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Channel Characterization and Comparison in Industrial Scenario from Sub-6 GHz to Visible Light Bands for 6G

PHOTONICS 2025年第3期12卷 257-257页

作者： Yin, Yue Tang, Pan Zhang, Jianhua Hu, Zheng Jiang, Tao Xia, Liang Liu, Guangyi Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China Beijing Univ Posts & Telecommun State Key Lab Informat Photon & Opt Commun Beijing 100876 Peoples R China China Mobile Res Inst Beijing 100053 Peoples R China

The industrial scenario is indispensable for ubiquitous 6G coverage, which demands hyper-reliable and low-latency communication for full automation, control, and operation. To meet these demands, it is widely believed that it is necessary to introduce not only the conventional sub-6 GHz bands but also high-frequency technologies, such as millimeter wave (mmWave), terahertz (THz), and visible light bands. In this paper, we conduct a channel characterization and comparison in the industrial scenario from the sub-6 GHz to visible light bands. The channel characteristics, including the path loss (PL), root mean square (RMS) delay spread (DS), and angle spread (AS), were analyzed with respect to the frequency dependence and the distance dependence. On the one hand, the visible light band exhibited significant differences in channel characteristics compared to the electronic wave band. Due to the line-of-sight transmission of VLC, the visible light band had a higher path loss, and the path loss exponent reached 3.84. Due to the Lambertian radiation pattern, which has a wide range of reflection angles, the AS of the visible light band was much larger than that of the electronic wave band, which were 1.73 and 0.80 for the visible light and THz bands, respectively. On the other hand, the blockage effect of the metal instruments in the industrial scenario will greatly affect the channel characteristics. As the transceiver distance grows large, signals from both sides of the receiver will be blocked by metal instruments, resulting in a decreasing trend in the RMS DS for the electronic wave band. Moreover, the statistical characteristics of the channel properties were modeled and compared with the 3GPP TR 38.901 standard. It was found that the height of the receiver caused the difference between the proposed model and the 3GPP model and needs to be taken into account when modeling. Furthermore, we extended the 3GPP model to the THz and VLC bands and provided the statistical par

关键词： channel characteristics comparison industrial scenario VLC mmWave THz sub-6 GHz

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Seamless Cross-Edge Service Migration for Real-Time Rendering Applications

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2024年第6期23卷 7084-7098页

作者： Li, Yuanzhe Wang, Shangguang Li, Yuanchun Zhou, Ao Xu, Mengwei Ma, Xiao Liu, Yunxin Tsinghua Univ Inst AI Ind Res AIR Beijing 100190 Peoples R China Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China

Seamless cross-edge migration for real-time rendering applications is challenging. The strong interactive nature of real-time rendering applications demands a downtime lower than 15 ms to achieve an imperceptible migration. Existing methods based on virtual machine migration and container migration suffer from unpleasant downtime brought by dirty page retransmission-induced repeated memory data copy and the shared storage failure-induced extensive disk data copy. In this article, we propose Cloud-assisted Service Migration (CSM) which leverages cloud-edge collaboration to achieve seamless service migration for real-time rendering applications. CSM improves service migration user experience in three folds: First, it introduces a dual rendering mechanism to bypass the peer-to-peer data copy and compresses the freezing stage. Second, a user equipment-centric session switch mechanism is proposed to save time by well coordinating application session switches and 5G user plane session switches. Third, a smooth switching mechanism is leveraged to prevent unpleasant frame flickers during session switching. We implement CSM in edge-rendering multiplayer games and deploy it on a 5G test bed with a full-stack user plane protocol stack. The evaluation results show that CSM can reduce downtime to < 14 ms and the service migration process is user imperceptible.

