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    05 August 2022, Volume 6 Issue 3
    Topic: IoT and Wireless Optical Communication
    Optical wireless communication and internet of things
    Zaichen ZHANG, Xiaohu YOU, Jian DANG, Liang WU, Bingcheng ZHU, Ji CHEN, Lei WANG
    2022, 6(3):  1-13.  doi:10.11959/j.issn.2096-3750.2022.00278
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    Optical wireless communication (OWC) entitles many advantageous properties such as unlicensed spectrum, high electromagnetic compatibility, compared with its radio frequency wireless counterpart, which enables it to be a potential important driving factor for the diverse developments of future internet of things (IoT).Starting from the optical sources and optical devices, some basic principles and limitations of OWC were introduced.Then, some key technologies, including channel modeling, signal modulation, array communication and high-precision positioning were discussed.Based on those and according to the requirements on peak data rate, sensing precision, energy transfer and security and confidentiality of the next generation IoT, the role of OWC as a technological enabler for next generation IoT was analyzed.Finally, related conclusions were given.

    Exploring the nonlinear coded superposed modulation MISO visible light communication system
    Zengyi XU, Wenqing NIU, Hui CHEN, Zhixue HE, Nan CHI
    2022, 6(3):  14-22.  doi:10.11959/j.issn.2096-3750.2022.00275
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    The light-emitting diode (LED) based visible light multi-input single-output (MISO) system usually suffers from the nonlinearity in LED and its incoherent nature in emission.Adopting precoding would alleviate this limitation at comparatively lower cost.Existing researches usually apply the same coding scheme to all the channels.An asymmetric coding scheme was proposed, which nonlinearly encodes one of the two channels in a MISO system.This solution enlarges the dynamic range of the uncoded channel at the cost of a higher bit error ratio (BER) in the coded one.When the BER threshold is set at 3.8×10-3, the uncoded channel gains a dynamic range 30% larger than that of the coded one.If this solution is combined with flexible forward error correction redundancy, it would allow the system to adapt to varying channel condition while still maintaining the communication in both channels.This research would be beneficial in the study on indoor or underwater visible light communication (VLC) system.

    Research progress of error correction coding in optical wireless communication system
    Jingyuan LIANG, Mengru LI, Jiafan WANG, Xizheng KE
    2022, 6(3):  23-36.  doi:10.11959/j.issn.2096-3750.2022.00276
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    The channel environment of the optical wireless communication is complicated, susceptible to various natural phenomena such as rain, snow, and fog.The channel code is usually used to correct the error caused by the channel noise.Common channel codes are Reed-Solomon (RS) code, Turbo code, low density parity check (LDPC) code, polarization code and other types.The development of the error correction code was combed, the research progress of the error correction code for the optical wireless communication were summarized and the comparative analysis was made, which introduced the progress of Xi'an University of Technology in this field of theory and experimentation.RS code, Turbo code, LDPC code were comparable to the error correction characteristics in rain, snow and fog environments.Finally, the future possible research direction and challenges were pointed out, providing references for the future development and research in the relevant fields.

    Industrial IoT oriented petahertz communication
    Nuo HUANG, Weijie LIU, Chen GONG
    2022, 6(3):  37-46.  doi:10.11959/j.issn.2096-3750.2022.00277
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    Compared with traditional radio frequency communication, petahertz communication (PetaCom) enjoys several distinct advantages including high data rate, low latency and high determinacy, exhibiting essential application potential in industrial internet of things (IIoT).However, IIoT oriented PetaCom suffers issues of link instability and interference in real scenarios.Starting from the basic concepts of IIoT and PetaCom, a comprehensive summary of IIoT oriented PetaCom was presented including channel modeling, physical-layer technologies, user networking, advantages and challenges.The goal is to provide guidance for relevant researches on IIoT oriented PetaCom in the future.

