Digital Terrestrial Multimedia Broadcasting (DTMB)

I joined ASTRI seminar entitled “Development of China DTV – Digital Terrestrial Multimedia Broadcasting” in HKSTP today (2 April 2009). The speaker was Prof. Jian Song who is Vice Dean of the Research Institute of Information Technology, Tsinghua University. He is also the director of “ASTRI – Tsinghua University Multimedia Broadcasting and Communication Joint Research Lab”.


He outlined the following items in his presentation:
i) Chinese Digital Terrestrial Television Broadcasting (DTTB) Standard;
ii) Key Technology of DTMB;
iii) System Performance of DTMB;
iv) IPR of DTMB;
v) Extended application of DTMB; and
vi) Various system based on DTMB.

Firstly, he introduced TV Broadcasting Networks (from Content, Distribution, and Transmission to End User) in China.

The requirements on DTTB service are shown as follows:
2006 Announcement
2007 Mandatory
2007 Dec 31 Officially launched in Hong Kong
2008 Massive deployment (Olympics Game in China on 8 Aug 2008)
2015 Analog TV shutdown

Prof. Song gave a brief introduction about Chinese Standard GB20600-2006 “Digital Television Terrestrial Multimedia Broadcasting (DTMB) to us.

There are two stations deployed DTMB in Hong Kong:
i) ATV: 1 HDTV + 2 SDTV programs within 8MHz.
ii) TVB: 1 HDTV + 2 SDTV programs within 8MHz.

Then, the speaker identified the major challenges and key techniques of DTMB as below:
i) Wideband
ii) High Speed Mobility
iii) Large Coverage
iv) Portable

The existing solutions are:
i) Frequency domain: DVB-T receiving antenna diversity is needed to support mobile reception, DVB-H support handhold
ii) Time domain: ATSC M/H, there is also an Orthogonal Frequency-Division Multiplexing (OFDM)-based system: MediaFLO (Forward Link Only) to support portable
iii) Time-Frequency joint processing: DTMB supports HDTV mobile reception, DMMB supports portable

Comparison of the performance between DTMB and DVB-T (European-based consortium standard), it is found that DTMB performance is more robust, higher payload data throughput, better mobile reception, better coverage, flexible broadcasting service and simple SFN equipment. But the DVB-T2 announced in June 2008 has several important features which help to make up the overall performance gap. That means DTMB must do better in the future!