DigiTAG

Web Letter

September 2014

DigiTAG seeks to inform members and non-members about important developments in the digital terrestrial television market. Each month, DigiTAG distributes its web letter with news updates and further exploration of one topic.

To subscribe to the DigiTAG Web Letter, send an email to the DigiTAG Project Office.

Research results of DVB-T2 &
DVB-T2 Lite trial

 

 

A recent paper [1] has been published by the RAI Research and Technology Innovation Centre (RAI CRIT) about its trial of transmitting high-definition (HD) and mobile television services from a single multiplex on the DTT platform. This paper, written by Gino Alberico and his team at RAI CRIT, received the award for best conference paper at IBC 2014.

The trial used a single multiplex to transmit HDTV services for fixed reception using the DVB-T2 standard and a profile of the DVB-T2 standard, DVB-T2 LITE, for the provision of services to mobile receivers. DVB-T2 LITE reduces the available DVB-T2 parameter settings based on the requirements for mobile and portable reception to allow for greater efficiency and reduced complexity for receiver chipsets.

The trial demonstrated the feasibility of providing television services to mobile devices from an existing DVB-T2 multiplex at a marginal cost. This is made possible through the use of the Future Extension Frame (FEF) feature of the DVB-T2 standard. The trial also showcased the ability of the DVB-T2 LITE profile to provide signal reception under demanding geographic conditions.

Trial implementation

The trial consisted of two parts – a laboratory with computer simulations and an outdoor field trial.

In the first phase, laboratory tests were conducted to confirm the effectiveness of the DVB-T LITE profile and the performance of the field implementation. The values obtained during the laboratory tests confirmed the theoretical expectations.

In the second phase, a field trial took place in 2013 in the Aosta Valley which provides a challenging topology in terms of signal propagation and reception. This field trial evaluated mobile coverage, determined the interoperability of the equipment from various manufacturers, and confirmed service reception.

The UHF channel 53 (frequency channel 730 MHz) was used to transmit the DVB-T2 multiplex from four transmitters at Gerdaz, Arpy, Salirod, and Courti, which were successively switched on. Each transmitter had a low transmitting power with three transmitters equipped with 50 W power amplifiers and one, at Salirod, with a 100 W capability. Horizontal polarization was used.

Two transport streams provided the fixed and mobile services. One transport stream provided three live HD programmes using statistical multiplexing with a bit rate of 28.7 Mbit/s while a second transport stream provided two SD services with a bit rate of 1.5 to 3.0 Mbit/s, depending on the modulation scheme used.  Both transport streams were encoded with MPEG-4 AVC.

Field trial measurements and results

Measurements for mobile and fixed reception were carried out in a specially-designed car and van. The mobile measurements were used to evaluate coverage area and to generate a field strength coverage map necessary for future network planning. The fixed location measurements made use of a telescopic mast up to 15 meters above ground to determine available field strength across the service area to verify consistency with laboratory predictions.

For mobile reception using the DVB-T2 LITE profile, three different Forward Error Correction (FEC) values (1/3, ½, 2/3) were used to test coverage results over 400 kilometers of roads. The difference in service availability due to a change in FEC values was small between 1/3 and ½ and slightly more with 2/3. As a result, the ½ FEC value was used in the later stages of the field trial since it provided a better compromise between robustness and transmission capacity.

Despite low transmitting power, very good mobile coverage was possible on highways as well as main and secondary roads. Excellent results were also obtained in urban areas and in some tunnels. No reception problems were encountered at speeds of 130 km/h using the PP4 carrier profile. However, when the carrier profile was changed to PP7, reception was not possible when travelling at speeds greater than 70 - 80 km/h, which confirmed laboratory results.

The fixed-point measurements allowed a confirmation of the reliability of the results obtained in the laboratory with computer simulations. It also allowed an evaluation of the DVB-T2 reception and verification of SFN synchronization. The measured field strength values supported the computer simulations thereby confirming the correct operation of the transmission equipment.

Trial parameters

Parameter

DVB-T2 Base

DVB-T2 Lite

Constellation
256 QAM, rotated
QPSK, rotated
FEC
¾
1/3 – ½ - 2/3 
FFT
32k
8k
Tg
1/128
1/16
Guard interval
28
56
Pilot pattern
PP7
PP4
Bit rate
28.7 Mbit/s
1.5 – 2.0 – 3.0 Mbit/s

 

Trial conclusions

The RAI CRIT trial demonstrates the feasibility of using a single multiplex to provide both HDTV and mobile television services using the DVB-T2 standard and the DVB-T2 LITE profile. With the FEF feature of the DVB-T2 standard, both type of services can co-exist within previously deployed networks and thus eliminate the need to deploy a separate mobile television network. Unlike other mobile broadcasting standards, it is now possible to deploy a mobile broadcast service with minimum network investments.

The field test showed the robustness of DVB-T2 LITE, especially in an area with a complex topology. However, because the trial used a prototype receiver and a car roof-top antenna, higher field strengths or a few additional transmission sites might be necessary to obtain similar coverage levels when using tablets and smartphones with integrated antennas. The use of the PP4 carrier profile provided excellent signal strength at high reception speeds and it could be assumed that reception is possible at speeds of 250 km/h, thus creating prospects for use on high-speed trains.

