Zigbee – 2,4 Ghz
ZigBee is an open standard for wireless connection between devices at short distance 10-70m.
ZigBee is primarily intended for building automation and measurement and control networks. The bandwidth requirement for these applications is not high ( think of the thermostat, doorbell or a light button), but the lifespan of the batteries is important for this application.
A battery-powered ZigBee device can run on a battery for several years. ZigBee has a datarate of 20k b/s to 200k b/s.
It is a simple and energy efficient solution (a complete Zigbee protocol stack can be built into an embedded controller).
Suppose you have an office building with large spaces and you need a flexible zone layout by means of system walls. Within these zones, for example, you want to be able to control the lighting and heating, or you want to be able to detect whether someone is present within a zone. Then Zigbee offers you the desired flexibility and the possibility to set up these zones completely wirelessly and therefore inexpensively.