DVB-H: Technology

I read some papers that provide specific information about the technical characteristics of the DVB-H technology but I consider more appropriate to provide a general view of the technical aspects, although for those readers that want to know more about that approach I recommend them to read the following article (link1) or the chapter 7 of the book “Mobile TV: DVB-H, DMB, 3G Systems and Rich Media Applications” by Amitabh Kumar (2007). As I mentioned before

DVB-H is built upon the principles of the DVB-T standard, the DVB-H standard adds functional elements that are necessary to fulfill the requirements of the mobile handheld devices reception case. DVB-T and DVB-H use the same physical layer and what is interesting is that DVB-H can be backward compatible with DVB-T. DVB-H like DVB-T can carry the same MPEG-2 transport stream and use the same transmitter and OFDM modulators for its signal. Another positive fact is that DVB-H system is compatible with DVB-T networks, that allows to share the use of the DVB frequency bands without jamming the performance of the cellular bands. (DigiTag, 2008) DVB-H uses IP datacasting. So the system requires a process that involves packaging of digital data into IP packets and then delivering these packets in a reliable manner. The use of IP has the advantage that the data including content is compatible with Internet technology, in other words the content can be managed by the same protocols and devices that are used extensively on the Internet (Kumar, A., 2007). So the DVB-H payload are IP-datagrams.

DVB-H systems have been made the following enhancements that distinguish it from DVB-T:

- Time slicing: DVB-H uses time slicing to reduce the power consumption. Time slicing means that the data from a particular services is delivered to the handheld device in bursts at given intervals of time. When the receiver is not receiving the wanted burst (tv content), the tuner contained in the handheld devices remains “inactive” that contributes to use less power. Time-slicing contribures with a 95% reduction in power consumption compared to continuously operating DVB-T tuners. Because in DVB-T the cannels follow sequentially, so the receiver for each channel needs to be active all the time because the data is continuously arriving (DigiTag, 2008). In the case of DVB-H the IP encapsulator gives the full capacity of the multiplex for a limited time to only one channel, is necessary to mention that power is consumed continually by other parts of the receiver notably the video and audio decoders and the display. (Kumar, A., 2007). Time slicing also contributes enabling smooth and seamless frequency handover. (GERARD FARIA, 2006)

- OFDM: The use of multiple carriers, OFDM (Orthogonal Frequency Division Multiplex) systems excel at handling multi-path interference (EBU-EUR / DVB-H, 2004) In addition to the 2k and 8k modes available in DVB-T, a new 4k mode ortogongal frequency division multiplexing is adopterd giving increased flexibility for network design, is an option complementing the 8K and28K modes that also available. (GERARD FARIA, 2006). This 4K mode is also used for a trading off mobility and single-frequency network (SFN) cell size, allowing a single antenna reception in medium SFNs at high speeds. (EBU-EUR / DVB-H, 2004)

- MPE-FEC(Multi Protocol Encapsulation-Forward Error Correction): the reception in handheld devices have small antennas and have low gain and require reception from different location (mobile environment), so is necessary a strong transmission system able to cope with transmission errors, improve C/N performance and Doppler effects in mobile channels (Kumar, A., 2007) . So the MPE-FEC module offers in addition to the physical layer transmission a complementary forward error function that offers improved transmission robustness. The MPE-FEC processing is takes place on the link layer process the IP input streams before they are encapsulated by means of the MPE. MPE-FEC is not mandatory for DVB-H. (EBU-EUR / DVB-H, 2004)

The following diagram provides a general view of the DVB-H protocol stack:

Figure 1: DVB-H Protocol Stack (Kmar, 2007)

I have found interesting the following diagram that show the system architecture for collaboration between mobile and broadcast operators:

Figure 2 (DigiTag,2008)

With this entry I tried to explain the most important technic features of DVB-H standard by using the ETSI Digital Video Broadcasting standards, for more information consult the standard specification.

