Research On Wireless Power Transfer And Covert Communication Technology Based On Intelligent Reflecting Surface

Stepping into the 21 st century,communication quality is becoming more and more reliable,and communication equipment is becoming more and more flexible.However,flexible equipment deployment is inseparable from effective energy supply methods.Traditional wired connection energy supply greatly reduces the flexibility of equipment.Therefore,Wireless Power Transfer(WPT)has become the focus of research.With the deepening of the research,the power transfer effect of WPT is often limited by many factors,so how to improve the transmitted energy under limited resources is an important research direction.Recently,an Intelligent Reflecting Surface(IRS)composed of a large number of passive reflecting units has been designed,which can adjust the signal beam,and has great research value in wireless communication networks.On the other hand,in order to ensure the security of wireless communication,Covert Communication(CC)hides the communication behavior,making it difficult for eavesdroppers to find legal communication.Based on the above research background,this thesis studies the energy and data integrated transmission and IRS-assisted WPT and CC from the shallower to the deeper.First of all,starting from WPT technology,the wireless power transmission and wireless data transmission are combined to realize the integrated transmission of data and energy,and using Universal Software Radio Peripheral(USRP)equipment to build a physical system.The baseband signal processing part of the system is implemented on the computer using Orthogonal Frequency Division Multiplexing(OFDM)technology,and then uses multi-carriers to insert additional energy signals,and designs corresponding power allocation schemes according to channel state information to reduce information bit error rate,increasing the energy collected.The simulation results show that the built system can realize the transmission of data and energy at the same time,and the performance of data transmission and power transmission of the system can also be improved through the power allocation scheme.Then,in order to improve the effect of WPT,the introduction of IRS to assist power transfer was considered,and in order to ensure the security of the communication system,the CC assisted by IRS was further considered.First,the scenario of a single passive device is proposed,which first receives energy through the energy node and then transmits data,and guarantees CC in communication.In this thesis,with the goal of maximizing the uplink throughput of the device,the uplink and downlink time of the system and the IRS phase shift matrix are jointly optimized.However,the proposed problem is difficult to solve directly,so this thesis designs an alternate iteration algorithm to solve the problem by using methods such as positive semi-definite relaxation and convex optimization.Finally,the single device is extended to the multi-device scenario,and on the basis of the original,the scheduling strategy among multiple devices and the resource allocation algorithm in this scenario are further studied.The simulation results show that the system throughput can be improved under certain concealment requirements by rationally designing the uplink and downlink time and the IRS phase shift matrix,and the introduction of IRS can also effectively improve the transmission energy and the concealment of wireless communication.