关键词： 5G core network downtime mobile edge computing service migration

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Near-term quantum algorithm for solving the MaxCut problem with fewer resources

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PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS 2024年 648卷

作者： Zhao, Xiumei Li, Yongmei Li, Jing Wang, Shasha Wang, Song Qin, Sujuan Gao, Fei Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China Comprehens Res Ctr Elect Informat Technol MIIT Weihai 264200 Peoples R China

MaxCut is an NP-hard combinatorial optimization problem in graph theory. The quantum approximate optimization algorithms (QAOAs) offer new methods for solving such problems, which are potentially better than classical schemes. However, the requirement of N qubits for solving graphs with N-vertex in QAOA, coupled with the large-N N trainability issue due to barren plateaus, poses a substantial challenge for noisy intermediate-scale quantum (NISQ) devices. Recently, a hybrid quantum-classical algorithm has been proposed for solving semidefinite programs (SDPs), named NISQ SDP Solver (NSS). In this paper, we study the performance of the NSS for solving MaxCut problem via the introduction of a near-term quantum algorithm and execution of experimental simulations. Since the MaxCut problem admits a relaxation into an SDP formulation, the SDP can be solved using NSS, with a subsequent classical post-processing step converting the hybrid density matrix into a MaxCut solution. After performing these steps, the near-term quantum algorithm will also inherit the advantages of NSS. We analyze the algorithm as compared to QAOAs and find that the depth of the quantum circuit is independent of the number of edges on the graph. Our algorithm requires logN N qubits and has O (1) circuit depth. This implies that it uses exponentially fewer qubits compared to QAOAs while also requiring a significantly reduced circuit depth to solve the MaxCut problem. To demonstrate the effectiveness of the NSS, we focused on 3-regular graphs, 9-regular graphs, and ER graphs. Numerical results indicate that the quantum algorithm achieves a comparable approximation ratio with classical methods by solving the original high dimensional problem within a lower dimensional ansatz space. Analysis under various initial states shows that the algorithm exhibits a remarkably stable performance.

关键词： Quantum computing Near-term quantum algorithms Semidefinite programs MaxCut problem

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Dual-band dynamic reconfigurable intelligent surface for signal enhancement in millimeter wave

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Science China(Technological Sciences) 2024年第4期67卷 1133-1138页

作者： YAO HuiMing DU XinRun WANG HengBin GAO Song PANG YaChen ZHENG HaiRong GONG HuiWen LI Yi XU JianChun ZHANG JianHua BI Ke State Key Laboratory of Information Photonics and Optical Communications School of ScienceBeijing University of Posts and TelecommunicationsBeijing 100876China Beijing Key Laboratory of Intelligent Telecommunications Software and Multimedia Beijing University of Posts and TelecommunicationsBeijing 100876China State Key Laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China

Millimeter wave with large bandwidth,high transmission rate,and low delay is considered a reliable alternative to cope with the spectrum ***,the fast attenuation and narrow beam characteristics make it difficult to achieve long-distance or wide-range ***,a 1-bit dual-band reflective reconfigurable intelligent surface(RIS)for signal enhancement in millimeter wave with 16×16 elements is designed,fabricated,and *** from most existent RIS,dynamic programming is realized at two separate frequency bands by integrating the PIN diodes and field-programmable gate array(FPGA).Particularly,the beam deflection,dual-beam,and multi-beam are created based on the coding theory and convolution operation,proving the effectiveness of wavefront ***,the far-field patterns and signal power with different coding sequences are measured and *** is indicated that the received signal power is 6–7 dB stronger than that without coding,which shows good agreement with the desired *** proposed reconfigurable metasurface exhibits great potential in beam forming,making it a promising candidate for progressive wireless communication applications.

关键词： dual-band millimeter wave reconfigurable intelligent surface signal enhancement

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BAFL: A Blockchain-Based Asynchronous Federated Learning Framework

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IEEE TRANSACTIONS ON COMPUTERS 2022年第5期71卷 1092-1103页

作者： Feng, Lei Zhao, Yiqi Guo, Shaoyong Qiu, Xuesong Li, Wenjing Yu, Peng Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China

As an emerging distributed machine learning (ML) method, federated learning (FL) can protect data privacy through collaborative learning of artificial intelligence (AI) models across a large number of devices. However, inefficiency and vulnerability to poisoning attacks have slowed FL performance. Therefore, a blockchain-based asynchronous federated learning (BAFL) framework is proposed to ensure the security and efficiency required by FL. The blockchain ensures that the model data cannot be tampered with while asynchronous learning speeds up global aggregation. A novel entropy weight method is used to evaluate the participating rank and proportion of the local model trained in BAFL of the devices. The energy consumption and local model update efficiency are balanced by adjusting the local training and communication delay and optimizing the block generation rate. The extensive evaluation results show that the proposed BAFL framework has higher efficiency and higher performance for preventing poisoning attacks than other distributed ML methods.

