Abstract: Time synchronization for nodes of a broadcast-only network is provided by combining two methods. The first method provides relative synchronization of communication frames of node broadcasts, so that all nodes have frames with aligned start and end times. The second method associates a network time with each frame at each node (i.e., each node locally tracks this network time). When a time-stamped message is received by a node, the node network time is set to the larger of its current value or the time stamp of the received message. Each node increments its network time by the same amount from one communication frame to the next.

Abstract: Time synchronization for nodes of a broadcast-only network is provided by combining two methods. The first method provides relative synchronization of communication frames of node broadcasts, so that all nodes have frames with aligned start and end times. The second method associates a network time with each frame at each node (i.e., each node locally tracks this network time). When a time-stamped message is received by a node, the node network time is set to the larger of its current value or the time stamp of the received message. Each node increments its network time by the same amount from one communication frame to the next.

Abstract: Distinct physical channels in a network are exploited to provide capabilities that go significantly beyond conventional hybrid networks. In a first aspect, distinct physical channels are employed to determine physical relationships of the nodes with respect to each other. For example, whether or not the nodes of an RF wireless system are in the same room of a building can be determined by using optical messages passed between the nodes. In a second aspect, a first physical channel is employed for synchronized broadcasting, and a second physical channel is employed to enhance the capabilities of the synchronized broadcast network. For example, the nodes of an RF wireless broadcast network can be selectively commissioned (i.e., sensitized) with optical signals to commands that are broadcast on the RF network.