ZigBee

Zigbee is a wireless technology developed as an global standard to address the unique needs of low-cost, low power wireless M2M networks. The Zigbee standard operates on the IEEE 80.15.4 physical radio specification and operates in unlicensed bands including 2.4 GHz, 900  MHz and 868 MHz.

The 802.15.4 specification upon which the Zigbee stack operates gained ratification by the Institute of Electrical and Electronics Engineers (IEEE) in 2003. The specification is a packet-based radio protocol intended for low-cost, battery-operated devices. The protocol allows devices to communicate in a variety of network topologies and can have battery life lasting several years.

The Zigbee Protocol

The Zigbee protocol has been created and ratified by member companies of the Zigbee Alliance. Over 300 leading semiconductors manufacturers, technology firms, OEMs and service companies comprise the Zigbee Alliance membership. The Zigbee protocol was designed to provide an easy-to-use wireless data solution characterized by secure, reliable wireless network architectures.

The Zigbee Basics

Zigbee is the product of the Zigbee Alliance, an organization of manufacturers dedicated to developing a new networking technology for small, ISM-band radios that could welcome even the simplest industrial and home end devices into wireless connectivity.

The Zigbee specification was finalized in December, 2004, and products supporting the Zigbee standard are just now beginning to enter the market.

Zigbee is designed a low-cost, low-power, low-data rate wireless mesh technology.

The Zigbee specification identifier three kinds of devices that incorporate Zigbee radios, with all three found in a typical Zigbee network (Figure 1):

Figure 1: ZigBee networks incorporate coordinators, routers, and reduced function end devicesin a variety of topologies (mesh topology shown)

• A coordinator, which organizes the network and maintains routing tables. 

• Routers, which can talk to the coordinator, to other routers, and to reduced function end devices.

• Reduced function end devices, which can talk to routers and the coordinator, but not to each others.

To minimize power consumption and promote long battery life in battery-powered devices, end devices can spend most of their time asleep, waking up only when they need to communicate and then going immediately back to sleep. Zigbee envisions that routers and the coordinator will be mains powered and will not go to sleep.

To illustrate how these components interrelate, consider Zigbee networking in office lighting. Several manufacturers are currently developing inexpensive sensors for fluorescent tubes that let lights be turned on and off by battery-powered wall switches, with no wires between switch and fixture. The light switch is the end device, powered by a button cell battery that will last for years; the switch wakes up and uses battery power only when flipped on or off to transmit the new state to the fluorescent tubes’ routers which, as they are already connected to the mains, are nor concerned with battery conservation. Any one of the fluorescent tubes can contain the coordinator. The implications are enormous for new office construction-no more electrical runs for lighting, and the ability to reconfigure lighting controls at almost zero cost.

Zigbee extends similar benefits to a wide range of industrial automation and control applications.

The Zigbee Advantage

The Zigbee protocol is designed to communicate data through hostile RF environments that are common in commercial and industrial applications.

Zigbee protocol features include:

 

• Support for multiple network topologies such as point-to-point, point-to-multipoint and mesh networks.

 

• Low duty cycle-provides long battery life.

 

• ·         Low latency.

 

• ·         Direct Sequence Spread Spectrum (DSSS).

 

• ·         Up to 65,000 nodes per network.

 

• ·         128-bit AES encryption for secure data connections.

 

• ·         Collision avoidance, retries and acknowledgements

 

Zigbee Applications

Zigbee enables broad-based deployment of wireless networks with low-cost, low-power solutions. Its provides the ability to run for years on inexpensive batteries for a host of monitoring and control applications. Smart energy/smart grid, AMR (Automatic Meter Reading), lighting controls, building automation systems, tank monitoring, HVAC control, medical devices and fleet applications are just some of the many spaces where Zigbee technology is making significant advancements.