Cognitive Spectrum Sharing Protocols for Energy Harvesting Wireless Sensor Nodes

Energy consumption is one of the primary concerns in the deployment of futuristic wireless sensor networks. On one hand due to advent of technologies such as Internet of Things (IoT), there has been tremendous growth in development of wireless sensor nodes, however, on the other hand these nodes are energy constrained, hence have limited lifetime. Energy harvesting from radio frequency (RF) signals has been proposed as a viable solution to alleviate this problem. Most of the recent work in the field of RF energy harvesting has involved cooperative relaying and cognitive radio networks. But now energy harvesting techniques have been employed to cooperative spectrum sharing framework as well. In this work, a hybrid time switching and power splitting spectrum sharing protocol for energy harvesting wireless sensor nodes is proposed. In the developed framework, an energy constrained sensor node adopts a time switching and power splitting based relaying protocol to harvest energy and spectrum from primary user. In exchange, it helps the primary user to achieve its target rate of performance. We have analyzed the impact of time duration allocated for energy harvesting and information reception/transmission at sensor node on the Quality of Service (QoS) of primary user. Further, we have proposed another energy harvesting and spectrum sharing protocol for multiple sensor nodes that not only optimizes the performance of primary system but also simultaneously maintains a satisfactory QoS of the secondary system. We have analyzed how increase in the number of energy harvesting sensor nodes improve the primary and secondary performance.