overview of the dvb-sh specifications

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS

Int. J. Commun. Syst. Network 2009; 27:198–214Published online 11 May 2009 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/sat.935

Overview of the DVB-SH specifications

Philip Kelley�,y

Alcatel-Lucent, Paris, France

SUMMARY

This article provides an overview of the DVB-SH specifications, and the context within which they havebeen developed. The main DVB-SH configurations are introduced, with explanations of both the technicaland frequency planning considerations that drive choices. Regulatory aspects in the European Union andUnited States of America are summarized. Then specific DVB-SH issues are being addressed, involvingreception conditions and channel characteristics, combining techniques for satellite and terrestrial signals,and synchronization and local content insertion. Some attention is paid to the reuse of DVB link andapplication layer features. Finally, a couple of likely service introduction scenarios are suggested. It isclaimed that DVB-SH fulfills the initial requirements of extending the present UHF-based service offer toother frequencies below 3GHz with a large area coverage, a reduced total network infrastructure cost andan expansion of the offer in terms of number of TV channels or multimedia services. Copyright r 2009John Wiley & Sons, Ltd.

KEY WORDS: DVB-SH; Mobile Television; Mobile Satellite Services

INTRODUCTION

On 13 June 2006, the Steering Board of the DVB (Digital Video Broadcast) Project endorsed thestudy mission report on ‘Satellite Service to Portable’ presented by the DVB Technical Module.This opened the way for the DVB Commercial Module to draw up the CommercialSpecifications for what is now known as the DVB-SH (Satellite to Handheld) standard.The design of this new specification was initiated on 28 June 2006, with the first meeting of the‘TM-SSP’ workgroup, which I have been extremely fortunate to chair. This was the mostrewarding professional project I ever experienced, gathering a group of extremely dedicated andcompetent individuals, most of whom today contribute to the articles collected in this issue ofthe International Journal of Satellite Communications and Networking.

DVB-SH did not start from scratch, but benefited from the foundations laid by previous DVBstandards [1,2], and specifically inherited from technologies stemming out of DVB-S2 [3,4] for itssatellite part and DVB-H [5] for its terrestrial component. The Commercial Specifications requestedthat ‘Where appropriate, existing international standards and relevant aspects of DVBspecifications shall be adopted and in particular the DVB-H, DVB-SFN, DVB-CBMS, DVB-S2

*Correspondence to: Philip Kelley, Alcatel-Lucent, 54 rue la Boetie, 75008 Paris, France.yE-mail: [email protected]

Copyright r 2009 John Wiley & Sons, Ltd.

and 3GPP specifications’. In particular making reference to the DVB-H case, the CommercialSpecifications requested that ‘the availability of the SSP tool kit will allow the extension of thepresent UHF-based service offer to new frequency bands with a common cross border allocation, areduced total network infrastructure cost and an expansion of the offer in terms of number ofchannels/services’. Another key requirement was the link to DVB-CBMS, which is the DVBworkgroup designing the IP Datacast (IPDC) specifications [6]. DVB-SH was able to accommodateIPDC with very little adjustments, then immediately benefiting from its very valuable features.

Again thanks to the dedication and focus of the expert members of the workgroup, the DVB-SH specifications were swiftly drafted, with everyone on board accepting compromises in theinterest of time. The ‘system’ and the ‘waveform’ draft specifications were made publiclyavailable as ‘DVB bluebooks’ as early as February 2007 and the standards [7,8] were publishedby ETSI in March–April 2008. The DVB workgroup then drafted the ‘DVB-SHImplementation Guidelines’ [9] that has been made available as DVB bluebook since May2008. Several field trials are currently being conducted by various organizations in Europe andin the United States of America, with the DVB workgroup now focusing on the sharing ofinformation and results between the key players conducting these trials.

DVB-SH AT A GLANCE

The DVB-SH standard [7–9] is engineered to provide users with ubiquitous IP-based multimediaservices on mobile handheld (mobile phones, personal multimedia players), vehicle-mounted,nomadic (laptops, palmtopsy) and stationary terminals The user accesses the services while onthe move, e.g. walking or while traveling in a car or on a train. While the main interest is inbroadcast services, typical applications may include

� broadcasting of classic Radio and TV content;� broadcasting of audio or video content customized for Mobile TV (e.g. virtual TV

channels, pod-casts);� data delivery (‘push’), e.g. for ring tones, logos;� video on demand services;� informative services (e.g. news);� interactive services, via an external communications channel for return channel (e.g.

UMTS).

