Abstract：SA is the final network architecture of 5G network evolution and development, which adopts a brand new network deployment. But it will coexist with current LTE networks for quite a long time. In order to ensure that UEs enjoy uninterrupted service in the mobile process, the network needs to provide efficient mobility management. Mobility management can be divided into cell reselection, handover, and redirection based on UE state. And it can be divided into intra-system mobility management and inter-system mobility management according to whether the service cells cross the system. To achieve the 0 ms interruption delay of handover, R16 had proposed several mobility management enhancement solutions. The paper mainly introduced the mobility management between NR cells, the interoperability between 4G/5G cells and the mobility management enhancement solutions in R16, which provided a reference for the mobility management optimization of 5G SA network.

Abstract：Dynamic spectrum sharing(DSS) technology allocates spectrum resources dynamically and flexibly for different communication technologies in the same frequency band. This technology is of great significance in the rapid deployment of 5G network to realize the smooth evolution from 4G to 5G, and the realization of 5G network wide coverage by using low frequency band. Although DSS can improve the utilization of spectrum resources by flexibly allocating spectrum resources in most cases, the introduction of DSS technology also brings additional spectrum cost. This paper will introduce the current mainstream DSS technology scheme and the corresponding cost calculation method, and analyze the advantages and disadvantages of various DSS technology schemes by comparing the cost loss before and after the introduction of DSS technology.

Abstract：December 2019, 3GPP determined more than 20 study and work items for 5G R17 version, of which RAN slicing enhancement technology is one of the key technologies enabling vertical industries. This article analyzes the key technical achievements of RAN slicing in the 3GPP R15 version, and combines the progress and existing problems of the existing technology. From the perspective of solving actual network problems and enabling richer applications, the latest study directions of R17 RAN slicing enhancement technology are discussed.

Abstract：With large scale commercializing of 5G network in 2020, operators in the whole world have accelerated 5G deployment. In this paper, the network architecture and evolution scheme of NSA and SA are introduced, the 5G NSA to SA , SA to NSA handover technology are studied, and SA to NSA optimized handover strategy in R16 is analyzed , which are under NSA/SA hybrid networking.

Abstract：Dynamic Spectrum Sharing(DSS) is emerging as an important technology for the smooth evolution to 5G, which can effectively improve the spectrum utilization efficiency of low frequency bands. One of the key points for the design and operation of DSS is to solve the problem of 4G LTE and 5G NR uplink physical layer conflicts. In this paper, the format selection and resource allocation for uplink(UL) physical channel and reference signal are studied in multiple dimensions. And a load-based uplink resource allocation method is proposed to provide configurations for DSS deployment.

Abstract：The continual development of new concepts and techniques in the field of air traffic surveillance generates constantly more diversified demands for an accurate understanding of its operating mechanism. Security research, which deals with one of the fundamental issues of air traffic surveillance, emerges throughout the system at all levels, and provides important clues for exploring the emergence of air traffic surveillance system. However, there is as yet no widely accepted architecture for security research on air traffic surveillance up to now. Therefore, this article focuses on wireless communication technologies and security in air traffic surveillance system. In order to focus on the systems view, we divide all technologies used in air traffic communications into two categories according to their application: air traffic control and information services. Air traffic control are used to enable communication between controllers and pilots or their aircraft. Information services are technologies which provide information to pilots to improve their situational awareness. It also points out the future research and development trends in the field of air traffic surveillance and some key issues which remain to be solved.

Abstract：Aiming at the problem that the vehicle logo detection has long detection time, low detection rate and few identifiable types, a method using You Only Look Once(YOLOv3) network is proposed. In order to make the network suitable for vehicle target detection of small targets, the target feature extraction structure Darknet-53 is replaced with Darknet-19 and the multi-scale prediction layer is reduced to two layers to reduce the number of network parameters. At the same time, in order to increase the proportion of the car logo in the image and let the convolutional neural network can learn more car logo features, this paper adopts a method of cutting the vehicle from the image and manually marking it, constructing a class of 46 vehicles Data set(VLDS-46). The experimental results show that when the model is used for vehicle logo detection, the real-time requirement can be achieved while achieving high detection rate, and the average detection time is 9 ms.

