NTT Group CSR > IP Retransmission of Digital Terrestrial Broadcasts

IP Retransmission of Digital Terrestrial Broadcasts NGN Field Trials(2)

In line with the policy of the Ministry of Internal Affairs and Communications (MIC) program for nationwide deployment of digital terrestrial broadcast, all terrestrial broadcast stations will complete their transition to digital format in July 2011. NGN too will contribute to this transition as an essential part of the communications infrastructure of the future.

Providing stable digital broadcasts in areas with poor signal reception

This is an illustration depicting people watching programs retransmitted for viewing on IP TV.

The current system of analog terrestrial broadcasts is scheduled for retirement on July 24, 2011, by which time all terrestrial stations will have completed the transition to the new digital broadcast format. MIC has proposed a policy promoting high-definition digital terrestrial broadcast retransmission for IP TV starting in 2008, with the intent of helping ensure stable digital broadcasts in areas with poor signal reception as well as providing consumers with an additional viewing option.
Digital terrestrial broadcast IP retransmission is being field tested via NGN as part of a study of the public sector use of digital terrestrial broadcasts carried out by NTT Communications under the auspices of MIC's official research programs for fiscal 2009. IP retransmission involves reception at IP transmission centers of digital terrestrial broadcast signals encoded in MPEG-2, the standard video codec for such broadcasts, followed by conversion in real time to H.264, an advanced video codec featuring superior data compression. These video and data broadcasting signals are then retransmitted via NGN using IP multicast technology for viewing on IP TVs equipped with suitable receivers.
TV programs retransmitted for IP TV will need to be identical to the original terrestrial broadcast in all aspects, including video quality, audio signals, and data content, and this uniformity is currently being verified by the Digital Terrestrial Broadcast Supplemental Retransmission Council.
Digital terrestrial broadcast IP retransmission can be performed over the Internet, but difficulties related to ensuring bandwidth sufficient for high-definition quality broadcasts as well as potential access from outside the broadcast area make such usage problematic.
NGN's ability to provide solutions to these issues through functionality such as QoS class priority control and IP multicasting targeting specific areas makes it an ideal medium for IP retransmission. Enabling the retransmission of digital terrestrial broadcasts in areas with poor reception should also help to bridge digital divides in Japan.

Configuration for field testing digital terrestrial broadcast IP retransmission

This is a diagram showing the configuration used for field testing digital terrestrial broadcast IP retransmission.

Employee views

A major challenge

Tatsuo Matsuoka: We worked with broadcasters and TV manufacturers to establish a standard technical format for digital terrestrial broadcast IP retransmission. We had no precedents to refer to, and it was only thanks to NTT's R&D strengths and the cooperation of the NTT business divisions and Group companies involved in implementing NGN that we were able to overcome various issues and make IP retransmission a reality.
Sachiyo Adachi: Since rights holder organizations, broadcasters, TV manufacturers and many others were involved and there was only a limited timeframe, deciding the technical format was a colossal task. We still need to do a lot in terms of aligning policy aspects and generally tidying things up before we can launch actual service.
Tetsuya Yamaguchi: I was in charge of technical issues. We were forced to accommodate any number of difficult requirements from broadcasters regarding provision of the same picture quality as digital terrestrial broadcast and synchronization of display and so forth, but thanks to our technical expertise in video codec and signal transmission technologies, we managed to pull through. Future issues include improving picture quality and reducing costs.

This is a photograph of Tatsuo Matsuoka of NTT Research and Development Planning Department, who participated in development.

This is a photograph of Sachiyo Adachi of NTT Research and Development Planning Department, who participated in development.

This is a photograph of Tetsuya Yamaguchi of NTT Cyber Solutions Laboratories, who participated in development.

Video codec: A device or program that compresses and decompresses a digital data stream or signal. Digital data is more suited than analog to computer processing and transmission via optical fiber networks.
IP multicast: A method of simultaneous transmission of identical content via an IP network to multiple users.
Digital Terrestrial Broadcast Supplemental Retransmission Council: A broadcasting industry organization comprising key Tokyo-based and other TV stations.
Digital divide: In this publication, digital divide refers in particular to inequality in access to information assets such as digital terrestrial broadcasting services.