The DVB-SH standard provides an efficient way of carrying these multimedia servicesover hybrid satellite and terrestrial networks at frequencies below 3GHz to a variety ofmobile and fixed terminals having compact antennas with very limited directivity. The use ofa satellite guarantees coverage of large rural regions, whereas terrestrial transmitters providecoverage in areas such as urban canyons where direct reception of the satellite signal is verydifficult.

The DVB-SH standard provides a universal coverage by combining a Satellite Component(SC) and a Complementary Ground Component (CGC): in a cooperative mode, the SC ensuresgeographical global coverage while the CGC provides cellular-type coverage. All types ofenvironment (outdoor, indoor) can then be served, using the SC from its first day of service,and/or the CCG that is to be progressively deployed. A typical DVB-SH system (see Figure 1) is

OVERVIEW OF THE DVB-SH SPECIFICATIONS 199

Copyright r 2009 John Wiley & Sons, Ltd. Int. J. Commun. Syst. Network 2009; 27:198–214

DOI: 10.1002/sat

based on a hybrid architecture combining an SC and a CGC consisting of terrestrial repeatersfed by a broadcast distribution network of various nature (DVB-S2, fiber, xDSLy). Therepeaters may be of three kinds:

� ‘Terrestrial Transmitters’ (TR(a)) are broadcast infrastructure transmitters, whichcomplement reception in areas where satellite reception is difficult, especially in urbanareas; they may be collocated with mobile cell site or standalone. Local content insertionat that level is possible, relying on adequate radio frequency planning and/or waveformoptimizations.

� ‘Personal Gap-fillers’ (TR(b)) have limited coverage providing local on-frequency re-transmission and/or frequency conversion; typical application is indoor enhancementunder satellite coverage; no local content insertion is possible.

� ‘Mobile transmitters’ (TR(c)) are mobile broadcast infrastructure transmitters creating a‘moving complementary infrastructure’. Typical use if for trains, commercial ships orother environments where continuity of satellite and terrestrial reception are notguaranteed by the fixed infrastructure. Depending on waveform configuration and radiofrequency planning, local content insertion may be possible.

CONFIGURATIONS

Orthogonal Frequency Division Multiplexing (OFDM) is the natural choice for terrestrialmodulation as it is the basis of both the DVB-H and DVB-T systems on the one hand, andWiFi, WiMax and LTE on the other hand. In addition, leveraging on DVB-S2, DVB-SH

DVB-SH SatelliteDVB-SH Signal

Content

Head-endSatelliteEarthStation

BroadcastDistributionNetwork

OFDM

OFDM

Distribution Signal

OFDMor TDM

OFDM

OFDM

PersonalGap-fillers

TerrestrialTransmitters

MobileTransmitters

Figure 1. Typical DVB-SH system.

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introduces a second scheme on the satellite link, a Time Division Multiplex (TDM) leading totwo reference architectures termed SH-A and SH-B:

� SH-A uses OFDM both on the satellite and the terrestrial link.� SH-B uses TDM on the satellite link and OFDM for the terrestrial link.

When assessing whether SH-A or SH-B should be selected, two main classes of satellitepayloads may be considered:

� Single DVB-SH physical layer multiplex per high power amplifier (HPA).� Multiple DVB-SH physical layer multiplex per high power amplifier. This is the case with

multibeam satellite with re-configurable antenna architecture based on large size reflectorsfed by arrays.

In the first case, SH-B takes advantage of satellite transponders operated in full saturationwhile SH-A requires satellite transponders operated in a quasi-linear mode. In the second case,SH-B provides little or no performance advantage over SH-A.

Beyond these pure performance considerations, the choice between SH-A and SH-B may beessentially driven by frequency planning constraints as outlined below, or by the flexibilitygained when decoupling satellite transmission parameters from the terrestrial ones.

The next step is to choose between physical layer or link layer techniques to combat longinterruptions of the line of sight typical of satellite reception with mobile terminals, andresulting for instance from the shading by buildings, bridges and trees. The choice is dictated bythe cost and required footprint of the memory to implement long interleaver at physical layer. Inthe short term, the combination of a short physical interleaver with a long link layer interleavercould be advantageous, especially for handheld terminals. On the longer term, or when targetingvehicular-mounted devices with no battery-life restrictions, the long interleaver at physical layermight be preferable in difficult reception conditions. This was particularly evidenced insimulations with the Land Mobile Satellite Intermediate Tree Shadowing channel model.Therefore, two types of receivers have been distinguished:

� The first (Class 1 Receiver) is able to cope with rather short interruptions and mobilechannel fading using appropriate mechanisms on the physical layer but supports thehandling of long interruptions using redundancy on the link layer.

