DVB-H Mobile TV flexible satellite distribution

Transcription

1 WHITE PAPER DVB-H Mobile TV flexible satellite distribution Abstract This white paper describes a number of the challenges facing largescale commercial deployment of Mobile TV (DVB-H). In order to achieve commercial success, a balance must be struck between the provision of more advanced and attractive services to increase revenue, and the cost of such provision. One of the most attractive ways to increase revenue is to provide localized content; however, this is also potentially highly expensive in terms of both bandwidth requirements and equipment costs. This white paper illustrates the flexible direct distribution architecture that offers the benefits of the lowest cost distribution model (typically satellite distribution) even when significant localized content is broadcast. UDcast - January 2007

2 TABLE OF CONTENTS 1. Introduction Challenges of Mobile TV operators Technical Challenges in the generic DVB-H chain Commercial Challenges DVB-H architectures Distributed Centralized Direct to Transmitter Local content revenues and impacts Introducing the Flexible Direct to Transmitter architecture Case study Assumptions Comparison of architectures Conclusions About UDcast UDcast - January 2007

3 1. INTRODUCTION The TV has been one of the most successful products to be developed during the second half of the 20th century. Certainly it has become a major part of our leisure time, with the average American consumer watching about four and a half hours per day (source Nielsen Media Research 2005) and the average European only slightly less. Yet, unlike its simpler predecessor, radio, it has struggled to be successfully used in a portable environment. As the photos illustrate, battery powered portable TVs have been around for years in various forms; nevertheless, they have not really caught on. Particularly when it comes to watching TV on the move, numerous problems with the products offered - such as short battery life and large and vulnerable antennas - have resulted in low take-up despite all the millions spent in development and advertising. However, the advent of comparatively cheap and low power LCD screens and improved battery technology has meant that in the last few years portable devices such as PDAs, DVD players or games consoles have been rather more successful. High-speed wireless technologies such as 3G mobile telephony have permitted video calls with high-bandwidth data and hence, in theory, the ability to watch live TV on the move. This capability has come at the cost of limited scalability, as the 3G video session is always a unique one-one connection rather than the one-to-many service that is required for a broadcast. As a result of the combination of the DVB-H (Digital Video Broadcast - Handheld) standard - explicitly defined for broadcasting to mobile devices - with these recent technical developments, mobile TV is now looking far more attractive than any time before. Yet while DVB-H works well in the handset, it presents a certain number of challenges for the operator seeking to deploy a broadcast on a large scale, something that must be done if mobile TV is to reach a mass audience. 3 - UDcast - January 2007

4 2. CHALLENGES OF MOBILE TV OPERATORS Because DVB-H is a broadcast technology operating in licensed radio frequencies, at least part of its challenge stems from the need to balance its spectrum requirements with those of other broadcasting services. DVB- H is largely adapted for the UHF ( MHz) spectrum, but it is also possible to deploy it in the L (1.67GHz) and S (2.2GHz) bands. The UHF bands offer excellent penetration of buildings and hence the largest cell size, but these frequencies are currently not available everywhere in the world. The optimum coverage of dense urban areas will in any case require significant investment in transmitters in order to achieve the required level of signal strength and quality. DVB-H, by reusing much of the previously defined DVB- T standard, is also able to reuse part of the equipment and planning set-up of DVB-T broadcasters; however, because DVB-T is not intended for mobile use, issues such as handover between broadcast zones and reception quality of the built-in antenna receivers do not apply. The distribution supplying content to the towers must be carefully engineered, and this adds to its cost and complexity. In the ideal world every tower would be easy to connect to via terrestrial distribution links, but this is not always possible since the preferred broadcast locations (hilltop towers and the tops of buildings) are not usually the sorts of places that have a ready-laid link TECHNICAL CHALLENGES IN THE GENERIC DVB-H CHAIN The key technical challenge for DVB-H is that within an SFN (Single Frequency s) all towers must broadcast the identical signal to within 100ns accuracy. This stringent requirement means that the latter part of the distribution path must be totally deterministic, up to every single bit transmitted. Although not as stringent in its requirement for synchronization, the rest of the distribution path also benefits from having as similar a path as possible, especially to transmitters in the same SFN. And beyond the boundary of the SFN, issues such as handover from one SFN to another (MFN handover) can be engineered to be smoother when the signals are deterministically related to each other. In the illustration below, loss-free handover is illustrated by the way that the wheel is transmitted by the two SFNs. The blue cell is broadcasting the left half then the right half, while the red cell broadcasts the middle first and then the edges. This means that handover from one to another can be performed with no loss of image. However, significant planning and coordination are needed to ensure that this occurs, and this is simpler when the paths through the distribution s to the adjacent SFN areas are similar. 4 - UDcast - January 2007

