China Multimedia Mobile Broadcasting Explained

China Mobile Multimedia Broadcasting (CMMB) is a mobile television and multimedia standard developed and specified in China by the State Administration of Radio, Film, and Television (SARFT).^[1] It is based on the Satellite and Terrestrial Interactive Multiservice Infrastructure (STiMi), developed by TiMiTech, a company formed by the Chinese Academy of Broadcasting Science.^{[2] [3]} Announced in October 2006, it has been described as being similar to Europe's DVB-SH standard for digital video broadcast from both satellites and terrestrial repeaters to handheld devices.

It specifies usage of the S-band/U-band and occupies 25 MHz bandwidth within which it provides 25 video and 30 radio channels with some additional data channels. Multiple companies have chips that support CMMB standard - Innofidei who was the first with a solution 28 March 2007.^{[4] [5]}

Other manufacturers, such as Unique Broadband Systems, were quick to enter the race and grab a share of the handheld broadcasting market with their hardware platform supporting both CMMB and DTMB (as well as others) standard waveforms.

RF Details

CMMB uses frequencies in the range 2635 - 2660 MHz (S-band) for satellite and "gap-filler" terrestrial broadcast, with additional terrestrial broadcast in the UHF band 470 – 862 MHz.^{[6] [7]} The channel bandwidth can be either 2 or 8 MHz, depending on data rate.^[8]

Coverage

China Satellite Mobile Broadcasting Corporation (CSMBC), as of 2 June 2010, had completed CMMB network coverage in 317 prefecture-level cities.^[9]

Versus DTMB

• The CMMB is not a Chinese national standard (GB), but the DTMB is GB 20600-2006.
• The CMMB uses QCIF or QVGA, so can not broadcast the HDTV (1080i/1080p), but the DTMB can.
• The CMMB is intended for use on small screen devices (such as GPS, PDA, or smartphone...) in a mobile scenario, while DTMB is intended for use on large screen devices (such as PC, LCD TV, PDP TV...) in a fixed scenario.

See also

• DTMB
• Digital Multimedia Broadcasting
• DVB (Digital Video Broadcasting)
• DVB-T (Digital Video Broadcasting - Terrestrial)
• DVB-H (Digital Video Broadcasting - Handheld)
• International standard

External links

• IEEE Spectrum Article
• https://archive.today/20130116033332/http://www.cbc.cn/ (Chinese)
• Unique Broadband Systems

Notes and References

1. China releases mobile TV industrial standard . Interfax China . 2006-10-25 . 2007-04-14 .
2. Web site: TiMi Technologies Co. Ltd. . Academy of Broadcasting Science . 2008-06-08 . 2008-01-31 . dead . https://web.archive.org/web/20090225130109/http://www.abs.ac.cn/en/Orgnization/Enterprises/200801/t20080131_2103.htm . 2009-02-25 .
3. News: China's mobile-TV spec similar to Europe's . EETimes . Mike Clendenin . 2006-12-18 . 2007-04-14 .
4. China releases first mobile TV chip based on CMMB standard - SARFT official . Interfax China . 2007-03-28 . 2007-04-14 .
5. News: Chip supports China's CMMB mobile TV . EETimes . Cai Yan . 2007-03-29 . 2007-04-14 .
6. Web site: CMMB Information . 2010-01-29 . Rohde & Schwarz .
7. Web site: SMS1186 . 2010-01-29 . Siano.
8. Web site: Test signals for the new CMMB and DVB-SH mobile TV systems . 2010-01-29 . Rohde & Schwarz.
9. Web site: 开通CMMB的317个城市及频道列表 — 中广互联 - SARFT.net | 中国广电第一门户 | 数字电视行业第一门户 . 2010-06-21 . dead . https://web.archive.org/web/20100614231552/http://www.sarft.net/a/20106/4722.htm . 2010-06-14 .