At the moment, mobile TV is mostly streamed over 3G networks. But sending an individual data stream to each viewer is inefficient and will be unsustainable in the long run if mobile TV takes off.【F1】
So the general consensus is that 3G streaming is a prelude to the construction of dedicated mobile-TV broadcast networks, which transmit digital TV signals on entirely different frequencies to those used for voice and data.
There are three main standards: DVB-H, favoured in Europe; DMB. which has been adopted in South Korea and Japan; and MediaFLO, which is being rolled out in America. Watching TV using any of these technologies requires a TV capable handset, of course. Although several new models were unveiled in has Vegas this week, no such handsels are yet available in Europe or America, and few in Asia.
In contrast, watching downloaded TV programmes on an iPod or other portable video player is already possible today.【F2】
And unlike a programme streamed over 3G or broadcast via a dedicated mobile-TV network, shows stored on an iPod can be watched on an underground train or in regions with patchy network coverage.
That suggests that some shows(such as drama)better suit the download model, while others(such as live news, sports or reality shows)are better suited to real-time transmission, notes Michelle de Lussanet of Forrester, a consultancy. The two approaches will probably co-exist. Future iPods may be able to receive real-time broadcasts, while mobile handsets will be able to store broadcast content or download it from PCs or PVRs for later viewing.
Just as there are several competing mobile-TV technologies, there are also many possible business models.【F3】
Mobile operators might choose to build their own mobile-TV broadcast networks; or they could form a consortium and build a shared network; or existing broadcasters could build such networks.
Some channels will be given away for free, while others are for paying subscribers only. The outcome will vary from country to country, depending on the regulatory environment and the availability of spectrum.
The big question is whether the broadcasters and mobile operators can agree how to divide the spoils, assuming there are any.【F4】
Broadcasters own the content, but mobile operators generally control the handsets, and they do not always see eye to eye.
【F5】
In South Korea, a consortium of broadcasters launched a free-to-air DMB network last month, but the country"s mobile operators were reluctant to provide their users with handsets able to receive the broadcasts, since they were unwilling to undermine the prospects for their own subscription-based mobile-TV services.