It's been quite some time since I mentioned ZigBee, the emerging low-cost sensor network based on IEEE 802.15.4 wireless standards in the 2.4 GHz band. Well, the ZigBee 1.0 specification is poised for publication this month - and possibly as early as this week.

The forthcoming spec defines the network, security and application software layers above the physical and MAC layers defined in 802.15.4.

In addition, the ZigBee Alliance, a consortium of technology companies, plans to announce a conformance and interoperability certification program, according to alliance board member Jon Adams, who is also director of radio technology and strategy at Freescale Semiconductor.

ZigBee represents an industry initiative to enable the construction of business and residential network applications using low-cost, low-power sensors that run on batteries with very long lives. Among these applications are lighting control; heating, ventilating and air conditioning (HVAC) environmental management; and industrial sensors.

Hotel sensor networks, for example, could automatically determine when there's no one in a room and then turn off lights, heat and air conditioning to conserve energy. Similarly, hotels could keep a guest's profile with room temperature preference on file, and the room could automatically be programmed to adjust to that environment upon guest check-in.

At the network layer, ZigBee specifies how the sensor network forms (in a mesh configuration), heals itself, grows, and routes messages, Adams explains. For security, 802.15.4 specifies 128-bit Advanced Encryption Standard encryption, but nothing about how to manage encryption keys. So ZigBee specifies key management.

At the application layer, ZigBee 1.0 has already defined basic applications for lighting, HVAC and industrial sensors; developers can simply add their own look and feel. For application developers who choose not to use the standard ZigBee profile, there are API calls in the 1.0 spec that define rules for how applications speak to the ZigBee system, Adams says.

Joanie Wexler is an independent networking technology writer/editor in Silicon Valley.