The mission of the ZigBee Working
Group is to bring about the existence of a broad range of interoperable
consumer devices by establishing open industry specifications for
unlicensed, untethered peripheral, control and entertainment devices
requiring the lowest cost and lowest power consumption communications
between compliant devices anywhere in and around the home.
The ZigBee membership
includes Philips, Honeywell and Invensys Metering Systems, and others and is
responsible for defining and maintaining higher layers above the MAC. The
alliance is also developing application profiles, certification programs,
logos and a marketing strategy. Philips Semiconductors and other chip
vendors plan to launch their first ZigBee products as early as 2003.
ZigBee was formerly known as PURLnet, RF-Lite, Firefly, and HomeRF Lite.
The ZigBee logo
The ZigBee specification is a combination of HomeRF Lite and the 802.15.4
specification. The spec operates in the 2.4GHz (ISM) radio band - the same
band as 802.11b standard, Bluetooth,
microwaves and some other devices. It is capable of connecting 255 devices
per network. The specification supports data transmission rates of up to 250
Kbps at a range of up to 30 meters. ZigBee's technology is slower than
802.11b (11 Mbps) and Bluetooth (1 Mbps) but it consumes significantly
less power.
ZigBee/IEEE 802.15.4 - General Characteristics:
- Dual PHY (2.4GHz and 868/915 MHz)
- Data rates of 250 kbps (@2.4 GHz), 40 kbps (@ 915 MHz), and 20 kbps
(@868 MHz)
- Optimized for low duty-cycle applications (<0.1%)
- CSMA-CA channel access Yields high throughput and low latency for low
duty cycle devices like sensors and controls
- Low power (battery life multi-month to years)
- Multiple topologies: star, peer-to-peer, mesh
- Addressing space of up to:
- 18,450,000,000,000,000,000 devices (64 bit IEEE address)
- 65,535 networks
- Optional guaranteed time slot for applications requiring low latency
- Fully hand-shaked protocol for transfer reliability
- Range: 50m typical (5-500m based on environment)
ZigBee/IEEE802.15.4 - Typical Traffic Types Addressed
- Periodic data
- Application defined rate (e.g., sensors)
- Intermittent data
- Application/external stimulus defined rate (e.g., light switch)
- Repetitive low latency data
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