Abstract：In the production of coal mines, accidents happen to workers once in a while because of absence of safety helmet. In order to establish digital safety helmet detection system, a wearing safety helmet detection model based on convolutional neural networks is proposed. Specifically, the model is based on advanced Darknet53 as model backbone, which is used to extract feature information from pictures. In addition, attention mechanism is introduced to enrich the propagation of information between features, enhancing the generalization of model. Finally, a wearing safety helmet pre-training dataset and a real mine scene dataset are built, and comprehensively comparative experiments are conducted on PyTorch platform to verify the effectiveness of the model designs, which achieves an excellent performance of 92.5 mAP on the real mine scene dataset.

Abstract：Compared with single image super-resolution, video super-resolution needs to align and fuse time series images. This frame-recurrent-based video super-resolution network consists of three parts：(1)The frame sequence alignment network extracts the image features and aligns the neighbor frames to the center frame；(2)The frame fusion network fuses the aligned frames and supplements the center frame information with the neighbor frame information；(3)The super-resolution network enlarges the fused image to obtain the final high-definition image. Experiments show that, compared with existing algorithms, video super-resolution technology based on frame loop network produces sharper images and higher quality.

Abstract：The image intensifier is usually powered by 3 V lithium batteries, as the battery voltage dropping, the change or adjustment of DC bias point may lead the internal high-voltage power supply output to be abnormal, which may cause the image tube to flicker, extinguish or highlight. Generally, the power supply characteristics of image intensifier is verified using a DC power supply with "Battery Simulating Function". This equipment has high power, multi functions and high price. The image intensifier needs little power, if the equipment is used, the utilization of the equipment will be so low that cause high cost of R&D. Based on the constant current source controlling LDO output, a DC-DC circuit which could simulate charging and discharging of 1.4 V~3.4 V batteries was designed. Software simulation and actual test results verified the output voltage can rise or fall linearly, and the rate could be adjusted in tens of milliseconds to hours. The function of simulating battery power supply is achieved. This circuit has low cost and its improved circuit can also be used for DC sweep analysis of power products in other applications.

Abstract：In the communication system, the receiving and transmitting synchronization can not be separated from the accurate clock frequency source. The accuracy of the clock frequency source directly affects the reliability of the system. AT cut crystal is an important part of the frequency source. Its frequency and temperature show a cubic function relationship, which makes it not suitable for a wide range of temperature application scenarios. In order to overcome the direct influence of temperature on frequency, this paper designs a kind of cubic function generating circuit for temperature compensation, including reference source, primary voltage generating circuit, cubic generating circuit and adding circuit, which can cancel the negative temperature coefficient produced by AT cut crystal in operation. The simulation results show that the reference circuit has a constant output of 1.856 V, the third-order circuit has a peak of 1.65 V and a trough of 0.85 V, and the added compensation circuit has a peak of 2.04 V and a trough of 1.74 V. The frequency error caused by the temperature change is well suppressed, and the problem that the output frequency of the oscillator changes with the temperature is solved.

Abstract：Because of high manned moving resistance, the self-designed omni-directional mobile robot cannot meet the task requirements. Aiming at this problem, the design of the omni-directional wheels of the robot is improved from two aspects, namely material selection and small wheel installation. And the correctness of the optimization design is preliminarily verified by means of ADAMS kinematic simulation. Finally, the old-style wheels and the new-style wheels are mounted respectively on the omni-directional mobile robot, used for manned experiment. The results show that after using the new design of omni-directional wheels, the mobile efficiency, stability and smoothness of the manned robot are greatly improved, which meets the task requirements.