    Theory and Technology
    Resource allocation for the semantic communication in the intelligent networked environment
    Jiujiu CHEN, Caili GUO, Chunyan FENG, Chuanhong LIU
    2022, 6(3):  47-57.  doi:10.11959/j.issn.2096-3750.2022.00279
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    Traditional resource allocation methods are difficult to meet the needs of various services to accurately understand the semantics of a large amount of multimedia data in the intelligent networked environment.Facing with this challenge, taking intelligent task-oriented internet of vehicles scenarios as an example, two resource allocation optimization criteria for the semantic communication were firstly proposed.Then, according to different dimensions of resources, the models and algorithms of the resource allocation for the semantic communication were described.Then, a semantic communication-oriented image dataset was constructed, and the performance advantages of the proposed resource allocation methods in the simulation scenario of the internet of vehicles were analyzed.Finally, the future challenges of the resource allocation for the semantic communication were presented.

    Optimization of multiple access in the energy harvesting wireless sensor network with delivery deadline constraint
    Aoqin YANG, Aoyu GONG, Ting FANG, Lei DENG, Qiang LI, Yijin ZHANG
    2022, 6(3):  58-70.  doi:10.11959/j.issn.2096-3750.2022.00283
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    With the wide application of the energy harvesting wireless sensor network (WSN) in many real-time communication scenarios, such as environmental monitoring, industrial automation and battlefield surveillance, the multiple access of such WSN needs to take into account both the delivery deadline constraint of data packets and the energy harvesting dynamics of sensor nodes.Due to the inherent decoupling of interference, delivery urgency and remaining energy, the design and optimization of such multiple access are more challenging than that of traditional multiple access that only needs to take into account the packet traffic pattern.A centralized access scheme was designed with the access actions relying on the global knowledge of current delivery urgency and remaining energy.And then, to avoid the costly overhead in the centralized access, a decentralized access scheme was designed with the access probabilities merely relying on the local knowledge of delivery urgency and remaining energy.Under the objective of maximizing the network throughput, the centralized access schemes were formulated with complete and simplified knowledge as two Markov decision processes (MDPs), respectively, and the backward induction algorithm was used to obtain optimal centralized policies for these MDPs.Furthermore, the decentralized access was formulated with simplified knowledge as a decentralized MDP, and the Markov policy search was used to propose an ε-optimal decentralized policy.Simulations under a wide range of network configurations were provided to verify the effectiveness of the simplified modeling and demonstrate the performance advantage of the proposed polices.

    Resilience characterization and evaluation model of field area network for the power distribution network
    Fang XIAO, Shuyan YANG, Bo WEN, Xiaorong ZHU
    2022, 6(3):  71-81.  doi:10.11959/j.issn.2096-3750.2022.00287
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    To analyze the robustness and reliability of field area network (FAN) in the power distribution network, a quantifiable network resilience characterization and evaluation model was proposed.The elasticity indicator was defined from network connectivity, robustness and redundancy, and the total network elasticity was calculated by the weighted sum.The resilience performance of FAN was evaluated by simulating random failures and malicious attacks.A single node failure was simulated and tested to evaluate the difference in network resilience a affected by different node failures and find the weak points of resilience in the network.The elastic characterization and evaluation model was extended to general network topologies, and simulation experiments were carried out using BA scale-free network and ER random network.The experimental results demonstrate the universality of the model.

    Energy-saving computation offloading scheme based on Sarsa algorithm in industrial internet of things
    Jun SUN, Shangweikang ZHAO
    2022, 6(3):  82-90.  doi:10.11959/j.issn.2096-3750.2022.00280
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    In order to reduce the total energy consumption of industrial internet of things systems with deadline requirements, a computing offloading scheme based on Sarsa algorithm was proposed.Based on the characteristics of Sarsa algorithm, the energy consumption optimization problem was coupled.The Sarsa algorithm iterated the external state value function, selected the appropriate edge computing server to offload the computing task, and then the particle swarm optimization algorithm solved the resource allocation problem.Finally, the environmental information was updated for the next round of algorithm iteration until the algorithm met the end conditions.The simulation results show that this scheme has faster convergence speed and effectively reduces the system energy consumption.