References:

DigiTag. (2008). Television on ahandheld receiver - broadcaster with DVB-H. Retrieved 07 20, 2009, from http://www.digitag.org/DTTResources/DVBHandbook.pdf

DVB. (2009). What is the DVB Project? Retrieved 7 2009, 15, from http://www.dvb.org/
EBU-EUR / DVB-H. (2004). DVB-H Standard Specification: ETSI EN 302 304 V1.1.1. Retrieved 07 2009, 19, from http://www.dvb-h.org/PDF/DVB-H%20Specification%20-%20En302304.V1.1.1.pdf

Faria, G., Henriksson, J., Stare, E., & Talmola, P. (2006). IEEE Xplore. Retrieved 06 2009, 13, from DVB-H: Digital Broadcast Services to Handheld Devices: http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F5%2F33232%2F01566629.pdf%3Farnumber%3D1566629&authDecision=-203

GERARD FARIA, J. A. (Genuary de 2006). DVB-H. Recuperado el 20 de 07 de 2009, de DVB-H: Digital Broadcast Services to Handheld Devices: http://www.dvb-h.org/PDF/01566629_DVB-H.pdf

Kumar, A. (2007). Mobile TV: DVB-H, DMB, 3G Systems and Rich Media Applications . Fucal Press Media Technoly Professional.

UE. (2008, 3 17). Mobile TV across Europe: Commission endorses addition of DVB-H to EU List of Official Standards. Retrieved 7 15, 2009, from http://europa.eu/rapid/pressReleasesAction.do?reference=IP/08/451

DVB-H: Indroduction

DVB-H technology is designed to use the digital terrestrial TV broadcast infrastructure to deliver multimedia services to mobiles. This technology is promoted by the EU as the mobile TV standard for Europe (UE, 2008). Nokia the most important mobile phones manufacturer have invested a big amount of resources on this techno, that is a fact that shows the importance of this technology. Nokia is integrating it in the latest released devices, for example the Nokia N96 and N77. For this reasons I will provide a detailed description of this technology in the next entrie.

The Digital Video Broadcast (DVB) Project is an industry consortium of over 270 companies (broadcasters, manufacturer, network operators, regulatory bodies and other) in over 35 countries commited to define and design technical standards for the global delivery of digital television and data services. (DVB, 2009)

The DVB Project started research investigation related to mobile reception of DVB-Terrestrial (DVB-T) signals in 1998, when commercial terrestrial digital TV was starting to be introduced in Europe. (Faria, Henriksson, Stare, & Talmola, 2006)

They realized that DVB-T services do not suit mobile devices special needs, because DVB-T standards have been defined for fixed receivers with large TV antennas and no limitations about the receiver battery power. (Kumar, A., 2007)

In the beginning of 2002 they started to work defining a system, they started by defining a set of commercial and technical requirements in order to design a system supporting handheld devices. The work led to a system called Digital Video Broadcasting-Handheld (DVB-H), which was published by ETSI the Standard EN 302 304 in November 2004. . (Faria, Henriksson, Stare, & Talmola, 2006)

DVB-H is a modification of the DVB-T standard that is currently a widely used technology with over 50 countries already having terrestrial transmissions in digital mode, and in some countries DVB-T is replacing the analog terrestrial transmissions. (DVB, 2009)

The DVB-H standard is an ideal medium for mobile TV delivery to handheld devices, improves robustness in difficult reception environments of indoor and outdoor and lowers battery power consumption. (Kumar, A., 2007)

The DVB Project developed a second standard, Digital Video Broadcasting Satellite Services to Handhelds devices (DVB-SH), for the broadcast delivery of audio, video and data services (for more information link)

According to the lecture literature some standards are divided and composed of several standards, the DVB-H system is an example which consist in a group of several standard documents. The DVB-H system standard represents the main central document specification of the technology, defining the mandatory and the optional elements of the architecture and referencing all other required standards documents:

- DVB-T: defines the physical transmission layer.
- DVB SI (Service Information): defines how to access the DVB-H services, defining how are they signaled.
- DVB Data Broadcast standard: includes the new tool on the link layer.
- The DVB Single Frequency Network Megaframe standard: defines the synchronization of terrestrial single frequency networks that use several transmitters.

According to the DVB Project official website DVB-H mobile TV services are on air in Italy, Finland, Switzerland, the Netherlands, Finland, Malaysia, Vietnam, Albania, the Philippines, Nigeria, Nambia and Kenia. In more than fifty countries DVB-H technical and commercial trials have taken place all over the world. Nowasays is taking place the analogue switch-off across Europre, the spectrum released in the UHF bands will contribute to the widespread deployment of DVB-H networks.

References:

DVB. (2009). What is the DVB Project? Retrieved 7 2009, 15, from http://www.dvb.org/

Faria, G., Henriksson, J., Stare, E., & Talmola, P. (2006). IEEE Xplore. Retrieved 06 2009, 13, from DVB-H: Digital Broadcast Services to Handheld Devices: http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F5%2F33232%2F01566629.pdf%3Farnumber%3D1566629&authDecision=-203

Kumar, A. (2007). Mobile TV: DVB-H, DMB, 3G Systems and Rich Media Applications . Fucal Press Media Technoly Professional.