Abstract：Traditional pig temperature measurement generally uses a mercury thermometer to measure the rectal temperature of the pig to determine the body temperature. This method cannot achieve real-time monitoring of the pig temperature. The system designed a pig temperature monitoring system based on the Internet of Things technology. The ESP8266 is used as the main controller and wireless communication module. The temperature sensor uses MF54 series NTC thermistor. The software and hardware adopt unbalanced bridge circuit and average filtering method, so that the accuracy of the measured data reaches ±0.1 ℃. Due to the activity of live pigs, the monitoring node is integrated on the ear tag of the pig, and the real-time monitoring of the body temperature is achieved by collecting the ear cavity temperature. The platform layer uses the mobile OneNET IoT platform, and develops a mobile application as the display terminal of the monitoring system. This system realizes real-time monitoring of pig body temperature, which has certain application value for pig disease prevention and intelligent breeding.

Abstract：Aiming at the problems of low measurement accuracy and high cost of conventional three-phase meter calibration device, this paper studies a three-phase multifunctional meter calibration device based on STM32F429 single-chip microcomputer. The hardware circuit of the device mainly includes voltage and current sampling range switching circuit, relay drive circuit, time clock circuit, RS232 serial communication module and display circuit. The voltage and current sampling range switching circuit converts the voltage and current signals collected by the current and voltage transformer into the measurement range of CS5463 chip. There are 4 UART ports for RS232 communication in STM32F429 chip, convenient to connect with other peripherals. After receiving the signal, the voltage and current data collected are displayed on the TFTLCD capacitive touch screen. Software design is mainly to initialize temporary variables and configure the relevant registers of CS5463, and then collect voltage and current at regular intervals. Through the analysis and comparison of the test results, the measurement accuracy of the device reaches 4 decimal places.

Abstract：With the improvement of wireless sensing systems and wireless network technologies, human-computer interaction, behavior recognition, and non-contact sensing detection based wireless signals has received increasing attention in wireless sensing. Aiming at the condition that water leakage accidents in home environment, this paper proposes a system for detecting water leakage in real time based commercial WiFi signals. It mainly uses the channel state information in commercial WiFi signals, captures signal changes caused by different characteristics of objects by receiving signals, and completes the three-step processing: data preprocessing, feature extraction, and machine learning classification to achieve the goal of real-time detection of leaks，and innovate the traditional leak detection system. In order to prove that the proposed system′s classification model is suitable for any ordinary home environment, this paper executes the test in real environment at the end, and the outputted results verify the feasibility of the system.

Abstract：In view of the application scenarios are sensitive to resource consumption and cost in wireless sensor networks, this paper studies and proposes a low resource polar code successive cancellation(SC) decoding architecture based on FPGA. The decoding architecture adopts the serial operation of the same level computing units, the parallel operation of different levels of computing units, and the parallel processing of different groups of decoding data. By reducing the number of processing elements(PE), reusing register storage resources, the architecture improves the utilization of hardware resources, and reusing decoding delay improves the throughput. According to the analysis of the comprehensive results of Xilinx xc7vx330t, when the code length is N=128, the architecture′s highest decoding clock frequency is 220.444 MHz, and the throughput is 89.86 Mb/s. Compared with the tree SC decoding architecture, its utilization ratio of computing unit is increased by 14.67 times. It saves 74.22% and 62.1% on Look-Up-Table(LUT) and Flip-Flop(FF) of main hardware resource indexes respectively.

Abstract：Aiming at the problems of large repetitive operation and easy incorrect operation in manual test of programmable logic controller, an automatic test method is designed and implemeted. This method includes batch automatic compilation of test cases, automatic execution, automatic display and storage of test results and automatic generation of test reports, covering basic functional testing and stress testing. Experiments show that the software based on this method can improve the accuracy and efficiency of the test.