    Graph signal processing based pilot pattern design and channel estimation for OFDM system
    Bin HE, Guobing LI, Yuan CHEN, Guomei ZHANG
    2022, 6(3):  91-102.  doi:10.11959/j.issn.2096-3750.2022.00288
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    Orthogonal frequency division multiplexing (OFDM) is one of the key technologies in the physical layer of the internet of things (IoT).Pilot design and channel estimation are key issues in OFDM systems.In view of the problem of performance loss by fixed pilot pattern due to the complexity and variety of IoT communication scenarios, a pilot design and channel estimation scheme based on graph signal processing (GSP) was proposed.Firstly, the time-frequency resource block was modeled as a graph signal, and the channel estimation problem was reformulated into a sampling and reconstruction problem of the graph signal.Then, considering the influence of time-frequency fading, a weighted graph adjacency matrix was designed to construct a graph topology structure based on the time-frequency position.On this basis, the pilot position is selected based on the graph signal sampling theory, a greedy pilot pattern design algorithm based on weighted graph topology was proposed.At the same time, signal reconstruction was performed based on the graph signal reconstruction method, and a channel estimation method based on the graph smoothness constraint was proposed.Compared with the conventional scheme, simulation results show that the proposed method achieves higher channel estimation accuracy in high-speed scenarios of double selective channels, and effectively reduces pilot overhead in low-speed scenarios.

    A distributed strategy for the multi-target rescue using a UAV swarm under communication constraints
    Hanqing YU, Yan LIN, Linqiong JIA, Qiang LI, Yijin Zhang
    2022, 6(3):  103-112.  doi:10.11959/j.issn.2096-3750.2022.00284
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    The current designs of the cooperative decision-making of an unmanned aerial vehicle (UAV) swarm usually adopt unreasonable assumptions on the communication ability between UAVs.Focusing on a multi-target rescue problem of a UAV swarm under constraints of energy, load and path, the limitation on the information sharing due to the communication constraints and the flight path of UAVs were taken into account.Firstly, the problem was formulated as a partially observable Markov decision process (POMDP).Then, a recurrent neural network was used to propose a deep-reinforcement-learning-based distributed rescue strategy, which is able to adapt to the changeable communication topology.Simulation results show that the proposed strategy outperforms other strategies under communication constraints, and further show that a careful joint setting of the size and communication ability of a UAV swarm is needed to achieve the best compromise between the UAV swarm rescue performance and the cost.

    Trajectory and communication scheduling optimization for the rechargeable UAV aided data collection system
    Qianwen LI, Jianfeng CHEN, Miao CUI, Guangchi ZHANG
    2022, 6(3):  113-123.  doi:10.11959/j.issn.2096-3750.2022.00285
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    A rechargeable unmanned aerial vehicle (UAV) aided wireless sensor network was considered, which consists of multiple ground terminals with a large amount of time-sensitive data to be collected.Due to the limited battery capacity, the UAV cannot collect the data from all terminals through a single flight mission, and it needs to return to the charging pile to replenish its flight energy several times during the whole mission.The optimization of the terminal scheduling, trajectory, flight speed and transmission rate for the UAV was studied to maximize the number of terminals whose data had been collected within the data lifetime limit.Due to the variable coupling and the existence of discrete binary scheduling variables, the considered optimization problem is difficult to solve.To tackle such a difficulty, an efficient algorithm was proposed based on the stochastic optimization and the feature engineering.Specifically, the flight hover communication protocol was introduced to simplify the UAV flight process.And then a terminal scheduling algorithm was innovatively proposed with the influence factor and the stochastic preference, which extracted the features that affect the service time of the UAV, optimized the weights of the features, and further simplified the optimization problem into multiple subproblems.The subproblems were then solved by using the block coordinate descent and successive convex approximation techniques.Simulation results show that the proposed optimization algorithm achieves significant performance gains over several benchmark schemes in the scenarios with different data lifetime requirements and different numbers of ground terminals.

