A new generation of low-power radio technologies is creeping into
our homes, in the form of wireless light switches and remote-controlled
plug sockets. But the next generation of home-automation kit is all
going to communicate every which way, assuming a common language can be
Zigbee, Z-Wave, and Bluetooth Low Energy would all like to play in
this space, and Intel is even trying to squeeze Wi-Fi into the role.
The industry believes the time is right for watches, key fobs and door
locks to be wirelessly enabled, and that it's finally time to replace
the aging infrared remote controls that have been controlling our TVs
for the last few decades.
Not that the IDrA (Infrared Data Association) is taking this lying
down. The group is quick to point out that the most expensive part of
building IR into a device is the plastic window covering the
transmitter, and has demonstrated a 1Gb/sec version of the standard.
But line of sight is always going to be a problem for IR, so for most
applications radio works better.
Still seeing infrared?
Several radio standards are competing for the title, all offering
limited bandwidth and very low power consumption, but differing both in
the details of their protocols and in how they expect the architecture
of our (home) wireless networks to evolve.
Groups such as the Bluetooth SIG and Ozmo Devices (who have been
demonstrating Intel's Cliffside low-power Wi-Fi) see the future filled
with client devices connected to more powerful servers. In the case of
Ozmo the "server" could be a games console or home computer, while the
Bluetooth SIG still reckons the mobile phone will be the most popular
server for their "Bluetooth Low Energy" standard. This divergence is
based on the technologies onto which the two approaches piggy-back:
Wi-Fi and Bluetooth respectively.
The standard formally known as Wibree, now christened "Bluetooth Low
Energy Technology", is designed to make use of much of the Bluetooth
silicon - not just the antenna as Nokia's original Wibree proposed. The
SIG reckons that should make the cost of bundling Low Energy an
insignificant increment on that of putting Bluetooth into a device.
Phones supporting Bluetooth should, from the end of 2009, automatically
support the Low Energy technology, though it remains to be seen if
there will be any Low Energy devices for them to talk to by then. The
idea is that watches, light switches etc. will only have the Low Energy
components, though the cost of those is still unknown.
Cliffside is a technology from Intel that does much the same thing
with Wi-Fi circuits. The argument is that as every device is going to
have Wi-Fi anyway you might as well make use of that circuit for your
low-power connections too. Cliffside allows a device to connect to a
traditional Wi-Fi network while simultaneously talking to
low-power-Wi-Fi devices, such as those recently demonstrated by Ozmo
All this traffic at 2.4GHz might see the channel getting a bit
crowded, if it wasn't already. But Ozmo reckons their technology will
scale well to 5.8GHz - another chunk of unlicensed space to which Wi-Fi
connections are increasingly shifting.
So the question becomes whether Bluetooth or Wi-Fi is going to be
the wireless technology embedded in everything by default - on which
technology the low-power variation can most usefully piggy-back.
Ozmo reckons its devices can out-perform Bluetooth, offering 9Mb/sec
bandwidth and with 2.5 times the battery life of a Bluetooth device.
But Bluetooth Low Energy should have 10 times the battery life of a
normal Bluetooth device, even if it won't be able to offer the same
Point to the window, point to the door
A 10x improvement in battery life is all very well, but to reach a
life measured in years rather than days you need to move away from
existing technologies and adopt something a little more radical.
Zigbee is a low-power protocol that can also fit into 2.4GHz, and
operating at such low bandwidth it can squeeze in around other
applications - one of the 16 bands used by Zigbee at 2.4GHz is actually
a Wi-Fi guard band, so will never be filled by networking kit. Zigbee
can also hang around at 433Mhz, but that's a very chaotic band for
interference, or 868Mhz, though there's not much room to breathe there.
Zigbee was designed from the ground up to be a very low-power
networking technology, and one that allows nodes to act as relays,
creating an auto-forming mesh network to extend coverage. Zigbee and
its competitor Z-Wave both offer a battery life measured in years, and
the first consumer products using the technologies are now on the
AlertMe.Com is typical. It uses Zigbee-equipped sensors operating at
2.4GHz and with a battery life of several years to monitor doors and
windows, as well as temperatures and user interaction, with
mesh-enabled nodes operating as status lights while routing connections
around the network. The mesh that AlertMe.Com creates only connects to
a single hub, but there's no reason for a Zigbee deployment to be
limited in that way.
AlertMe.Com is working on more devices, including a
remotely-controlled plug socket, which should provide a standard
platform for home automation. This first deployment will be controlled
by AlertMe.Com as all traffic must be routed through their servers, but
it won't be long before we see more open Zigbee hardware on the shelves.
So if you believe the future will be devices connecting to
peripherals then it's most likely going to be Bluetooth Low Energy or
low-powered Wi-Fi, depending on which is the dominant embedded
technology. But if you see a future in networks of nodes around the
home then Z-Wave or Zigbee is the technology of choice.
If, on the other hand, you want to see high-definition video or
uncompressed audio flying around the house then you'll need something
else entirely, and we'll be looking at some of the options there soon.