During the trial, a large amount of data was collected and can now serve as a database for future network planning of mobile services. In addition, the RAI CRIT test bed is now being used by many manufacturers to assess their DVB-T2 and DVB-T2 LITE receivers.

With the advent of smartphones and tablets, demand for wireless access to video content is increasing. And the technology to bring such services to viewers can vary. However, this trial illustrates the success in using a broadcast technology to provide mobile linear television services to large audiences. This could be useful, for example, when broadcasting live events, such as major sporting events. In such a scenario, broadcasting is the most efficient manner to reach a maximum number of viewers simultaneously.

 

 

Source: Natalie Mouyal, on behalf of the DigiTAG Project Office

 
[1] Alberico, G, A. Bertelia, S. Ripamonti, M.Tabone, “DVB-T2 LITE: exploiting broadcast HDTV networks for services to mobile receivers,” which is available at: http://www.theiet.org/communities/multimedia/ibc/2014.cfm

About DigiTAG

DigiTAG is an association of stakeholders in the digital terrestrial TV industry and has members from broadcasting, network operators, regulatory, and professional equipment and consumer electronics manufacturing organisations throughout the world. DigiTAG has recently re-launched with new Statutes and the mission of defending and promoting digital terrestrial television on a worldwide basis, and, notably, will work tirelessly to protect spectrum for broadcasting, regardless of the technical standard used on the DTT platform.
Visit the DigiTAG website
Please contact the DigiTAG office if you have any news that you would like to include in the next DigiTAG Web Letter.
To unsubscribe from the DigiTAG Web Letter, please click here and put 'UNSUBSCRIBE' in the subject title of your email.

DTT NEWS ROUND-UP

For access to the full articles archive, please go to DigiTAG News

 

France - Coverage of HD/DTT platform to reach 85% of population

The broadcast regulator has announced that the coverage of high-definition services on the DTT platform is set to increase.

On 23 September, the 10th phase of the roll-out of the HD / DTT platform will take place in the southern part of the country (Languedoc-Roussillon). As a result, coverage will increase from 80% of the population to 85% of the population.

Source: CSA website

Spain - Telecom operators to pay for filters to block interference to DTT reception

Despite not yet having established a plan for resolving DTT interference issues, the government has announced that telecom operators will need to assume some of the costs.

The government has announced that it is still studying the the issue of resolving interference to the DTT platform caused by the launch of LTE services in the 800 MHz band.

Source: Europa Press

Croatia - HAKOM issues local DTT license

The communications regulator has allocated a new licenses to operate a local DTT multiplex.

The license has been allocated to Odašiljači i veze (OiV) for the operation of a multiplex in the region of Zaprešić. Specifically, services will be available in the cities of Zaprešić, Bistra, Luka, Jakovlje, Dubravica, Pušća, Marija Gorica and Brdovec.

Source: HAKOM website

Australia - Government calls for DTT platform migration to MPEG-4 AVC

In a keynote address at the communications conference RadComms, the Communications Minister Malcolm Turnbull called on broadcasters to switch to the MPEG-4 AVC standard on the DTT platform.

He calls on all broadcasters to do so in order to free up spectrum capacity for the provision of new broadcast services such as high-definition content. Such a transition should be managed by the broadcast industry.

Source: Ministry website

Romania - Ancom opens consultation on licenses to operate DTT multiplexes

The communications regulator Ancom has opened a public consultation on its draft decision to award to national DTT multiplex licenses.

These two licenses had not been awarded during the previous license allocation process last Spring. In addition, licenses to operate 40 regional and 19 local multiplexes are also available.

Source: Ancom website

Ukraine - Zeonbud begins unencrypting DTT platform

The National Council on Television and Radio is calling on broadcasters to sue the DTT platform operator Zeonbud.

This follows the continued encryption of television services on the DTT platform.

Source: Tele-Sat News

Sri Lanka - ASO to be completed by 2020

The government has announced that the country will complete digital switchover by 2020.

The DTT platform will use the ISDB-T standard and will benefit from technical and financial support from the Japanese government. Digital switchover is expected to cost LKR 22 billion (EURO 131 million) of which RS 17 billion (EURO 101 million) will be sourced from Japanese investments.

Source: Daily News

Uganda - UCC aims to complete digital switchover by December

The Uganda Communications Commission (UCC) has announced that it plans to complete the roll-out of the DTT platform by the end of the year.

It also plans to begin analogue switch-off in December 2014 so as to complete the process by June 2015.

Source: Biz Tech Africa

India - Launch of mobile TV services using DVB-T2 Lite

The public service broadcaster Doordarshan has announced plans to launch mobile television platform using the DVB-T2 Lite standard.

The mobile television platform will offer viewers access to 20 free-to-air television services. Doordarshan is currently in negotiations with commercial broadcasters to jointly launch the platform.

Source: The Hindu Business Line