Abstract：Aiming at the inconsistency between the density of point cloud generated by sequence images and that generated by laser scanning,a density control method based on structure from motion is proposed.The method firstly compares the density of the point cloud generated by the sequence image with the density of the target point cloud to determine whether to increase or decrease the density of the point cloud generated by the sequence image. Secondly,the image feature points are extracted,and the cell size is set according to the spatial mapping relationship between the image feature points and the corresponding generated point cloud. The feature points closest to the center of each cell are used to represent all points in the cell to which they belong,so that the density is reduced,and the feature points in each cell are interpolated by least squares fitting to increase the density. Then，KLT feature point tracking algorithm is used to get matching points. Finally,the image point cloud is generated based on the matching point pairs.The experimental results show that this method can control the density of point cloud generated by the image by adjusting the cell size or interpolation step size，achieving a good control effect.

Abstract：In this study, image processing technology and machine learning algorithm are combined to identify and classify the three most common diseases of rice, namely rice blast, bacterial leaf blight and bacterial streak. Firstly, the lesion part of rice disease image is segmented and the image set of rice disease is established. Then, according to the pathological appearance of different disease spots, characteristic parameters from various aspects are extracted and optimized. Then, BP neural network is used to build the model and classify the optimized features. Finally, the BP classification model is improved by optimizing the selection process of weights and thresholds in BP algorithm with simulated annealing algorithm and adaptive genetic algorithm. The results show that the improved algorithm has high accuracy in rice disease identification and is feasible. This method is more efficient and accurate than traditional manual diagnosis method.

Abstract：Aiming at the problems of data fragmentation and easy tampering during the production, transportation and construction of prefabricated components, this paper proposes a prefabricated component management system based on RFID and blockchain. Firstly, the design ideas and system architecture of the system are introduced in detail. Secondly, the App is designed based on the business processes of production, transportation and construction, and the implementation ideas of data storage and query are analyzed. Finally, the management system was implemented and tested for deployment. The system uses RFID technology to uniquely identify each prefabricated component and stores the data collected by the App in the blockchain. Utilizing the characteristics of blockchain decentralization and non-tampering, it provides managers with authentic and reliable traceability data, thereby improving construction efficiency.

Abstract：In order to solve the problem that monitoring the working load of the ball mill during its operation, a monitoring system of the mill material based on digital signal processor(DSP) is designed. The hardware of the system is mainly composed of four kinds of circuit, i.e., the power circuit, the grinding sound acquisition circuit, the signal processing circuit and the Liquid Crystal Display(LCD) data display circuit. The system collects the grinding sound signal through the pickups, transforms grinding signal in time domain to frequency domain by discrete Fourier transform(DFT), calculates grinding energy according to Parseval′s theorem. Finally, the system gets the relationship between energy and material by polynomial fitting. The system processes the grinding sound signal in real time by DSP. Meanwhile, for the monitor personnel can optimize the production process, the processed spectrum, sound intensity(decibel value) and material ratio are displayed on the LCD touch screen. The experimental results show that the system can effectively monitor the working condition of the mill and calculate the load ratio of the mill, and it has been applied in the actual operation of the ball mill.

Abstract：Nuclear physics experiments,radiation medicine and other fields are inseparable from the radiation source and its detection. By using DAC, FPGA and direct digital synthesis(DDS)technology to build a virtual radiation source system,the types of radiation source and detector can be flexibly selected, and the relative distance and angle between radiation source and detector can be set. According to the experimental spectral line, the amplitude signal is transmitted at a certain frequency,and it enters the FPGA digital processing platform through the network port. FPGA receives the amplitude signal and processes it to get the pulse signal with specific detector characteristics. The 14 bit digital-to-analog conversion chip LTC1667 is used to convert the digital signal from FPGA to analog signal. Pulse amplitude analyzer is used to collect and analyze the pulse signal and obtain the energty spectrum through the corresponding software.The results show that the virtual radiation source can not only achieve the similar effect, but also have more flexibiliy,convenience and safe.

Abstract：An ECU of a gas engine is used as a test object, and an ECU offline(EOL) test system is developed based on the STM32F103 series main control chip. It consists of a host computer, a test board layer, and a test ECU. It can implement switching detection, analog detection, and frequency detection and etc. The host computer transmits data instructions, and the test board layer performs, which can complete the detection of ECU hardware and functions. The application shows that the EOL system has the advantages of short time consumption, high efficiency and stable work.

