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    COMMUNICATIONS THEORIES & SYSTEMS
  • COMMUNICATIONS THEORIES & SYSTEMS
    Joint Optimization of Communications and Computing Resources Allocation for Deterministic Transmission in Wireless Edge Networks
    Lanjing Chen, Zhiyong Chen, Bin Xia, Xin Jiang, Feng Hu
    2022, 19(5): 1-11.
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    Motivated by 5th generation wireless systems (5G), a large number of emerging applications appear, which put forward higher requirements for the task's transmission determinacy, which refers to the delay and jitter. To satisfy the deterministic requirement, mobile edge computing (MEC) is envisioned as a promising technique for reducing the end-to-end delay significantly. In this paper, we consider delay-sensitive task and jitter-sensitive task, and then formulate the joint communications and computing optimization problem under the latency, the total bandwidth, the total transmission power of base station (BS) and the computing ability of the MEC server constraints to minimize the delay and jitter in a multi-user MEC system. Because of the problems are non-convex, we decouple them into some subproblems and propose the corresponding algorithms to obtain a suboptimal solution. Finally, numerical results show that the proposed algorithms have a significant performance gain over the traditional solution in terms of the delay and the jitter.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Cognitive RAN Slicing Resource Allocation Based on Stackelberg Game
    Tengteng Ma, Yong Zhang, Siyu Yuan, Zhenjie Cheng
    2022, 19(5): 12-23.
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    The cognitive network has become a promising method to solve the spectrum resources shortage problem. Especially for the optimization of network slicing resources in the cognitive radio access network (RAN), we are interested in the profit of the mobile virtual network operator (MVNO) and the utility of secondary users (SUs). In cognitive RAN, we aim to find the optimal scheme for the MVNO to efficiently allocate slice resources to SUs. Since the MVNO and SUs are selfish and the game between the MVNO and SUs is difficult to reach equilibrium, we consider modeling this scheme as a Stackelberg game. Leveraging mathematical programming with equilibrium constraints (MPEC) and Karush-Kuhn-Tucker (KKT) conditions, we can obtain a single-level optimization problem, and then prove that the problem is a convex optimization problem. The simulation results show that the proposed method is superior to the non-cooperative game. While guaranteeing the Quality of Service (QoS) of primary users (PUs) and SUs, the proposed method can balance the profit of the MVNO and the utility of SUs.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Asymptotic Analysis and Precoding Design of Integrated Access and Backhaul in Full-Duplex mmWave Networks
    Yi Zhang, Shuai Han, Weixiao Meng, Xunan Li, Yue Chen
    2022, 19(5): 24-45.
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    In this paper, we consider a full-duplex (FD) millimeter wave (mmWave) multiuser integrated access and backhaul (IAB) system with massive MIMO, %Editor: Abbreviations and acronyms are often defined the first time they are used within the abstract and again in the main text and then used throughout the remainder of the manuscript. Please consider adhering to this convention. The target journal may have a list of abbreviations that are considered common enough that they do not need to be defined. and the system asymptotic performance and interference cancellation schemes are investigated. First, the asymptotic performance of the IAB system with massive MIMO is analyzed. As the number of macro base station (MBS) and small base station (SBS) antennas approaches infinity, the FD self-interference (SI), inter-tier interference and noise can be eliminated, which means that only multiuser interference remains in the system. Then, multiuser interference can be suppressed by the base band (BB) precoders. Since all interference and noise are suppressed, the spectral efficiency of the SBS and users are infinite in theory. Then, two interference suppression precoding schemes are proposed. A block diagonalization (BD)-based interference cancellation scheme is designed based on the channel characteristics and null space projection. The FD SI, inter-tier interference and multiuser interference are eliminated by BB precoders. Instead of eliminating interference completely, a signal to leakage and noise ratio (SLNR)-based precoding scheme is derived to suppress both interference and noise. By utilizing the Rayleigh-Ritz theorem, the SLNRs of the SBS and users are optimized. Simulation results show that all the interference can be effectively eliminated by the BD-based scheme at the cost of spectral efficiency performance loss, while the SLNR-based scheme can balance interference and noise and achieve higher spectral efficiency with comparatively low interference level. Therefore, the BD-based scheme is more suitable for interference elimination cases, and the SLNR-based scheme can improve the system performance in low interference scenarios.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Linear Network Coding Based Fast Data Synchronization for Wireless Ad Hoc Networks with Controlled Topology
    Die Hu, Xuejun Zhu, Min Gong, Shaoshi Yang
    2022, 19(5): 46-53.
