Z-Wave uses the frequency of 868.42 MHz that belongs to the SRD (Short Range Device) frequency band that was licensed for smart home applications in Europe, Africa and the better part of Asia.
Z-Wave uses a standard line encoding and for high security application applications such as electronic door locks or roof windows, a single TAN system is applied that meets highest security standards.
Every communication is reconfirmed by the receiver so that the transmitter can retransmit in case of connection problems or give a proper alert to the user.
Every mains powered device acts as a router for all other devices. In case a message can not be sent directly to the receiver due to some obstacle the network with automatically re-route this message via other nodes. This ensures a very high reliability of a Z-Wave based wireless network. Every Z-Wave network consists of up to 232 notes which can own additional notes (slave devices).
Typical wireless ranges for communication between different devices are 25 m inside and up to 100 m outside buildings. The 868 MHz radio wave can penetrate walls very well.
More information about the Z-Wave technology can be found online: