Intelligent Reflecting Surface Assisted Transmission Optimization Strategies in Wireless Networks

Wireless Power Transfer(WPT)technology can provide real-time power for many terminal devices in Internet of Things(IoT)through millimeterWave(mmWave)to support applications with large capacity and low latency.Although the intelligent reflecting surface(IRS)can be adopted to create effective virtual links to address the mmWave blockage problem,the conventional solutions only adopt IRS in the downlink from the Base Station(BS)to the users to enhance the received signal strength.In practice,the reflection of IRS is also applicable to the uplink to improve the spectral efficiency.It is a challenging to jointly optimize IRS beamforming and system resource allocation for wireless energy acquisition and information transmission.In this paper,we first design a Low-Energy Adaptive Clustering Hierarchy(LEACH)clustering protocol for clustering and data collection.Then,the problem of maximizing the minimum system spectral efficiency is constructed by jointly optimizing the transmit power of sensor devices,the uplink and downlink transmission times,the active beamforming at the BS,and the IRS dynamic beamforming.To solve this non-convex optimization problem,we propose an alternating optimization(AO)-based joint solution algorithm.Simulation results show that the use of IRS dynamic beamforming can significantly improve the spectral efficiency of the system,and ensure the reliability of equipment communication and the sustainability of energy supply under NLOS link.

On Differentiation Among Pilot Signals of Multiple Mobile Targets in Retro-Reflective Beamforming for Wireless Power Transmission

An experimental study is conducted on several retro-reflective beamforming schemes for wireless power transmission to multiple wireless power receivers(referred to herein as“targets”).The experimental results demonstrate that,when multiple targets broadcast continuous-wave pilot signals at respective frequencies,a retro-reflective wireless power transmitter is capable of generating multiple wireless power beams aiming at the respective targets as long as the multiple pilot signals are explicitly separated from one another by the wireless power transmitter.However,various practical complications are identified when the pilot signals of multiple targets are not appropriately differentiated from each other by the wireless power transmitter.Specifically,when multiple pilot signals are considered to be carried by the same frequency,the wireless power transmission performance becomes heavily dependent on the interaction among the pilot signals,which is highly undesirable in practice.In conclusion,it is essential for a retro-reflective wireless power transmitter to explicitly discriminate multiple targets’pilot signals among each other.

Power Line Monitoring Data Transmission Using Wireless Sensor Network

The WSN used in power line monitoring is long chain structure, and the bottleneck near the Sink node is more obvious. In view of this, A Sink nodes’ cooperation mechanism is presented. The Sink nodes from different WSNs are adjacently deployed. Adopting multimode and spatial multiplexing network technology, the network is constructed into multi-mode-level to achieve different levels of data streaming. The network loads are shunted and the network resources are rationally utilized. Through the multi-sink nodes cooperation, the bottlenecks at the Sink node and its near several jump nodes are solved and process the competition of communication between nodes by channel adjustment. Finally, the paper analyzed the method and provided simulation experiment results. Simulation results show that the method can solve the funnel effect of the sink node, and get a good QoS.

Design and Optimization of Inductive Wireless Power Transmission System

The inductive wireless power transmission system is actually applied to the principle of magnetic field coupling, com- bined with the flexibility of the electrical equipment to achieve flexible and safe power supply. In the realization process of wird^ power transmission, the key point lies in the transmission efficiency and power transmission capability. However, wireless trans-mission still has some disadvantages in these two aspects. In this case, there is an air gap between the transmitting winding and the receiving winding. If it is too large and the coupling coefficient is too low, in view of this situation, it is necessary to carry out re-search from aspects such as raising the coupling coefficient and controlling the air gap. The article firstly describes the development ofwireless power transmission technology and transmission principles, etc. Secondly, it analyzes the output control ofwireless power fransmission systems. Uird,it conducts simulation analysis using loosely coupling transfomers and proposes an optimized solution. The simulation design and inspection process were proposed. The main purpose of this paper is to analyze the current wireless energy transmission system and clarify the direction in which it should be strengthened. The significance of this study is to provide a feasible direction for the further optimization of the wireless energy transmission system.

Secure Transmission Scheme Based on Dual-Thresholds for Simultaneous Wireless Information and Power Transfer

This paper studies a simultaneous wireless information and power transfer system with multiple external eavesdroppers and internal curious users.We model the random network by Poisson cluster process in consideration of the case where eavesdroppers hide around certain targets.Focusing on the users that work in harvesting-transmitting mode with time switching receivers,we establish communication model via time division multiple access.On this basis,we propose a lightweight secure transmission scheme based on dual-thresholds for physical-layer security enhancement,which consists of two protocols applied to the downlink(DL) and uplink(UL) transmission respectively.In the DL,we design a dynamic information-power switching transmission protocol based on signal-to-noise ratio threshold,which provides an opportunistic approach to reform the fixed period allocation of information and power transfer;in the UL,an energy threshold is proposed for users to control the transmission,which is called a user-led on-off transmission protocol.Furthermore,we give a comprehensive performance analysis for the proposed scheme in terms of delay,reliability,security and secrecy throughput.Based on the analysis results,we optimize the two thresholds and the DL-UL allocationcoefficient to maximize the secrecy throughput.Simulation results show the proposed scheme can bring about a substantial secrecy gain.

Battery Charger for Electric Vehicles based on a Wireless Power Transmission

In this paper,the case of a battery charger for electric vehicles based on a wireless power transmission is addressed.The specificity of every stage of the overall system is presented.Based on calculated and measured results,relevant capacitive compensations of the transformer and models are suggested and discussed in order to best match the operating mode and aiming at simplifying as much as possible the control and the electronics of the charger.

Theoretical Design of Energy Harvesting Module or Wireless Power Transmission Receiver Using Magnetic Field of 0.2 mT at 60 Hz

This paper presents a theoretical design method for a magnetic energy harvesting module. This module consists of an air-core coil and resonant capacitor. With a simple RLC circuit model, it can derive an equation of harvesting energy as a function of coil size. In order to demonstrate the magnetic field, a uniform magnetic field is generated by the developed coil system. From the experimented results, it is successfully demonstrated 100 mW of energy harvesting from a magnetic field of 0.09 mT at 60 Hz. This value is in good agreement with the estimated results. Harvested energy is proportional to the square of the magnetic flux density. However, ICNIRP2010 provides a guideline that an acceptable level for human health in a public space is 0.2 mT at power-line frequency. This paper also discuss the possibilities of several applications related with both magnetic energy harvesting and wireless power transmission.

Retro-reflective Beamforming Technique with Applications in Wireless Power Transmission

Retro reflective beamforming technique has the potential of enabling efficient wireless power transmission over long distance(on the order of meters and even kilometers).In retro reflective beamforming,wireless power transmission is guided by pilot signal:Based upon pilot signal broadcasted by a wireless power receiver,a wireless power transmitter delivers focused microwave power beam(s)onto the location of wireless power receiver.When the wireless power receiver’s location is not fixed or when the wireless power receiver’s location is unknown to the wireless power transmitter,the microwave power beam would follow the wireless power receiver’s location dynamically as long as the wireless power receiver broadcasts pilot signal periodically.This paper reviews our research endeavors in recent years on retro reflective beamforming technique targeting three applications:(1)wireless charging for low power mobile/portable electronic devices,(2)space solar power satellites(SSPS)application,and(3)wireless charging in fully enclosed space.The feasibility and potential of retro reflective beamforming technique with applications in wireless power transmission are demonstrated by some preliminary experimental results.

Wireless Power Transmission into Metallic Tube Using Axial Slit for Infrastructure Diagnostics

Wireless power transfer (WPT) using a metallic tube with axial slits was attempted to demonstrate WPT using magnetic resonance coupling to the diagnostics infrastructure. The transmission efficiency was measured at various distances using the transmission and receiver resonator in the tube. Furthermore, the transmission and receiver resonator were set respectively outside and inside of the tube. Experiment results were assessed computationally using the finite-difference time-domain (FDTD) simulation. As a result, the transmission efficiency of the transmitter and receiver resonators in the metallic slit tube was higher than that of the case without a metallic tube in the range of the normalized transmission-distance of x/d > 0.4. In the simulation, the current density on the metallic tube around both transmitter and receiver coil were connected. These results reveal that the slit on the tube plays a role of the relay coil.

Wireless Power Transmission with Short and Long Range Using Inductive Coil

In today’s time each individual needs remote framework, yet at the same time control transmission for low power gadgets are wired in nature. Consistent power supply is one of the real issues in the motivation behind the utilization of remote sensor network. Yet, in the power arrangement of remote Sensor Network, the battery has an extremely constrained lifetime and is not supplanted yet by some other persistent power framework. There are separate techniques proposed for shorter and more separate power transmission: Inductive coupling, resonant inductive coupling and air ionization for short separations;microwave and Laser transmission for longer separations. The pioneer of the field, Tesla endeavoured to make a capable, remote electric transmitter more than a century back that has now observed an exponential development. This paper overall lights up all the effective strategies proposed for transmitting power without wires. This study is important for find out the future ways of power transmission. These methods are so important in today’s world because of drastic wastage of power. Common wireless power transmission is a point-to-point control transmission. It was demonstrated that the power transmission effectiveness could approach near 100%.

Optimal Design of Wireless Power Transmission Systems Using Antenna Arrays

Three design methods for wireless power transmission(WPT)systems using antenna arrays have been investigated.The three methods,corresponding to three common application scenarios of WPT systems,are based on the method of maximum power transmission efficiency(MMPTE)between two antenna arrays.They are unconstrained MMPTE,weighted MMPTE,and constrained MMPTE.To demonstrate the optimal design process with the three methods,a WPT system operating at 2.45 GHz is designed,simulated,and fabricated,in which the transmitting(Tx)array,consisting of 36 microstrip patch elements,is configured as a square and the receiving(Rx)array,consisting of 5 patch elements,is configured as an L shape.The power transmission efficiency(PTE)is then maximized for the three application scenarios,which yields the maximum possible PTEs and the optimized distributions of excitations for both Tx and Rx arrays.The feeding networks are then built based on the optimized distributions of excitations.Simulations and experiments reveal that the unconstrained MMPTE,which corresponds to the application scenario where no radiation pattern shaping is involved,yields the highest PTE.The next highest PTE belongs to the weighted MMPTE,where the power levels at all the receiving elements are imposed to be equal.The constrained MMPTE has the lowest PTE,corresponding to the scenario in which the radiated power pattern is assumed to be flat along with the Rx array.

A Radio⁃Frequency Loop Resonator for Short⁃Range Wireless Power Transmission

A microstrip loop resonator loaded with a lumped capacitor is proposed for short-range wireless power transmission applications.The overall physical dimensions of the proposed loop resonator configuration are as small as 3 cm by 3 cm.Power transmission efficiency of greater than 80%is achieved with a power transmission distance smaller than 5 mm via the strong coupling between two loop resonators around 1 GHz,as demonstrated by simulations and measurements.Experimental results also show that the power transmission performance is insensitive to various geometrical misalignments.The numerical and experimental results of this paper reveal a bandwidth of more than 50 MHz within which the power transmission efficiency is above 80%.As a result,the proposed microstrip loop resonator has the potential to accomplish efficient wireless power transmission and high-speed(higher than 10 Mbit/s)wireless communication simultaneously.

Tracking Galloping Profile of Transmission Lines Using Wireless Inertial Measurement Units

Galloping of power transmission lines might bring about huge damage such as massive power outage and collapse of the transmission towers. To realize forecast of the galloping and provide data for study on the galloping mechanism, this paper proposes an online monitoring system for tracking galloping profile of power transmission lines based on wireless inertial measurement units (WIMUs). The system is composed of three modules: wireless inertial measurement nodes, monitoring base station, and remote monitoring station. After detailing the hardware system, the corresponding software which positions and displays galloping profile of the transmission line in real-time is outlined. The feasibility of the proposed on-line monitoring system is demonstrated through a series of experiments at the State Grid Key Laboratory of Power Overhead Transmission Line Galloping (Zhengzhou, China) by taking into account different vibration patterns.

An Adaptive Wireless Power Sharing Control for Multiterminal HVDC

Power sharing among multiterminal high voltage direct current terminals(MT-HVDC)is mainly developed based on a priority or sequential manners,which uses to prevent the problem of overloading due to a predefined controller coefficient.Furthermore,fixed power sharing control also suffers from an inability to identify power availability at a rectification station.There is a need for a controller that ensures an efficient power sharing among the MT-HVDC terminals,prevents the possibility of overloading,and utilizes the available power sharing.A new adaptive wireless control for active power sharing among multiterminal(MT-HVDC)systems,including power availability and power management policy,is proposed in this paper.The proposed control strategy solves these issues and,this proposed controller strategy is a generic method that can be applied for unlimited number of converter stations.The rational of this proposed controller is to increase the system reliability by avoiding the necessity of fast communication links.The test system in this paper consists of four converter stations based on three phase-two AC voltage levels.The proposed control strategy for a multiterminal HVDC system is conducted in the power systems computer aided design/electromagnetic transient design and control(PSCAD/EMTDC)simulation environment.The simulation results significantly show the flexibility and usefulness of the proposed power sharing control provided by the new adaptive wireless method.

OFDM Wireless Downhole Transmission Systems and Proposed SLM Method for PAPR Reduction