5 Probably the best way to ensure that such smooth handover is achieved is to have a centralized, hierarchical distribution made up of common equipment at each level and broadcasting a common signal throughout. However although it simplifies the technical design, a single signal has a number of commercial (and possibly regulatory) drawbacks, as it removes the possibility of localization COMMERCIAL CHALLENGES In addition to the technical issues, there is also the question of commercial viability. The two main sources of revenues from the DVB-H services are subscription fee and advertising revenues. The results of numerous customer trials show the high willingness of mobile users to pay for the Mobile TV service (50-70% of trial participants declare satisfaction, as well as the interest in paying for the service), and this seems to be confirmed by the initial success of the first commercial deployments in Italy and Finland. First and foremost, subscribers are looking for a similar programming experience to that from traditional TV. This includes the availability of local TV stations, regional news, and coverage of regional sports events. Then, as an additional step, the subscription value can be increased by providing locally adapted services; for example, weather and traffic news that is specific to the area that the watcher is in, not to the whole country. Traditionally TV business rely on advertising revenues, thus the combination of both subscription and advertising will guarantee an adequate revenue level. In order to preserve an adequate revenue level, advertising revenues are likely to become critically important. Currently, many TV stations around the world are offering regionalized advertising so that the same 30 seconds of prime time advertising slot can be sold to different clients in the various regions. That brings in new advertisers by enabling smaller local businesses, which do not wish to pay for a national advertisement that will be wasted on viewers who are not potential customers, to still place their TV commercials on topprofile national channels. With a reasonable number of regions, the total revenue for the TV station may well be significantly higher than with a single national advertiser. National advertising can also take advantage of localised spot broadcasting, by adapting spots to local requirements. This could be contact information for outlets in the area where the advertisement is being shown, or different choice or presentation of products depending on local preferences or demographics. The latest multimedia technologies, when combined with various "canned" advertising services, are now making the cost of creating video advertising extremely attractive. Local video advertising, significantly less costly than a national campaign, massively increases the potential advertiser base, enabling a muchimproved advertising sales pitch. Hence the potential for localization greatly increases the commercial viability of the DVB-H service. DVB-H seems likely to share the audience with the FM radio services more than anything else, by providing both video and audio content. It is worth noting that 5 - UDcast - January 2007

6 local radio business model is driven by local content - announcements of local events, local traffic reports and so on. There may in fact be regulatory issues that drive this - such as a requirement that local affiliates or regional studios provide some of the programming - but even if this is not the case, advertising content is also a strong driver for local content. The recent advances in IPTV and cable TV are changing the shape of advertising industry, by introducing the Addressable Advertising concept, with higher and higher resolution of addressability of the audience, and future Mobile TV s will be required to cope with the new advertising standards. However, localization has a significant impact on the sort of architecture to be employed. 3. DVB-H NETWORK ARCHITECTURES 3.1. DISTRIBUTED SFN Cell Contribution SFN Distribution IPE Manager IP SFN DVB-H + MIP SFN imposes synchronized outputs The traditional distributed DVB-H architecture has an IP Encapsulator per region (or per SFN), which receives content via the contribution IP. The distribution is then used to distribute the MPEG-2 Transport Stream to the modulators within the local SFN cells. The distributed architecture lends itself well to local programming and is similar to the of a cellular phone operator. The IP contribution is designed to reuse any of existing and inexpensive IP multicast backbones. Thanks to the possibility of aggregated management of multiple s with only a single IPE Manager console, the entire system is very easy to configure and control. At the same time, though it requires advanced and separated distribution s for the transport streams within each SFN cell. 6 - UDcast - January 2007

7 3.2. CENTRALIZED SFN Cell IP National Distribution Cell Distribution IPE Manager SFN DVB-H + MIP In the centralized architecture, there are no external contribution s, but the distribution is thus considerably larger and more complex. The centralized architecture does not directly rule out localization of the content, but it is clearly optimised for centralized content. This architecture is similar to national broadcasting s today. The IP Encapsulation is managed at the national head-end, and the each transport stream need to be distributed nation-wide via dedicated data links. Because of its centralization, it is relatively simple to engineer, but the terrestrial distribution it is not much less expensive than the distributed architecture. 7 - UDcast - January 2007

