The consumer electronics industry has talked about home automation since low-cost microcontrollers first appeared on the market a few decades ago. While some envision homes straight out of The Jetsons, most entrepreneurs have looked for practical ways to make today's homes more comfortable, energy-efficient, and safe. A key missing ingredient, however, has been a technology for networking large numbers of sensors and controllers freely distributed around the home.
A home automation network technology should be flexible, easy to deploy, and easy to use. It should be able to relay sensor data and controller commands in a timely, reliable, and (when necessary) secure fashion. And it should enable devices that are small, inexpensive, and consume minimal power. Ideally, it should be wireless, support ad hoc and mesh networking, and enable devices that can run for years off a small battery. ZigBee, a solution ten years in the making, meets all of these requirements.
ZigBee supports up to 64,000 devices on a single network. The latest standard supports both a basic feature set (ZigBee) and an enhanced feature set (ZigBee PRO). The latter permits self-powered devices as well as devices that can harvest energy from their surroundings using the optional ZigBee "Green Power" feature. Recognizing that key applications often have very different requirements, the ZigBee Alliance has also developed more detailed standards for specific applications such as smart energy, remote controls, and health monitoring.
A Big Deal
However, technical capabilities and detailed standards alone do not guarantee success. ZigBee has made substantial progress in recent years: It's been quietly integrated in TV remote controls and set top boxes. That puts ZigBee firmly in the hands of consumers and in a popular device that is strategically positioned to talk to both home automation networks and the Internet.
The emergence of ZigBee-based TV remote controls is a fairly big deal. Until recently, virtually all remote controls used infrared communications due to its simplicity, low cost, and good battery life. However, infrared has some major disadvantages. Infrared requires line of sight access and must be pointed at the target device. Low-cost infrared remotes can send but not receive data. Consequently, there is no way to command a misplaced infrared remote control to emit an audible signal.
Thanks to ZigBee's digital radio technology, infrared is no longer the obvious choice for remote controls. ZigBee-based remote controls do not require line of sight access; the target device may be placed inside a cabinet or even controlled from an adjacent room. ZigBee-based remote controls can receive as well as send: They can be placed in "find me" mode when misplaced, receive and display messages, and perform other tasks requiring two-way communications. According to the ZigBee Alliance, ZigBee-based remote controls deliver longer battery life than infrared-based remote controls.
By integrating ZigBee with set top boxes, cable TV operators are able to deliver entirely new services. For example, Comcast's ZigBee-enabled Xfinity set top box offers home security and energy management features and services. Users can remotely adjust thermostats and turn lights off or on via their smartphones. Customers subscribing to Comcast's premium security service can even access streaming video from cameras installed inside their homes.
A Growing Market
The home automation market is young and ZigBee faces quite a bit of competition. The Enocean Alliance emphasizes the use of energy harvesting devices for building automation. The Z-Wave Alliance targets home automation using technology developed by Sigma Designs. Insteon offers home automation products using a mix of radio and power line communications. ANT and ANT+ are open specifications targeting smart buildings (ANT) as well as health and fitness markets (ANT+). Each of these competing solutions enjoys broad support.
However, as the market grows there will be increased demand for interoperability. At first, this demand may be satisfied through the use of gateways that interconnect otherwise incompatible networks in the same home. And some vendors may choose to support multiple networking solutions. But ultimately there will be pressure to consolidate. Because ZigBee has the flexibility to serve a wide range of applications, it may be best positioned to lead the home automation industry as it begins to mature.
Some may believe that Wi-Fi and Bluetooth have all short-range wireless requirements covered. However, while Wi-Fi and Bluetooth continue to enhance and broaden their capabilities, ZigBee can do things that Wi-Fi and Bluetooth can't. ZigBee is simpler than Wi-Fi and consumes much less power. Though a low-power version of Bluetooth has been developed--Bluetooth low energy (BLE)--it (like Bluetooth classic) is primarily intended for connecting personal devices over short distances. Only ZigBee was designed from the ground up to network a large number of sensors and controllers distributed around the home.
Don't expect large home automation networks to suddenly materialize. Instead, they will grow from small home automation networks. Having made inroads in remote controls and set top boxes, ZigBee is well positioned. Now it's up to vendors to turn hypothetical applications such as energy management into compelling, money-saving applications that will drive home automation sales.
Ira Brodsky is a St. Louis, Missouri-based consultant and the author of The History of Wireless: How Creative Minds Produced Technology for the Masses.