Abstract：Fiber-optic communication system is widely used in industrial field. To solve the problems that the existing system lacks generality and flexibility, a set of fiber-optic communication system with strong versatility and light structure is designed in this paper. FPGA is used as the main controller, it can receive the instruction and data from the host computer through the USB3.0 bus, complete data transmission and reception on the fiber-optic communication link, and control the SerDes and the fiber-optic transceiver to complete the conversion and transmission of signals. The experimental results show that the system can communicate correctly and reliably under the rate of 1.6 Gb/s.

Abstract：In the view of difficulty of automatic pick-up of badminton, this paper studied the multi-sensor data fusion technology and path planning, and designed a badminton pick-up robot which doesn′t hurt the badmintons. The ball picking robot uses a lidar and a camera as sensing units to improve the accuracy of positioning and identifying badminton; DC motors, mechanical parts, etc. are used as the robot′s action execution units to realize the robot′s displacement and ball picking actions. The test results show that the badminton ball picking robot has a ball injury rate of less than 5%, an average ball picking speed of 20 to 30 pieces/min, and a ball picking time of less than 0.4 seconds. The entire robot system has certain practicality.

Abstract：This paper presents a high efficiency AC/DC switching power supply topology without inductor. Through the control of the final discharging voltage(discharge time) of the energy-storage capacitor, the initial charging voltage of the capacitor is controlled. So the output load can get the constant voltage or constant current. In the charging and discharging process of the energy-storage capacitor, the AC input energy is directly transmitted to the load terminal through the energy-storage capacitor. At the same time, the energy stored in the energy-storage capacitor is fully transferred to the load terminal. So this topology transition efficiency is high. In the charging and discharging process of the energy-storage capacitor, the rate of the AC input voltage determines the instantaneous value of the charging and discharging current of the energy-storage capacitor, and then determines the instantaneous value of the input current.

Abstract：In allusion to the problem that traditional multiplier mixing method is affected by local oscillator and there exists interferences and distortions, which greatly affects the performance of receiver, a bipolar junction transistor(BJT) switch mixing method is proposed. The mathematical formula of switch mixing is deduced in detail, and two mathematical models, I-type and II-type switch mixing models are proposed by using Fourier series expansion of square wave. Based on NPN BJT switch, a mixing circuit is designed, and simulation is carried out on Multisim software environment. AM signal is used as an example to mix on BJT switch. Acceleration capacitor is added to eliminate negative peak cutting distortion and intermediate frequency signal is filtered out. The results of simulation are ideal. It is proved theoretically and practically that BJT switch mixing method prevents the interference of local oscillator signal, which can enhance receiver performance.

Abstract：Distributed generation(DG) with clean and renewable energy as its core is susceptible to weather, season, and climate conditions. It has the characteristics of intermittent and random power generation. Large-scale access to the distribution network will affect the quality of power and reduce the stability of the power grid, which will cause fluctuations in the grid voltage. In view of the shortcomings of the traditional voltage regulation methods, a strategy for grid voltage regulation by using battery energy storage systems(BESSs) is proposed to adjust the grid voltage while the state of charge(SOC) of the battery also performs real-time monitoring to prevent overcharging and overcharging of the battery during charging and discharging.

Abstract：A terahertz(THz) device with tunable transmission frequency was designed based on the metal-insulator phase transition characteristics of VO2 and double split ring resonator. The transmission characteristics of the structure are studied by using the finite-difference time-domain(FDTD) theory. The results show that when the external temperature rises from 25 ℃ to 85 ℃ and exceeds the phase transition temperature of VO2(68 ℃), the transmittivity at 0.63 THz and 1.91 THz increases from 6.3% and 0.5% to 66.6% and 45.2%, and the modulation depth reaches 82.7% and 97.8% respectively, showing good tunable characteristics. The mechanism of resonant absorption and the process of temperature control are analyzed.