8 3.3. DIRECT TO TRANSMITTER SFN Cell National Distribution only Distribution Contribution DVB-H + MIP IP SFN IPE Manager "Direct to Transmitter" is the logical extension of the centralized architecture. Rather than using a terrestrial distribution, the encoded signals are transmitted via satellite to all transmission towers. This architecture is much less expensive to deploy in terms of capital expenditure since the distribution is simply a single satellite, but localization is difficult to introduce without sending multiple separate high-bandwidth streams to the satellite, drastically increasing the operational costs of the. 4. LOCAL CONTENT REVENUES AND IMPACTS In order to understand the impact local content has on the different architectures (distributed, centralized and direct to transmitter) it is perhaps worth looking at them visually. The addition of local content makes the distributed and centralized architectures rather similar in terms of impact on the components, as the two images below illustrate. Regional or local content SFN Cell SFN Cell Contribution SFN Distribution IP SFN National Distribution Cell Distribution IP SFN IPE Manager SFN DVB-H + MIP IPE Manager A full TS per SFN cell DVB-H + MIP distributed with local content centralized with local content 8 - UDcast - January 2007

9 Content for the two s follows a similar path but, since there are differences about where the aggregation occurs, the size of the distribution and contribution s differs. In the centralized model local content must be brought to the central location for encapsulation and subsequent distribution, thus requiring a high capacity distribution. The direct-to-transmitter model is an extreme example of centralization and, although it is technically elegant, it suffers from one simple practical problem. Each local area requires its own expensive satellite bandwidth for the entire MPEG2 Transport Stream, even though in most practical cases 80-90% of its content is national and thus shared between all areas. Obviously the degree of localization affects very strongly the distribution cost, and since every stream incurs the same bandwidth charge the total could range anywhere from 10- to 100-fold that of a single stream. Contribution IP IPE Manager SFN SFN Distribution A full TS per SFN cell DVB-H + MIP & demux & demux & demux & demux SFN Cell An initial nationwide roll-out using the direct-to-transmitter model would at first sight make sense, since the capital expenditure would be so much reduced; however, introducing localization in order to bring in local content to satisfy viewers and maximize potential advertising revenue is very hard and expensive using this model. In the typical mobile TV broadcast service one might expect 80% of the content to be common nationwide with perhaps 15% being regional and 5% local to a particular urban areas. In the traditional direct to transmitter model supporting such content, the cost of the capital expenditure and ongoing operational costs required to implement it are very high. Thus the rollout of local TV services (local channels or advertising) is problematic from the cost perspective in all traditional centralised DVB-H models. 9 - UDcast - January 2007

10 5. INTRODUCING THE FLEXIBLE DIRECT TO TRANSMITTER ARCHITECTURE The ideal solution is to use the direct-to-transmitter approach but introduce in the path at each transmission tower some device that is able to remove selected content from the IP encapsulated MPEG2 Transport Stream not required for the local area, and then regenerate the stream without it. The creation of such a adaptation device is far from straightforward, requiring intimate knowledge of both satellite transmission and DVB-H. That combination of specialities is one that UDcast, uniquely, possesses. IPE Manager Synchronous isplicers regenerate the content Distribution isplicer SFN Cell Contribution isplicer IP One TS Aggregates national + local content isplicer isplicer UDcast has developed the patented UDcast isplicer adapter (the 'i' in the name stands for isochronous), which allows for the synchronous, completely deterministic regeneration of the encapsulated stream. The result combines the low capital and operational expenditure offered by satellite transmission with not only the content flexibility of the distributed model, but also the synchronization and handover advantages of the centralized model. Moreover, UDcast's unique background and long involvement with both DVB-H and satellite distribution mean that their new solution is assured to function correctly despite the innovativeness of the technology. In this unique solution, a single transport stream is created by the IPE, which contains all the local content for all regions as well as the common national data. The stream is completely standard except for some additional in-bound control, added to the PSI/SI metainformation, which identifies which cells particular local content is destined for. However, it has to be noted that since the transport stream includes all the content for all areas it consumes more encapsulation bandwidth than would be the case if the encapsulation included only the content that can be broadcast by a single DVB-H transmitter. The isplicer filtering algorithm uses the modified PSI/SI information to identify which parts of the stream are to be discarded, and reconstructs the stream so that it comprises only relevant content. The filters perform this task in real time in a completely deterministic fashion so that not only are the 100ns timing requirements of DVB-H adhered to, but the synchronization between different towers is also guaranteed UDcast - January 2007

11 6. CASE STUDY In order to illustrate the advantages of the flexible direct-to-transmitter model, it is probably best to use a case study with cost structure representative of each architecture. The example presented is based around the requirements for a country similar in surface and size of the population to France. It assumes that DVB-H is rolled out to cover 2/3 of the population, which corresponds to about 1/3 of the surface area of the country. The costing used is conservative in terms of pricing and is not intended to be anything more than an indicative one suitable for comparison. The case study makes revenue assumptions based purely on subscription income, assuming that the service deployed by each operators is taken up by 18.75% of the total addressable population. Advertising and increased subscription revenues would clearly be in addition, and it is not taken into account in this comparison for sake of simplicity UDcast - January 2007

