Energy Efficient k-hop Clustering in Cognitive Radio Sensor Network for Internet of Things

The design and development of energy and spectrum efficient solutions are important in the success of Internet of Things (IoT). Due to presence of enormous number of smart devices such as sensors, actuators, and different household devices achieving such scalable and efficient solutions are challenging. A wireless sensor network (WSN) with dynamic spectrum access (DSA) capability, known as cognitive radio sensor network (CRSN) is recently introduced to deal with spectrum scarcity problem. Although the spectrum scarcity is reduced with DSA paradigm, the energy efficient solutions are still required to be addressed due to involvement of energy constrained devices in CSRN. Clustering is one of the efficient ways to optimize the energy consumption in the networks. Due to combination of both WSN and cognitive radio network (CRN), existing solutions of WSN and of CRNs are not applicable to CRSN. In this paper, we propose a neighbour discovery algorithm and two greedy k-hop clustering schemes (k-SACB-WEC, and k-SACB-EC) for CRSN with the aim focusing on IoT applications which require constant intra-cluster and inter-cluster communications. We focus on achieving bi-channel connectivity while maximizing network life. In our clustering different parameters such as nodes’ residual energy, spectrum awareness, appearance probability of primary users (PUs) of channels, channel quality, robustness on PUs’ arrival, and euclidean distance betweeen nodes are taken into consideration to select the hop count and common channels for clusters. Through simulation, we have highlighted the performance improvements of our proposed schemes in terms of the lifetime of the network, number of clusters, stability of networks, and frequency of re-clustering over recently reported clustering algorithm in CRSN. The simulation results show that k-SACB-WEC generates at least 40% less number of clusters as compared to k-SACB-EC, NSAC, PSEP, SAC-WCM and CogLEACH. Also in terms of network stability, the k-SACB-WEC achieves at least approximately 100% higher number of rounds before the first node dead than the compared competitive approaches.