Bilişsel radyo algılayıcı ağlarda kümeleme, ağ kodlaması ve kapsama alanı azamileştirilmesi

The spectrum scarcity challenge is a natural consequence of increasing demand for wireless communication. This situation has triggered the use of opportunistic spectrum access schemes in wireless communications. The key technology addressing this challenge and enabling opportunistic spectrum access is cognitive radio. Wireless sensor network (WSN) suffers from the spectrum scarcity problem due to the fixed frequency assignment policy. Cognitive radio stands as a promising solution to this problem in WSNs. Wireless sensor nodes with cognitive radio capability can access different spectrum bands dynamically. This defines a new sensor networking paradigm, i.e., Cognitive Radio Sensor Networks (CRSN). The unique characteristics of CRSN necessitates energy-efficient and spectrum-aware solutions. In this thesis, we first propose a spectrum-aware clustering protocol for CRSN. We form non-isolated clusters between event and sink in accordance with event-driven communication nature. Simulation results show that our protocol is more energy-efficient than other protocols in literature. Next, we investigate the effect of network coding in CRSN. Network Coding is a novel technique enabling encoding operation instead of store-and-forward approach. The advantages and disadvantages of using network coding are presented. Finally, we consider wireless networked control system consisting of separate cognitive radio sensor subnetworks. The system state is estimated using Kalman filter. We find critical packet arrival probability for bounded expected state estimation covariance and obtain the maximum total coverage area of CRSN with maximum cost-efficiency.