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    20 January 2022, Volume 38 Issue 1
    Reviews
    Technology development, application and prospect of cellular vehicle-to-everything (C-V2X)
    Shanzhi CHEN, Yuming GE, Yan SHI
    2022, 38(1):  1-12.  doi:10.11959/j.issn.1000-0801.2022007
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    V2X (vehicle-to-everything) is a promote and profound reform-and-innovation in transportation and automobile industries.It is changing the people’s travel mobility modes and ways of society energy consumption.The requirements and challenges of V2X communication performance in data rate, latency, and reliability, being required and challenged by intelligent transportation and automated driving applications were analyzed.The critical technologies and international standards evolutions of cellular vehicle-to-everything (C-V2X) were introduced, including LTE-V2X and NR-V2X.Then, the advantages of applying C-V2X were analyzed for vehicle-vehicle and vehicle-infrastructure cooperation in intelligent transportation and automated driving.Meanwhile, the field testing and industrial practice of C-V2X in China were presented, and the roadmap was envisioned for developing intelligent transportation and intelligent connected vehicles (ICV) in China.For example, the envisions include actively promoting the construction of “5G+C-V2X” and new type infrastructure, exploring the development mode of vehicle-infrastructure cooperation based on V2X, and eventually supporting China to reach the national low “carbon peak” and to achieve the national “carbon neutralization” strategic goals.

    Communication and remote sensing integrated LEO satellites:architecture, technologies and experiment
    Mugen PENG, Shijie ZHANG, Hongtao XU, Mengfei ZHANG, Yaohua SUN, Ying CHENG
    2022, 38(1):  13-24.  doi:10.11959/j.issn.1000-0801.2022021
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    Low earth orbit (LEO) satellite system is one of the most important infrastructures to gather spatial information and break the broadband digital divide.The integration of communication and remote sensing is an effective way to solve the existing problems of system independence, satellite resource waste, and late response to emergency service requests.Firstly, the status of communication and remote sensing in LEO satellite systems were outlined, and then a communication and remote sensing integrated scheme and architecture were put forward to meet the integration requirements.In addition, a hardware composition and corresponding experiment based on this architecture was introduced.Finally, the relevant challenges and future development were discused.

    Research and Development
    Low complexity radar signal classification based on spectrum shape
    Liang YIN, Rui LIN, Xiaolei WANG, Yuliang YAO, Lin ZHOU, Yuan HE
    2022, 38(1):  25-35.  doi:10.11959/j.issn.1000-0801.2022011
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    In order to solve the problems of high computational complexity, low recognition accuracy of low signal to noise ratio (SNR) environment and low fidelity of simulation data in radar signal modulation recognition, a low complexity radar signal classification algorithm based on spectrum shape was proposed.Signal spectrum was normalized, feature parameters were extracted by spectrum sampling method, and then machine learning classification model was trained.The test results of the data generated by the radar signal source show that the classification accuracy of Barker code, Frank code, LFM code, BPSK, QPSK modulation and conventional radar signals is more than 90% (SNR≥3 dB).The algorithm has low computational complexity, can adapt to the change of signal parameters, and has good generalization.

    Energy-efficiency priority based beamforming design and optimization in IRS-assisted SWIPT system
    Xiaorong XU, Weiwei ZHU, Jianrong BAO, Weiping ZHU, Wei FENG, Yingbiao YAO
    2022, 38(1):  36-46.  doi:10.11959/j.issn.1000-0801.2022001
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    Intelligent reflecting surface (IRS)-assisted simultaneous wireless information and power transfer (SWIPT) system is set as research background.Joint design and optimization of energy-efficiency priority based active beamforming at multi-antenna transmitter and passive beamforming at IRS were investigated.The optimization objective was to maximize minimum energy-efficiency, which was subject to transmitter power control, energy constraint at energy harvesting (EH) receiver and IRS phase shift constraint.Alternating direction method of multipliers (ADMM) was implemented to solve this non-linear non-convex optimization problem.Firstly, the fraction objective function was transformed via Dinkelbach’s approach.Singular value decomposition (SVD) andsemi-definite relaxation (SDR) were applied to obtain active beam forming vector at transmitter.Simulation results indicate that, IRS assisted SWIPT could significantly reduce energy threshold at EH receiver.The achievable energy-efficiency of the proposed strategy is 300 KB/J when total circuit power consumption is -15 dBm.Maximum energy-efficiency can be achieved with the maximum numbers of passive reflecting elements and transmitter antennas.

