A new standard from the Institute of Electrical and Electronic Engineers (IEEE) opens the world of wireless communications to inexpensive applications, from sensors and switches for industrial and residential use to smart tags and badges, interactive toys, inventory tracking and much more. The standard, IEEE 802.15.4,™ provides for low data rate connectivity among relatively simple devices that consume minimal power and typically connect at distances of 10 m (30 feet) or less.
IEEE 802.15.4, “Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low Rate Personal Area Networks (LR-WPANs),” addresses fixed, portable and moving devices that operate at data rates of 10 to 50 kbps. It allows devices to form short range ad-hoc networks within which they can interact directly.
“This is an enabling standard,” says Pat Kinney, chair of IEEE 802.15 Task Group 4. “It builds a framework so existing low end wired devices can participate in wireless networks and also creates a path for many new applications. The potential uses have several things in common. They all involve relatively simple, low speed wireless links that need so little power that a set of AA batteries might last three to five years or even longer. We believe a host of new applications will be based on the standard. These might include motion sensors that control lights or alarms, wall switches that can be moved at will, meter reader devices that work from outside a house, game controllers for interactive toys, tire pressure monitors in cars, passive infrared sensors for building automation systems and asset and inventory tracking devices for use in retail stock rooms and warehouses.”
According to Jose A. Gutierrez, chief technical editor of the standard, IEEE 802.15.4 is based on a vision of a new wireless niche for communication among things. “It is the first wireless scheme to allow simple sensor and actuator devices to share a single standardized wireless platform. The IEEE 802.15.4 specification complements the IEEE 802 set of wireless standards to enable sensor-rich environments. It accommodates lower end applications by trading off higher speed and performance for architectures that benefit from low power consumption and cost.”
Wireless links under IEEE 802.15.4 can operate in three unlicensed frequency bands. These accommodate data rates of 20 kb/s in the 858 MHz band, 49 kb/s in the 902 to 928 MHz band and 250 kb/s in the 2.4 GHz band. When lines of communication exceed 30 feet, the standard allows for the creation of self-configuring, multi-hop network topologies. It also provides features that allow devices operating under the standard to coexist with other wireless devices, such as those that comply with 802.11,™ or Wi-Fi“ and IEEE 802.15.1™ or Bluetooth.™ IEEE 802.15.4 was sponsored by the IEEE Computer Society, LAN/MAN Standard Committee.