A home control network typically consists of a complex mix of nodes powered by A/C and battery power, and ones that are both fixed and mobile. All nodes need to be able to communicate with each other seamlessly.

In the Z-Wave technology, nodes are differentiated as being in one of three fundamental node types: controllers, routing slaves and slaves. All node types work together and can be mixed in any combination:

Nodes that are able to start networks or to initiate communication with a large number of other nodes are based on one of the controller protocol stacks. Nodes that only initiate communication with a well-defined set of nodes can be based on the routing slave protocol stack. Nodes that do not initiate communication, but only need to react to communications requests from others nodes, can be based on a slave protocol stack.

Z-Wave supports battery-powered devices such as handheld remotes and moving sensors within each node type. Also, the full support of portable nodes - such as remote controls - is critical for the success of any wireless home control solution, and so is provided by Z-Wave.

Network Reliability

Even in a medium-sized home, it is likely that two nodes that need to communicate are not within direct RF communication range. Mesh networking provides an elegant solution to this problem. Figure 2 shows a typical mesh network, with a solid line illustrating the communications path between two nodes that are not able to communicate directly.

The mesh network also serves as the basis for Z-Wave's self-healing functionality. RF communications links vary over time due to their strong correlation to the physical environment. For example, when doors open or close, furniture is moved, or there are simply many people moving around, RF links may fail because the environment is changing. In these situations the self-healing mechanisms in the Z-Wave technology automatically reroute messages via other nodes to their destinations.