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20 August 2022, Volume 38 Issue 8

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Topic: UAV-Assisted Air-Ground Wireless Communication Technology

UAV-assisted MEC systems: architecture, key technology, and future challenges

Tiankui ZHANG, Yu XU, Yuanwei LIU, Dingcheng YANG, Yuanhong REN

2022, 38(8):  3-16.  doi:10.11959/j.issn.1000-0801.2022237

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With the fast deployment of 5G and the on-going development of 6G, unmanned aerial vehicle (UAV)-assisted mobile edge computing (MEC) technology has significant advantages in the terms of overcoming the geographic restrictions, addressing the computational requirements of terminal devices, and enhancing the task offloading rate of the systems, which attracts wide attentions in academia and industry.The concept and the technique advantages of the UAV-assisted MEC systems were firstly clarified, and a general UAV-assisted MEC architecture was proposed, along with the definition of each function module.Then the classic application scenarios were summarized, and the existing key techniques were sorted out, based on which the design methods for the UAV-assisted MEC were achieved.Finally, the research directions and the potential challenges in the future were prospected and clarified.

Bionic UAV architecture for fast swarm fusion

Ziming ZENG, Chao DONG, Xiaojun ZHU, Ziye JIA

2022, 38(8):  17-27.  doi:10.11959/j.issn.1000-0801.2022240

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UAV swarm operation is an important part of the future battlefield.UAVs in the cluster cooperate to complement each other and coordinate tasks to improve the overall performance of the system.In animal groups such as ants, wolves, pigeons, fish, etc., their individuals behave similarly to a single drone, while ant colonies, wolves, and pigeon colonies can rely on the rules between individuals to achieve more complex behaviors through group coordination and organization.Different creatures exhibit different abilities and can undertake different tasks on the battlefield.Considering the topology and communication mechanism between creatures, a fusion architecture of bionic drone swarms was proposed which aims to enable different types of bionic UAV swarms to be freely integrated and improve the coordination level of the whole UAV swarm architecture.

Multi-agent heterogeneous network selection method based on 5G UAV communication

Yu DING, Chenkai LI, Huimei HAN, Weidang LU, Yuanhong REN, Yuan GAO, Jiang CAO

2022, 38(8):  28-36.  doi:10.11959/j.issn.1000-0801.2022239

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The combination of 5G UAV communication and different wireless access technologies makes wireless heterogeneous networks present a diversified development trend.However, various types of service requests by users have different requirements on the heterogeneous networks, which leads to the problem of network selection.A multi-agent heterogeneous network selection method based on 5G UAV communication was proposed.Specifically, the users were divided into multiple agents.From the two aspects of the user side and the network side, the delay and transmission rate requirements of the user side and the load balancing requirement of the network side were comprehensively considered as the relevant parameters of immediate reward.The simulation results show that the proposed heterogeneous network selection method can select the appropriate network according to the needs of users of different service types, balance the load of the network, and make full use of the resources of the heterogeneous wireless network.

Coordinated air-ground scheduling for UAV-assisted cell-free massive MIMO

Danhao DENG, Chaowei WANG, Fan JIANG, Weidong WANG

2022, 38(8):  37-44.  doi:10.11959/j.issn.1000-0801.2022242

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Cell-free massive multiple-input multiple-output (MIMO) technology uses a large number of access points (AP) to provide efficient communication services for terrestrial users.However, massive APs and users increase the demand for channel state information detection, especially for users with high moving speeds.In order to reduce the consumption of pilot resources, a dual system architecture that integrates unmanned aerial vehicle-assisted (UAV-assisted) communications and cell-free massive MIMO communications was proposed.The architecture was able to predict the movement trajectories of high-speed users and use UAVs to provide them with reliable communications.A UAV trajectory design and user scheduling scheme based on deep reinforcement learning (DRL) was further proposed, which maximized the system sum rate under the premise of satisfying various constraints.Simulation results demonstrate that the proposed scheme is able to predict user trajectories and improve system sum rate compared with existing schemes.

