If you have ever enjoyed frustration-free, satnav assisted drives or the hissing serenade that preceded an important fax, then you can thank the city with no street names - Tokyo.

A capital city without road names is a huge handicap. Collectively, the Japanese (especially trainee post workers) and bewildered visitors have spent decades lost in Tokyo's labyrinthine arteries - most, literally, without a name.

But rather than just name the streets and number the buildings, the locals had a uniquely Japanese answer to the problem: improve an existing technology, in this case the fax, to send maps and directions to visitors. In the 1980s Japan shrank fax machines, making them popular and affordable, and later repeated it with the satnav to ease the headache of getting from A to B.

Alas, Tokyo's complex subway still remains a challenge even to residents, something your correspondent pondered while making his uncertain way to a laboratory in western Tokyo. The lab is home to the Tokyo Ubiquitous Network Project, where scientists are planning a computer infrastructure that they say will fill such information gaps for good and enable us to give our maps, guidebooks and A-Zs that longed-for heave-ho.

Heading the project is Tokyo University professor Ken Sakamura -who, with the aid of the Japanese government, is well on his way to building the world's first truly public ubiquitous computer network. It's "an infrastructure for the 21st century", he says, adding that it will see our everyday landscape guide us, inform us and generally hold our hand in an increasingly puzzling world.

Sakamura foresees scenarios resembling those in the film Minority Report, where the hero passes intelligent ad boards and shops in the mall which acknowledge him by name and try to flog him stuff. However the real-life version, in Japan at least, will be less intrusive, Sakamura insists.

Complete control

"With this system the user is in complete control. As a user of such a network we will see our enviros us," Sakamura says. "We seek only to chip or tag objects and the environment, never people. With this system you can choose to read which you wish. The ubiquitous communicator - the pocket device you use to read the information around you - can only read and write, which means your identity is protected."

Japan's government sees enormous benefits from making every object readable this way. Improved guidance for the blind is one, painless interactive guidance for the tourists Japan desperately yearns for is another, and even salarymen and befuddled gaijin reporters trying to get around hostile cities will benefit from the scheme. Working with Sakamura's outfit and Japan's top technology companies such as Hitachi, the country's Information Ministry has just spent ¥1bn (£4.2m) on a month-long field trial that covered several blocks of the famousGinza shopping district.

During the trial last month, PDA-style communicators were handed out to reporters and tourists, who were then free to wander around picking up information on their PDAs as they went.

Anyone emerging with a communicator at the Ginza metro station, for example, had a 3D, real-time image of the landscape above them beamed to their PDA, making it a cinch to see which exit you might want if you were headed, say, for the Mitsukoshi department store. Head towards the store itself and RFID tags in the building sense your presence then zap to your PDA a woman's image welcoming you to the store. To learn more about this Tokyo landmark's history, touch the screen.

In the future, commercial applications could include pushing you news of sales if you have registered interest, or even digital money-off coupons to tempt you inside.

Getting commerce involved is important, says Sakumura, as the cost of building the infrastructure will be gargantuan. The pilot scheme used a variety of electronic tags that can transmit information; some of which are tiny and cheap, such as Hitachi's sand grain-sized passive RFID tags. Other infrared tags, which can beam out signals at longer ranges, are more expensive. Add this to the cost of installation and many trillions of yen will be needed to build, install and maintain a truly ubiquitous network, says Sakamura. "Ginza used only a thousand tags and that cost ¥1bn."

The Ginza trial also highlighted some of the technical and security issues that have yet to be dealt with. Teething problems included cross-interference from illegal radio transmitters, as well as difficulties using the rather bulky prototype reader. "In the future the job of the reader will be done by your mobile phone, using a remote server," Sakamura says. "There are also still some regulation issues and security issues to iron out - one prankster even managed to slip in his own tag on to a Ginza lamppost that led readers to a porn site."

Double-edged sword

If ubiquitous networks are going to take off, Japan is surely the place to watch. The nation has already primed itself by accepting RFID tags - tracing the provenance of food, or in "smart shops" that chip their clothes for ease of inventory and to satisfy customer queries instantly. Even children are chipped "for their own safety" - raising, of course, questions of privacy. Surely there will be more abuse of tagging in a ubiquitous computing world?

"Yes, the technology is a double-edged sword," says the professor. "For example, ubiquitous networks will be great for teleworking, working from where you like with a small terminal linked to embedded computers or multiple tags linked to a big server, but it also means the boss knows exactly where you are. But as long as you the user agrees to reveal such information or can choose to withhold it, we will be OK."

Clearly, one benefit of the project is the embedding of tags in existing "tactile walkways" - such as bumps at the side of the road indicating a pedestrian crossing - for the blind. Sakamura demonstrated in his lab how a white cane equipped as an RFID reader could become a directional sensor, interacting with information being beamed by the tags embedded in the street.

Adding extra details such as announcing the distance across the street at a road crossing and flagging up hazards such as stairways are also part of Sakamura's project that the government hopes to have in place in Japan's streets within the next five years.

With an extra 10,000 tags planned to be dotted around Kobe and Tokyo before the end of the year to kickstart the new information infrastructure, other fully functioning guidance and information systems will not be far away.

"Just as we built up roads, the next step in civilisation is to build a total information network that will form part of the fabric of things around us," says Sakamura.

His vision is of all physical objects embedded with microcomputers with communication capabilities, sensors, actuators and so on, to supply us with location specific information. "They will operate in a concerted manner, processing, exchanging information with each other within the ubiquitous computing architecture. Making available location-specific information anytime, anywhere, to anyone."

You might still find some things are lost in translation, but perhaps you wouldn't be lost in Tokyo ever again.

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