UE. (2008, 3 17). Mobile TV across Europe: Commission endorses addition of DVB-H to EU List of Official Standards. Retrieved 7 15, 2009, from http://europa.eu/rapid/pressReleasesAction.do?reference=IP/08/451

DAB-IP and T-DMB

DAB (digital audio broadcasting) is a method for the digital transmission of digital radio signals for mobile reception through direct broadcasts from the satellite or terrestrial transmitters to DAB receivers, was developed by EUREKA project 147. Was initially designed for the transimssion of audio, but currently supports also multimedia broadcasting, video, text, image, and other application. (TNO-ICT, 2007)

There are many DAB variants, each with specific transport protocols for the specific services. In our context of Mobile TV the important standard is T-DMB and DAB-IP. This standards are recongnized by ETSI, IEC and CENELEC. (WorldDMB, 2009)

The Digital Multimedia Broadcasting (DMB) is a video and multimedia technology based on DAB. It offers a wide range of services, such as mobile TV (T-DMB), traffic and safety information (security), interactive programs, data information and many other applications. DMB is one of the world's most successful mobile TV standard, with over 8 million devices sold. Countries in Europe and Asia have implemented commercial services. (WorldDMB, 2009)

According to corporative information, on 1st December 2005 Korea became the first country to ever launch a consumer facing Mobile TV service. This was done using DMB.

The following video is interesting because shows how DMB works, the functionalities and applications and the benefits:

It says that in Europe, Germany starts using DMB mobile TV services coinciding with the 2006 FIFA World Cup. The technology has since proven popular on a worldwide scale: 14 European countries and 9 further countries have carried out test or trials. These include: Australia, the Czech Republic, Denmark, France, Ghana, Indonesia, Italy, Kuwait, Luxembourg, Malaysia, Malta, the Netherlands, New Zealand, Norway, Portugal, Singapore, South Africa, Spain, Sweden, Switzerland and the UK. More information of the geographic distribution can bee seen in this link. (WorldDMB, 2009)

DAB-IP is another extension of the DAB technology to provide TV broadcasting over DAB. The following is the definition of DAB-IP provided on WorldDMB official web site: “DAB-IP is an alternative possibility for digital multimedia and video broadcasting. It was used in the UK on a trial basis over a period of about 18 months which finished end of 2007. Unlike DMB, this variant is not fully standardised by ETSI, but makes use of a hook that was designed exactly for that purpose - DAB IP Tunnelling. Based on this transport system for IP datagrams via DAB, the provider BT Movio applied protocols and source coding algorithms designed by Microsoft. It should be noted that in the meantime all of these specifications (ASF and VC-1) are in public domain apart from one - WMA.”

References

WorldDMB. (2009). DMB - Mobile Television . Retrieved 07 1, 2009, from DMB - Mobile Television : http://www.worlddab.org/introduction_to_digital_broadcasting/dmb_-_mobile_television WorldDMB. (2009).

WorldDMB: Standards and Technical Specifications . Retrieved 07 2009, 1, from WorldDMB: Standards and Technical Specifications : http://www.worlddab.org/introduction_to_digital_broadcasting/standards_specs

Mobile TV broadcast

Introduction

In this second part of the blog I will focus on the discussion of Mobile TV broadcast standards in Europe, trying to cover the following issues: technologies, markets, and regulatory action. The reason I decide to focus on the broadcast issue is because broadcast remains the foreseeable future the most efficient way for the large-scale provision of TV service, and is still an “open” issue.

The broadcast technologies that have allowed us to watch TV in our homes, have been modified and adapted to allow mobile handsets to receive the same programs. Broadcast standards are poised to enable mobile TV for the mass market, in the same way to what high definition (digital TV) is doing for the home TV market.

Standards / Technologies

In this first part of the second part of the blog I will discuss about the broadcast technologies. Mobile TV broadcast concerns the simultaneous broadcast (delivery) of multimedia content to a big number of consumer with handset devices. So it is necessary a bearer technology to allow the TV services. This bearer technology relates to the physical and transport layer aspects, including de/modularion and transmission, content formats (audio and video), security and service description. The bearer technology is responsible for the quality of service that the consumer experiences. The following diagram shows the different layers: (TNO-ICT, 2007)

The broadcasts involve multiple technologies for mobile TV, such as digital video broadcasting for handhelds (DVB-H), digital multimedia broadcasting for TV (DMB-T), DVB-T, and analog TV, in simultaneous transmissions.

