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    Towards Near-Field Communications for 6G: Challenges and Opportunities
    LIU Mengyu, ZHANG Yang, JIN Yasheng, ZHI Kangda, PAN Cunhua
    ZTE Communications    2024, 22 (1): 3-15.   DOI: 10.12142/ZTECOM.202401002
    Abstract175)   HTML14)    PDF (2702KB)(400)       Save

    Extremely large-scale multiple-input multiple-output (XL-MIMO) and terahertz (THz) communications are pivotal candidate technologies for supporting the development of 6G mobile networks. However, these techniques invalidate the common assumptions of far-field plane waves and introduce many new properties. To accurately understand the performance of these new techniques, spherical wave modeling of near-field communications needs to be applied for future research. Hence, the investigation of near-field communication holds significant importance for the advancement of 6G, which brings many new and open research challenges in contrast to conventional far-field communication. In this paper, we first formulate a general model of the near-field channel and discuss the influence of spatial nonstationary properties on the near-field channel modeling. Subsequently, we discuss the challenges encountered in the near field in terms of beam training, localization, and transmission scheme design, respectively. Finally, we point out some promising research directions for near-field communications.

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    MetaOracle: A High-Throughput Decentralized Oracle for Web 3.0-Empowered Metaverse
    CHEN Rui, LI Hui, LI Wuyang, BAI He, WANG Han, WU Naixing, FAN Ping, KANG Jian, DENG Selwyn, ZHU Xiang
    ZTE Communications    2024, 22 (2): 11-18.   DOI: 10.12142/ZTECOM.202402003
    Abstract165)   HTML7)    PDF (1003KB)(89)       Save

    Recent rapid advancements in communication technology have brought forth the era of Web 3.0, representing a substantial transformation in the Internet landscape. This shift has led to the emergence of various decentralized metaverse applications that leverage blockchain as their underlying technology to enable users to exchange value directly from point to point. However, blockchains are blind to the real world, and smart contracts cannot directly access data from the external world. To address this limitation, the technology of oracles has been introduced to provide real-world data for smart contracts and other blockchain applications. In this paper, we focus on mitigating the risks associated with oracles providing corrupt or incorrect data. We propose a novel Web 3.0 architecture for the Metaverse based on the multi-identifier network (MIN), and its decentralized blockchain oracle model called MetaOracle. The experimental results show that the proposed scheme can achieve minor time investment in return for significantly more reliable data and increased throughput.

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    Integrated Sensing and Communication: Who Benefits More?
    DU Ruolin, WEI Zhiqiang, YANG Zai
    ZTE Communications    2024, 22 (3): 37-47.   DOI: 10.12142/ZTECOM.202403006
    Abstract157)   HTML17)    PDF (1776KB)(192)       Save

    This paper compares the benefits of communication-assisted sensing and sensing-assisted communication in the context of integrated sensing and communication (ISAC). Communication-assisted sensing leverages the extensive cellular infrastructure to create a vast and cooperative sensor network, enhancing environmental perception accuracy and coverage. On the other hand, sensing-assisted communication utilizes advanced sensing technologies to improve predictive beamforming and channel estimation performance in high-frequency and high-mobility scenarios, thereby increasing communication efficiency and reliability. To validate our analysis, we present an example of channel knowledge map (CKM)-assisted beam tracking. This example demonstrates the practical advantages of incorporating CKM in enhancing beam tracking accuracy. Our analysis confirms that communication-assisted sensing may offer greater development potential due to its wide coverage and cost-effectiveness in large-scale applications.

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    Special Topic on Integrated Sensing and Communication (ISAC) Technologies for Future Wireless Communication
    YUAN Jinhong, FEI Zesong, WEI Zhiqiang
    ZTE Communications    2024, 22 (3): 1-3.   DOI: 10.12142/ZTECOM.202403001
    Abstract153)   HTML17)    PDF (444KB)(175)       Save
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    Optimization of High-Concurrency Conflict Issues in Execute-Order-Validate Blockchain
    MA Qianli, ZHANG Shengli, WANG Taotao, YANG Qing, WANG Jigang
    ZTE Communications    2024, 22 (2): 19-29.   DOI: 10.12142/ZTECOM.202402004
    Abstract139)   HTML6)    PDF (1237KB)(92)       Save

    With the maturation and advancement of blockchain technology, a novel execute-order-validate (EOV) architecture has been proposed, allowing transactions to be executed in parallel during the execution phase. However, parallel execution may lead to multi-version concurrency control (MVCC) conflicts during the validation phase, resulting in transaction invalidation. Based on different causes, we categorize conflicts in the EOV blockchain into two types: within-block conflicts and cross-block conflicts, and propose an optimization solution called FabricMan based on Fabric v2.4. For within-block conflicts, a reordering algorithm is designed to improve the transaction success rate and parallel validation is implemented based on the transaction conflict graph. We also merge transfer transactions to prevent triggering multiple version checks. For cross-block conflicts, a cache-based version validation mechanism is implemented to detect and terminate invalid transactions in advance. Experimental comparisons are conducted between FabricMan and two other systems, Fabric and Fabric++. The results show that FabricMan outperforms the other two systems in terms of throughput, transaction abort rate, algorithm execution time, and other experimental metrics.

