White space devices are unlicensed radiofrequency devices that must have certain capabilities in order to avoid harmful interference to licensed operations. In general, they must be location-aware, must be able to contact a geolocation database and may not operate without receiving a positive control signal. A number of white space devices can use a control channel to communicate with a control station. In addition to meeting the geolocation and positive control requirements given above, the control station coordinates the channels used by the white space devices so as to minimize their aggregate interference. In one embodiment, a control channel uses a separate frequency band with high availability and reliability but low throughput. Embodiments optimize channel assignments where the potential interference depends on the mutual distances between the white space devices. Potential interference reductions of 20-30 dB have been found in simulations. Other embodiments are disclosed.