Analysis of propagation characteristics of UAV communication scenarios based on parabolic equation

Hui HAN, Yulong HAO, Cheng YANG, Jian WANG

2022, 38(8):  45-53.  doi:10.11959/j.issn.1000-0801.2022247

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To improve the analysis accuracy of the propagation characteristics of UAV millimeter-wave communication scenarios, a method based on the parabolic equation was developed to analyze the propagation characteristics of UAV communication scenarios and simulate the propagation characteristics in urban and suburban areas.The results show that the proposed method can effectively express the influence of terrain parameters on the UAV air-ground communication link.Overall, the prediction results are consistent with the ITU-R statistical method in both scenarios.Effective prediction of the propagation characteristics of millimeter-wave UAV application scenarios can be realized with the proposed method, which may support the design, development, and testing of UAV millimeter-wave communication systems.

Research and application of air-to-ground continuous coverage technology for air-space emergency communication system

Shengwei CHEN, Fan LI, Guangping YANG, Jian ZHOU, Yu SU

2022, 38(8):  54-64.  doi:10.11959/j.issn.1000-0801.2022241

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To solve the problem of small coverage area and discontinuous coverage of large fixed-wing aerospace emergency base stations, a design scheme for continuous coverage of UAV emergency base stations was proposed.Based on the analysis of the coverage capability of the single antenna of the airborne base station, a multi-antenna coverage scheme with inner antenna plus edge antenna was proposed.Taking the roll angle, pitch angle and other parameters of the UAV flight into consideration, the installation plan of multi-antenna mounting that guarantees continuous coverage was designed.Then the link budget was carried out according to the 3GPP propagation loss model, and the UAV flight plan was planned according to the continuous coverage area requirements.Simulation and flight test results show that the proposed scheme can achieve 50 km² continuous signal coverage of the ground by the mobile base station on the UAV without using the intelligent control of the antenna angle of the PTZ.

Research and Development

Energy efficiency joint optimization algorithm for mixed-ADC massive MIMO systems

Haiyan CAO, Zhongliang WANG, Hao XU, Qianhong CHEN, Fangmin XU

2022, 38(8):  65-74.  doi:10.11959/j.issn.1000-0801.2022150

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An energy efficiency optimization algorithm was proposed for the uplink of massive MIMO system with mixed precision analog-to-digital converter (ADC) at the receiver.Based on the maximum ratio combining detection algorithm (MRC), the approximate closed-form expression of system uplink energy efficiency was derived.Firstly, the proportion of high-precision ADC was determined, and then the quantization accuracy of low-resolution ADC, the user’s transmission power and the number of antennas at the base station was taken as the optimization objectives to alternately iterate to obtain the optimal energy efficiency value.Furthermore, the influence on energy efficiency and spectrum efficiency was analyzed by adjusting the proportion of high-precision ADC.The simulation results show that the proposed algorithm has high energy efficiency, and can achieve a better balance between energy efficiency and spectrum efficiency by adjusting the proportion of high-precision ADC.

Technical perspective and simulation platform for 5G integrated communication and high precision localization

Xinghua JIA, Peng LIU, Wangdong QI, Shengheng LIU, Yongming HUANG, Jialu LI, Jia XU

2022, 38(8):  75-85.  doi:10.11959/j.issn.1000-0801.2022164

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Providing integrated communication and positioning services for smart terminals using widely deployed 5G infrastructure has been a promising way during the 5G standard evolution.Especially in an indoor scenario where the global navigation satellite system fails, high-accuracy localization services can be provided based on the 5G infrastructure, and thus, 5G integrated communication and localization will enable much vertical industry applications.However, there still exist many technical challenges for providing sub-meter-level 5G localization in practical applications.In addition, there is no unified testbed or platform to support the development of 5G localization.Firstly, the challenges that 5G positioning methods face in achieving indoor sub-meter accuracy were analyzed.Then the design of 5G positioning simulator focusing on 5G classical scenarios was introduced.Numerical results show that the uplink-angle-of-arrival-based approach can achieve sub-meter localization accuracy.Finally, the industrialization prospects of 5G indoor high-accuracy positioning technology were proposed.

