Mobile TV's picture still fuzzy

One of the trends that is sure to attract a lot of attention at the mobile industry's biggest trade show, 3GSM, next week is the concept of delivering TV to handsets. But there are three questions mobile TV must answer before it has a chance of success. Does anyone want it, can it be made to work reliably and will it make money?

These are questions to which nobody knows the answers — least of all the people who failed to ask the same questions of 3G before investingbns. Yet these are the people who are keenest to sell TV on mobile phones and PDAs to the masses.

History isn't kind to the idea of mobile TV. Pocket TVs were first promised in 1966, first available in 1977 and first affordable in 1988: by 1999 most of the manufacturers had lost enthusiasm for the market. Most pocket TVs are bought in a mild gush of gadget desire and then left in a drawer until the batteries leak.

On the other hand, the Sony PSP and the video iPod have made the small screen sexy again: with mobile phones fully equipped to display telly on the move, the only thing that can stop operators pushing the service is if nobody wants it.

Maybe not even then. There have been a spate of user trials, with mixed results. With so many variables — content, number of channels, handset type and technical characteristics of each broadcaster are different each time — there is no easy way to compare even those trials in one country, let alone those around the world.

In the UK, O2's trials saw between three and five hours of TV consumption a week, but BT/Virgin Mobile could only clock up just over an hour — and a marked reluctance to spend more than a fiver doing so. So an operator determined to find evidence that mobile TV is a good idea will be able to do so — and with the fear that everyone else is doing it, that determination will be easy to conjure up.

In an ideal world, mobile TV would be just another digital service delivered alongside connectivity and voice over the existing 3G system. Unfortunately, the bandwidth demands it makes are well beyond any current or projected network capacity: even with full HSDPA, a 3G system will be saturated if half the subscribers watch just seven minutes a day.

Put another way, five minutes of TV a day takes as much bandwidth as 2,000 minutes of voice a month — but will never be able to generate an appreciable fraction of the revenue.

Any viable mass-market service will have to use another band to broadcast its signals, so that one transmission reaches hundreds or thousands of subscribers. And while mobile TV needs much less spectral space than existing telly — because it can use more efficient digital encoding and because it can be optimised for the much smaller screens of hand-held devices — finding the right spectrum is one of the hardest problems to solve.