Zigbee, the short range, low data rate wireless communications standard, will come to the market cheap and quick, according to Bob Heile, chair of the Zigbee Alliance - which has just published its specification.

The basic Zigbee specification - an implementation of the IEEE 802.15.4 standard - has been ratified by the ZigBee Alliance standards group (PDF press release). There could be Zigbee-certified products as soon as the end of January, and single-chip Zigbee parts costing less than $5 during the first quarter of 2005, according to Bob Heile, the chairman of the Alliance.

Other Zigbee proponents include Bob Metcalfe who, as a venture capitalist, has money in the standard's prospects.

"It won't kill Bluetooth, but it might replace it"
"Analysts are predicting between 5 million and 50 million Zigbee devices in the first year," says Heile. "I think we'll do some number in between." Zigbee is so new, analysts don't know how to rate it: "It'll be bigger than a breadbox, and smaller than a house," jokes Heile.

The standard is intended for wireless controls, of heating, lighting and security, and any other communication job that can be done with a short-range, low-power, long battery-life device. Its 250 kbit/s speed might sound slow, but with great sloth comes great battery life (as Stan Lee might have put it). And a long battery-life is vital for devices that will be fit-and-forget. "You don't want a bigger power drain," says Heile. "You don't want to go back to that device ever again."

"250 kbit/s? For sensors that's a lot of bandwidth," says Heile. "Go slower. It's simpler." The market for sensors is so big that it is worth developing something that meets its needs exactly, he explains. There is no need to adapt something designed for a slightly different need. "It's an enormous space, with enormous potential. It's worth developing something optimised for it."

With that space, Zigbee does not have to displace other standards, but will co-exist with them. Although it can do much of what Bluetooth does (see below), Zigbee is not gunning for the older standard. "Bluetooth would have to fail on its own merits," says Heile. "Then Zigbee could move in from the lower end, and 802.11 from the higher end. If it does a good job on synchronisation and headsets, Bluetooth won't go away."

Of course, if it did, then 250kbit/s would be fast enough for a phone headset, if QoS was provided...

Standards progress
"We said we'd have a specification completed by the end of 2004," says Heile, and the alliance has now got a standard for the communications stack. Now he wants to move to the next phase - setting up testing methodologies, interoperability tests, and getting groups to work on specific Zigbee applications.

But these will be on-stream very quickly, as prototypes are used to test the test methodologies. "We're 90 percent there, and will finish our conformance test methodology in thirty to sixty days," says Heile. "Round about the end of January."

After that, the Zigbee brand will be enforced as tightly as that for Wi-Fi. "Any Zigbee device will have to go through a test house and what we call an 'unplug' fest," says Heile. "We will have those quarterly, or more frequently if necessary."

With a Zigbee fest coming in Monterey, California, in the middle of January, this means that products could be earning their Zigbee badges by early February, says Heile: "in the first quarter of 2005, for sure".

Zipping down the price curve
Will there be products to brand? Oh yes. "The specification has been reasonably stable for months," says Heile. This has allowed some companies to jump the gun, and come out with "Zigbee-ready" devices. One impressive example is a phone which was shown at a Zigbee festival in Korea earlier this month.

But this is the exception. Most of the early branded products will be generic Zigbee platforms, much like NIC cards, intended to be built into other devices and systems. And they will tumble in price.

Heile knows three silicon vendors that will have single-chip Zigbee units, costing less than $5, in the first quarter, and this will fuel the take-off. "I'm amazed at how fast it's come down the price curve," he says. "It is coming out of the gate at $5."

And, since it uses the same 2.4GHz band, Zigbee and Bluetooth will be combined in single chip implementations: "We don't need an extra radio, we sneak in and grab cycles," says Heile. It is then a tiny incremental cost to add Zigbee to any device that has Bluetooth.

Zapping lights and drinks machines
As Zigbee develops, applications will be built; the most popular could be standardised and "Alliance approved". For some reason, the most quoted Zigbee example is an interface to control lighting, which will need its own user interface developed.

These application standards will be somewhat like Bluetooth profiles concedes Heile, but will be much easier to define: "Zigbee has been architected to make it easier to build solutions. With 20-20 hindsight, we did it more carefully." The Zigbee stack is one tenth the size of the Bluetooth stack, he says.

Other applications will include security as well as heating, ventilation and air-conditioning (HVAC).

In the longer-term, Heile expects Zigbee to be built into mobile phones (using those dual-function Zigbee-Bluetooth chips) and used for almost everything - controlling the environment at home, unlocking doors and buying things from vending machines.

"The phone manufacturers want you to use that phone for everything," he says. "They don't want you to put that phone down." Other devices that control Zigbee-enabled systems will be subsumed into the phone, he explains.

This sort of application was envisaged for Bluetooth, but never really emerged, he explains. "Bluetooth has a longer network join time. It takes too long to associate, and when there are many people it causes confusion." Zigbee associates in 30ms, fast enough to make it quicker to use a phone than put a coin into a vending machine.

Some phone manufacturers are talking of using Near Field Communications to connect phones to transactions, but Heile believes NFC is just a gateway. "NFC devices need to be in contact," he explains. The server will use NFC to treat the phone as a hardware token, establishing credentials and then passing the communications to a protocol of choice which - he believes - will often be Zigbee.

Learning from the past
Zigbee's fast take-off will be due to experience gained elsewhere. Bluetooth is about six years old, and when it was launched, the idea of mixed-signal chips combining radio and digital signal processing on one chip was unheard of.

Its security architecture also learns from the past, anticipating the need for security and setting up communications that do not compromise it. "Zigbee does not pass MAC addresses," says Heile. "We guarantee there is no man-in-the-middle attack."

Zigbee for IT
For IT people, Zigbee could push their job into facilities management (see Get ready for the sensor turf wars). "It's a whole new area," he says, where new possibilities might allow tenants in offices to reconfigure their own lighting if they change partitions, and where IT managers may be needed to support functions that facilities managers used to do with clipboards.

Bob Heile is chair of the IEEE 802.15 Working Group on WPANs, and the IEEE 802.15a Task Group looking at Ultra Wide-band (UWB). He is also chief technical officer for Appairent Technologies.