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    Fast data synchronization in wireless ad hoc networks is a challenging and critical problem. It is fundamental for efficient information fusion, control and decision in distributed systems. Previously, distributed data synchronization was mainly studied in the latency-tolerant distributed databases, or assuming the general model of wireless ad hoc networks. In this paper, we propose a pair of linear network coding (NC) and all-to-all broadcast based fast data synchronization algorithms for wireless ad hoc networks whose topology is under operator's control. We consider both data block selection and transmitting node selection for exploiting the benefits of NC. Instead of using the store-and-forward protocol as in the conventional uncoded approach, a compute-and-forward protocol is used in our scheme, which improves the transmission efficiency. The performance of the proposed algorithms is studied under different values of network size, network connection degree, and per-hop packet error rate. Simulation results demonstrate that our algorithms significantly reduce the times slots used for data synchronization compared with the baseline that does not use NC.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Bit-Interleaved Polar Coded Modulation with Iterative Successive Cancellation List Decoding
    Hang Mu, Zheng Ma, George K. Karagiannidis, Panagiotis D. Diamantoulakis
    2022, 19(5): 54-68.
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    This paper introduces bit-interleaved polar coded modulation with iterative detection/decoding (BIPCM-ID). In order to enable the soft output of successive cancellation list (SCL) decoding, two types of re-encoders are proposed, namely the max-re-encoder and min-re-encoder, respectively. Regarding the iterative decoding, we analytically verify that the average mutual information (AMI) between the transmitted and decoded symbols can approach the Shannon bound with the proposed schemes. Moreover, bit error rate (BER) and block error rate (BLER) in single-user and multi-user scenarios are studied. Finally, simulation results show that the performance of BIPCM-ID outperforms other bit-interleaved coded modulation (BICM) systems with LDPC and Turbo codes, while also reducing the computational complexity.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Jitter Enhanced Full Digital RF Transmitter and PWM RFPA for 5G Broadband Communications
    Linxin Yin, Dake Liu, Yong Bai
    2022, 19(5): 69-86.
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    RFPA (radio frequency power amplifier) based on PWM (pulse width modulation) can be perfect linear without using complicated DPD (digital pre-distortion) hardware. However, PWM RFPA need ultra-high PWM time resolution (less than 10 ps) for wide-band 5G, which is limited by CMOS technologies (can reach 40 ps). It limits the complexity of modulation so that PWM RFPA cannot be really commercialized so far in wideband radio/mobile technologies. This paper presents our contribution by introducing jitter into PWM. For the first time, we demonstrate that jitter can improve the PWM time resolution equivalently reaching less than 2.6 ps. Hence PWM RFPA can be used in 5G supporting 256QAM OFDM modulation based on currently available digital CMOS technologies. We demonstrate that jitter can refine the inherent resolution of PWM hardware circuit modulation. The jitter makes the MCS (modulation and coding scheme) of the bandwidth OFDM system improved from 16QAM to 256QAM in the band n28 of 3GPP 38.101. We also verified that 5G 256QAM OFDM modulation is achievable in the 3GPP band n20, Softbank band28 and NTT Docomo band28. The RMS EVM (root mean square error vector magnitude) of 256QAM OFDM modulation is about -44 dB.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Tradeoffs in Covert Wireless Communication with a Controllable Full-Duplex Receiver
    Yue Zhao, Zan Li, DanyangWang, Nan Cheng
    2022, 19(5): 87-101.