12 6.1. ASSUMPTIONS The ideal solution is to use the direct-to-transmitter approach but introduce in the path at each transmission tower some device that is able to remove selected content from the IP encapsulated MPEG2 Transport Stream not required for the local area, and then regenerate the stream without it. The creation of such a adaptation device is far from straightforward, requiring intimate knowledge of both satellite transmission and DVB-H. That combination of specialities is one that UDcast, uniquely, possesses. Market Assumptions Equipment costs Urban Area 354 IPE (cap) 30,000 Surface km 2 (op p.a.) 3,000 Cell Surface 497 km 2 Direct Equip 10,000 Cells (local content areas) 100 (cap) (op p.a.) 1,000 Transmitters &/ Cells 25 Tx + Amp (cap) 70,000 Target Population 39 Million (op p.a.) 8,300 Content : National Regional Local 8 Mbps 1.5 Mbps 0.5 Mbps Satellite Uplink (cap) (op p.a.) 100,000 10,000 Annual Fee Per User 100 Sat (B:w (p.a.) 150,000 per Mb Market Share 18.5 % Revenue Million As noted above, the estimated revenue is calculated from the subscription income alone. Further details of precisely how the various equipment costs have been estimated and how the different s have been priced are available from UDcast upon request UDcast - January 2007

13 6.2. COMPARISON OF ARCHITECTURES The table below shows the costs of capital (CAPEX) and annual operational expenditure (OPEX) required for the different architectures. The total annual column consists of the operational cost plus the amortized capital expenditure spread over four years. The subscription revenue % column then takes the total annual cost as a percentage of the annual subscription revenue ( Million). Capex ( 000) Opex p.a. ( 000) Total annual ( 000) Subscription Revenue % Distributed (no localization) Distributed (with localization) Centralized (no localization) Centralized (with localization) Direct (no localization) Direct (with localization) Flexible Direct (no localization) Flexible Direct (with localization) 185,270 39,935 86, % 185,270 39,935 86, % 181,558 39,910 85, % 211, , , % 105,130 12,013 38,296 5 % 135, , , % 105,823 12,013 38,469 5 % 105,823 24,869 52,325 7 % The traditional distributed architecture is the most flexible one, representing no increase in the cost independently of the availability of local content. An additional further decrease of cost is possible through the direct to transmitter architecture. The use of satellite distribution compared to terrestrial distribution is a clear winner in both opex and capex terms, so long as there is no wasteful repetition of bandwidth. Since the direct-to-transmitter architecture is convenient, presents clear advantages from an ease of synchronization perspective, and is similar to current methods of distribution, this ought to be a very attractive model. Unfortunately, a requirement for local content ruins the architecture's effectiveness because, while its capital expenditure remains low, the operational cost skyrockets due to the requirement to send multiple copies of the same data over expensive satellite links. Fortunately, the flexible direct architecture is able to offer the same low capital and operational costs as other satellite technologies while offering similar local content capability to the distributed architecture UDcast - January 2007

14 7. CONCLUSIONS The simplicity, synchronization advantages and low capital investment required for the satellite architectures mean that deployment of such direct-to-transmit s is very attractive from a commercial perspective. However their great drawback - the apparent requirement for centralized content - has previously meant that operators would be locked into a centralized business model even if, as seems likely, offering of custom local content would increase their customer satisfaction and revenue. Fortunately the "Flexible Direct" architecture, based on the DVB-H isplicer technology, allows the low costs of satellite distribution to be combined with the flexibility of the terrestrial distributed architecture. Not only does this increase ROI, it also reduces the risk of misreading the requirement for local content. ABOUT UDCAST UDcast is the leader in the DVB-H IP Encapsulation providing its s, as wells Mobile TV transmission (DVB-H isplicer) and monitoring equipments to 70% of global DVB-H deployments and trials. The solutions of UDcast are deployed in the countries like USA, Finland, France, UK, Spain, Italy, Germany, Netherlands, China, Hong Kong, Singapore, Taiwan, Philippines, Indonesia, Malaysia, Vietnam, India, Australia, and South Africa. The equipments and technologies of UDcast are selected by Nokia, Motorola, Alcatel-Lucent, Harris and other global Mobile TV integrators as part of their commercial solutions. UDcast has been at the forefront of DVB-H development from the very beginning, and was involved in the standardization process through ETSI, as well as in the development and standardisations of protocols enabling satellite IP communication UDcast - January 2007

15 AUTHORS Dr Antoine Clerget Dr Luc Ottavj Filip Gluszak CONTACT UDCAST Headquarters: 2455 route des Dolines BP Sophia Antipolis Cedex FRANCE Tel. +33 (0) Fax. +33 (0) For more information please visit our website: UDcast - January 2007

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