At present, mud pulse transmission systems are widely used in downhole data transmission. But the systems are very low in transmission efficiency, only 5-10 bits/s, with very large anti-inter-symbol-interference (ISI). It cannot meet high requirements for high-speed transmission of modern logging system. The development of communication technology has laid some foundation for this requirement. For this purpose, the Orthogonal Frequency Division Multiplexing (OFDM) Wireless Downhole Transmission Systems are proposed for the first time because of their high transmission rate, anti-inter-symbol-interference (ISI), and high spectral efficiency, etc. Due to non-linear power amplifier (PA) of logging systems with limited dynamic range, the drawbacks of high peak-average power ratio (PAPR) may outweigh all the potential benefits of OFDM wireless downhole transmission systems. Selective mapping (SLM) method can reduce the PAPR of OFDM logging signals without distortion. But at the receiver, the conventional SLM method needs exact bits of side information (SI) to recover the data signal. The probability of erroneous SI detection has a significant influence on the error performance of the system. And individual transmissions of SI result in the reduction of bandwidth efficiency. To restore the exact data signal, our scheme codes the SI bits by linear block codes (LBC), and is easily decoded by syndrome decoding. And then the coding SI bits are superimposed onto the logging signals to omit SI bits transmission. The theory and simulation results show that the proposed method has better performance than the conventional one. Accordingly, the OFDM wireless downhole transmission systems can tackle the high PAPR problem, and highten the transmission rate of logging signals.

Design of a Loop Resonator with Improved Power Transmission Efficiency Using a Ferrite Plate

We propose a novel resonator that can reduce magnetic field leakage using a ferrite plate. The proposed resonator consists of a rectangular loop, a ferrite plate, and an L-matching network. The ferrite plate is used as an H-field reflector to direct more H-field to each resonator, and the L-matching network is employed to match the 50 Ω of the feed cable at 13.56 MHz. Two identical resonators with dimensions of 30 cm × 15 cm are separated by 50 cm, and the resulting transmission efficiency is about ?12.3 dB at 13.56 MHz. This is about 4.2 dB higher than the resonators without the ferrite plate.

Microwave Power Transmission for Space-Based Solar Power (MPT-SBSP)

This paper examines the definition of MPT-SBSP and implementation model of such technology.It surveys the latest development and affirms the feasibility and a bright future of this technology,emphasizing the existing issues must be solved by more educated individuals and organizations for the early realization of this"beyond-the-realm-of-cost"technology.Because once this technology is successfully applied in large-scale,humans won’t have to worry about the energy crisis in the future.

Theoretical and experimental studies of retro-reflective antenna array for microwave power transmission from space solar power satellite to earth

The development of space solar power satellites aims to harvest solar power by artificial satellites over the earth’s geostationary orbit and then deliver the harvested power to the earth wirelessly.The retro-reflective antenna array technique is believed to be a close-to-optimal technical approach to achieve efficient wireless power transmission from a geostationary satellite to the earth,as it is capable of generating a microwave power beam aiming at a ground station on the earth via analyzing a pilot signal broadcasted by the ground station.In this paper,some of our preliminary research outcomes on retro-reflective antenna array for space solar power applications are reported.In the theoretical part of this paper,closed-form formulations with precision better than the classic theory of phased array are derived to analyze the performance of retro-reflective antenna array when the far zone condition is not satisfied between the space solar power satellite and the ground station.In the experimental part of this paper,a bench-scale retro-reflective antenna array with physical dimensions of about 0.6 m by 0.6 m is fabricated and tested.The theoretical and experimental results demonstrate that the microwave beam generated by a satellite-borne retro-reflective antenna array could be adjusted in real time to aim at the location from which the pilot signal stems.Based on the theoretical and experimental studies of this paper,systematic research endeavors are being conducted on the retro-reflective antenna array for space solar power applications.

Wireless Power Feeding with Strongly Coupled Magnetic Resonance for a Flying Object

Wireless power feeding was examined with strongly coupled magnetic resonance for an object moving in 3-D space. Electric power was transmitted from the ground to an electrically powered toy helicopter in the air. A lightweight receiver resonator was developed using copper foil. High Q of greater than 200 was obtained. One-side impedance matching the transmitter side was proposed to cope with high transmission efficiency and the receiver’s weight reduction. Results show that the efficiency drop near the ground was drastically improved. Moreover, the measured efficiency showed good agreement with theoretical predictions. A fully equipped helicopter of 6.56 g weight was lifted up with source power of about 5 W to an altitude of approximately 10 cm.

Characterization of Blue-Green Light Non-Line-of-Sight Transmission in Seawater

The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve communication in non-line-of-sight (NLOS) transmission mode. Compared to line-of-sight (LOS) transmission, NLOS transmission does not require alignment and can be adapted to various underwater environments. The scattering coefficients of seawater at different depths are different, which makes the scattering of light in different depths of seawater different. In this paper, the received optical power and bit error rate (BER) of the photodetector (PD) were calculated when the scattering coefficients of blue-green light in seawater vary from large to small with increasing depth for NLOS transmission. The results show that blue-green light in different depths of seawater in the same way NLOS communication at the same distance, the received optical power and BER at the receiver are different, and the received optical power of green light is greater than that of blue light. Increasing the forward scattering coverage of the laser will suppress the received optical power of the PD, so when performing NLOS communication, appropriate trade-offs should be made between the forward scattering coverage of the laser and the received optical power.