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    This paper investigates the tradeoff of the communication link and the eavesdropping link in covert communication in the presence of a full-duplex (FD) receiver. When a warden (Willie) attempts to detect the signal transmitted from a legitimate transmitter (Alice), the controllable FD receiver (Bob) can transmit with random power to impose interference uncertainty to Willie and force it to make an incorrect decision. To maximize the average transmission rate (ATR) of Alice-Bob and the average covert probability (ACP) for Willie, we propose a multi-objective optimization framework to optimize Bob's power uncertainty range (PUR) and spatial position jointly, subject to the sufficient condition for covert communication and the none-deployed-zone (NDZ). Due to the presence of multiple optimization objectives and nonconvex constraints, the nondominated sorting genetic algorithm II (NSGA-II) is utilized to explore the Pareto front and to give a set of solutions that reflect tradeoffs between the two conflicting objectives. Simulation results reveal that the solutions determined by the NSGA-II have larger values for both ATR and ACP than the other two baselines. Simulations also show the positive effect of the width of the PUR of Bob on the Pareto front.
  • COMMUNICATIONS THEORIES & SYSTEMS
    A Uniform Reference Line Based Differential Phase Shifter with Wide Phase Range and Wide Bandwidth
    Canrong Fu, Bowei Xu, Shaoyong Zheng
    2022, 19(5): 102-111.
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    To implement the multi-way phase shifting maintaining the compact size and simplicity in structure, the uniform reference line concept was proposed for the differential phase shifter. However, the performance in bandwidth and phase range deteriorates with the additional requirements considered. To solve this problem, a quarter wavelength coupled line section loaded with open/short stubs is proposed as the basic element to implement the main line and also reference line. According to the theoretical analysis on this basic element, the loading stubs can be used to control the phase shift and also the phase slope of the basic element without affecting the amplitude property. With the predetermined parameters of the uniform reference line, only two parameters are required for the implementation of different differential phase shifts. This demonstrates the high simplicity of the proposed structure. For demonstration, an eight-way differential phase shifter operating at 3.5 GHz was implemented using the vertically installed planar structure. The prototype was further fabricated and measured. Good agreement between simulation and measurement can be observed. The implemented phase shifter can provide a wide range of phase shifting values from 45° to 315° with reference to the uniform reference line over a relative bandwidth of 62.3%.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Elliptical Cell Based Beamforming Design with an Improved β-Fairness Power Allocation for HSR Communication Systems
    Ximei Liu, Deli Qiao
    2022, 19(5): 112-128.
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    In this paper, a beamforming scheme to improve the coverage in high-speed railway communication systems is investigated. A dedicated coverage model, where the coverage cell is an ellipse rather than the traditional circular or linear, is considered. Based on the elliptical coverage cell, an optimization problem for the beamforming design is formulated to maximize the percentage of railway coverage, subject to the constraints on equal expected designed propagation gain (the gain obtained by a combination of designed beam and propagation channel) on the elliptical curve, i.e., the expectation of designed propagation gain on the elliptical curve are all equal. Considering that the coverage can be improved by increasing the minimum designed propagation gain on the railway, the problem can be recast to maximizing the equal expected designed propagation gain on the elliptical curve. Subsequently, a beamforming design with an improved β-fairness power allocation, where the optimization problem is formulated to maximize the minimum expected received power over time with the constraints on elliptical cell based beamforming and mobile service amount, is proposed to further improve the coverage. An alternating iteration algorithm is developed to find the optimal beamforming vector and the instantaneous transmit power. Through numerical results, it is found that the beamforming designed on the elliptical curve covers longer railway than beamforming designed on the railway directly, and the coverage of elliptical cell based beamforming can be increased with the eccentricity. In addition, beamforming with the improved β-fairness power allocation can further improve the railway coverage and mobile service amount simultaneously. Moreover, it is shown that the larger eccentricity of the ellipse with appropriately chosen BS location, the larger coverage distance.
    • NETWORKS & SECURITY
  • NETWORKS & SECURITY
    A Physical Layer Authentication Mechanism for IoT Devices
    Xinglu Li, Kaizhi Huang, ShaoyuWang, Xiaoming Xu
    2022, 19(5): 129-140.
