Z-wave
Z-Wave is a wireless communications standard developed by Danish company Zensys (http://www.zen-sys.com) and the Z-wave alliance (http://www.z-wavealliance.org).
It is designed for low-power and low-bandwidth appliances, such as home automation and sensor networks.
Radio specifications
Bandwidth: 9600 bps
Modulation: GFSK
Range: Approx. 100 feet (30 meters indoors) and more than 300 feet (100 meters) outdoors.
Frequency band: The Z-Wave Radio uses the 900MHz ISM frequency bands. 908.42MHz in the US 868.42MHz in Europe.
Radio specifics
In Europe, the 868MHz 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 908MHz band, but US legislation imposes a 1mW 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 a 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. 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. A Z-wave network can consist of up to 232 units with the option of bridging networks if more units are required
Application areas
Z-wave is designed for low-power networks. Battery life of Z-wave units is usually several years on AA batteries. 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.
| 