� The second (Class 2 Receiver) is able to handle long interruptions (in the order ofmagnitude of 10 s) directly on the physical layer. This is made possible via the use of alarge memory directly accessible to the receiver chip.

FREQUENCY PLANNING

Considering spectrum allocation, SH-B needs a dedicated sub-band for satellite transmission,completed with a part of the sub-band available for the terrestrial local component to re-enforcereception of the satellite programs. Comparatively, SH-A allows on-channel terrestrialrepetition of the satellite content in the same sub-band as the satellite transmission, leavingall the remaining sub-bands available for terrestrial-only transmission. Such single-frequencyconfigurations are called ‘SH-A SFN’ configurations.



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On the other hand, for the SH-A SFN case, not only the OFDM modulation type is re-usedbetween satellite and terrestrial links, but also the sub-carriers modulation and coding arestrictly identical to allow a repetition at the same carrier frequency in an SFN mode. For theSH-B, carrier’s parameters are independent, only the content of the satellite carrier should berepeated on the terrestrial one.

Taking the example of a 15MHz MSS band, split in three sub-bands of 5MHz, there wouldbe three satellite beams allocated to three countries, with each country able to reuse two sub-bands of 5MHz for terrestrial-only transmission.

In SH-A SFN systems, the terrestrial repeaters strictly generate the same carrier symbols thanthe satellite, in the same 5MHz sub-band, each transmitter being synchronized with itsneighbors and with the satellite. This synchronization is based on the transmission of an SHIPpacket, very similar to DVB-T’s MIP [10], which allows to synchronize SH-frames together atthe output of transmitters, the terrestrial ones being slaves of the satellite signal. The feedingnetwork includes a compensation of the earth–space delays and of the signal regeneration at theterrestrial level, thus producing an overall earth–space SFN broadcast network. There, two fullsub-bands of 5MHz remain available for terrestrial-only transmission.

In SH-B systems, a different 5MHz sub-band is used to transmit the satellite content via aterrestrial network where it needs to be re-enforced. Since the receiver can make use, at physicallayer level, of both the symbols received from the satellite and the terrestrial transmitters, thesame synchronization technique is applied as for SH-A. Hence, information symbols from agiven program are close enough in time to be combined at the decoder input and improve theoverall link performance. Furthermore, terrestrial transmission, because of its higher signal-to-noise ratio, allows higher spectrum efficiency than the broad satellite transmission. Therefore,the terrestrial carrier can convey additional local content in the same 5MHz terrestrial sub-band, which repeats the satellite content. As a result, there is one full 5MHz sub-band plusa portion of a second 5MHz sub-band available for terrestrial-only transmission.

The following table provides the theoretical total capacity per 5MHz satellite bandwidth and perbeam in a 3-color reuse pattern, in satellite-only coverage (SAT) and in terrestrial coverage (TER).Note that this TER capacity includes the repetition of the SAT capacity, expressed in Mbps.

WaveformSH-A SH-B

SFN MFN MFN

Hybrid network frequencyconfiguration Typical Maximal Typical Maximal Typical Maximal

Multibeam satellite systemwith 3� 5MHz spectrumassigned, 5MHz allocatedto each satellite beam ina 3-color re-use pattern

Mbps:SAT/beam

2.5 10.0 2.5 10.0 2.66 10.64

TER/beam 10.0 30.0 7.5 20.0 7.42 20.53

Higher total capacity can be achieved through more satellite frequency-reuse, more powerfulsatellites, more CGC transmitters density or more advanced terminal technologies (e.g. antennadiversity). Taking the example of a 6-beam, 3-color reuse system as illustrated in Figure 2, it canbe easily seen that typical system capacity in 15MHz reaches 45Mbps with SH-A or SH-BMFN, and 60Mpbs with SH-A SFN.

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SOME REGULATORY ASPECTS

European union

L-band and 2.5GHz S-band. No specific regulatory instruments on the designation of thefrequency bands for satellite use have been adopted by the European Union in these bands.

2GHz S-band (i.e. 1980MHz to 2010MHz uplink and 2170MHZ to 2200MHz downlink). On14th February 2007, the European Commission adopted a Decision ‘on the harmonized use ofradio spectrum in the 2GHz frequency bands for the implementation of systems providing mobilesatellite services’, which gives priority to the development of MSS in the 2GHz bands. Such aEuropean Decision is mandatory for all Member States of the European Union. Pursuant to thedecision, Member States are obliged to designate and make available as of 1 July 2007 the 2GHzS-bands for systems providing mobile satellite services, which can include the use of CGCs.