    Secure communication optimization for double-IRS assisted SWIPT system
    Jianfeng CHEN, Miao CUI, Guangchi ZHANG, Qingqing WU, Hui ZENG
    2022, 38(1):  47-60.  doi:10.11959/j.issn.1000-0801.2022015
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    Two intelligent reflecting surfaces (IRS) was applied to ensure the physical layer security of the information transmission in a simultaneous wireless information and power transfer (SWIPT) system, where a multi-antenna base station (BS) simultaneously transmits information and energy to multiple single-antenna information receivers (IR) and energy receivers (ER) and the ERs are regarded as potential information eavesdroppers.The system deploys two IRSs to ensure the security of information transmission while meeting the requirements of energy transmission.Due to the inter-IRS signal reflection, the variables of the considered optimization problem are highly coupled, thus the problem is difficult to solve.To tackle this difficulty, an algorithm based on the alternating optimization, semidefinite relaxation, and successive convex approximation methods was proposed to obtain a suboptimal solution to the problem.Simulation results show that the proposed algorithm can significantly increase the total rate of the IRs and guarantee the security of the information transmission and the requirement of energy transmission, as compared to some existing benchmark schemes.

    Offline visual aid system for the blind based on image captioning
    Yue CHEN, Yu GUO, Yuanyan XIE, Zhenqiang MI
    2022, 38(1):  61-72.  doi:10.11959/j.issn.1000-0801.2022014
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    In view of the inconveniences of existing visual aid systems for the blind, the method of running the image captioning model on portable mobile devices based on model pruning was discussed.Model pruning techniques and image captioning models were reviewed.An improved model pruning algorithm for image captioning model was proposed.Experimental results show that, on the premise of ensuring accuracy, the image captioning model after pruning can greatly reduce processing time and power consumption capacity, and can quickly and accurately describe environmental information and voice broadcast anytime and anywhere.

    Research on optimization of indoor positioning batch ranging system based on DS-TWR algorithm
    Hongwei SUN, Xuehong CAO, Liangbao JIAO, Lin MENG, Ziheng LIU, Feng YUAN
    2022, 38(1):  73-82.  doi:10.11959/j.issn.1000-0801.2022018
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    Aiming at the current problems of the ultra wide band (UWB) indoor positioning system based on the double sided two-way ranging (DS-TWR) algorithm, there are more communication times and a higher conflict rate in a multi-tag environment, an improved algorithm was proposed.The Hash algorithm to hash and distribute the communication content between the tag and the anchor was used, so that the anchor could reply to multiple tags in a regular and unified manner during each ranging process, which greatly reduced the number of times the anchor sends RES (responds) data.Experimental results show that the improved algorithms’ communication times between a tag and the anchor were reduced by 15% compared with the traditional DS-TWR algorithm, which increases the time proportion of the anchor receiving state in ranging, thereby reducing the anchor receiving RNG (range) data.The collision rate of packets, the success rate of ranging has increased by 43.6%.Due to the reduction in the number of communications required in each positioning cycle and the reduction in the collision rate between data packets, a smaller channel capacity would be required, thereby increasing the label capacity of the positioning system, which has strong engineering significance.

    A flexible pruning on deep convolutional neural networks
    Liang CHEN, Yaguan QIAN, Zhiqiang HE, Xiaohui GUAN, Bin WANG, Xing WANG
    2022, 38(1):  83-94.  doi:10.11959/j.issn.1000-0801.2022004
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    Despite the successful application of deep convolutional neural networks, due to the redundancy of its structure, the large memory requirements and the high computing cost lead it hard to be well deployed to the edge devices with limited resources.Network pruning is an effective way to eliminate network redundancy.An efficient flexible pruning strategy was proposed in the purpose of the best architecture under the limited resources.The contribution of channels was calculated considering the distribution of channel scaling factors.Estimating the pruning result and simulating in advance increase efficiency.Experimental results based on VGG16 and ResNet56 on CIFAR-10 show that the flexible pruning reduces FLOPs by 71.3% and 54.3%, respectively, while accuracy by only 0.15 percentage points and 0.20 percentage points compared to the benchmark model.

