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.

Z-Wave Alliance

The Z-Wave Alliance is a consortium of more than one hundred independent manufacturers who have agreed to build wireless home control products based on the Z-Wave standard. Principal members include Danfoss, Intel, Intermatic, Leviton, Monster Cable, Universal Electronics, Wayne-Dalton and Zensys.

Radio specifications

Bandwidth: 9,600 bit/s or 40,000 bit/s, fully interoperable

Modulation: GFSK

Range: Approximately 100 feet (or 30 meters) assuming "open air" conditions, with reduced range indoors depending on building materials, etc.

Frequency band: The Z-Wave Radio uses the 900 MHz ISM frequency bands. 908.42 MHz in the US 868.42 MHz in Europe.

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.

Sampling of Z-Wave Certified Products

Home automation | Wireless networking