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    Deadlock Detection: Background, Techniques, and Future Improvements
    LU Jiachen, NIU Zhi, CHEN Li, DONG Luming, SHEN Taoli
    ZTE Communications    2024, 22 (2): 71-79.   DOI: 10.12142/ZTECOM.202402009
    Abstract136)   HTML13)    PDF (438KB)(121)       Save

    Deadlock detection is an essential aspect of concurrency control in parallel and distributed systems, as it ensures the efficient utilization of resources and prevents indefinite delays. This paper presents a comprehensive analysis of the various deadlock detection techniques, including static and dynamic approaches. We discuss the future improvements associated with deadlock detection and provide a comparative evaluation of these techniques in terms of their accuracy, complexity, and scalability. Furthermore, we outline potential future research directions to improve deadlock detection mechanisms and enhance system performance.

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    Building a Stronger Foundation for Web3: Advantages of 5G Infrastructure
    FENG Jianxin, PAN Yi, WU Xiao
    ZTE Communications    2024, 22 (2): 3-10.   DOI: 10.12142/ZTECOM.202402002
    Abstract131)   HTML12)    PDF (1211KB)(66)       Save

    The emergence of Web3 technologies promises to revolutionize the Internet and redefine our interactions with digital assets and applications. This essay explores the pivotal role of 5G infrastructure in bolstering the growth and potential of Web3. By focusing on several crucial aspects—network speed, edge computing, network capacity, security and power consumption—we shed light on how 5G technology offers a robust and transformative foundation for the decentralized future of the Internet. Prior to delving into the specifics, we undertake a technical review of the historical progression and development of Internet and telecommunication technologies.

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    Link Budget and Enhanced Communication Distance for Ambient Internet of Things
    YANG Yibing, LIU Ming, XU Rongtao, WANG Gongpu, GONG Wei
    ZTE Communications    2024, 22 (1): 16-23.   DOI: 10.12142/ZTECOM.202401003
    Abstract127)   HTML3)    PDF (1976KB)(166)       Save

    Backscatter communications will play an important role in connecting everything for beyond 5G (B5G) and 6G systems. One open challenge for backscatter communications is that the signals suffer a round-trip path loss so that the communication distance is short. In this paper, we first calculate the communication distance upper bounds for both uplink and downlink by measuring the tag sensitivity and reflection coefficient. It is found that the activation voltage of the envelope detection diode of the downlink tag is the main factor limiting the backscatter communication distance. Based on this analysis, we then propose to implement a low-noise amplifier (LNA) module before the envelope detection at the tag to enhance the incident signal strength. Our experimental results on the hardware platform show that our method can increase the downlink communication range by nearly 20 m.

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    Special Topic on Near-Field Communication and Sensing Towards 6G
    WEI Guo, ZHAO Yajun, CHEN Li
    ZTE Communications    2024, 22 (1): 1-2.   DOI: 10.12142/ZTECOM.202401001
    Abstract125)   HTML16)    PDF (366KB)(289)       Save
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    On Normalized Least Mean Square Based Interference Cancellation Algorithm for Integrated Sensing and Communication Systems
    YU Xiaohui, YU Shucheng, LIU Xiqing, PENG Mugen
    ZTE Communications    2024, 22 (3): 21-28.   DOI: 10.12142/ZTECOM.202403004
    Abstract125)   HTML5)    PDF (1389KB)(135)       Save

    Integrated sensing and communication (ISAC) technology is a promising candidate for next-generation communication systems. However, severe co-site interference in existing ISAC systems limits the communication and sensing performance, posing significant challenges for ISAC interference management. In this work, we propose a novel interference management scheme based on the normalized least mean square (NLMS) algorithm, which mitigates the impact of co-site interference by reconstructing the interference from the local transmitter and canceling it from the received signal. Simulation results demonstrate that, compared to typical adaptive interference management schemes based on recursive least square (RLS) and stochastic gradient descent (SGD) algorithms, the proposed NLMS algorithm effectively cancels co-site interference and achieves a good balance between computational complexity and convergence performance.

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    Near-Field Beam Training for Holographic MIMO Communications: Typical Methods, Challenges and Future Directions
    SHEN Jiayu, YANG Jun, ZHU Chen, DENG Zhiji, HUANG Chongwen
    ZTE Communications    2024, 22 (1): 41-52.   DOI: 10.12142/ZTECOM.202401006
    Abstract119)   HTML5)    PDF (3394KB)(487)       Save

    Holographic multiple-input multiple-output (HMIMO) has become an emerging technology for achieving ultra-high frequency spectral efficiency and spatial resolution in future wireless systems. The increasing antenna aperture leads to a more significant characterization of the spherical wavefront in near-field communications in HMIMO scenarios. Beam training as a key technique for wireless communication is worth exploring in this near-field scenario. Compared with the widely researched far-field beam training, the increased dimensionality of the search space for near-field beam training poses a challenge to the complexity and accuracy of the proposed algorithm. In this paper, we introduce several typical near-field beam training methods: exhaustive beam training, hierarchical beam training, and multi-beam training that includes equal interval multi-beam training and hash multi-beam training. The performances of these methods are compared through simulation analysis, and their effectiveness is verified on the hardware testbed as well. Additionally, we provide application scenarios, research challenges, and potential future research directions for near-field beam training.