According to several news I have read on Internet (News1, News2) the European Commission (EC) is attempting to settle on a single standard for mobile TV broadcast across the European Union (EU), and it looks like DVB-H may come out on top. But the industry represented by the European Mobile Broadcasting Council (EMBC), argues that EC position is favoring a technology standard over others.

According to the study “Mobile TV” (TNO-ICT, 2007), requested by the “Policy Department Economic and Scientific Policy” of the UE, the four technologies that currently dominate the Mobile TV landscape are Digital Audio Broadcasting-Internet Protocol (DAB-IP), Forward Link Only (FLO), Terrestrial Digital Multimedia Broadcasting (T-DMB) and Digital Video Broadcast- Handheld (DVB-H). All four technologies are fully capable of supporting mobile TV.

In the next 4 entries I will discuss each of this 4 technologies that are currently dominating the market (in the UE).

References:

TNO-ICT. (2007, 10). Study: Mobile TV. Retrieved 6 31, 2009, from Study: Mobile TV: http://www.dvb-h.org/PDF/M3-3_01-07_Mobile-TV-Study.pdf

3G Standardization

In the last post I tried to resume and provide a general view of the 3G technologies used to deliver Mobile TV, in this section I will try to describe how these standards have been formalized. While much has been written about the promise of 4G and the evolution to LTE, the reality is that 3G networks are still evolving and maturing with many network capabilities still untapped.

In the last chapter I describe that 3G is the result of the evolution of two branches, the standardization efforts have also followed this two branches in the 3G partnership association project.

We can find 3GPP closely associated with the developments of GSM networks to UMTS (3GPP). And the migration of CDMA networks to 3G is coordinated by the 3GPP2 (3GPP2, 2007). More information can be accessed in the official sites of these two groups. (Kumar, 2007)

3GPP and 3GPP2 have some architectural differences between the two groups, interoperability and compatibility of application was needed so they had to work on the unification of standards. So was necessary a migration process of networks from 2G, circuit-switched voice-based networks using SS7 signaling, toward 3G networks based on IP interoperable with Internet. (Kumar, 2007)

3G platforms have corrected evolved to an IP core for voice and data, that allows the use of more efficient coding for voice and migrating all signaling protocols to IP based technologies.

The process have resulted in the following IP based multimedia platform architectures for the networks:
● IP Multimedia System (IMS) 3GPP
● Ip Multi-Media Domain (IMD) 3GPP2.

It have been necessary a process of convergence of the two standards 3GPP and 3GPP2, with the scope to allow interworking of both technologies. (Kumar, 2007)

But the convergence is difficult to achieve, because the need to maintain the technologies of WCDMA frequency division duplex (FDD) and TDD, which have different propagation characteristics and therefore different network designs. In the multimedia area there are standards defined and used by 3GPP and 3GPP2 for video and audio coding that are different. So that forces handset manufacturers to use a player that is able to work with multiple standards, that is necessary to provide interoperability in multiple networks. (Kumar, 2007)

Mobile TV using 3G technologies benefits operators because they can use their own spectrum and use the same business model. It is important to say that 3G services are offered by mobile providers and mobile television is offered by television networks. In Europe alone there are currently 19 operators offering 3G mobile TV services. (ERICSSON, 2006)

This is the last point of the discussion of unicast Mobile TV using 3G technologies, next sections I will focus on the discussion of Mobile TV using broadcast technologies which is an interesting “open” issue for the players and regulatory authorities.


References

3GPP. (s.f.). 3GPP. Recuperado el 26 de 5 de 2009, de 3GPP: http://www.3gpp.org/about-3gpp
3GPP2. (2007). 3GPP2. Recuperado el 25 de 05 de 2009, de 3GPP2: http://www.3gpp2.org/Public_html/Misc/AboutHome.cfm
ERICSSON. (2006). ERICSSON. From Mobile TV: the road to mass market: http://www.ericsson.com/solutions/news/2006/q1/20060119_mobile_tv_standards.shtml
Kumar, A. (2007). Mobile TV: DVB-H, DMB, 3G Systems and Rich Media Applications . Fucal Press Media Technoly Professional.