Z-Wave

Z-Wave is the interoperable wireless communication standard developed by Danish company Zensys and the Z-Wave Alliance. It is designed for low-power and low-bandwidth appliances, such as home automation and sensor networks
Radio specifications
Bandwidth: 9,600 bit/s or 40,000 bit/s, fully interoperable
Radio specifics
In Europe, the 868 MHz band has a 1% duty cycle limitation, meaning that a Z-wave unit can only transmit 1% of the time. This limitation is not present in the US 908 MHz band, but US legislation imposes a 1 mW transmission power limit (as opposed to 25 mW in Europe). Z-wave units can be in power-save mode and only be active 0.1% of the time, thus reducing power consumption dramatically.

Topology and routing
Z-wave uses an intelligent mesh network topology and has no master node. A message from node A to node C can be successfully delivered even if the two nodes are not within range providing that a third node B can communicate with nodes A and C. If the preferred route is unavailable, the message originator will attempt other routes until a path is found to the 'C' node. Therefore a Z-wave network can span much further than the radio range of a single unit. In order for Z-wave units to be able to route unsolicited messages, they cannot be in sleep mode. Therefore, most battery-operated devices will opt not to be repeater units. A Z-wave network can consist of up to 232 units with the option of bridging networks if more units are required.

Application areas
Due to the low bandwidth, Z-wave is not suitable for audio/video applications but is well suited for sensors and control units which typically only transmits a few bytes at a time.