    Offloading strategy with edge optimization of time delay and energy consumption in integrated satellite-terrestrial relay network
    Meinan ZHANG, Mingqi ZHANG, Fei DING, Hengheng ZHUANG, Hairong MA
    2022, 6(3):  124-132.  doi:10.11959/j.issn.2096-3750.2022.00289
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    The integrated satellite-terrestrial relay network (ISTRN) is a necessary part of the next-generation wireless communication system, and has important practical significance for accelerating the construction of my country's air-space-terrestrial integrated network system.In the traditional ISTRN architecture, a large amount of signaling needs to be forwarded to the ground control center for processing, which increases the delay of network control and management.A new cloud fog computing architecture was proposed, which constructs a sub-regional edge fog computing layer between the ground access and the central cloud to improve the flexibility of business flow management and control.Under the cloud network framework, a Q-learning based edge computing offloading strategy was designed, and the offloading performance was evaluated by time delay and energy consumption.Simulation results show that, compared with Min-min algorithm and backtracking algorithm, Q-learning based computational offload algorithm has better performance in terms of time delay and energy consumption, and can achieve a balance between the joint optimization of time delay and energy consumption.

    Comprehensive influence evaluation algorithm of complex network nodes based on global-local attributes
    Weijin JIANG, Ying YANG, Tiantian LUO, Wenying ZHOU, En LI, Xiaowei ZHANG
    2022, 6(3):  133-145.  doi:10.11959/j.issn.2096-3750.2022.00282
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    Mining key nodes in the network plays a great role in the evolution of information dissemination, virus marketing, and public opinion control, etc.The identification of key nodes can effectively help to control network attacks, detect financial risks, suppress the spread of viruses diseases and rumors, and prevent terrorist attacks.In order to break through the limitations of existing node influence assessment methods with high algorithmic complexity and low accuracy, as well as one-sided perspective of assessing the intrinsic action mechanism of evaluation metrics, a comprehensive influence (CI) assessment algorithm for identifying critical nodes was proposed, which simultaneously processes the local and global topology of the network to perform node importance.The global attributes in the algorithm consider the information entropy of neighboring nodes and the shortest distance nodes between nodes to represent the local attributes of nodes, and the weight ratio of global and local attributes was adjusted by a parameter.By using the SIR (susceptible infected recovered) model and Kendall correlation coefficient as evaluation criteria, experimental analysis on real-world networks of different scales shows that the proposed method is superior to some well-known heuristic algorithms such as betweenness centrality (BC), closeness centrality (CC), gravity index centrality(GIC), and global structure model (GSM), and has better ranking monotonicity, more stable metric results, more adaptable to network topologies, and is applicable to most of the real networks with different structure of real networks.

    Service and Application
    Date recognition based on multi feature extraction
    Min WANG, Jia WU, Shuo SUN, Sheng LI, Kang WANG
    2022, 6(3):  146-152.  doi:10.11959/j.issn.2096-3750.2022.00286
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    Drug production date and expiration date are important indicators to measure the safety and effectiveness of drugs.The production date and validity period of liquid drugs in vertical bags are printed with numbers of 0~9.The recognition of the drug date of the hospital needs to meet the requirements of high speed and accuracy.The conventional template matching method and neural network recognition method have large amount of calculation and complex training.A drug date recognition method was proposed based on multi feature extraction.The combination of vertical line feature and three features for fine feature extraction of different digital characters has advantages of small amount of calculation and fast recognition speed.Compared with the recognition method of single extracted feature, it can effectively distinguish 10 different numbers, especially suitable for numbers of similar shape.It can provide patients with safe drug use guarantee, improve the management mode of the medical staff, improve the work efficiency, so as to improve the level of the pharmaceutical service of the hospital.


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
Deputy Editor-in-Chief:LIU Hualu
Director:LI Caishan
Address:F2, Beiyang Chenguang Building, Shunbatiao No.1 Courtyard, Fengtai District, Beijing, China
Tel:010-53878076、53879096、53879098
E-mail:wlwxb@bjxintong.com.cn
ISSN 2096-3750
CN 10-1491/TP
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