Abstract
A wireless sensor network consisting of nodes with cognitive radio capabilities will be allowed to act as secondary users by dynamically utilizing another spectrum allocated to multi-channel WLAN primary users. The proposed techniques will he based on the use of a two-tier hierarchical scheme, with secondary nodes accessing the primary user's spectrum through a cluster head. The proposed schemes are set such as 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. The system performance will be evaluated for two priority schemes and four accessing techniques.