Guy Kewney

I have spent a week struggling with the concept of 'a phone' and 'a computer' and in the end, what originally seemed perfectly obvious has become a nightmare of confusion and doubt.

Take this device I'm looking at now - only 312MB of Ram, two relatively slow processors. Bundled software includes a photo editor, email, plus the ability to open most Microsoft Office documents, and on top of that, a built-in video camera capable of recording a couple of hours of 30 frames per second (fps) footage.

And what is this little marvel? It's the new Sendo X multimedia phone, which is a Symbian OS-powered device that's the size of a typical mouse or smaller, really.

Next to it is the device I've been using to do today's interviews. I've been calling people in China, California and Vancouver and just talking, making notes and interacting generally.

It has rather less Ram than the Sendo X phone at 256MB, but at least this is real Ram, not Flash, as well as eight hours of battery life. It's actually a Centrino notebook PC with an extra-capacity battery.

So, what's all this got to do with my nightmare? Well, it started because someone in China rang me in something of a panic.

"Our biggest rival in the phone business has just made all our hardware obsolete," he said, "And we'd like you to advise us on whether we should build a Wi-Fi phone."

The white paper I wrote for him ran to several thousand words, so I won't even try to summarise it here; but the problem I discovered while writing it was that there really isn't a way of making something that carries voice over Wi-Fi, without turning the thing from a phone into a computer.

The problem is power consumption. The radio in a mobile phone is pretty powerful and will happily communicate with a base station more than 20 miles away. The radio in a Wi-Fi system struggles to get a signal more than 100 yards.

So, something is badly wrong when the Wi-Fi system, with a far weaker signal, runs out of battery power first. But that's what happens.

The explanation is that Wi-Fi doesn't have a 'reservation' scheme. The thing is on all the time, full blast. It has to be, or the base station (access point) won't know it exists. And it uses maximum transmit power, because there's no way of turning the 'volume' down.

Some time in the future, this incredibly wasteful arrangement will give way to a different system. When the Wi-Fi device meets the Wi-Fi access point they will simply swap business cards, and agree to keep in touch. And then both will go quiet until one side or the other needs to send or receive data.

In much the same way as mobile phones do today, they'll use only as much transmitter power as it takes to reach the other one - microwatts, if that's all that's needed.

This technology is known as transmit power control, or TPC, and is already approved for one variant of Wi-Fi, the 802.11h standard. But nobody is actually shipping such a thing yet.

The future, however, isn't here yet. And there are, in fact, several Wi-Fi phones on the market.

Most of the ones sold have been bought by hospitals, because Wi-Fi works pretty well in that environment, and standard mobile phones are banned anywhere near the equipment that keeps patients alive.

And you can easily distinguish these things from the small, neat pocket-sized Nokias and Samsungs and so on, by the fact that where the typical mobile phone weighs around an ounce or two, these things weigh at least half a pound, often more. They have to, because that's how much battery you need.

Of course, these days, you can use a pocket PC as a phone. Toshiba, for example, recently announced its E800/805 with Voice-over-Internet, using the Wi-Fi radio.

But what do we mean by a pocket PC? Take a look at the Psion Teklogix Netbook. It's clearly a notebook: big screen, full-size keyboard, clamshell design. It's available with Symbian or Windows CE, not Windows. It's a pocket computer in everything but size.

It's perfectly feasible to make a Wi-Fi phone that weighs less than an ounce. You'd do it by taking a perfectly ordinary Bluetooth headset, fitting it with keypad and display, and 'pairing' it with another Bluetooth device in your pocket.

That second device would be a personal hub, along the lines of the personal mobile gateway invented by IXI Mobile. It would weigh rather more than a phone because it would be a dual-standard Wi-Fi and GSM radio, plus a fairly powerful PC.

In the neighbourhood of an open Wi-Fi port, it would use Voice-over-Internet to transmit and receive digitised voice; if all it could find was a GSM base station, it would switch.

Of course, it doesn't strictly need the keypad. A Bluetooth headset connected to a modern phone can use voice instructions to make and answer calls.

You can even get it to tell you who is calling, so you don't really need the display either. Does that make a Bluetooth headset a phone? Or a computer terminal? Or a computer?

Now perhaps you can appreciate my confusion. And unfortunately I don't think it's going to become much clearer.

Like this story? Spread the news by clicking below:

 del.icio.us     Digg this     reddit!