The Commission then drafted a common selection procedure of satellite operators to becarried out by the Commission. This draft had to be approved through a formal ‘co-decision’process by both the European Parliament in its plenary session of 21 May 2008, and theEuropean Council on 30 June 2008, respectively. The Commission subsequently issued a call for

Figure 2. Example of satellite multibeam.



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application on 7 August 2008, which was answered by four satellite operators. Applicants had tocommit that on the service launch date no later than 1 September 2009, at least 60% of theaggregate area of Member States be covered; and that at the latest 7 years from the publicationof the Commission selection decision, services be provided in all Member States and to at least50% of the population and over at least 60% of the aggregate land area of each Member State.

The authorizations for the provision of CGCs on their territories shall be granted by Memberstates to the selected applicants, subject to the following common conditions:

(a) operators shall use the assigned radio spectrum for the provision of CGCs of mobilesatellite systems;

(b) CGCs shall constitute an integral part of a mobile satellite system and shall be controlledby the satellite resource and network management mechanism; they shall use the samedirection of transmission and the same portions of frequency bands as the associatedsatellite components and shall not increase the spectrum requirement of the associatedmobile satellite system;

(c) independent operation of CGCs in case of failure of the SC of the associated mobilesatellite system shall not exceed 18 months;

(d) rights of use and authorizations shall be granted for a period of time ending no laterthan the expiry of the authorization of the associated mobile satellite system.

United States of America (all bands)

In the United States of America, the available bandwidth is limited by the Table of FrequencyAllocations to 20MHz (i.e. 2180–2200MHz coupled with the uplink band 2000–2020MHz).In these bands, ancillary terrestrial components (ATC) may be operated in conjunction withMSS networks. These ATC are the U.S. equivalent of the European CGC, and are subject to allapplicable conditions and provisions of the FCC MSS authorization. The FCC generallyimposes to an MSS licensee that wishes to include ATC to meet five requirements:

� geographic coverage: An MSS licensee must provide space-segment service across theentire geographic area where the ATC can be deployed;

� coverage continuity: MSS operators must maintain space station coverage over therelevant geographic area, which implies timely replacement of satellites in the eventcoverage should degrade as a result of satellite failure. In order to implement thiscondition, a non-geostationary MSS system licensee is required to maintain an in-orbitspare, while a geostationary MSS system licensee is required to maintain a spare satelliteon the ground within 1 year of commencing operations and launch it into orbit during thenext commercially reasonable launch window following a satellite failure;

� commercial availability: The MSS service via satellite must be commercially available as aprerequisite to any offering of the ATC service;

� an integrated offering: MSS licensees must offer an integrated service. MSS licensees mustmake an affirmative showing to the FCC that demonstrates that their ATC serviceoffering is truly integrated with their MSS offering. As an example, MSS licensees thatwish to provide ATC services could demonstrate that they use a dual-mode handset toprovide the proposed ATC service;

� in-band operation: The ATC operations must remain limited to the precise frequencyassignments authorized for the MSS system.

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DVB-SH PHYSICAL LAYER OUTLINE

3G networks have raised market expectations for indoor coverage to a level that needs to bematched. Good indoor coverage with an infrastructure lighter than 3G networks entails aselection of new tools for enhancing the signal robustness. For example a state-of-the-artforward error correction (FEC) scheme, 3GPP2 Turbo code over 12 kbits blocks, is used. Inaddition, DVB-SH uses a highly flexible channel interleaver that offers time diversity fromabout 100ms to several seconds depending on the targeted service level and correspondingcapabilities (essentially memory size) of terminal class.

A functional description of the components required on the transmitter side in the case of anSH-B system is provided in Figure 3. The different technology sub-modules are grouped asfollows:

(A) Multi-Protocol Encapsulation (MPE), forward error protection, interleaving and frameadaptation.

(B) OFDM modulator including TPS and reference signal insertion as well asFourier Transform processing. The multicarrier modulation concept is derived fromDVB-T.

(C) TDM modulator including Pilot field insertion and roll-off filtering. The single carriermodulation concept is adapted from DVB-S2 technology.

RF

RF

MPE

MPE-FECTime-slicing

Extended

MPE-FEC

SH

IP

SH-FRAMEfiltering

Timeinterleaver

TurboEncoding

TS

SH-FRAME

filtering

Time

interleaver

Turbo

Encoding

QPSK 8PSK

8,7,6,5MHz 1.7MHz

16APSK

Pilots PL-slots

CGC-OFDM DVB-SH modulator

SC-TDM DVB-SH modulator

IP

Signalling

Field

DVB-SH

TPS8k,4k,2k

QPSK

8,7,6,5MHz

1k

16QAM

1.7MHz

Feature introduced / updatedby DVB-SH

Existing feature in DVB-T/H

Existing feature in DVB-S2

DVB-SH IP encapsulator

Figure 3. SH-B architecture-Transmitter side.



