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    30 June 2022, Volume 6 Issue 2
    Intelligent Wireless Positioning and Tracking Technology
    Low-power internet of underwater things: vision and key technologies
    Yang LIU, Cuican LI, Mugen PENG
    2022, 6(2):  1-9.  doi:10.11959/j.issn.2096-3750.2022.00270
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    With the explosion of underwater sensing devices and the pursuit of energy conservation, the concept of low-power internet of underwater things has been put forward.Inspired by RF-based backscatter networks, the low-power internet of underwater things architecture uses underwater acoustic backscatter technology to realize the low-power and low-cost communication of underwater sensor nodes, which has a wide application prospect in underwater fields such as the long-term underwater detection.Firstly, the principle and architecture of low-power internet of underwater things was introduced.Then, the key technologies faced by the architecture were proposed and analyzed, such as perception, communication, networking, resource allocation, security and so on.Finally, the future research directions of low-power internet of underwater things were discussed.

    A frequency offset compensation method based on all phase FFT amplitude
    Yingjie ZHU, Wuxiong ZHANG, Huiyue YI, Hui XU
    2022, 6(2):  10-18.  doi:10.11959/j.issn.2096-3750.2022.00274
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    Distance measurement is an important part of the wireless location technology.The ranging accuracy of millimeter wave based distance measurement depends on the frequency estimation accuracy of beat signals from the targets, but the existing frequency estimation algorithms have the shortcomings of either high complexity or low accuracy.In order to improve the ranging accuracy, the frequency compensation value and frequency estimation method based on all phase FFT amplitude was proposed to improve the performance of frequency estimation.Firstly, the signal amplitude was estimated based on the relationship between its all phase FFT and its conventional FFT spectrum.Moreover, using the relationship between the estimated signal amplitude, the signal spectrum amplitude and frequency compensation value, the frequency compensation value was solved by Newton iterative algorithm.Then, the frequency compensation value was used to shift the frequency of the signal, and the frequency compensation value was estimated again to obtain the final estimation value of the signal frequency, from which the distance of the target was calculated.Finally, simulation results were presented to show that the proposed method has higher distance measurement accuracy than the existing methods.

    Research on Wi-Fi indoor positioning technology based on knowledge graph
    Jiandong LI, Jingjing YANG, Ming HUANG
    2022, 6(2):  19-25.  doi:10.11959/j.issn.2096-3750.2022.00265
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    Among the common Wi-Fi indoor positioning methods, most of the research focuses on the positioning accuracy, a little is on the application system to organize and process the existing indoor data efficiently in order to realize the indoor location service.To deal with these issues, the knowledge graph with the traditional indoor positioning technology was combined, and a practical positioning system was built with a variety of software development technologies.The system integrates the physical space and the information space.The information space includes indoor information acquisition, cloud services, information storage and computing parts.The physical space expresses the structure of the indoor space and data relationships.Finally, the WEBGL technology was used to display intuitive positioning and realize the visualization of indoor signal data and positioning results.The system has a complete data storage and use mechanism.After integrating the existing data information of the indoor internet of things equipment, it can provide users with room-level location services.The step-by-step positioning function of the system helps to reduce the time consumption of the system.

    A study of testing-index and certification systems of IoT terminals for smart city in China
    Jing YANG, Jinfeng XIE, Yi CHEN
    2022, 6(2):  26-37.  doi:10.11959/j.issn.2096-3750.2022.00269
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    IoT terminals are the essential element for smart city, with intelligent facilities and refined management.Furthermore, the reliability of applications in smart city depends on the quality of IoT terminals.However, the quality of IoT terminals in smart city is hard to assure due to the lack of unified testing-index and certification systems for IoT terminals.To address the challenge, the definition and classification of IoT terminals in smart city were firstly analyzed.Then standardization objects for IoT terminals were given.A testing-index system for IoT terminals was proposed based on the objects of standardization for IoT terminals.Considering IoT terminals' communication and application properties in smart city, a certification system of IoT terminals was also proposed.The testing-index and certification systems provide references for IoT terminal testing and pave the way to improve the quality of IoT terminals.

    Theory and Technology
    Concept, architecture and key technologies of industrial internet
    Jin QI, Wei WANG, Mengxi CHEN, Bin XU, Zhenjiang DONG, Yanfei SUN
    2022, 6(2):  38-49.  doi:10.11959/j.issn.2096-3750.2022.00272
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    As one of the key paths to realize the digital transformation of traditional industries, the industrial internet has attracted widespread attention in both the academia and the industry.As the content of the industrial internet is quite extensive, while its system architecture and key technologies are constantly evolving and developing, it also confronts problems such as unclear conceptual scope, unsound system architecture, and unclear key technologies.In order to further explore the above issues, the basic concepts of the industrial internet were clarified by sorting the relationship between the industrial internet and three other concepts of the industrial internet of things, industry 4.0/5.0, and intelligent manufacturing.Based on the analysis of the industrial internet system architecture and the key technologies involved, the challenges faced by the industrial internet were summarized and the future research directions in the industrial internet field were looked forward.

