A device is operable to use received signals to divide time into a succession of frames, each frame having plural consecutive timeslots, and into a succession of four or more superframes. A transmitter is operated only in a single timeslot in one frame. A receiver is operated in the other timeslots in the frame and for all timeslots of immediately preceding and following frames, and in no other frames. This allows devices to predict periods in which to hibernate or carry out intensive tasks. The device determines which timeslots of the first frame are occupied to provide local awareness information, and transmits it as a code on its transmit timeslot along with payload data. This allows other devices in a network to obtain information about their local environment and about the environment of their neighbors. Routing decisions are made on this basis.