Routing planning and handoff based on LSTM traffic prediction

Bin ZHUGE, Linchao WANG, Yang SONG, Yu SHAO, Ligang DONG, Xian JIANG

2022, 38(8):  86-100.  doi:10.11959/j.issn.1000-0801.2022172

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With the continuous development and evolution of network technology in recent years, the user’s demand for network resources is becoming larger and larger, and the content is becoming more and more complex.The traditional network architecture is difficult to meet the current flexible network needs.The revolutionary technology of SDN endows the network with programm ability and evolvability, and realizes more flexible management of network resources.In order to improve the utilization of network resources, a traffic prediction agent based on LSTM model was proposed, which provides a theoretical basis for routing planning.By predicting the network traffic in advance, we can take defensive measures before the traffic surge to ensure the security and stability of the network.The function of route planning and lossless path switching based on traffic prediction was realized.

A multi-hop D2D and social awareness based novel relay selection algorithm

Liang LI, Xinjie YANG

2022, 38(8):  101-110.  doi:10.11959/j.issn.1000-0801.2022235

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The social domain was introduced to multi-hop D2D (device-to-device) communication in cellular network scenarios, and a novel relay selection algorithm for multi-hop D2D communication under cellular network was proposed.Unlike existing relay selection algorithms, the proposed algorithm selects relays for each hop in reverse order, which reduces the signaling overhead caused by algorithm implement.Then, social domain information of mobile terminals was introduced to the algorithm and its influence on the algorithm’s performance was studied, which was found significant enough not to be overlooked hence providing useful guidance to designing algorithms in practical systems.Moreover, via extensive Monte Carlo simulations, it is discovered that the proposed algorithm outperforms the benchmarks in terms of data throughput and energy efficiency in absence of social relationship information.In a more practical implementation with social relationship information included, the proposed algorithm though naturally achieving less throughput, significantly outperforms the benchmarks in energy efficiency.

Research on 5G core network service model intelligent prediction

Nan FENG, Helin LIU, Quan ZHOU, Haijun YANG, Mineng FU, Daping ZHONG

2022, 38(8):  111-119.  doi:10.11959/j.issn.1000-0801.2022046

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Performance analysis of generalized orthogonal code index modulation system

Lina BIAN, Huizhen FENG, Xiaoping JIN, Weizhong LOU, Chongxiao QU

2022, 38(8):  120-128.  doi:10.11959/j.issn.1000-0801.2022166

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In order to improve the transmission efficiency of the code index modulation (CIM) system, a generalized orthogonal code index modulation (GQCIM) system with lower complexity was proposed, which was a single input single output (SISO) system.CIM system used spreading codes and constellation symbols to transmit information, but only activated two spreading code indexes and one modulation symbol.GQCIM system overcame the limitation of only activating one modulation symbol at a time in a novel way, at the same time, made full use of the orthogonality of modulation symbols, increased the spreading code index to transmit more additional information bits, and improved the transmission efficiency of the system.In addition, the theoretical performance of GQCIM system was analyzed and derived the upper bound of bit error rate performance.Then the performance of GQCIM was verified by Monte Carlo simulation, and the theoretical and simulation performance of GQCIM system was found to be consistent.And under the same transmission efficiency, the results show that the performance of GQCIM system is better than the same orthogonal modulation system, such as generalized code index modulation (GCIM) system, CIM system, code index modulation aided quadrature spatial modulation (CIM-QSM) system, code index modulation aided spatial modulation (CIM-SM) system, pulse index modulation (PIM) system.

Big data intelligent analysis technology for 5G network

Aihua LI, Xiaobo WU, Chao CHEN, Bin WEI, Yuanyuan SHI

2022, 38(8):  129-139.  doi:10.11959/j.issn.1000-0801.2022052

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5G services are characterized by diversified forms, personalized requirements and extreme experience, which require the network to be able to efficiently perceive business characteristics and meet business requirements.Meanwhile, the introduction of complex technologies such as 5G slicing, edge computing and multi-access collaboration increases the complexity of end-to-end resource management and scheduling.As the network topology center and service convergence point, 5G core network needs to integrate artificial intelligence technology, improve the ability of big data analysis, and realize the automation and intelligence of the network .The research progress of the international organization for standardization in the field of 5G network intelligence was firstly introduced, then the architecture and characteristics of 5G network big data intelligent analysis system was proposed, and the potential three key technologies of network big data intelligent analysis were finally further analyzed.

