010, the China Satellite Mobile Broadcasting Corporation (CSMBC) had rolled out CMMB network coverage in 317 prefecture-level cities.
CMMB is not a Chinese national standard (GB)—that designation belongs to DTMB (GB 20600-2006). CMMB uses QCIF or QVGA resolution, so it cannot broadcast high-definition TV (1080i or 1080p), whereas DTMB can. CMMB is designed for small-screen devices like GPS units, PDAs, and smartphones in mobile settings, while DTMB targets large screens such as PCs, LCD TVs, and plasma displays in fixed locations.
- field
- Mobile television and multimedia broadcasting standard
- nationality
- China
- known_for
- Mobile TV standard using S-band/U-band, 25 video and 30 radio channels
- announced
- October 2006
- first_chip_support
- 28 March 2007 by Innofidei
Lore & Background
CMMB was developed by SARFT and based on STiMi technology from TiMiTech, a company formed by the Chinese Academy of Broadcasting Science. It was announced in October 2006 and occupies 25 MHz bandwidth, providing 25 video and 30 radio channels with additional data channels. The standard uses frequencies in the S-band (2635–2660 MHz) for satellite and gap-filler terrestrial broadcast, plus UHF band (470–862 MHz) for additional terrestrial broadcast, with channel bandwidth of either 2 or 8 MHz.
Reader's Guide
CMMB represents a significant effort by China to establish a mobile television standard for handheld devices, distinct from the national DTMB standard intended for fixed large-screen use. It was designed for small screen devices such as GPS, PDA, or smartphones in mobile scenarios, using QCIF or QVGA resolution and thus unable to broadcast HDTV. By June 2010, China Satellite Mobile Broadcasting Corporation had completed CMMB network coverage in 317 prefecture-level cities. Multiple chip manufacturers supported the standard, with Innofidei first on 28 March 2007, followed by others like Unique Broadband Systems offering hardware supporting both CMMB and DTMB waveforms. Though not a Chinese national standard (GB), CMMB was widely deployed and comparable to Europe's DVB-SH standard.
Did You Know?
- CMMB was announced in October 2006.
- It is based on the Satellite and Terrestrial Interactive Multiservice Infrastructure (STiMi) developed by TiMiTech.
- Innofidei was the first company with a CMMB chip solution on 28 March 2007.
- As of 2 June 2010, CMMB network coverage was completed in 317 prefecture-level cities.
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