    Research and application of Web of things resource management framework
    Yangqun LI, Dengyin ZHANG
    2022, 6(2):  50-64.  doi:10.11959/j.issn.2096-3750.2022.00271
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    Web of things (WoT) connects all things together through the Web and realizes the sharing of resources, such as data or services provided by things, to fully implement their potential value.However, these resources are distributed in various places and belong to different organizations.The WoT resource management based on central infrastructure can no longer meet the new situation of continuous expansion of application scale, rapid changes in demand, and continuous increase of data types.In response to these new problems and new requirements, WoTRMF (Web of things resource management framework) was proposed.Firstly, based on this framework, the WoT resource management mechanism from the following aspects was reviewed, including distributed management of resources, efficient publish and discovery of resources, cost-effective, secure and efficient sharing of resources, and a unified resource management platform.Then, according to the requirement of distributed management, a P2P technology based on geographic location was proposed to realize distributed automatic management of WoT resources, so as to meet the high availability requirements of WoT applications and improve the efficiency of resource management.Aiming at the requirement of efficient resource publishing/discovery, an intelligent WoT resource publishing mechanism based on probabilistic topics was proposed to realize automatic classification and orderly publishing and storage of resources.Aiming at the security access requirements of resources, a secure and trusted WoT resource sharing mechanism based on blockchain was proposed.According to the requirement of unified resource management, the functional implementation model of WoTRMF was given.Finally, through the application case of WoTRMF framework in smart city security management, its characteristics of openness, flexibility, scalability and intelligence were analyzed.

    Differential privacy budget optimization based on deep learning in IoT
    Dan LUO, Ruzhi XU, Zhitao GUAN
    2022, 6(2):  65-76.  doi:10.11959/j.issn.2096-3750.2022.00264
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    In order to effectively process the massive data brought by the large-scale application of the internet of things (IoT), deep learning is widely used in IoT environment.However, in the training process of deep learning, there are security threats such as reasoning attacks and model reverse attacks, which can lead to the leakage of the original data input to the model.Applying differential privacy to protect the training process parameters of the deep model is an effective way to solve this problem.A differential privacy budget optimization method was proposed based on deep learning in IoT, which adaptively allocates different budgets according to the iterative change of parameters.In order to avoid the excessive noise, a regularization term was introduced to constrain the disturbance term.Preventing the neural network from over fitting also helps to learn the salient features of the model.Experiments show that this method can effectively enhance the generalization ability of the model.As the number of iterations increases, the accuracy of the model trained after adding noise is almost the same as that obtained by training using the original data, which not only achieves privacy protection, but also guarantees the availability, which means balance the privacy and availability.

    User authentication of industrial internet based on HHT transform of mouse behavior
    Yigong ZHANG, Qian YI, Jian LI, Congbo LI, Aijun YIN, Shuping YI
    2022, 6(2):  77-87.  doi:10.11959/j.issn.2096-3750.2022.00268
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    The rapid development of the industrial internet had caused widespread concern about the network security, and the end-user authentication technology was considered a research hotspot.According to the characteristics of human-computer interaction in industrial internet, an experimental website was designed.24 users' mouse behavior data in an uncontrolled environment were collected within 2.5 years to conduct case studies.Hilbert-Huang transform (HHT) was used to extract frequency domain features of mouse behavior signals, combined with time domain features to form a time-frequency joint domain feature matrix of 163-dimensional to characterize user mouse behavior patterns.Bagged tree, support vector machine (SVM), Boost tree and K-nearest neighbor (KNN) were used to build a user authentication model, and the comparison result showed that the Bagged tree had the best internal detection effect in this case, with an average false acceptance rate (FAR) of 0.12% and an average false rejection rate (FRR) of 0.28%.In external detection, the FAR was 1.47%.Compared with the traditional mouse dynamics method, the frequency domain information of mouse behavior extracted by HHT can better realize the user authentication, and provide technical support the security of the industrial internet.

