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How ZigBee Compares

December 1, 2006 By: Wise Guy Sensors


ZigBee Apps vs. Bluetooth and WiFi

What applications are served better by ZigBee than by other wireless standards such as Bluetooth and WiFi?

Signed, Apps Picker

Wise Guy: ZigBee, Bluetooth, and WiFi, all wireless networking protocols, are best suited for different applications.

ZigBee addresses the unique needs of remote monitoring-and-control and sensor-network applications, which typically have very low bandwidth requirements (20–250 Kbps). It enables the deployment of large-scale low-power networks, and devices that can run for years on inexpensive batteries.

By contrast, Bluetooth is primarily a cable replacement for point-to-point connection of consumer devices. And WiFi is a networking technology developed for data-intensive communications such as video streaming and graphics-rich Web browsing. Both Bluetooth and WiFi have much higher power requirements, with battery life measured in weeks.

Typical ZigBee customers have looked at a range of wireless protocols and have chosen ZigBee for its low power requirements, network scalability, and reliability.

ZigBee networks use a line-powered infrastructure and battery-operated end devices (sensors as well as light switches, thermostats, etc.). Sensors often sleep for much of their lives and wake on activation or for periodic timed status updates. Duty cycles of 1% can provide several years of battery life: Most battery-powered devices can last five years or more using AA or AAA batteries. This is due to sleep currents that are typically below 1 μA and active currents (when using the radio) of 25–35 mA.

ZigBee network scalability and reliability is achieved through mesh networking. Networks can scale to hundreds and thousands of devices and all will communicate using the best available path for reliable message delivery. If one path stops working, a new path is automatically discovered and used without stopping the system operation. This long-term reliability is critical for many building automation systems that are expected to last 20–30 years once installed.

Zee Major Difference Between ZigBee and Z-Wave

Okay, but there are other low-data rate standards, too, right? For instance, I've noticed that both ZigBee and Z-Wave are competing in the home automation arena. How do these two compare?

Signed, Z. Wonderer

Wise Guy: The key difference between ZigBee technology and Z-Wave is that Z-Wave is a proprietary RF wireless communications technology designed for residential and light commercial control and status reading applications, operating at 868.42 MHz (E.U.) or 908.42 MHz (U.S.) and a data throughput of 9.6 Kbps. There is only one vendor of the Z-Wave technology platform: Zensys.

ZigBee is a global wireless standard based on the IEEE 802.15.4 standard providing control and monitoring capabilities for building, home, and industrial control applications. Multi-channel frequency bands include 2.4 GHz, 902–928 MHz, and 868–870 MHz at data rates of 250, 40, and 20 Kbps respectively. The ZigBee Alliance boasts more than 200 members with multiple vendors offering the technology platform.

The ecosystem of companies developing ZigBee products now offers standard commissioning tools, network maintenance tools, gateway devices, and even some of the network devices themselves. This lets system designers pick and choose among elements that they need to develop and elements that can be integrated from other suppliers. Even the integration of ZigBee itself can be simplified by using embedded ZigBee modules that are now available from several suppliers. Use of these modules can eliminate the need for a new designer to learn how to integrate the RF technology onto their hardware.

Wise Guy is the problem-solving persona of WINA, the Wireless Industrial Networking Alliance (www.wina.org). This month, WINA thanks Ember Corp. for its wise answers. Send your questions to
wiseguy@questex.com.






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