Section 20.6. Other Related Technologies

20.6. Other Related Technologies

Other sensor-network based technologies use low-power nodes. The one discussed in this section is the ZigBee technology .

20.6.1. Zigbee Technology and IEEE 802.15.4

The ZigBee technology is a communication standard that provides a short-range low-cost networking capability that allows low-cost devices to quickly transmit small amounts of data, such as temperature readings for thermostats, on/off requests for light switches, or keystrokes for a wireless keyboard. Other ZigBee applications are in professional installation kits for lighting controls, heating, ventilation , air conditioning, and security. Even the Bluetooth short-range wireless technology found in laptops and cellphones lacks the affordability , power savings, and mesh-networking capabilities of ZigBee.

ZigBee comes from higher-layer enhancements by a multivendor consortium called the Zigbee Alliance. IEEE standard 802.15.4/ZigBee specifies the MAC and physical layers . The 802.15.4 standard specifies 128-bit AES encryption; ZigBee specifies how to handle encryption key exchange. The 802.15.4/ZigBee networks run in the unlicensed frequencies, 900 MHz and 2.4 GHz band , based on a packet radio standard and support many cordless telephones, allowing data to be sent over distances up to 20 meters .

ZigBee devices, typically battery powered , can transmit information much farther than 20 meters, because each device within listening distance passes the message along to any other device within range. Only the intended device acts on the message. By instructing nodes to wake up only for those split-second intervals when they are needed, ZigBee device batteries might last for years . Although this technology is targeting for manufacturing, health care, shipping, and homeland defense, the ZigBee Alliance is initially keeping its focus small.