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For the OFDM part, the possible choices are QPSK, 16QAM and non-uniform 16QAM withsupport of hierarchical modulation. A 1k-mode is proposed in addition to the usual 2k, 4k and8k modes, which does not exist in either DVB-T or DVB-H. This mode targets mainly L-Bandwhere the planned channel bandwidth is 1.712MHz. For the TDM part, the choices are QPSK,8PSK, 16APSK for power and spectral efficient modulation format, with a variety of roll-offfactors (0.15, 0.25, 0.35).

SPECIFIC ISSUES ADDRESSED BY DVB-SH

Reception conditions and DVB-SH features

The following table summarizes the reception conditions addressed by DVB-SH, acrossthe different types of environment (Rural, Urban or Suburban). For each case, thecharacteristics and typical parameters of the channels are given, with the relevant DVB-SHfeatures:

Receptioncondition Situation Characteristics Environment Coverage

Channelcharacteristics

Typical channelparameter and

relevantDVB-SH features

ReceptionconditionA

Outdoorpedestrian

Up to 3 km/h Rural Satellite Stationary: lowdelay/low spread

LOS: AWGN/RiceK410 dB:additionalmargin to copewith fadingFor shadowed,Ko7 dB: timeinterleavingto mitigateeffects

Low speed: largesignal variation

LMS channel modelat low speed: timeinterleaving

Urban Terrestrial Stationary:Rayleigh/verylow Doppler

TU6 channel:lowcode rate improves;antenna diversityalso improves

Low speed/Rayleigh/lowDoppler

Higher marginsto cope withslow fadingeffects

Sub-urban Terrestrial,hybrid

For terrestrialsame as above

For terrestrialsame asabove

No hybridchannel modelavailable


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ReceptionconditionB1

Light-in-door

Up to 3 km/h,lightlyshieldedbuilding

Rural �

Urban Terrestrial Channel is thesame asReception Awith highpenetrationmargins

TU6 channel:lowcode rate improves;antenna diversityalso greatlyimproves


Same as abovefor terrestrialNo hybridchannel modelavailable

ReceptionconditionB2

Deep-indoor

Up to 3 km/h,highlyshieldedbuilding

Rural �

Urban Terrestrial Channel is thesame asReception Awith higherpenetrationmargins asin B1

TU6 channel:lowcode rate improves;antenna diversityalso greatlyimproves

Sub-urban Terrestrial Same as above(lower margins)

Same as above

ReceptionconditionC

Mobile(vehicle)withrooftopantenna

Up to200 km/h

Rural Satellite Large signalstrength variationdepending onenvironment

LMS channel modelat medium/highspeeds for differentenvironments

Urban Terrestrial Multiple Rayleighfading pathsDelay spreaddepends mainlyon networkcharacteristics

Channel models likeTU6 cover thisscenario at least forlow or mediumpower repeaters.Critical SFNscenarios requirechannel models withhigher delay spread


For terrestrialsame as above

For terrestrial sameas above




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ReceptionconditionD

Mobile(portable)in-car

Up to130 km/h

Rural y

Urban Terrestrial Multiple Rayleighfading pathsDelay spreaddepends mainlyon networkcharacteristics

Channel models likeTU6 cover thisscenario at least forlow or mediumpower repeaters.Critical SFNscenarios requirechannel models withhigher delay spread

Sub-urban Terrestrial Same as above Same as above

�For Reception conditions B1 and B2 in the rural environment, under satellite coverage, it is assumed that the satellitesignal is assisted by personal gap-fillers (TR (b)). The link budget applies to these TR(b), not to the end-user terminal.yFor Reception condition D in the rural environment, under satellite coverage, it is assumed that the satellite signal isassisted by mobile transmitters (TR (c)). The link budget applies to these TR(c), not to the end-user terminal.

Combining techniques

Combining techniques between the satellite and the CGC differ depending on the DVB-SHconfigurations:

� SH-A, SFN: No specific combining techniques are needed. The satellite signal isconsidered as coming from an additional repeater in an SFN. Delay spread has to betaken into account to determine the maximum cell radius as a function of the guardinterval. Taking as example the case of OFDM 2k mode, 5MHz bandwidth, the followingtable provides the maximum cell radius to ensure SFN between the satellite and terrestrialnetwork at the edge of one repeater:

Max cell radius (km) Max delay in ms GI5 1/4 GI5 1/8 GI5 1/16 GI5 1/32

12 79.8 80.64 40.32 20.16 10.086 39.9 80.64 40.32 20.16 10.083 19.5 80.64 40.32 20.16 10.081 6.55 80.64 40.32 20.16 10.08

� SH-B: The satellite and terrestrial signal is demodulated by separate demodulators(Figure 4). Three combining techniques are applicable:

– The signal is selected after the FEC (Turbo) decoding. The signal that provides the bestquality is chosen (‘Selective combining’). This method does not seem to provide thebest results.

