Research On The Mechanism And Scheduling Strategy Of Resonant Beam Wireless Energy Transmission

The Internet of Everything(IOE)is an important development trend for 5G communication technology and Internet of Things(Io T),the ubiquitous high efficiency mobile computing and high-rate communication place greater demands on the endurance of sensors and devices in the network.The Wireless Power Transfer(WPT)technology is an ideal solution to break through the endurance bottleneck for mobile communication and computing devices.However,the existing WPT technology still faces challenges with distance,power,safety,and other factors that cannot be realized simultaneously.Resonant Beam Charging(RBC)technology is a revolutionary technology to solve the aforementioned challenges experienced by WPT technologies,which can concurrently realize multi-meter distance,multi-watt power,safe,and multi-device energy supply.Therefore,this thesis will investigate the problems faced by the Resonant Beam System(RBS)for energy and information transmission.On the one hand,we establish a resonant beam end-to-end energy transmission model to study the transmission performance of the resonant beam in free space.Then,we utilize the end-to-end transmission model to validate the inherent safety of resonant beam transmission and optimize the structure of safe transmission systems.On the other hand,to improve the efficiency of the RBS,multiple scheduling strategies are designed for the differential service demand of receivers,which can ensure the multi-terminal functioning for as long as feasible.The contributions of this thesis are as follows.· We propose an end-to-end energy transmission model based on electromagnetic field propagation to accurately evaluate the power density and transmission efficiency of resonant beam transmission in free space between the transmitter and the receiver.Based on the structure of RBS,the resonant beam transmission in free space can be viewed as the process of electromagnetic wave propagation back and forth between the two wave source planes,the power density at any point in the resonator can be accurately obtained to further calculate end-to-end transmission efficiency by combining with the Fox-Li iterative algorithm.The output power of the RBS with determined parameters can then be obtained numerically using the power transmission model.Finally,the calculation results show that 4W electrical power and 12 bps/Hz spectral efficiency can be achieved in the RBS.· We develop an analytical safe model and demonstrate that resonant beam trans-mission is inherently safe,i.e.,resonant beam transmission can guarantee human body safety(i.e.no radiation hazard to humans)based on system infrastructure.First,we abstract the process of external object invasion into the model of invading object blocking resonant beam.Then,by examining the change in electromagnetic field distribution,the changes in excitation suppression and transmission efficiency are investigated.Furthermore,the output power of the RBS and the irradiance(i.e.,irradiation power density)on the invading object can be investigated.By comparing the irradiance on the invading object with the maximum permissible exposure(MPE)requirement for human skin in “Safety of Laser Products IEC 60825-1",we can evaluate whether the resonant beam transmission is human safe.The simulation results illustrate that 1 W electric power can be transferred safely at 5 m distance in the RBS.In addition,the maximum irradiance 0.8 W/cm2 on the invading object in RBS is only 1/10 of the maximum irradiance 8 W/cm2 on the invading object in the laser system,and the human safety of the RBS is superior to that of the laser system.· To overcome the power constraint of inherently safe in RBS,we design a selfprotection RBS for safely transferring higher power over a longer distance without mechanical control.By reflecting and refracting the partially outgoing resonant beam at the receiver,the low-power protective beam surrounds the resonant beam in 360 degrees.The protective beam will return to the intra-cavity again after extra-cavity transmission and affect the reflectivity of output reflector with the self-mixing interference-effect.Then,we establish the analysis model of external object invasion in self-protection RBS.The invading object will first contact the low-power protective beam.As the invasion depth increases,the system’s pumping power threshold grows above the input pumping power,causing both the resonant beam and protective beam to be cut off at the same time.Therefore,human safety can be guaranteed during energy transmission.The simulation results illustrate that 3 W electrical power,12 bps/Hz spectral efficiency can be transferred safely at 2 m distance in the self-protection RBS.· We propose the Round-Robin Scheduling(RRS),High-Priority Scheduling(HPS),and Channel-Dependent Scheduling(CDS)algorithms for the differentiated service demands of receivers to improve the Quality of Service(Qo S)and transmission efficiency of the RBS.The remaining energy of battery,usage status,and placement of multiple receivers accessing the RBS are different;therefore,based on the adaptive feedback mechanism and the transmission mechanism of resonant beam,the receivers have different demands for charging services.For the service demand of each receiver,the service time is divided into several equal time slots based on the Time Division Multiplexing(TDM)method,and the service is supplied simultaneously to multiple receivers at each time slot according to the scheduling strategy.Then,the performance of three scheduling algorithms is evaluated under different service times and the number of receivers with specific transmitting power.The numerical analysis reveals that a reasonable scheduling strategy can achieve the goals of improving Qo S,maximizing revenue,and increasing the service efficiency of the RBS.