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    When Internet of Things (IoT) nodes access the network through wireless channels, the network is vulnerable to spoofing attacks and the Sybil attack. However, the connection of massive devices in IoT makes it difficult to manage and distribute keys, thus limiting the application of traditional high-level authentication schemes. Compared with the high-level authentication scheme, the physical layer authentication scheme realizes the lightweight authentication of users by comparing the wireless channel characteristics of adjacent packets. However, traditional physical layer authentication schemes still adopt the one-to-one authentication method, which will consume numerous network resources in the face of large-scale IoT node access authentication. In order to realize the secure access authentication of IoT nodes and regional intrusion detection with low resource consumption, we propose a physical layer authentication mechanism based on convolution neural network (CNN), which uses the deep characteristics of channel state information (CSI) to identify sending nodes in different locations. Specifically, we obtain the instantaneous CSI data of IoT sending nodes at different locations in the pre-set area, and then feed them into CNN for training to procure a model for IoT node authentication. With its powerful ability of data analysis and feature extraction, CNN can extract deep Spatio-temporal environment features of CSI data and bind them with node identities. Accordingly, an authentication mechanism which can distinguish the identity types of IoT nodes located in different positions is established to authenticate the identity of unknown nodes when they break into the pre-set area. Experimental results show that this authentication mechanism can still achieve 94.7% authentication accuracy in the case of a low signalto- noise ratio (SNR) of 0 dB, which means a significant improvement in authentication accuracy and robustness.
  • NETWORKS & SECURITY
    DDoS Detection for 6G Internet of Things: Spatial-Temporal Trust Model and New Architecture
    Yinglun Ma, Xu Chen, Wei Feng, Ning Ge
    2022, 19(5): 141-149.
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    With the rapid development of the sixth generation (6G) network and Internet of Things (IoT), it has become extremely challenging to efficiently detect and prevent the distributed denial of service (DDoS) attacks originating from IoT devices. In this paper we propose an innovative trust model for IoT devices to prevent potential DDoS attacks by evaluating their trustworthiness, which can be deployed in the access network of 6G IoT. Based on historical communication behaviors, this model combines spatial trust and temporal trust values to comprehensively characterize the normal behavior patterns of IoT devices, thereby effectively distinguishing attack traffic. Experimental results show that the proposed method can efficiently distinguish normal traffic from DDoS traffic. Compared with the benchmark methods, our method has advantages in terms of both accuracy and efficiency in identifying attack flows.
  • NETWORKS & SECURITY
    Real-Time Monitoring System for Rotor Temperature of a Large Turbogenerator Based on SmartMesh IP Wireless Network Communication Technology
    Zhiting Zhou, Hui Li, Yong Yang, Haibo Zhang, Zhennan Fan
    2022, 19(5): 150-163.
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    In this study, a real-time rotor temperature monitoring system for large turbogenerators using SmartMesh IP wireless network communication technology was designed and tested. The system is capable of providing comprehensive, accurate, continuous, and reliable real-time temperature monitoring for turbogenerators. Additionally, it has demonstrated satisfactory results in a real-time monitoring test of the rotor temperature of various famous large-scale turbogenerators and giant nuclear power half-speed turbogenerators designed and manufactured in China. The development and application of this wireless temperature measurement system would aid in improving the intelligent operation quality, safety, and stability of China's large turbine generators and even the entire power system.
  • NETWORKS & SECURITY
    Sharing of Encrypted Lock Keys in the Blockchain-Based Renting House System from Time- and Identity-Based Proxy Reencryption
    Zhiwei Wang, Liping Qian, Danwei Chen, Guozi sun
    2022, 19(5): 164-177.
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    To design an efficient protocol for sharing the encrypted lock keys in the renting house system, we introduce a new notion called time- and identitybased proxy reencryption (TIPRE) and the blockchain platform. Our CPA secure TIPRE scheme is constructed from Green et al.'s identity-based proxy reencryption scheme by adding the time property. In every time period, a time stamp authority generates a public key embedded with the current time stamp for each user. In our protocol for the renting house system, the TIPRE scheme is the primary building block, and the blockchain platform serves instead of a trusted third party, such as a real estate agency between landlords and tenants. The TIPRE scheme allows the landlord to change the lock key at each time period for safety. The blockchain platform allows the landlords and tenants to directly interact, and all of the interactions are recorded in the blockchain database to provide the desired security requirements, such as nonrepudiation and unforgeability. Finally, we provide the secure analysis of our protocol and test its performance by implementing it in the MacBook Pro and the Intel Edison development platforms.
