IEEE802.15.4 LR-WPAN is a standard that pertains to the physical layer and the media access control of the data link layer of low-rate wireless personal area networks. It is the basic scheme for many low rate wireless protocols. An example of this is zigbee, a specification for low data rate wireless star, tree and mesh networking. It is a standard that is maintained by the IEEE 802.15 working group.

Typical applications that use this standard require reliable data communications over a 10-100m range. However, some protocols can operate up to several kilometers. Typical transfer rates can range from 20kbits/s up to 250kbit/s, but lower rates are also possible in low power, low bandwidth applications. The focus on the standard is to provide a low cost, low power communications method.

The physical layer of devices that support this specification can operate in a number of RF bands, particular to the legal requirements of the target market. A lower 868MHz band can be used in Europe, 902-928MHz for North America and 2.4GHz bands are used globally, overlapping WiFi. The modem uses Direct Sequence Spread Spectrum (DSSS), Offset Quadrature Phase Shift Keying (OQPSK) or a combination of binary keying and amplitude shift keying. The MAC layer transfers frames and controls the access and connection associations on the shared physical medium. It also manages the beaconing of nodes on the network. IEEE 802.15.4 can coexist to a reasonable extent with IEEE 802.15.1 Bluetooth and IEEE 802.11 WiFi and wireless standards. It can do this because it has a different modulation method, so Bluetooth and WiFi just look like noise sources referred to as co-channel interference. IEEE 802.15.4 direct sequence spread spectrum (DSSS), clear channel assessment (CCA), dynamic channel selection scanning and the acknowledge transmission and retries mechanisms make the standard robust in this way.

One application where LR-WPAN devices are used is home automation, including systems for intelligent lighting control. Lighting can account for over 25% of a commercial building’s energy use, and intelligent control can reduce this energy requirement substantially. LR-WPAN devices are also used in smart grid applications. A smart grid is a digital communications network for information transfer associated with the electrical grid that focuses on sustainability and efficiency of distribution of power. This includes smart meters monitoring power consumption in homes.