– Combining is done before de-interleaving. The signals are combined, weightedaccording to their specific reception qualities. While it should provide better resultsthan the previous method, this ‘Maximum ratio combining method’ only works if thesatellite branch and the terrestrial branch use the same code rate and interleaverparameters.

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– Combining is done after de-interleaving and before FEC decoding. In this‘Complementary code combining’ method, exploitation of the low mother code rateto transmit complementary punctured streams (e.g. via TDM and OFDM) allows tocombine them into an un-punctured stream instead of only using maximum ratiocombining. With this method, different interleaver profiles and even different coderates may be used for the satellite and terrestrial signals.

� The SH-AMFN case is quite similar to SH-B. The same content is available over differentcarriers, in different frequency bands. The ‘Maximum ratio combining’ and the‘Complementary code combining’ methods are applicable, with the same result thatdifferent interleaver profiles and different code rates can be used for the satellite andterrestrial signals. The use of two separate demodulators could also be envisaged tosupport seamless handover.

Local content insertion

‘Local content’ is the name given to content transmitted through terrestrial sub-bands, which isnot the repetition of the content transmitted in satellite-only coverage, which is called ‘Commoncontent’. There are two different methods for Local content insertion, depending on the ratiobetween the Local content and Common content bitrates.

� If this ratio is greater than 2, the ‘hierarchical modulation’ method can be used: content issplit into two transport streams (TS). The first TS is input to the primary interface of theterrestrial modulator; this TS is exactly the same as the one going to the satellitetransmitter. The second TS is input to the secondary interface of the terrestrial modulatorto carry Local content.

Figure 4. DVB-SH-B receiver block-diagram.



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� Otherwise, the ‘content removal’ method can be used: a single TS is generated andtransmitted to all transmitters, either satellite or terrestrial. Using the SHIP synchronization,the transmitters will forward the only relevant part of the TS. The satellite transmitterremoves all the local content. The terrestrial transmitters remove the part of the localcontent they need not forward.

The principles of synchronization are illustrated in Figure 5, where

� SH Frame Information Packet (SHIP) inserter performs the insertion of a GPS-basedtimestamp (70.1 us accuracy) in the SH-FRAME indicating the transmission time of thebeginning of the next SH Frame.

� SFN adapters in the transmitters (repeaters) perform buffering of incoming MPEG-TSpackets and transmission of SH Frame aligned with GPS relative time stamp.

DVB-SH LINK AND SERVICE LAYERS OUTLINE

DVB-H presents a layered system structure that is one reason of its success: equipmentsoperating on a specific layer can easily interconnect to equipments operating on an adjacentlayer. Acknowledging this approach, DVB-SH reuses to the most extent the DVB-H link andservice layer in order to achieve seamless interoperability with DVB-H and to benefit from allavailable DVB-H link layer features as well as the already developed DVB-H ecosystem. Thislayered approach is presented in Figure 6:

� a set of IPDC servers deliver IP streams, including the video streams;� these IP streams are encapsulated by a DVB-SH IP encapsulator; the latter performs IP to

MPE encapsulation according to [11], PSI/SI insertion and MPE-IFEC protection anddelivers an MPEG2 TS for the DVB-SH modulator;

� the DVB-SH modulators deliver a radio signal ultimately received by the DVB-SHreceiver, which performs baseband demodulation and decoding and processes theMPEG2 TS in the link layer client;

� the latter processes sections, MPE, MPE-FEC, MPE-IFEC, PSI/SI, and delivers an IPstream to the IPDC client;

� the IPDC client processes the IP streams, for example to deliver the Electronic ServiceGuides (ESG), the security decryption and the video and audio play out.

DistributionNetwork

DVB-SHTransmitters

SHIPinserter

SFNadapters

IPencapsulator

ContributionNetwork

Serviceplatform

Transit delay < 1 second

Figure 5. SFN synchronization.

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Key features of DVB-SH link and service layers are

� support of MPE:

– DVB-H provides an IP multicast transport on top of MPEG2 TS. To encapsulate theIP datagrams over MPEG2 TS, MPE [11, section 7] is applied. As the DVB-SHphysical layer is also MPEG2 TS based, DVB-SH reuses MPE for the transport of IPdatagrams over DVB-SH physical layers.

