A method and system by which a base station in a Wireless Regional Area Network (WRAN), and more generally a transceiver in a cognitive radio (CR) system, can communicate with other transceivers to fairly share transmission and reception of scheduled use (“occupancy”) of frames on a single channel within a frame-based, on demand spectrum contention system. The method and system disclose how the base station can initiate contentions for an increased share of the frames available in the following superframe of the CR system. The method and system assure fair and efficient access to the transmission channel by a random number based contention process.