Engineering and Application

5G network automation: from manual operating to full autonomous

Yong ZHAN, Feng WU

2022, 38(8):  140-150.  doi:10.11959/j.issn.1000-0801.2022088

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To realize automatic management via digitization and intellectualization has become a key technology for thousands of industries to reduce their operation and maintenance costs.As an enabler of digitization and intellectualization, 5G mobile communication system has evolved from manual operating network to human-assisted automation network.Based on the study of automatic technologies of 5G network, the L0～L5 autonomous network levels proposed by 3GPP were analyzed, several key technologies for intent-driven 5G autonomous network including intent life-cycle maintenance and solutions for intent conflict were discussed.Last but not least, a practice of intent-driven 5G autonomous network was proposed: solution of intent-driven application experience assurance.

Research and application practice of knowledge graph technology system for telecom-operators

Dongming ZHAO

2022, 38(8):  151-162.  doi:10.11959/j.issn.1000-0801.2022145

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Knowledge graph plays an important role in knowledge search, work order processing, intelligent service, fault analysis and other fields of China Mobile business and maintenance scenario.The knowledge graph technology system of China Mobile was systematically studied.Based on application scenarios and service objects, it can be divided into question ＆amp; answer retrieval knowledge graph, work-order analysis knowledge graph, system operation and maintenance knowledge graph and business operation knowledge graph.The technical architecture, business architecture and construction methods were introduced, and the planning goal of the evolution and development of knowledge graph was ultimately leaded.

Design and implementation of AI-based all-scenario intelligent base station power-saving system

Wei ZHAO, Bei LI, Ning MENG, Tingwei WANG, Junfan LIN, Le CHEN, Yuhua HU, Hanyuan YANG

2022, 38(8):  163-170.  doi:10.11959/j.issn.1000-0801.2022169

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In the context of intensive network construction, how to realize automatic, intelligent, and experienceguaranteed base station energy consumption management has become a pain point for current operators in operation management.A 3G/4G/5G smart base station power saving solution with full intelligent detection, full-scenario modeling, and full-process self-service was innovatively proposed.The coverage scene was distinguished by a dynamic time warping algorithm, and the SARIMA model was used to predict the time frame to build the model dynamically.Monitoring indicators ensured quality of experience, automatically issue power-saving strategies, and promptly raise SMS alerts.In the case that the user had no perception, the energy consumption of the base station was saved to the greatest extent at the cell granularity level.This method had been implemented on a pilot study in a province.The average annual power saving efficiency of a single station in the pilot area can reach 9.24% per day per station, which can be put in actual production.

Carrier-grade NTP clock synchronization scheme of SD-WAN network

Qiangen ZHAO, Yu WANG, Ling TANG, Yongming YAN

2022, 38(8):  171-177.  doi:10.11959/j.issn.1000-0801.2022092

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SD-WAN is developing rapidly, and telecom operators and Internet companies are constantly expanding their layout.As a technology with diverse forms, SD-WAN has not made a clear specification for clock synchronization.The importance of clock synchronization to SD-WAN technology implementation and business running was analyzed.The advantages and disadvantages of the clock synchronization scheme of Internet public NTP service widely used in SD-WAN realizations were sketched.Thus the clock synchronization scheme of self-built NTP service in different scenarios was discussed.Furthermore, a clock synchronization method using management tunnel to transmit encrypted NTP synchronization data was designed, which made SD-WAN platform and devices obtain higher security and stability in time synchronization.

Research on manufacturing energy consumption optimization platform technology based on knowledge-base

Weiwei YANG, Sining WANG, Guide ZHENG, Yaqiong SONG

2022, 38(8):  178-185.  doi:10.11959/j.issn.1000-0801.2022142

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China’s manufacturing industry accounts for the largest proportion of the economy and involves a huge scale.It is of practical significance for enterprises to gradually realize energy consumption optimization through digital technology.Taking automobile manufacturing as an example, a scheme of energy consumption optimization based on knowledge-base was proposed, including the analysis of the characteristics of energy consumption in manufacturing industry, the key technologies of energy consumption optimization and the presentation of application practice.Starting with the production equipment of the enterprise, the law affecting energy consumption was found and a knowledge-base was build through the information of manufacturing execution system and equipment operation status of the enterprise, and the optimization of energy consumption was realized through machine learning algorithms such as neural network and correlation analysis.