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25 June 2024, Volume 22 Issue 2

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The whole issue of ZTE Communications June 2024, Vol. 22 No. 2

2024, 22(2):  0. 

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Special Topic

Special Topic onAdvancements in Web3 Infrastructure for the Metaverse

Victor C. M. LEUNG, CAI Wei

2024, 22(2):  1-2.  doi:10.12142/ZTECOM.202402001

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Building a Stronger Foundation for Web3: Advantages of 5G Infrastructure

FENG Jianxin, PAN Yi, WU Xiao

2024, 22(2):  3-10.  doi:10.12142/ZTECOM.202402002

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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.

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

2024, 22(2):  11-18.  doi:10.12142/ZTECOM.202402003

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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.

Optimization of High-Concurrency Conflict Issues in Execute-Order-Validate Blockchain

MA Qianli, ZHANG Shengli, WANG Taotao, YANG Qing, WANG Jigang

2024, 22(2):  19-29.  doi:10.12142/ZTECOM.202402004

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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.

Utilizing Certificateless Cryptography for IoT Device Identity Authentication Protocols in Web3

WU Zhihui, HONG Yuxuan, ZHOU Enyuan, LIU Lei, PEI Qingqi

2024, 22(2):  30-38.  doi:10.12142/ZTECOM.202402005

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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.

Hierarchical Federated Learning Architectures for the Metaverse

GU Cheng, LI Baochun

2024, 22(2):  39-48.  doi:10.12142/ZTECOM.202402006

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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.

Review

Learned Distributed Query Optimizer: Architecture and Challenges

GAO Jun, HAN Yinjun, LIN Yang, MIAO Hao, XU Mo

2024, 22(2):  49-54.  doi:10.12142/ZTECOM.202402007

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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.

Review on Service Curves of Typical Scheduling Algorithms

GAO Yuehong, NING Zhi, HE Jia, ZHOU Jinfei, GAO Chenqiang, TANG Qingkun, YU Jinghai

2024, 22(2):  55-70.  doi:10.12142/ZTECOM.202402008

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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.

Deadlock Detection: Background, Techniques, and Future Improvements

LU Jiachen, NIU Zhi, CHEN Li, DONG Luming, SHEN Taoli

2024, 22(2):  71-79.  doi:10.12142/ZTECOM.202402009

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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.

Research Papers

A Distributed Acoustic Sensing System for Vibration Detection and Classification in Railways

ZHU Songlin, WANG Zhongyi, XIE Yunpeng, SUN Zhi

2024, 22(2):  80-84.  doi:10.12142/ZTECOM.202402010

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A distributed acoustic sensing (DAS) system is proposed and a data processing method for vibration is designed in this paper. The proposed DAS system is based on the Rayleigh scattering signal and utilizes phase-sensitive optical time-domain reflectometry (?-OTDR) to demodulate the environmental vibration. It can collect the vibration information in railways and implement vibration classification based on the feature of sensed vibration signals. This system has been deployed in Guangzhou Shenzhen High-Speed Railway, and the experimental results validate its effectiveness.

Adaptive Hybrid Forward Error Correction Coding Scheme for Video Transmission

XIONG Yuhui, LIU Zhilong, XU Lingmin, HUA Xinhai, WANG Zhaoyang, BI Ting, JIANG Tao

2024, 22(2):  85-93.  doi:10.12142/ZTECOM.202402011

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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.

Waveguide Bragg Grating for Fault Localization in PON

HU Jin, LIU Xu, ZHU Songlin, ZHUANG Yudi, WU Yuejun, XIA Xiang, HE Zuyuan

2024, 22(2):  94-98.  doi:10.12142/ZTECOM.202402012

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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.

Cooperative Distributed Beamforming Design for Multi-RIS Aided Cell-Free Systems

ZHU Yuting, XU Zhiyu, ZHANG Hongtao

2024, 22(2):  99-106.  doi:10.12142/ZTECOM.202402013

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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.