ZigBee's unfinished symphony

Rupert Goodwins: A new home networking standard promises much, but something odd's happening behind the scenes.

How do you launch a new networking standard? Once, they just arrived on the desks of engineers. Now networking is part of everyone's lives and even Dixons' sales staff have heard of 802.11, that's no longer good enough. The ground has to be prepared, the marketing message tuned and the product ready to go when people know they want it. It has to have a name, not just a number -- Gigabit Ethernet, Wi-Fi, Bluetooth. And now, say hello to ZigBee.

Also known as 802.15.4 to its friends, ZigBee comes from people like Philips, Motorola and Mattel -- yes, Barbie and HotWheels Mattel -- which should give you a clue that it's not something that Cisco's going to build into its carrier-grade backbone routers anytime soon. ZigBee is a 20 to 200kbps, 800MHz, 900MHz and 2.4GHz wireless networking protocol that's aimed at home control, low-speed computer peripherals, toys, PDAs and other battery-operated devices.

To that end, it's designed to be simple, cheap and very low power, with a ZigBee device running from six months to two years on a pair of AA batteries. The high speeds only work over 10 metres or so -- up to 75m if you use the lower speeds -- but nodes can form a mesh, repeating signals between themselves to give you a much longer range.

ZigBee looks like a good idea, for all the same reasons that Bluetooth initially looked like a good idea. "It's not a network," said the Bluetooth bods at launch, "it's a cable replacement." But nobody was quite serious enough about the non-network bits, and the standard was too complex to be cheap and reliable quickly enough. Things are being sorted out now, yet we're a long way from the five-dollar Bluetooth chip in every mobile phone. ZigBee may escape that fate, not least because the ZigBee hive mind has been watching Bluetooth and taking notes. They seem to be asking the right questions. Unfortunately, they seem a little uncertain about answering them.

The major concerns for any new wireless network are security, coexistence, performance and cost. ZigBee security is particularly fascinating, because the combination of mesh mode and household control raises the possibility that a hacker 20 doors away could set up a wormhole through all the intervening ZigBee nodes and turn your lights out at the most inopportune moment. Coexistence -- well, you remember the fuss about Bluetooth and 802.11b interfering with each other? ZigBee's got to cope with both those standards and the forthcoming 802.11g 55Mbps. The last thing you want is your TV refusing to accept commands from your remote just because next door's downloading another 10MB Windows update. But who to ask?

It's at this point that things got a bit silly for this intrepid hack. A quick Google search showed that the main Web site was www.zigbee.org, thoroughly passworded. Some other references on the Web produced a couple of plausible email addresses within Philips, Motorola and Honeywell, so off went the emails. That was two weeks ago, and I've yet to get an answer to any of the questions -- everyone seems friendly, but there's always someone else who's better equipped to answer my queries, and they'll be along later.

Back to Google, and a quick rootle through the cache reveals that zigbee.org wasn't always closed. Perhaps it got shut because the members-only area, containing many internal and confidential discussions, wasn't always closed either. Meeting minutes as recent as June this year are available to those who are churlish enough to peek. I admit it. I peeked.

So. Here are the answers nobody could give me. Security? Wasn't even started until March this year, progress has been slow. Coexistence is being investigated, but there are no hard facts -- people are worried that "802.11 has the concept that they 'own' 2.4GHz" and "IEEE politics" might get in the way. Lots of technical details, like how to do the low-speed mode, the mesh stuff and the programming model, are still being mulled over. And the marketing? They're worried about that too. There's been a big increase in interest, apparently, but this has been mostly "accidental". And the Web site is "very poor". That's from one of around thirty documents: there are nuggets in each.

All absolutely typical of a work in progress, but something that sits uneasily with reports elsewhere that silicon is almost ready and ZigBee is just about cooked. At least this time we can see the loose ends, rather than find them out over years of frustration a la Bluetooth, but this is hardly the stuff of a rock-solid marketing machine on top of its game. I'd be surprised if we saw any ZigBee kit until at least this time next year. But I look forward to the next big tranche of internal documents finding their way onto the Web. Now, that's what I call networking.

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