– MPEG2 TS-based transport and MPE enable to reuse most signaling concept ofDVB-H also for DVB-SH.

� Support of time slicing:

– DVB-H uses the real-time parameters, specifically the Delta-t information, conveyedwithin MPE and MPE-FEC headers in order to inform the start of the next burst.DVB-SH re-uses this concept: each MPE, MPE-IFEC and MPE-IFEC section carriedby the MPEG2 TS over DVB-SH physical layer includes the same Delta-t information.

– This mechanism enables to power off the terminal during periods where no relevantbursts for this service are transmitted. This also enables hand-over even for receiverswith a single demodulator in case the infrastructure provisions to appropriatelysynchronize the transmitted TS.

– In addition, time slicing enables the efficient support of variable bit rate services sinceDelta-t can be adapted for each burst size. This is one way to efficiently supportstatistical multiplexing.

� Support of link layer protection:

– DVB-H permits the use of link layer protection by applying MPE-FEC [11, section 9]to counteract terrestrial fading. DVB-SH also supports the use of MPE-FEC.

– Alternatively, DVB-SH provides a multiburst MPE-IFEC protection [9], betteradapted to satellite coverage, especially with class 1 receivers.

– With link layer protection, individual protection for each service is enabled.Depending on the service requirements and the physical layer performance, thetransmitter can select from a variety of link layer parameters, e.g. using single burstMPE-FEC or multiburst MPE-IFEC. Each FEC protection scheme can be fullyconfigured to the service requirements thanks to a number of parameters.

DVB-SHIP

Encapsulator

MPEG2 TS

DVB-SH

Modulator

MPE DATA + PSI/SI + MPE (I)FEC

IP

DVB-SH physical layer

IPDC

Servers

SRTP/UDP

DVB-SHBasebandreceiver

DVB-SHLink layer

client

IPDC

client

Figure 6. DVB-SH layered approach.



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� Support of IPDC features:

– DVB-SH is fully compatible with the DVB IPDC specifications, including ESG,Content Delivery Protocols and Service Purchase and Protection. This enables the fastdeployment of services on top of DVB-SH physical and link layers through the reuseof the IPDC protocol stack.

– DVB-SH uses updated PSI/SI to convey system and program parameters. Thisenables smooth transition scenarios between DVB-SH and DVB-H networks, inparticular, for handovers: dual-mode receivers may receive content on one or theother technique seamlessly.

INTRODUCTION SCENARIOS

The following scenarios are presented for illustration purposes only, and are the result of anarbitrary selection among many possibilities. In the real world, regulatory and businessconsiderations will determine the actual course of action.

‘Vehicular first’ introduction scenario

A scenario initially targeting vehicular reception (reception condition C) could be envisaged asfollows:

� Step 1: Launch of a satellite, targeting Class 1 receivers using MPE-IFEC for long timeinterleaving, and diversity antennas, covering a large territory.

� Step 2: In parallel, deployment of a CGC to enhance vehicular reception in deep urban areas.� Step 3: Extension of the CGC to accommodate handheld reception in major urban/

suburban areas (Reception condition A), while user cooperation would be required forhandset satellite reception in rural areas. Introduction of local content, enriching greatlythe offer of TV channels. Use of personal gap-fillers for indoor reception, and of mobiletransmitters for in-car (reception condition D).

� Step 4: Launch of an additional satellite and/or further re-enforcement of the CGC and/orClass 2 receivers to improve all reception conditions.

‘Handheld first’ introduction scenario

In several regulatory contexts, the introduction of a CGC before the launch of a satellite couldresult in the following scenario:

� Step 1: Deployment of a CGC, targeting Class 1 handheld receivers using MPE-IFEC forlong time interleaving and diversity antennas, in high-density urban areas (e.g. covering30% of the population of a country). Local content is introduced from Day 1, providing avery rich offer of TV channels. Use of personal gap-fillers for indoor reception, and ofmobile transmitters for in-car (reception condition D).

� Step 2: Launch of a satellite, allowing countrywide coverage in vehicular reception(reception condition C), and with handsets in reception condition A, with some usercooperation where the CGC has not been deployed yet.

� Step 3: Extension of the CGC to accommodate handheld reception and improve vehicularreception in more urban/suburban areas.

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� Step 4: Launch of an additional satellite and/or further re-enforcement of the CGC and/orClass 2 receivers to improve all reception conditions.