  • NETWORKS & SECURITY
    Dynamic Backup Sharing Scheme of Service Function Chains in NFV
    Dong Zhang, Zhifan Zheng, Xiang Lin, Xiang Chen, ChunmingWu
    2022, 19(5): 178-190.
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    Service function chains (SFC) mapping takes the responsibility for managing virtual network functions (VNFs). In SFC mapping, existing solutions duplicate VNFs with redundant instances to provide high availability in response to failures. However, as a compromise, these solutions result in high resource consumption due to device maintenance. In this paper, we propose a novel method named dynamic backup sharing (DBS) that allows SFCs to dynamically share backups to reduce resource consumption. DBS formulates the problem of sharing backups among different VNFs as an integer linear programming (ILP). Thereafter, we design a novel online algorithm based on dynamic programming to solve the problem. The experimental results indicate that DBS outperforms state-ofthe- art works by reducing resource consumption and improving the number of accepted requests.
  • NETWORKS & SECURITY
    Joint Trajectory and Passive Beamforming Optimization in IRS-UAV Enhanced Anti-Jamming Communication Networks
    Zhifeng Hou, Jin Chen, Yuzhen Huang, Yijie Luo, XimingWang, Jiangchun Gu, Yifan Xu, Kailing Yao
    2022, 19(5): 191-205.
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    This paper investigates the anti-jamming communication scenario where an intelligent reflecting surface (IRS) is mounted on the unmanned aerial vehicle (UAV) to resist the malicious jamming attacks. Different from existing works, we consider the dynamic deployment of IRS-UAV in the environment of the mobile user and unknown jammer. Therefore, a joint trajectory and passive beamforming optimization approach is proposed in the IRS-UAV enhanced networks. In detail, the optimization problem is firstly formulated into a Markov decision process (MDP). Then, a dueling double deep Q networks multi-step learning algorithm is proposed to tackle the complex and coupling decision-making problem. Finally, simulation results show that the proposed scheme can significantly improve the anti-jamming communication performance of the mobile user.
  • NETWORKS & SECURITY
    Resource Allocation and Trajectories Design for UAV-Assisted Jamming Cognitive UAV Networks
    Zhenhui Tao, Fuhui Zhou, YuhaoWang, Xiaodong Liu, QihuiWu
    2022, 19(5): 206-217.
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    Unmanned aerial vehicle (UAV) communications are subject to the severe spectrum scarcity problem. Cognitive UAV networks are promising to tackle this issue while the confidential information is susceptible to be eavesdropped. A UAV jamming assisted scheme is proposed. A joint resource allocation and trajectories optimization problem is formulated in a UAV-assisted jamming cognitive UAV network subject to diverse power and trajectory constraints. An alternative optimization algorithm is proposed to solve the challenging non-convex joint optimization problem. Extensive simulation results demonstrate the superiority of our proposed scheme and many meaningful insights are obtained for the practical design of cognitive UAV networks.
  • NETWORKS & SECURITY
    Anti-Attacking Modeling and Analysis of Cyberspace Mimic DNS
    Lei He, Quan Ren, Bolin Ma, Weili Zhang, JiangxingWu
    2022, 19(5): 218-230.