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    Recent Advances in Video Coding for Machines Standard and Technologies
    ZHANG Qiang, MEI Junjun, GUAN Tao, SUN Zhewen, ZHANG Zixiang, YU Li
    ZTE Communications    2024, 22 (1): 62-76.   DOI: 10.12142/ZTECOM.202401008
    Abstract117)   HTML5)    PDF (1394KB)(266)       Save

    To improve the performance of video compression for machine vision analysis tasks, a video coding for machines (VCM) standard working group was established to promote standardization procedures. In this paper, recent advances in video coding for machine standards are presented and comprehensive introductions to the use cases, requirements, evaluation frameworks and corresponding metrics of the VCM standard are given. Then the existing methods are presented, introducing the existing proposals by category and the research progress of the latest VCM conference. Finally, we give conclusions.

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    RIS-Assisted Cell-Free MIMO: A Survey
    ZHAO Yaqiong, KE Hongqin, XU Wei, YE Xinquan, CHEN Yijian
    ZTE Communications    2024, 22 (1): 77-86.   DOI: 10.12142/ZTECOM.202401009
    Abstract117)   HTML7)    PDF (1473KB)(237)       Save

    Cell-free (CF) multiple-input multiple-output (MIMO) is a promising technique to enable the vision of ubiquitous wireless connectivity for next-generation network communications. Compared to traditional co-located massive MIMO, CF MIMO allows geographically distributed access points (APs) to serve all users on the same time-frequency resource with spatial multiplexing techniques, resulting in better performance in terms of both spectral efficiency and coverage enhancement. However, the performance gain is achieved at the expense of deploying more APs with high cost and power consumption. To address this issue, the recently proposed reconfigurable intelligent surface (RIS) technique stands out with its unique advantages of low cost, low energy consumption and programmability. In this paper, we provide an overview of RIS-assisted CF MIMO and its interaction with advanced optimization designs and novel applications. Particularly, recent studies on typical performance metrics such as energy efficiency (EE) and spectral efficiency (SE) are surveyed. Besides, the application of RIS-assisted CF MIMO techniques in various future communication systems is also envisioned. Additionally, we briefly discuss the technical challenges and open problems for this area to inspire research direction and fully exploit its potential in meeting the demands of future wireless communication systems.

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    Utilizing Certificateless Cryptography for IoT Device Identity Authentication Protocols in Web3
    WU Zhihui, HONG Yuxuan, ZHOU Enyuan, LIU Lei, PEI Qingqi
    ZTE Communications    2024, 22 (2): 30-38.   DOI: 10.12142/ZTECOM.202402005
    Abstract113)   HTML6)    PDF (671KB)(87)       Save

    Traditional methods of identity authentication often rely on centralized architectures, which poses risks of computational overload and single points of failure. We propose a protocol that offers a decentralized approach by distributing authentication services to edge authentication gateways and servers, facilitated by blockchain technology, thus aligning with the decentralized ethos of Web3 infrastructure. Additionally, we enhance device security against physical and cloning attacks by integrating physical unclonable functions with certificateless cryptography, bolstering the integrity of Internet of Thins (IoT) devices within the evolving landscape of the metaverse. To achieve dynamic anonymity and ensure privacy within Web3 environments, we employ fuzzy extractor technology, allowing for updates to pseudonymous identity identifiers while maintaining key consistency. The proposed protocol ensures continuous and secure identity authentication for IoT devices in practical applications, effectively addressing the pressing security concerns inherent in IoT network environments and contributing to the development of robust security infrastructure essential for the proliferation of IoT devices across diverse settings.

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    A Survey on Task Scheduling of CPU-GPU Heterogeneous Cluster
    ZHOU Yiheng, ZENG Wei, ZHENG Qingfang, LIU Zhilong, CHEN Jianping
    ZTE Communications    2024, 22 (3): 83-90.   DOI: 10.12142/ZTECOM.202403010
    Abstract111)   HTML13)    PDF (848KB)(84)       Save

    This paper reviews task scheduling frameworks, methods, and evaluation metrics of central processing unit-graphics processing unit (CPU-GPU) heterogeneous clusters. Task scheduling of CPU-GPU heterogeneous clusters can be carried out on the system level, nodelevel, and device level. Most task-scheduling technologies are heuristic based on the experts’ experience, while some technologies are based on statistic methods using machine learning, deep learning, or reinforcement learning. Many metrics have been adopted to evaluate and compare different task scheduling technologies that try to optimize different goals of task scheduling. Although statistic task scheduling has reached fewer research achievements than heuristic task scheduling, the statistic task scheduling still has significant research potential.

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    Hierarchical Federated Learning Architectures for the Metaverse
    GU Cheng, LI Baochun
    ZTE Communications    2024, 22 (2): 39-48.   DOI: 10.12142/ZTECOM.202402006
    Abstract110)   HTML6)    PDF (1189KB)(77)       Save

    In the context of edge computing environments in general and the metaverse in particular, federated learning (FL) has emerged as a distributed machine learning paradigm that allows multiple users to collaborate on training a shared machine learning model locally, eliminating the need for uploading raw data to a central server. It is perhaps the only training paradigm that preserves the privacy of user data, which is essential for computing environments as personal as the metaverse. However, the original FL architecture proposed is not scalable to a large number of user devices in the metaverse community. To mitigate this problem, hierarchical federated learning (HFL) has been introduced as a general distributed learning paradigm, inspiring a number of research works. In this paper, we present several types of HFL architectures, with a special focus on the three-layer client-edge-cloud HFL architecture, which is most pertinent to the metaverse due to its delay-sensitive nature. We also examine works that take advantage of the natural layered organization of three-layer client-edge-cloud HFL to tackle some of the most challenging problems in FL within the metaverse. Finally, we outline some future research directions of HFL in the metaverse.

