The decision announced this month by Dutch telco KPN to end its mobile broadcast service, MobielTV, based on DVB-H technology, seemed like the death knell for broadcast mobile services. This followed a series of other cessations of trials or services based on DVB-H after failure to gain sufficient levels of usage by subscribers, combined with the fact that it requires dedicated spectrum and infrastructure that could otherwise be distributed among more popular services. Indeed, KPN was considering reallocating its DVB-H spectrum to standard digital terrestrial (DTT) broadcast services and away from mobile communications altogether.
But while the KPN move does herald the end for DVB-H, there are signs that mobile broadcast itself will eventually come into its own. In one sense, DVB-H was ahead of its time in that it was deployed before mobile TV networks were capable of distributing sufficiently high-quality pictures, and before devices were capable of displaying them effectively. This seemed to be conformed when Qualcomm in the United States closed its mobile services based on a different broadcast technology called FLO, selling the resulting liberated spectrum to AT&T.
In the wake of these developments, a number of European operators are trying a newer technology called Integrated Mobile Broadcast (IMB), which they believe addresses the shortcomings of DVB-H and will drive increased customer interest in mobile TV as tablets become more ubiquitous. Three big operators of cellular networks, Vodafone, Orange and O2, have been trailing IMS in the UK, which is being watched closely by other service providers. For example, the Hong Kong quadruple-play operator PCCW has said it will deploy IMS services if the trials in the UK and Europe are successful, assuming that devices supporting the standard become available.
IMS emerged from the 3rd Generation Partnership Project (3GPP) and has been endorsed by the GSM Association. As well as offering broadcast services to customers, one of its strengths that DVB-H lacked is the ability to integrate seamlessly with traditional unicast or on-demand services over 3G networks. This is important because mobile TV, just like fixed-line Internet TV, will be delivered most efficiently via a combination of unicast and broadcast, with the best option varying not just according to the content, but also with time. A news channel might become quite popular during a major breaking story, but less so when nothing much is happening. At times of peak viewing, it would make sense to broadcast it so only a single stream is sent over any given link. But at quiet times, broadcast might consume unnecessary bandwidth over downstream links serving only subscribers who are not watching that channel at the time.
This ability to integrate broadcast and unicast was cited as a major advantage of IMB by Olivier Dhatel, director of mobile TV at Orange in France. Another advantage is that being based on the Universal Mobile Telecommunications System (UMTS), one of the 3G technologies, it can use existing cellular towers and antennas, which means it can be deployed gradually on the basis of demand rather than requiring a major once-off infrastructure upgrade like DVB-H. Finally, and perhaps most persuasively in Europe, IMB can run in a tranche of 3G spectrum called time-division duplex spectrum. This is already part of the 3G allocation under licences held by many European mobile operators, but it has remained largely unused because of a lack of appropriate technology. Currently, 3G TDD spectrum is available to more than 150 operators across 60 countries covering more than half a billion subscribers.
While the case for IMB remains to be finally proven, Dhatel believes that mobile broadcast will be resurrected in some form in any case.
“We still feel at some point we will need a broadcast technology in order to maintain quality of service when mobile TV gains mass market acceptance,” Dhatel said.
This attitude is not confined to Europe, or even the special case of Hong Kong. In Japan, interest in mobile broadcast is growing with the Radio Regulatory Council, an advisory panel to Japan’s Internal Affairs and Communications Minister Kazuhiro Haraguchi, recommending a consortium led by NTT Docomo to be the developer of infrastructure for a new system for launch in April 2012to broadcast music, sports, news and movies to mobile devices. The motivation there is to help mobile operators lift themselves out of a stagnant market for traditional mobile services; while in Europe, the mood is more positive in the light of booming tablet sales creating a critical mass of devices more suitable for mobile TV.