    An access scheme based on the random access occasion dynamic allocation
    Shaoxiong JING, Yue YUAN, Jiawei XIONG, Junxuan WANG
    2022, 6(2):  88-94.  doi:10.11959/j.issn.2096-3750.2022.00266
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    With the rapid development of the internet of things (IoT), the application of machine type communication (MTC) in life has grown substantially, and the deployment of machine type devices (MTD) has become more and more intensive.In this case, if there is an unexpected situation such as a power outage and a network failure, a large-scale MTD will initiate access to the base station at the same time when the device is powered on.When the device accesses the base station, it needs to complete the downlink synchronization, system message receiving, random access (RA) and other processes.However, the preamble resources that can be allocated by the base station are limited and cannot meet such a huge access demand, which causes network congestion and affects the access probability and access delay of the device.In order to alleviate the access conflict of RA, a dynamic random access occasion (RO) adjustment scheme was proposed based on the uplink and downlink subframes and physical random access channel (PRACH) configuration, and time-based part of the MTD with high delay requirements allocates specific preamble resources.The simulation results show that this scheme can effectively improve the throughput of the system and reduce the access delay of the device.

    Performance optimization for mMTC in 5G network with multiple random access schemes
    Wen ZHAN, Yiwen LIANG, Xinghua SUN, Xuesong TAN
    2022, 6(2):  95-105.  doi:10.11959/j.issn.2096-3750.2022.00267
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    To optimize the support for massive machine type communication (mMTC) services with different traffic characteristics, packet-based random access (PBRA) scheme coexists with the connection-based random access (CBRA) scheme in 5G networks.Yet, given the traffic characteristic of mMTC, which random access scheme should be chosen is still an open issue.To address this issue, the network throughput and signaling overhead analysis of mMTC with PBRA and CBRA were presented, and the problem of throughput maximization while maintaining the signaling-to-throughput ratio below a certain level was solved.Based on this, the optimal access scheme selection strategy and the corresponding optimal network parameter configuration were obtained and verified via simulations.

    Weighted mixed regression localization method based on three-dimensional Voronoi diagram division
    Fenfang LI, Xiaochao DANG, Zhanjun HAO
    2022, 6(2):  106-116.  doi:10.11959/j.issn.2096-3750.2022.00273
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    With the development of the wireless communication technology and sensing technology, various technologies based on wireless sensor networks are applied.These technologies are widely used in the fields of intelligent agriculture, intelligent transportation, fire rescue and so on.Node localization technology is one of the basic technologies of wireless sensor networks.Location information is a part of the sensing data, which determines the specific measures to be taken in the next step.Due to the complexity of the three-dimensional (3D) space localization environment, the application of the plane positioning method in 3D space will have some limitations.Aiming at above problems, the weighted hybrid regression location algorithm WMR-SKR based on a 3D Voronoi diagram was studied.The localization algorithm was divided into two stages: offline training and online testing.The 3D space was divided into Voronoi diagrams according to the anchor nodes in the network.In the offline training stage, the sequence composed of the coordinates of the anchor nodes and Voronoi cell vertices was used as the training set for training.In the online test stage, the coordinates of unknown nodes in the network were predicted through the trained localization model.Simulation results show that the WMR-SKR algorithm can effectively reduce the node localization error and improve the node localization speed in 3D space.

    Measurement and modeling of indoor off-body channel in the 9.5~10.5 GHz band
    Shanhu HUANG, Jun SUN, Haofei CHANG, Wenjun LV, Qin YANG
    2022, 6(2):  117-126.  doi:10.11959/j.issn.2096-3750.2022.00263
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    In order to explore the wireless propagation characteristics of high-frequency indoor off-body channel, off-body channel measurements were carried out on multiple typical indoor scenes in the 9.5~10.5 GHz frequency band.In terms of large-scale fading, through studying the path loss, it is found that the human body occlusion factor has a sine function relationship with the rotation angle, and a negative exponential relationship with the distance between the receiver and transmitter.Therefore, a new type of off-body channel loss model related to distance and angle was established, and the accuracy and applicability of the new model was proved based on the shadow fading.In terms of small-scale fading, by analyzing the linear correlation between path loss and root mean square (RMS) delay spread, a new type of RMS delay spreading model related to distance and angle was obtained.It proves that the greater the distance between the antenna at the transceiver end and the occlusion factor caused by the rotation of the human body, the more severe the path loss and multipath fading.The new channel model can be used to design the off-body link of the internet of things environment body area network (BAN), providing a theoretical and practical basis for the future design of indoor wireless communication systems.

Copyright Information
Quarterly,started in 2017
Cpmpetent Unit:Ministry of Industry and Information Technology of the People's Republic of China
Sponsor:Posts & Telecom Press Co.,Ltd.
Publisher: China InfoCom Media Group
Editor:Editor Board of Chinese Journal on Internet of Things
Editor-in-Chief:YIN Hao
Executive Editor-in-Chief:ZHU Hongbo
Director:LI Caishan
Address:F2, Beiyang Chenguang Building, Shunbatiao No.1 Courtyard, Fengtai District, Beijing, China
ISSN 2096-3750
CN 10-1491/TP
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