During operation of a secondary communication system 100, a device will perform spectrum sensing of certain channels (either by itself or as part of a group of nodes 104). When activity is found on a channel from a primary user, other devices will be notified that the channel is not available for use. The device may then modify its spectrum sensing to assist another device (or group of devices) that have not yet found activity on a different set of channels. By assigning additional channels to devices with extra capacity, the overall spectrum-sensing efficiency and performance of the communication system 100 is raised.