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    Near-Field Wireless Power Transfer, Sensing and Communication with Bessel Beams
    CAO Xinghan, YIN Huarui, YOU Changsheng
    ZTE Communications    2024, 22 (1): 53-61.   DOI: 10.12142/ZTECOM.202401007
    Abstract108)   HTML3)    PDF (1747KB)(326)       Save

    The Bessel beam, characterized by its unique non-diffracting properties, holds promising applications. In this paper, we provide a detailed introduction and investigation into the theory and research of the Bessel beam, with a special focus on its generation and applications in the near-field region. We provide an introduction to the concepts, properties, and foundational theories of the Bessel beam. Additionally, the current study on generating Bessel beams and their applications is categorized and discussed, and potential research challenges are proposed in this paper. This review serves as a solid foundation for researchers to understand the concept of the Bessel beam and explore its potential applications.

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    Learned Distributed Query Optimizer: Architecture and Challenges
    GAO Jun, HAN Yinjun, LIN Yang, MIAO Hao, XU Mo
    ZTE Communications    2024, 22 (2): 49-54.   DOI: 10.12142/ZTECOM.202402007
    Abstract106)   HTML2)    PDF (408KB)(105)       Save

    The query processing in distributed database management systems (DBMS) faces more challenges, such as more operators, and more factors in cost models and meta-data, than that in a single-node DMBS, in which query optimization is already an NP-hard problem. Learned query optimizers (mainly in the single-node DBMS) receive attention due to its capability to capture data distributions and flexible ways to avoid hard-craft rules in refinement and adaptation to new hardware. In this paper, we focus on extensions of learned query optimizers to distributed DBMSs. Specifically, we propose one possible but general architecture of the learned query optimizer in the distributed context and highlight differences from the learned optimizer in the single-node ones. In addition, we discuss the challenges and possible solutions.

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    Multi-View Image-Based 3D Reconstruction in Indoor Scenes: A Survey
    LU Ping, SHI Wenzhe, QIAO Xiuquan
    ZTE Communications    2024, 22 (3): 91-98.   DOI: 10.12142/ZTECOM.202403011
    Abstract105)   HTML2)    PDF (750KB)(99)       Save

    Three-dimensional reconstruction technology plays an important role in indoor scenes by converting objects and structures in indoor environments into accurate 3D models using multi-view RGB images. It offers a wide range of applications in fields such as virtual reality, augmented reality, indoor navigation, and game development. Existing methods based on multi-view RGB images have made significant progress in 3D reconstruction. These image-based reconstruction methods not only possess good expressive power and generalization performance, but also handle complex geometric shapes and textures effectively. Despite facing challenges such as lighting variations, occlusion, and texture loss in indoor scenes, these challenges can be effectively addressed through deep neural networks, neural implicit surface representations, and other techniques. The technology of indoor 3D reconstruction based on multi-view RGB images has a promising future. It not only provides immersive and interactive virtual experiences but also brings convenience and innovation to indoor navigation, interior design, and virtual tours. As the technology evolves, these image-based reconstruction methods will be further improved to provide higher quality and more accurate solutions to indoor scene reconstruction.

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    Review on Service Curves of Typical Scheduling Algorithms
    GAO Yuehong, NING Zhi, HE Jia, ZHOU Jinfei, GAO Chenqiang, TANG Qingkun, YU Jinghai
    ZTE Communications    2024, 22 (2): 55-70.   DOI: 10.12142/ZTECOM.202402008
    Abstract102)   HTML8)    PDF (814KB)(85)       Save

    In recent years, various internet architectures, such as Integrated Services (IntServ), Differentiated Services (DiffServ), Time Sensitive Networking (TSN) and Deterministic Networking (DetNet), have been proposed to meet the quality-of-service (QoS) requirements of different network services. Concurrently, network calculus has found widespread application in network modeling and QoS analysis. Network calculus abstracts the details of how nodes or networks process data packets using the concept of service curves. This paper summarizes the service curves for typical scheduling algorithms, including Strict Priority (SP), Round Robin (RR), Cycling Queuing and Forwarding (CQF), Time Aware Shaper (TAS), Credit Based Shaper (CBS), and Asynchronous Traffic Shaper (ATS). It introduces the theory of network calculus and then provides an overview of various scheduling algorithms and their associated service curves. The delay bound analysis for different scheduling algorithms in specific scenarios is also conducted for more insights.

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    Low-Complexity Integrated Super-Resolution Sensing and Communication with Signal Decimation and Ambiguity Removal
    DAI Qianglong, ZHOU Zhiwen, XIAO Zhiqiang, ZENG Yong, YANG Fei, CHEN Yan
    ZTE Communications    2024, 22 (3): 48-55.   DOI: 10.12142/ZTECOM.202403007
    Abstract101)   HTML7)    PDF (1387KB)(140)       Save

    Integrated sensing and communication (ISAC) is one of the main usage scenarios for 6G wireless networks. To most efficiently utilize the limited wireless resources, integrated super-resolution sensing and communication (ISSAC) has been recently proposed to significantly improve sensing performance with super-resolution algorithms for ISAC systems, such as the Multiple Signal Classification (MUSIC) algorithm. However, traditional super-resolution sensing algorithms suffer from prohibitive computational complexity of orthogonal-frequency division multiplexing (OFDM) systems due to the large dimensions of the signals in the subcarrier and symbol domains. To address such issues, we propose a novel two-stage approach to reduce the computational complexity for super-resolution range estimation significantly. The key idea of the proposed scheme is to first uniformly decimate signals in the subcarrier domain so that the computational complexity is significantly reduced without missing any target in the range domain. However, the decimation operation may result in range ambiguity due to pseudo peaks, which is addressed by the second stage where the total collocated subcarrier data are used to verify the detected peaks. Compared with traditional MUSIC algorithms, the proposed scheme reduces computational complexity by two orders of magnitude, while maintaining the range resolution and unambiguity. Simulation results verify the effectiveness of the proposed scheme.

