An Energy-efficient Clustering Based Interference Reduction in Cognitive Radio Sensor Networks

Cognitive Radio (CR) is promising technique for access of spectrum resources. The sensors deployed vast environmental area are in need of hundreds to thousands of sensor nodes which is mostly energy constrained and their batteries are not rechargeable in most Wireless Sensor Networks applications. A Cognitive Radio Sensor Network (CRSN) is defined as wireless sensor network equipped with cognitive capability. Among many approaches of spectrum sensing, cooperative spectrum sensing is regarded as a most effective method to improve the reliability of spectrum sensing(to improve the primary user detection). Clustering is considered as energy efficient technique among many routing protocols to enhance network lifetime and energy consumption of sensor nodes. In order to increase network capacity and spectrum utilization in wireless system, frequency reuse is introduced which is defined as a process of reusing frequencies in cluster (repeating partition of cells) and interference between neighboring femtocell users which uses same frequency in overlap region is degraded by using Cluster Aware Soft Frequency Reuse (CASFR). Whereas, scheme is proposed by combining the CASFR algorithm with spectrum pairwise coupling algorithm from an energy efficient clustering based co-operative spectrum sensing (ECS) scheme to increase the network capacity, spectrum and energyefficiency, and network lifetime.