A communications system includes spaced apart sensing nodes each configured to receive signals within occupied portions of a frequency spectrum, and a coordinator node configured to communicate with the spaced apart sensing nodes. The coordinator node determines the occupied portions of the frequency spectrum, and determines unoccupied portions of the frequency spectrum based upon the occupied portions. A pair of wireless communications devices is configured to communicate with each other and with the coordinator node. The pair of wireless communications devices may operate within an unoccupied portion of the frequency spectrum based on using a communications signal comprising a continuous phase modulated waveform, with at least one waveform parameter being selected to reduce interference with the occupied portions of the frequency spectrum.