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    Impacts of Model Mismatch and Array Scale on Channel Estimation for XL-HRIS-Aided Systems
    LU Zhizheng, HAN Yu, JIN Shi
    ZTE Communications    2024, 22 (1): 24-33.   DOI: 10.12142/ZTECOM.202401004
    Abstract96)   HTML5)    PDF (1234KB)(209)       Save

    Extremely large-scale hybrid reconfigurable intelligence surface (XL-HRIS), an improved version of the RIS, can receive the incident signal and enhance communication performance. However, as the RIS size increases, the phase variations of the received signal across the whole array are nonnegligible in the near-field region, and the channel model mismatch, which will decrease the estimation accuracy, must be considered. In this paper, the lower bound (LB) of the estimated parameter is studied and the impacts of the distance and signal-to-noise ratio (SNR) on LB are then evaluated. Moreover, the impacts of the array scale on LB and spectral efficiency (SE) are also studied. Simulation results verify that even in extremely large-scale array systems with infinite SNR, channel model mismatch can still limit estimation accuracy. However, this impact decreases with increasing distance.

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    Design of LCoS-Based Twin 1×40 Wavelength Selective Switch
    WANG Han, LIU Maoqi, FENG Zhenhua, LIU Minghuan, MAO Baiwei
    ZTE Communications    2024, 22 (4): 18-28.   DOI: 10.12142/ZTECOM.202404004
    Abstract95)   HTML9)    PDF (3044KB)(109)       Save

    Wavelength selective switch (WSS) is the crucial component in the reconfigurable optical add/drop multiplexer (ROADM), which plays a pivotal role in the next-generation all-optical networks. We present a compact architecture of twin 1×40 liquid crystal on silicon (LCoS)-based WSS, which can be regarded as a 4f system in the wavelength direction and a 2f system in the switching direction. It is designed with theoretical analysis and simulation investigation. Polarization multiplexing is employed for two sources of twin WSS by polarization conversion before the common optical path. The WSS system attains a coupling efficacy exceeding 96% for 90% of the ports through simulation optimization. The 3 dB bandwidth can be achieved by more than 44 GHz at a 50 GHz grid for all 120 channels at all deflection ports. This work establishes a solid foundation for developing high-performance WSS with larger port counts.

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    Degree of Freedom Analysis for Holographic MIMO Based on a Mutual-Coupling-Compliant Channel Model
    SUN Yunqi, JIAN Mengnan, YANG Jun, ZHAO Yajun, CHEN Yijian
    ZTE Communications    2024, 22 (1): 34-40.   DOI: 10.12142/ZTECOM.202401005
    Abstract93)   HTML9)    PDF (1783KB)(285)       Save

    Degree of freedom (DOF) is a key indicator for spatial multiplexing layers of a wireless channel. Traditionally, the channel of a multiple-input multiple-output (MIMO) half-wavelength dipole array has a DOF that equals the antenna number. However, recent studies suggest that the DOF could be less than the antenna number when strong mutual coupling is considered. We utilize a mutual-coupling-compliant channel model to investigate the DOF of the holographic MIMO (HMIMO) channel and give a upper bound of the DOF with strong mutual coupling. Our numerical simulations demonstrate that a dense array can support more DOF per unit aperture as compared with a half-wavelength MIMO system.

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    Joint Beamforming Design for Dual-Functional Radar-Communication Systems Under Beampattern Gain Constraints
    CHEN Guangyi, ZHANG Ruoyu, REN Hong, LIN Xu, WU Wen
    ZTE Communications    2024, 22 (3): 13-20.   DOI: 10.12142/ZTECOM.202403003
    Abstract93)   HTML4)    PDF (1245KB)(104)       Save

    The joint beamforming design challenge for dual-functional radar-communication systems is addressed in this paper. The base station in these systems is tasked with simultaneously sending shared signals for both multi-user communication and target sensing. The primary objective is to maximize the sum rate of multi-user communication, while also ensuring sufficient beampattern gain at particular angles that are of interest for sensing, all within the constraints of the transmit power budget. To tackle this complex non-convex problem, an effective algorithm that iteratively optimizes the joint beamformers is developed. This algorithm leverages the techniques of fractional programming and semidefinite relaxation to achieve its goals. The numerical results confirm the effectiveness of the proposed algorithm.

