Research On Energy Balance-oriented Uneven Clustering Routing Protocol For Cognitive Radio Sensor Networks

Cluster-based cognitive radio sensor networks(CRSNs)are effective solutions to solve the energy efficiency and spectral efficiency problems faced by legacy wireless sensor networks.However,most existing clustering protocols for CRSNs adopt uniform clustering,which builds clusters with the same size.Cluster Heads(CHs)close to the sink need to perform heavy inter-cluster relay and forwarding tasks,which causes uneven energy distribution among CHs and may result in energy hole problem.The existing uneven clustering protocols leave control overhead and multi-hop inter-cluster routing out of consideration,and they adopt constant weight coefficients for cluster radius calculation instead of reasonably setting their values according to specific network configurations.To solve the above problems,this paper studies the uneven clustering routing protocol design for CRSNs,and the specific research contents are shown as follows:Firstly,an energy balance-oriented uneven clustering routing protocol(EBUCRP)is proposed in this paper.By fully considering the energy consumption of control information exchange and data transmission,EBUCRP theoretically derives the optimal cluster radius of each unit.The obtained results can guide the cluster radius settings under specific network configurations.Besides,CHs selection criterion and relays selection criterion based on node communication capability are defined from joint energy and spectral efficiency perspectives to help select high-quality CHs and next-hop relays,which can ensure efficient network operation.In addition,EBUCRP strictly restricts the energy consumption of control information exchange during network operation to help conserve node energy.Simulation results show that EBUCRP gains obvious advantages over other competing protocols in enhancing the lifetime and network surveillance capability of both single-hop and multi-hop CRSNs.Secondly,in order to further balance the residual energy among intra-cluster nodes and prolong the network lifetime,radio frequency energy harvesting(RF EH)and simultaneous wireless information and power transfer(SWIPT)techniques are introduced,and an RF EH and SWIPT-based EBUCRP(RS-EBUCRP)routing protocol is proposed on the basis of EBUCRP.Energy management mechanism is proposed for EH-CRSNs nodes to determine their own state and perform corresponding operations according to their residual energy,which can help avoid data transmission failure due to lack of energy.Moreover,RF EH capability quantification-based CHs selection and cluster construction criteria are defined by RS-EBUCRP to improve the energy utilization and balance the residual energy among nodes.Furthermore,to save the energy of EH-CRSNs nodes,power splitting ratio ρ used to divide the received power for information decoding and EH is theoretically derived by RS-EBUCRP,and the transmision power of cluster members to realize intra-cluster SWIPT is deduced with the constraint of balancing the residual energy among nodes within the same cluster.Simulation results show that RS-EBUCRP performs better than other competing protocols in extending the network lifetime and balancing the residual energy among intra-cluster nodes.In this paper,uneven clustering routing protocols suitable for single-hop and multi-hop CRSNs are proposed on the basis of in-depth research,and they overcome the limitations of the existing clustering routing protocols,such as unbalanced residual energy among nodes and poor network scalability.The research results can help improve the overall performance of CRSNs and guarantee effective data transmission while extending the network lifetime.