Abstract
A wireless sensor network consisting of nodes with cognitive radio capabilities is to be considered. This feature is to be used to allow these nodes, which will be considered as secondary users, to utilize dynamically another spectrum allocated to multi-channel WLAN primary users. A two-level hierarchical scheme is to be considered, with sensor nodes accessing the primary user's spectrum through a cluster head. The proposed algorithm is used to enhance the main QoS performance metrics of the secondary users such as delay and throughput with minimal effects on the performance of the primary users.