    Adaptive channel status based access class barring scheme for traffic emergency communication
    Jiao WANG, Gongan QIU, Shibing ZHANG
    2022, 38(1):  95-101.  doi:10.11959/j.issn.1000-0801.2022009
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    In high-density cellular vehicle-to-everything (C-V2X), effective massive access method of cluster communications is the basis to assure the performance index for different services and enhance the spectrum efficiency under limited resource.An improved access class barring (ACB) scheme was proposed using channel status information based on computing power of communication terminal in C-V2X.The base station estimated the communication density within its cover range, generated the ACB factor using the communication density, and broadcasted the ACB.According to signal to interference plus noise ratio (SINR) and ACB factor of the received broadcast signal, the vehicular communication terminal computed the access probability, and compared with ACB factor.When the access probability was more than the ACB factor, the terminal selected a preamble randomly from the preamble pool with the probability which equal to the access probability or one.The terminal transmited the selected preamble to the base station for finishing the access program.The simulation results show that the scheme proposed has 5%~20% advantage over S-Aloha and machine to machine opportunistic splitting algorithm (M2M-OSA) schemes in average access collision probability.It reduces the average access delay effectively.

    Quality of service based hierarchical resource allocation algorithm
    Cheng DING, Jinrong CHEN, Xiaodong CAO, Yi WANG
    2022, 38(1):  102-111.  doi:10.11959/j.issn.1000-0801.2022005
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    Wireless sensor network (WSN) is widely used in the internet of things (IoT) scene because of its small size, low cost and strong sensing ability.How to improve the quality of service (QoS) under the premise of load balancing in WSN has become the focus of many scholars.Based on the study of heuristic resource allocation method and hierarchical structure resource allocation method in WSN, a quality of service based hierarchical resource allocation algorithm (QoSHRA) was proposed.Firstly, the resource allocation method based on low energy adaptive clustering hierarchy (LEACH) made the whole network form a hierarchical structure.Then, QoSHRA was used for resource allocation.The simulation results show that QoSHRA can further save the energy consumption of network transmission, ensure the effectiveness of service allocation, and improve the satisfaction rate of network resource QoS requirements on the premise of ensuring network load balancing.

    Analysis and testing on the interference due to atmospheric duct of 5G
    Xingang SONG, Xingzheng LI, Zhimin ZHAO, Yan WANG
    2022, 38(1):  112-120.  doi:10.11959/j.issn.1000-0801.2022006
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    Abstact: 5G (time division duplexing, TDD) system will be effected by the interference from 5G system due to atmospheric duct.The risk and current situation of 5G system in 2.6 GHz band were introduced and the interference characteristics of 5G interference due to atmospheric duct were summarized.Then based on the interference test results of the interference from 5G system due to atmospheric duct, the interference due to atmospheric duct influences under different frame offset, different service load and different antenna dip configuration were analyzed.Finally, the suggestions for the optimization of 5G interference due to atmospheric duct in 2.6 GHz band were obtained.

    Engineering and Application
    Research on clustering algorithm based 6G typical usage scenarios
    Ning JIN, Qingyang WANG
    2022, 38(1):  121-131.  doi:10.11959/j.issn.1000-0801.2022013
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    Compared with the three classic 5G usage scenarios, the content and types of 6G typical usage scenarios will be more abundant and diverse.How to refine 6G usage scenarios objectively and efficiently has become a major challenge.Based on this, the clustering algorithm was used to study the 6G usage scenarios.Firstly, the 6G service and performance indicators were considered.Then, the demand values of 6G service were collected and the indicators were scored.Finally, the sample data were analyzed by different clustering algorithms.According to the clustering results, eight typical usage scenarios of 6G were proposed, which could provide some reference for 6G research in the industry.

    Security risk analysis of power 5G hybrid networking
    Xiaojian ZHANG, Jiaxuan FEI, Haitao JIANG, Qigui YAO
    2022, 38(1):  132-139.  doi:10.11959/j.issn.1000-0801.2022017
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    5G communication technology provides strong support for the power internet of things, and it also introduces new security challenges in the application process of the power industry.Starting from the analysis of the needs of the power 5G business, five 5G networking deployment and construction plans were proposed, and a comparative analysis of them was conducted in security and cost.And then, a hybrid networking architecture of 5G and power communication networks was proposed, and the 5G network slicing architecture was re-segmented according to business scenarios.Finally, from the four parts of terminal access, edge computing, network channel and core network, the security risks introduced by 5G technology were analyzed in detail.