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    With the rapid development of information technology, the cyberspace security problem is increasingly serious. Kinds of dynamic defense technology have emerged such as moving target defense and mimic defense. This paper aims to describe the architecture and analyze the performance of Cyberspace Mimic DNS based on generalized stochastic Petri net. We propose a general method of anti-attacking analysis. For general attack and special attack model, the available probability, escaped probability and nonspecial awareness probability are adopted to quantitatively analyze the system performance. And we expand the GSPN model to adjust to engineering practice by specifying randomness of different output vectors. The result shows that the proposed method is effective, and Mimic system has high anti-attacking performance. To deal with the special attack, we can integrate the traditional defense mechanism in engineering practice. Besides, we analyze the performance of mimic DNSframework based on multi-ruling proxy and input-output desperation, the results represent we can use multi ruling or high-speed cache servers to achieve the consistent cost of delay, throughput compared with single authorized DNS, it can effectively solve 10% to 20% performance loss caused by general ruling proxy.
    • EMERGING TECHNOLOGIES & APPLICATIONS
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Large Spacing Array with Offset Phase Center Elements for Highly Integrated Applications
    Hailing Jiang, Hui Tian, Shubo Dun, Junyi Zhang
    2022, 19(5): 231-240.
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    A scanning and uniform array architecture with large spacing, low complexity and high scalability is presented for high integration massive array applications. It is constructed by offset phase center elements arranged in a uniform and regular way, but its spacing can be larger than that of traditional arrays. An ideal model of the offset phase center element is established and its far-field distribution is derived. To suppress grating lobes, the phase center of any element is designed to be movable without changing its physical position. Using genetic algorithm (GA), a new constraint condition limiting the number of phase center changes is proposed to solve the objective function of the minimum values of grating lobes (GLs) and side lobes (SLs). It is shown that the optimal results can be achieved by two changes of phase centers. A multimode circular patch is developed and designed, and characteristics of the offset phase center are analyzed and verified. A prototype array of 12×12 offset phase center elements is implemented based on multi-mode circular patches. Full wave simulation results of radiation patterns show that the level of grating lobes is suppressed at least 7dB with 1.12λ spacing, while the scanning angle is 20°.
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Collision Classification MAC Protocol for Underwater Acoustic Communication Networks Using Directional Antennas
    Jianmin Yang, Gang Qiao, Qing Hu, Lingji Xu, Peng Xiao, Jiarong Zhang
    2022, 19(5): 241-252.
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    Traditional underwater acoustic communication networks (UACNs) generally use omnidirectional transmission technology that causes a large number of data-packet collisions, thus resulting in low network throughput and high end-to-end delays. Compared with omnidirectional transmission technology, directional technology only sends and receives data packets in a specified direction. This can significantly reduce the probability of collisions and improve network performance. However, it also causes a deafness problem, which occurs when the sending node sends a data packet to the receiving node but the receiving node is unable to reply to the sender, because its antenna beam is closed. To resolve this issue, this study proposes a collision classification media access control (CC-MAC) protocol for UACNs. With this protocol, the underwater acoustic channel is divided into two subchannels, and the nodes transmit corresponding data types on them. The sending node can estimate the current status of the receiving node (i.e., no collision, normal collision, deafness) according to the type of the data packet received and the sub-channel it arrived on, and it can choose correct options to improve network efficiency. Finally, we verify the performance of CC-MAC via simulations, showing that the protocol achieved higher network throughput and lower end-toend delays.
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Solve the False-Positive Problem of the Mimic System Based on the Best Mimic Component Set
    Yuwen Shao, Zheng Zhang, XiaomeiWang, Chuanxing Pan, JiangxingWu
    2022, 19(5): 253-266.
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    At present, there is a problem of false positives caused by the too vast mimic scope in mimic transformation technology. Previous studies have focused on the “compensation” method to deal with this problem, which is expensive and cannot fundamentally solve it. This paper provides new insights into coping with the situation. Firstly, this study summarizes the false-positive problem in the mimic transformation, analyzes its possible harm and the root causes. Secondly, three properties about the mimic scope are proposed. Based on the three properties and security quantification technology, the best mimic component set theory is put forward to solve the false-positive problem. There are two algorithms, the supplemental method and the subtraction method. The best mimic component set obtained by these two algorithms can fundamentally solve the mimic system's false-positive problem but reduce the cost of mimic transformation. Thus make up for the lack of previous researches.
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Demand Prediction Based Slice Reconfiguration Using Dueling Deep Q-Network
    Wanqing Guan, Haijun Zhang
    2022, 19(5): 267-285.