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    Waveguide Bragg Grating for Fault Localization in PON
    HU Jin, LIU Xu, ZHU Songlin, ZHUANG Yudi, WU Yuejun, XIA Xiang, HE Zuyuan
    ZTE Communications    2024, 22 (2): 94-98.   DOI: 10.12142/ZTECOM.202402012
    Abstract93)   HTML7)    PDF (907KB)(72)       Save

    Femtosecond laser direct inscription is a technique especially useful for prototyping purposes due to its distinctive advantages such as high fabrication accuracy, true 3D processing flexibility, and no need for mold or photomask. In this paper, we demonstrate the design and fabrication of a planar lightwave circuit (PLC) power splitter encoded with waveguide Bragg gratings (WBG) using a femtosecond laser inscription technique for passive optical network (PON) fault localization application. Both the reflected wavelengths and intervals of WBGs can be conveniently tuned. In the experiment, we succeeded in directly inscribing WBGs in 1×4 PLC splitter chips with a wavelength interval of about 4 nm and an adjustable reflectivity of up to 70% in the C-band. The proposed method is suitable for the prototyping of a PLC splitter encoded with WBG for PON fault localization applications.

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    Monolithically Integrated Photonic Structures for Stable On-Chip Solar Blind Communications
    HE Rui, HU Qiang, RAN Junxue, WANG Junxi, WEI Tongbo
    ZTE Communications    2024, 22 (4): 3-8.   DOI: 10.12142/ZTECOM.202404002
    Abstract89)   HTML11)    PDF (1549KB)(102)       Save

    A solar-blind multi-quantum well (MQW) structure wafer based on AlGaN materials is epitaxial growth by metal-organic chemical vapor deposition (MOCVD). The monolithically integrated photonic chips including light-emitting diodes (LEDs), waveguides, and photodetectors (PDs) are presented. The results of the finite-difference time-domain (FDTD) simulation confirm the strong light constraint of the waveguide designed with the triangular structure in the optical coupling region. Furthermore, in virtue of predominant ultraviolet transverse magnetic (TM) modes, the solar blind optical signal is more conducive to lateral transmission along the waveguide inside the integrated chip. The integrated PDs demonstrate sufficient photosensitivity to the optical signal from the integrated LEDs. When the LEDs are operated at 100 mA current, the photo-to-dark current ratio (PDCR) of the integrated PD is about seven orders of magnitude. The responsivity, specific detectivity, and external quantum efficiency of the integrated self-driven PD are 74.89 A/W, 4.22×1013 Jones, and 3.38×104%, respectively. The stable on-chip optical information transmission capability of the monolithically integrated photonic chips confirms the great potential for application in large-scale on-chip optical communication in the future.

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    Kullback-Leibler Divergence Based ISAC Constellation and Beamforming Design in the Presence of Clutter
    TANG Shuntian, WANG Xinyi, XIA Fanghao, FEI Zesong
    ZTE Communications    2024, 22 (3): 4-12.   DOI: 10.12142/ZTECOM.202403002
    Abstract88)   HTML4)    PDF (1696KB)(109)       Save

    Integrated sensing and communication (ISAC) is regarded as a pivotal technology for 6G communication. In this paper, we employ Kullback-Leibler divergence (KLD) as the unified performance metric for ISAC systems and investigate constellation and beamforming design in the presence of clutters. In particular, the constellation design problem is solved via the successive convex approximation (SCA) technique, and the optimal beamforming in terms of sensing KLD is proven to be equivalent to maximizing the signal-to-interference-plus-noise ratio (SINR) of echo signals. Numerical results demonstrate the tradeoff between sensing and communication performance under different parameter setups. Additionally, the beampattern generated by the proposed algorithm achieves significant clutter suppression and higher SINR of echo signals compared with the conventional scheme.

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    Research on Multi-Core Processor Analysis for WCET Estimation
    LUO Haoran, HU Shuisong, WANG Wenyong, TANG Yuke, ZHOU Junwei
    ZTE Communications    2024, 22 (1): 87-94.   DOI: 10.12142/ZTECOM.202401010
    Abstract84)   HTML4)    PDF (432KB)(141)       Save

    Real-time system timing analysis is crucial for estimating the worst-case execution time (WCET) of a program. To achieve this, static or dynamic analysis methods are used, along with targeted modeling of the actual hardware system. This literature review focuses on calculating WCET for multi-core processors, providing a survey of traditional methods used for static and dynamic analysis and highlighting the major challenges that arise from different program execution scenarios on multi-core platforms. This paper outlines the strengths and weaknesses of current methodologies and offers insights into prospective areas of research on multi-core analysis. By presenting a comprehensive analysis of the current state of research on multi-core processor analysis for WCET estimation, this review aims to serve as a valuable resource for researchers and practitioners in the field.

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    Sensing and Communication Integrated Fast Neighbor Discovery for UAV Networks
    WEI Zhiqing, ZHANG Yongji, JI Danna, LI Chenfei
    ZTE Communications    2024, 22 (3): 69-82.   DOI: 10.12142/ZTECOM.202403009
    Abstract83)   HTML5)    PDF (1633KB)(80)       Save

    In unmanned aerial vehicle (UAV) networks, the high mobility of nodes leads to frequent changes in network topology, which brings challenges to the neighbor discovery (ND) for UAV networks. Integrated sensing and communication (ISAC), as an emerging technology in 6G mobile networks, has shown great potential in improving communication performance with the assistance of sensing information. ISAC obtains the prior information about node distribution, reducing the ND time. However, the prior information obtained through ISAC may be imperfect. Hence, an ND algorithm based on reinforcement learning is proposed. The learning automaton (LA) is applied to interact with the environment and continuously adjust the probability of selecting beams to accelerate the convergence speed of ND algorithms. Besides, an efficient ND algorithm in the neighbor maintenance phase is designed, which applies the Kalman filter to predict node movement. Simulation results show that the LA-based ND algorithm reduces the ND time by up to 32% compared with the Scan-Based Algorithm (SBA), which proves the efficiency of the proposed ND algorithms.

