Research Of Some Key Technologies Of Energy Harvesting Cooperative Wireless Sensor Networks

As one of the most promising paradigm in ”Internet Plus”,the Internet of Things(Io T)is envisioned to make Internet ubiquitous and pervasive.During the actualization process of the Io T concept,Wireless Sensor Networks(WSNs)technologies play a critical part in maintaining the ubiquitous and pervasive environments.With the ever-growing demand for significant data collection and processing in long period applications for IOT,traditional WSNs have faced severe challenges in energy management.Due to the limited energy resource of sensor nodes,the previous energy management approaches are impossible to fundamentally compensate energy depletion.Many self-powered technologies have appeared to resolve the energy supply problem in traditional battery-powered WSNs,ambient energy harvesting technologies and wireless energy transfer technologies are typical solutions,which can resolve the energy supply problem and make it possible for the sensor nodes to operate perpetually.In this paper,the sensor networks that combine the energy harvesting and wireless energy transfer technologies are termed as Energy Harvesting Cooperative WSNs(EHC-WSNs).We focus on energy efficiency maximization and network throughput optimization problems for energy cooperation in EHC-WSNs.In order to solve the hot spot issue and maximize the efficiency of energy charging phase,a Region-based Proactive Energy Cooperation(RPEC)strategy is developed,which is used to charge the life-critical cooperators or receivers in time.Following the principle of opportunistic routing theory,multi-hop routing decision to optimize the relay nodes selection is made based on the differences among sensor nodes,in terms of both their distance to sink,the residual energy of each other,energy generation rate and energy consumption.Through detailed study the characteristics of energy consumption in EHC-WSNs,an energy-cooperative-based energy-neutral management strategy is proposed to optimize the network energy efficiency and improve the network throughput.In addition,we propose the graphene-grid deployment strategy to guarantee energy coverage and network connectivity,whereby a energy cooperation management mechanism is designed under the energy-neutral operation.Specifically,it contains the following aspects:1.We build the energy harvesting cooperative network model for the large-scale EHCWSNs and define two different types of relay nodes(cooperator and receiver).We introduce the imbalanced approach,which is based on the distances to cooperator and the initial energy of receivers,into proactive charging scheduling algorithm for the selection of next energy receiver,and a Region-based Proactive Energy Cooperation(RPEC)strategy is developed.2.We calculate the optimal transmission distance under the ideal scenarios,and further adopt a new concept called Energy Equivalent Node(EEN)which is a virtual node based on optimal transmission distance theory.Then,we introduce the forwarder list based on the distances to EEN,the residual energy and forwarded number of each relay node into opportunistic routing decision.By converting optimal forwarder selection from the multi-dimensional problem to one-dimensional problem,an Opportunistic Energy Cooperative Routing(OECR)algorithm is proposed to optimize the relay nodes selection.3.We compare the differences between the traditional battery-powered energy model and the energy harvesting cooperative energy model,and formulate the energyneutral operation of cooperator and receiver respectively.We explore the optimal throughput of the cooperator according to the energy-neutral management strategy and design an Energy-neutral-based Energy Cooperation Mechanism(ENECM)to maximize the energy efficiency and optimize the network throughput.4.We introduce the graphene-grid deployment into energy harvesting cooperative network model,which can leverage the extraordinary structural property in graphene to guarantee energy coverage and network connectivity.We design an Graphene-based Optimal Relay Placement Strategy(GORPS)to solve the efficient energy coverage problem and maximizing energy utilization problem.