    Research and practice of SASE cloud security
    Chaoyang YE, Xin WANG, Shicong ZHANG, Zhiyong ZHAN, Yisha LIU
    2022, 38(1):  140-149.  doi:10.11959/j.issn.1000-0801.2022019
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    With the development of the Internet today, earth shaking changes have taken place compared with the traditional network.In today's network reform, "cloud" has become the mainstream direction of the evolution of enterprise IT architecture, so the requirements for cloud security are becoming higher and higher.The practical deployment scheme of SASE cloud security architecture was introduced to solve the problem of cloud security for customers.A unique and complete SASE solution was proposed, which combined security functions with SD-WAN functions, and realized real-time monitoring, intelligent analysis and automatic interception of malware or malicious activities by building a unified management and control platform and centralized deployment of core security resource pool.Practice has proved that the scheme achieves the expected results in unified management and control, intrusion detection and defense, fine access control and so on, and can fully ensure the cloud security of enterprises.

    Research on SSB 1+X beam technology of 5G network
    Bei LI, Yuhua HU, Xinyan WANG, Guoping XU, Guanghai LIU, Tian XIAO, Chen CHENG, Yi LI
    2022, 38(1):  150-158.  doi:10.11959/j.issn.1000-0801.2022012
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    Beam scanning and spatial dimensions in 5G was introduced in the 3GPP standard.When UE connects gNodeB, gNodeB uses SSB beam rotation to detect the optimal beam of UE.After UE was connected, the CSI-RS configuration information could be obtained and the CSI could be normal feedback,gNodeB adopted the optimal beam transmitted by the CSI-RS beam in turn.5G antennas flexibly configure the number of beams and take into account coverage in both horizontal and vertical dimensions.The development of broadcast beams and the horizontal 7 beams facing challenges were presented, the horizontal 7 beam and 1+X beam schemes were analyzed.Finally, efficiency was presented.

    Application research of distribution network based on quantum secure communication and 5G hard-slicing private network
    Zhongping WU, Lujie WANG, Jianuo XU, Yanbo WANG, Liwei ZHANG
    2022, 38(1):  159-169.  doi:10.11959/j.issn.1000-0801.2022003
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    With its significant advantages of ultra-low latency, ultra-high bandwidth, and ultra-large-scale connection, 5G technology effectively compensates for the shortcomings of traditional optical fiber communication in the distribution network field, and provides a new network communication method for power distribution applications.However, the information security issues brought by the applications of 5G technology have appeared gradually.Based on this, a distribution network application scheme based on quantum secure communication and 5G hard-slicing private network was proposed.An end-to-end 5G hard-slicing private network for distribution network services was customized, and ensuring data transmission security by quantum secure communication technology.And this scheme has been deployed and verified in the actual distribution service network scenario, and the results showed that the average delay of 5G hard-slicing private network was 16.89 ms, the download sending and receiving rates were 380 Mbit/s and 371 Mbit/s, respectively, the upload sending and receiving rates were 31.2 Mbit/s and 30 Mbit/s, which meets the communication requirements of distribution network applications.Based on quantum secure communication technology, the quantum bit error rate was 0.75%, and the transmitted data can be encrypted and decrypted smoothly, which verified the feasibility of quantum secure communication and 5G hard-slicing technology in the distribution network.

    Research on MEC traffic offloading scheme in 5G smart campus business scenarios
    Ling LI, Hua WANG
    2022, 38(1):  170-178.  doi:10.11959/j.issn.1000-0801.2022002
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    MEC (multi-access edge computing) is one of the key technologies of 5G.Through the integration of communication and computing technologies, service localization and close deployment can be realized.At present, 5G smart campus has spawned many new application scenarios.The key step to construct the 5G smart campus is how to offload user data to the MEC platform to realize the deep integration of technology and business.Firstly, the overall architecture of 5G smart campus was introduced.Then, three traffic offloading technologies and their advantages and disadvantages were expounded.Finally, the scheme selection of traffic offloading in campus resource visits, access to electronic resources, smart education and campus security monitoring was discussed.It is expected to provide theoretical support for the upcoming construction of 5G smart campus.

Copyright Information
Authorized by: China Association for Science and Technology
Sponsored by: China Institute of Communications
Posts and Telecom Press Co., Ltd.
Publisher: Beijing Xintong Media Co., Ltd.
Editor-in-Chief: Chen Shanzhi
Editorial Director: Li Caishan
Address: F2, Beiyang Chenguang Building, Shunbatiao No.1 Courtyard, Fengtai District, Beijing, China
Postal Code: 100079
Tel: 010-53879277
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E-mail: dxkx@ptpress.com.cn
Mailing Code: 2-397
ISSN 1000-0801
CN 11-2103/TN
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