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    Cooperative Distributed Beamforming Design for Multi-RIS Aided Cell-Free Systems
    ZHU Yuting, XU Zhiyu, ZHANG Hongtao
    ZTE Communications    2024, 22 (2): 99-106.   DOI: 10.12142/ZTECOM.202402013
    Abstract80)   HTML255)    PDF (1611KB)(79)       Save

    Cell-free systems significantly improve network capacity by enabling joint user service without cell boundaries, eliminating inter-cell interference. However, to satisfy further capacity demands, it leads to high-cost problems of both hardware and power consumption. In this paper, we investigate multiple reconfigurable intelligent surfaces (RISs) aided cell-free systems where RISs are introduced to improve spectrum efficiency in an energy-efficient way. To overcome the centralized high complexity and avoid frequent information exchanges, a cooperative distributed beamforming design is proposed to maximize the weighted sum-rate performance. In particular, the alternating optimization method is utilized with the distributed closed-form solution of active beamforming being derived locally at access points, and phase shifts are obtained centrally based on the Riemannian conjugate gradient (RCG) manifold method. Simulation results verify the effectiveness of the proposed design whose performance is comparable to the centralized scheme and show great superiority of the RISs-aided system over the conventional cellular and cell-free system.

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    Trajectory Tracking for MmWave Communication Systems via Cooperative Passive Sensing
    YU Chao, LYU Bojie, QIU Haoyu, WANG Rui
    ZTE Communications    2024, 22 (3): 29-36.   DOI: 10.12142/ZTECOM.202403005
    Abstract80)   HTML2)    PDF (1614KB)(64)       Save

    A cooperative passive sensing framework for millimeter wave (mmWave) communication systems is proposed and demonstrated in a scenario with one mobile signal blocker. Specifically, in the uplink communication with at least two transmitters, a cooperative detection method is proposed for the receiver to track the blocker’s trajectory, localize the transmitters and detect the potential link blockage jointly. To facilitate detection, the receiver collects the signal of each transmitter along a line-of-sight (LoS) path and a non-line-of-sight (NLoS) path separately via two narrow-beam phased arrays. The NLoS path involves scattering at the mobile blocker, allowing its identification through the Doppler frequency. By comparing the received signals of both paths, the Doppler frequency and angle-of-arrival (AoA) of the NLoS path can be estimated. To resolve the blocker’s trajectory and the transmitters’ locations, the receiver should continuously track the mobile blocker to accumulate sufficient numbers of the Doppler frequency and AoA versus time observations. Finally, a gradient-descent-based algorithm is proposed for joint detection. With the reconstructed trajectory, the potential link blockage can be predicted. It is demonstrated that the system can achieve decimeter-level localization and trajectory estimation, and predict the blockage time with an error of less than 0.1 s.

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    Secure SSL/TLS Communication System Based on Quantum Keys
    WANG Jigang, LU Yuqian, WEI Liping, JIANG Xinzao, ZHANG Han
    ZTE Communications    2024, 22 (3): 106-115.   DOI: 10.12142/ZTECOM.202403013
    Abstract77)   HTML8)    PDF (838KB)(124)       Save

    Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols facilitates a secure framework for identity authentication, data encryption, and message integrity verification. However, with the recent development in quantum computing technology, the security of conventional key-based SSL/TLS protocols faces vulnerabilities. In this paper, we propose a scheme by integrating the quantum key into the SSL/TLS framework. Furthermore, the application of post-quantum algorithms is used to enhance and complement the existing encryption suites. Experimental results show that the proposed SSL/TLS communication system based on quantum keys exhibits high performance in latency and throughput. Moreover, the proposed system showcases good resilience against quantum attacks.

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    Intelligence Driven Wireless Networks in B5G and 6G Era: A Survey
    GAO Yin, CHEN Jiajun, LI Dapeng
    ZTE Communications    2024, 22 (3): 99-105.   DOI: 10.12142/ZTECOM.202403012
    Abstract74)   HTML6)    PDF (637KB)(92)       Save

    As the wireless communication network undergoes continuous expansion, the challenges associated with network management and optimization are becoming increasingly complex. To address these challenges, the emerging artificial intelligence (AI) and machine learning (ML) technologies have been introduced as a powerful solution. They empower wireless networks to operate autonomously, predictively, on-demand, and with smart functionality, offering a promising resolution to intricate optimization problems. This paper aims to delve into the prevalent applications of AI/ML technologies in the optimization of wireless networks. The paper not only provides insights into the current landscape but also outlines our vision for the future and considerations regarding the development of an intelligent 6G network.

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    Ultra-Low Linewidth Frequency Stabilized Integrated Lasers: A New Frontier in Integrated Photonics
    GU Zhenqian, YANG Zhen, ZHA Lulu, HU Junhui, CHI Nan, SHEN Chao
    ZTE Communications    2024, 22 (4): 29-39.   DOI: 10.12142/ZTECOM.202404005
    Abstract70)   HTML3)    PDF (2662KB)(143)       Save

    With the advancement of photonic integration technology, ultra-low linewidth frequency-stabilized lasers have demonstrated significant potential in precision measurement, quantum communication, atomic clocks, etc. This review summarizes the latest developments in integrated photonics for achieving ultra-low linewidth lasers, particularly breakthroughs made by integrating Brillouin lasers. We discuss the design principles, manufacturing processes, performance characteristics, and potential value of these lasers in various applications.