CONCLUSION

At the physical layer, DVB-SH provides a state-of-the-art FEC scheme and a highly flexibleinterleaver, which successfully address the challenges of both terrestrial and satellite-mobilechannels. The interleaver copes with the long interruptions due to obstacles typical of satellitechannels. Terrestrial reception is improved, in particular indoor, as the waveform providesminimal C/N requirements at a given spectrum efficiency.

In configurations where SFN combination of the satellite and terrestrial signals is notpossible, DVB-SH uses advanced complementary code combining techniques to secure additivereception of both signals. And in the case of terminals equipped with limited memory, the MPE-IFEC inter-burst protection handles the long interruptions of satellite channels.

Leveraging on the experience accumulated in the DVB project in developing market drivenopen standards for the provision of new services, and relying on the rich family of existing DVBstandards (DVB-H, DVB-S2, DVB-IPDC, etc.), the DVB-SH set of specifications allows thedevelopment of products and services for user terminals that can be easily operated in dualmode with other DVB-based similar services. In particular, making reference to the DVB-Hcase, and thanks to its satellite component, DVB-SH allows the extension of the present UHF-based service offer to other frequencies below 3GHz with a large area coverage, a reduced totalnetwork infrastructure cost and an expansion of the offer in terms of number of TV channels ormultimedia services.

ACKNOWLEDGEMENTS

The author of this article expresses his gratitude to the many persons having contributed to the DVB-SHstandard. In particular, M. M. Riccardo De Gaudenzi (European Space Agency), Christian Rigal andOlivier Courseille (Thales Alenia Space), Laurent Roullet (Alcatel-Lucent), Ernst Eberlein and HolgerStadali (Frauhnhofer Institute Erlangen) and Nghia Pham (Eutelsat) have provided numerous documentsfrom which he has largely borrowed. And he owes a special thank to Prof. Dr-Ing. Ulrich Reimers,Chairman of the Technical Module of the DVB, for his continuous support and friendly advice.

REFERENCES

1. Reimers U (ed.). DVB—The Family of International Standards for Digital Video Broadcasting (2nd edn). Springer:Berlin, Heidelberg, New York, 2004, ISBN 3-540- 43545-X.

2. Reimers U. DVB—the family of international standards for digital video broadcasting. Proceedings of the IEEE2006; 94(1):173–182.

3. Reimers U, Morello A. DVB-S2: the second generation standard for satellite broadcasting and unicasting.International Journal of Satellite Communications and Networking 2004; 22(3):249–268.

4. Morello A, Mignone V. DVB-S2: the second generation standard for satellite broadband services. Proceedings of theIEEE 2006; 94(1):210–227.

5. Faria G, Henriksson J, Stare E, Talmola P. Digital broadcast services to handheld devices. Proceedings of the IEEE2006; 94(1):194–209.



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6. ETSI TS 102 468(2007-11): Digital Video Broadcasting (DVB); IP Datacast over DVB-H: Set of Specifications forPhase 1.

7. ETSI TS 102 585(2008-04 ): Digital Video Broadcasting (DVB); System Specifications for Satellite Services toHandheld Devices (SH ) below 3GHz.

8. ETSI EN 302 583(2008-03 ): Digital Video Broadcasting (DVB); Framing Structure, Channel Coding and Modulationfor Satellite Services to Handheld Devices (SH) below 3GHz.

9. ETSI TS 102 584(2008-12 ): DVB-SH Implementation Guidelines.10. ETSI TS 101 191(2004-06 ): Digital Video Broadcasting (DVB); DVB Mega-Frame for Single Frequency Network

(SFN ) Synchronization.11. ETSI EN 301 192(2008-04 ): Digital Video Broadcasting (DVB); DVB Specification for Data Broadcasting (DVB-

DATA).

AUTHOR’S BIOGRAPHY

Philip Kelley is the Vice-President, Standards and Regulatory Affairs at Alcatel-Lucent Mobile Broadcast. Philip Kelley has more than 20 years of experience inTelecommunications and Information Systems, including positions in marketing andbusiness management within Alcatel, Thomson, McDonnell Douglas and Alstom. Heis a member of the Steering Board of the Digital Video Broadcasting consortium(DVB), Chairman of the DVB workgroup responsible for the design of the DVB-SHstandard, and Secretary General of the French ‘Forum de la Television Mobile’. Hejoined Alcatel in 1992. His previous responsibilities within Alcatel-Lucent include thepositions of Director, New Applications for the Mobile Communications Group,Business Development Director for Intelligent Networks and Director of Marketingfor Network Applications. He holds an engineering degree from France’s Sup’Aeroand an MPhil from Columbia University (New York).

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overview of the dvb-sh specifications

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