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    To satisfy diversified service demands of vertical industries, network slicing enables efficient resource allocation of a common infrastructure by creating isolated logical networks. However, uncertainty and dynamics of service demands will cause performance degradation. Due to operation costs and resource constraints, it is challenging to maintain high quality of user experience while obtaining high revenue for service providers (SPs). This paper develops an optimal and fast slice reconfiguration (OFSR) framework based on reinforcement learning, where a novel scheme is proposed to offer optimal decisions for reconfiguring diverse slices. A demand prediction model is proposed to capture changes in resource requirements, based on which the OFSR scheme is triggered to determine whether to perform slice reconfiguration. Considering the large state and action spaces generated from uncertain service time and resource requirements, deep dueling architecture is adopted to improve the convergence rate. Extensive simulations validate the effectiveness of the proposed framework in achieving higher long-term revenue for SPs.
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Attention-Based Multi-Scale Prediction Network for Time-Series Data
    Junjie Li, Lin Zhu, Yong Zhang, Da Guo, Xingwen Xia
    2022, 19(5): 286-301.
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    Time series data is a kind of data accumulated over time, which can describe the change of phenomenon. This kind of data reflects the degree of change of a certain thing or phenomenon. The existing technologies such as LSTM and ARIMA are better than convolutional neural network in time series prediction, but they are not enough to mine the periodicity of data. In this article, we perform periodic analysis on two types of time series data, select time metrics with high periodic characteristics, and propose a multi-scale prediction model based on the attention mechanism for the periodic trend of the data. A loss calculation method for traffic time series characteristics is proposed as well. Multiple experiments have been conducted on actual data sets. The experiments show that the method proposed in this paper has better performance than commonly used traffic prediction methods (ARIMA, LSTM, etc.) and 3%-5% increase on MAPE.
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Adaptive 3D Routing Protocol for Flying Ad Hoc Networks Based on Prediction-Driven Q-Learning
    Min Zhang, Chao Dong, Simeng Feng, Xin Guan, Huichao Chen, QihuiWu
    2022, 19(5): 302-317.
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    The routing protocols are paramount to guarantee the Quality of Service (QoS) for Flying Ad Hoc Networks (FANETs). However, they still face several challenges owing to high mobility and dynamic topology. This paper mainly focuses on the adaptive routing protocol and proposes a Three Dimensional Q-Learning (3DQ) based routing protocol to guarantee the packet delivery ratio and improve the QoS. In 3DQ routing, we propose a Q-Learning based routing decision scheme, which contains a link-state prediction module and routing decision module. The link-state prediction module allows each Unmanned Aerial Vehicle (UAV) to predict the link-state of Neighboring UAVs (NUs), considering their Three Dimensional mobility and packet arrival. Then, UAV can produce routing decisions with the help of the routing decision module considering the link-state. We evaluate the various performance of 3DQ routing, and simulation results demonstrate that 3DQ can improve packet delivery ratio, goodput and delay of baseline protocol at most 71.36%, 89.32% and 83.54% in FANETs over a variety of communication scenarios.
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Coverage Analyses on Directional Transmissions Ultra-Dense Networks with Imperfect Beam Alignment
    Yining Xu, Sheng Zhou
    2022, 19(5): 318-328.
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    Blockage and imperfect beam alignment are two principal difficulties in high-frequency bands directional transmissions. In this paper, the coverage performance of downlink directional transmissions in ultra-dense networks is analyzed, with the consideration of beam alignment error and link blockage through stochastic geometry. Numerical experiments demonstrate that narrower beam leads to higher coverage probability with perfect beam alignment, but it is not the case with imperfect beam alignment. Therefore, the optimal beamwidth that maximize the coverage probability is characterized and a closed-form approximation of the optimal beamwidth is derived under imperfect beam alignment, accordingly. Furthermore, the optimal beamwidth is a monotonically increasing function of the standard deviation of the beam alignment error, and a monotonically decreasing function of the beamwidth of correspondent communication end, indicating that the beamwidth of the communication pairs ought to be jointly designed.