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    Special Topic on Advancements in Web3 Infrastructure for the Metaverse
    Victor C. M. LEUNG, CAI Wei
    ZTE Communications    2024, 22 (2): 1-2.   DOI: 10.12142/ZTECOM.202402001
    Abstract69)   HTML15)    PDF (411KB)(76)       Save
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    Adaptive Hybrid Forward Error Correction Coding Scheme for Video Transmission
    XIONG Yuhui, LIU Zhilong, XU Lingmin, HUA Xinhai, WANG Zhaoyang, BI Ting, JIANG Tao
    ZTE Communications    2024, 22 (2): 85-93.   DOI: 10.12142/ZTECOM.202402011
    Abstract68)   HTML7)    PDF (1158KB)(61)       Save

    This paper proposes an adaptive hybrid forward error correction (AH-FEC) coding scheme for coping with dynamic packet loss events in video and audio transmission. Specifically, the proposed scheme consists of a hybrid Reed-Solomon and low-density parity-check (RS-LDPC) coding system, combined with a Kalman filter-based adaptive algorithm. The hybrid RS-LDPC coding accommodates a wide range of code length requirements, employing RS coding for short codes and LDPC coding for medium-long codes. We delimit the short and medium-length codes by coding performance so that both codes remain in the optimal region. Additionally, a Kalman filter-based adaptive algorithm has been developed to handle dynamic alterations in a packet loss rate. The Kalman filter estimates packet loss rate utilizing observation data and system models, and then we establish the redundancy decision module through receiver feedback. As a result, the lost packets can be perfectly recovered by the receiver based on the redundant packets. Experimental results show that the proposed method enhances the decoding performance significantly under the same redundancy and channel packet loss.

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    Video Enhancement Network Based on CNN and Transformer
    YUAN Lang, HUI Chen, WU Yanfeng, LIAO Ronghua, JIANG Feng, GAO Ying
    ZTE Communications    2024, 22 (4): 78-88.   DOI: 10.12142/ZTECOM.202404011
    Abstract68)   HTML1)    PDF (1179KB)(50)       Save

    To enhance the video quality after encoding and decoding in video compression, a video quality enhancement framework is proposed based on local and non-local priors in this paper. Low-level features are first extracted through a single convolution layer and then processed by several conv-tran blocks (CTB) to extract high-level features, which are ultimately transformed into a residual image. The final reconstructed video frame is obtained by performing an element-wise addition of the residual image and the original lossy video frame. Experiments show that the proposed Conv-Tran Network (CTN) model effectively recovers the quality loss caused by Versatile Video Coding (VVC) and further improves VVC's performance.

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    Multi-View Structured Light 3D Measurement System
    LU Ping, ZHANG Yingjie, DENG Fangwei, LIU Wei, HUANG Shijun
    ZTE Communications    2024, 22 (4): 53-58.   DOI: 10.12142/ZTECOM.202404008
    Abstract62)   HTML6)    PDF (1049KB)(66)       Save

    Vision-based measurement technology benefits high-quality manufacturers through improved dimensional precision, enhanced geometric tolerance, and increased product yield. The monocular 3D structured light visual sensing method is popular for detecting online parts since it can reach micron-meter depth accuracy. However, the line-of-sight requirement of a single viewpoint vision system often fails when hiding occurs due to the object’s surface structure, such as edges, slopes, and holes. To address this issue, a multi-view 3D structured light vision system is proposed in this paper to achieve high accuracy, i.e., Z-direction repeatability, and reduce hiding probability during mechanical dimension measurement. The main contribution of this paper includes the use of industrial cameras with high resolution and high frame rates to achieve high-precision 3D reconstruction. Moreover, a multi-wavelength (heterodyne) phase expansion method is employed for high-precision phase calculation. By leveraging multiple industrial cameras, the system overcomes field of view occlusions, thereby broadening the 3D reconstruction field of view. Finally, the system achieves a Z-axis repetition accuracy of 0.48 μm.

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    A Privacy-Preserving Scheme for Multi-Party Vertical Federated Learning
    FAN Mochan, ZHANG Zhipeng, LI Difei, ZHANG Qiming, YAO Haidong
    ZTE Communications    2024, 22 (4): 89-96.   DOI: 10.12142/ZTECOM.202404012
    Abstract60)   HTML2)    PDF (1065KB)(66)       Save

    As an important branch of federated learning, vertical federated learning (VFL) enables multiple institutions to train on the same user samples, bringing considerable industry benefits. However, VFL needs to exchange user features among multiple institutions, which raises concerns about privacy leakage. Moreover, existing multi-party VFL privacy-preserving schemes suffer from issues such as poor reliability and high communication overhead. To address these issues, we propose a privacy protection scheme for four institutional VFLs, named FVFL. A hierarchical framework is first introduced to support federated training among four institutions. We also design a verifiable replicated secret sharing (RSS) protocol 3 2 -sharing and combine it with homomorphic encryption to ensure the reliability of FVFL while ensuring the privacy of features and intermediate results of the four institutions. Our theoretical analysis proves the reliability and security of the proposed FVFL. Extended experiments verify that the proposed scheme achieves excellent performance with a low communication overhead.

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