Described herein are methods, metrics and apparatus for bandwidth allocation for cognitive radio. Information that needs to be passed between different components of a dynamic spectrum management (DSM) system for dynamic bandwidth allocation along with the corresponding interfaces is identified. Methods and associated metrics for measuring network performance, evaluating channel sensing results and handling various bandwidth allocation scenarios are presented. Also provided is an admission control mechanism for quality of service support. Alternate channel monitoring may be performed in the background so that when a new channel is needed, an alternate channel may be immediately allocated and service disruption to the DSM system is reduced. A channel may be dynamically assigned as the primary channel in multiple channel scenarios to support tasks such as transmission of acknowledgment frames. Hybrid mode devices that may access a television white space (TVWS) database and perform spectrum sensing are also described.