关键词： Blockchain Training Data models Servers Collaborative work Computational modeling Load modeling Blockchain federated learning security asynchronous learning learning efficiency

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Cross-Domain Integration for General Sensor Data Synthesis: Leveraging LLMs and Domain-Specific Generative Models in Collaborative Environments

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IEEE SENSORS JOURNAL 2024年第24期24卷 42311-42326页

作者： Zhou, Xiaomao Hu, Yujiao Jia, Qingmin Xie, Renchao Future Network Res Ctr Purple Mt Labs Nanjing 211111 Peoples R China Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China

Synthetic data has emerged as a critical component in the fields of machine learning and data science, providing a solution to overcome limitations associated with real-world data, including scarcity, privacy concerns, and the high cost of acquisition. While the existing generative models demonstrate promising results in synthesizing various sensor data, they are struggling to enhance performance and generalization. In this article, we introduce a large language models (LLMs)-driven framework that leverages the power of LLMs in concert with various domain-specific generative models (DGMs) for general sensor data synthesis. Specifically, our method employs LLMs as the core to interpret task requests, decompose a complex task into a manageable set of subtasks, and delegate each subtask to the most suitable DGM, thereby automatically constructing customized data generation pipelines. Meanwhile, DGMs contribute their expertise to generate high-fidelity, domain-relevant data, whose specialized knowledge can be further enhanced by the LLM's broad linguistic knowledge via knowledge transfer. In addition, the integration of diffusion model (DM)-based reinforcement learning (RL) is promising to enhance the framework's ability to optimally utilize DGMs, resulting in data generation with superior quality and control flexibility. Experimental results demonstrate the effectiveness of LLMs in augmenting DGMs via knowledge transfer and in facilitating multimodal data synthesis through collaborative interactions with diverse DGMs, which is further improved by the DM-based refinement process.

关键词： Diffusion model (DM) generative models knowledge transfer large language models (LLMs) reinforcement learning (RL) sensor data synthesis Diffusion model (DM) generative models knowledge transfer large language models (LLMs) reinforcement learning (RL) sensor data synthesis

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An optimal bound for factoring unbalanced RSA moduli by solving Generalized Implicit Factorization Problem

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JOURNAL OF SUPERCOMPUTING 2025年第1期81卷 1-24页

作者： Zhang, Ran Bi, Jingguo Li, Lixiang Peng, Haipeng Beijing Univ Posts & Telecommun Sch Cyberspace Secur Beijing 100876 Peoples R China Beijing Univ Posts & Telecommun Informat Secur Ctr State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China State Key Lab Cryptol POB 5159 Beijing 100878 Peoples R China

The integer factorization problem, concerning the product of two primes N = pq, has been a focal point for researchers since its rise to prominence with the RSA algorithm, a renowned public key scheme. It is well known that the integer factorization problem can be solved by the Number Field Sieve (NFS) algorithm in sub-exponential time, this challenge may also find resolution in polynomial time under certain conditions for the primes. In this paper, we revisit the problem of factoring RSA moduli with the implicit hint, where the implicit hint is the shared bits of primes. As for k RSA moduli, we present a novel implicit factorization approach applicable when the unknown multiples ap of the prime factors p share a certain number of most significant bits (MSBs) or least significant bits (LSBs). By drawing inspiration from addressing the Approximate Common Divisor Problem (ACDP), we transform this problem into solving the small roots of k-1 trivariate polynomials. To compute these small roots, we employ Coppersmith's method to construct a lattice basis for the modular polynomials. We modify the lattice basis by introducing new variables, achieving an optimal bound in the MSB and LSB cases. Our attack breaks the RSA system and improves upon all previous attacks on such variants when the amount of the shared bits is sufficiently large. Concluding our paper, we meticulously validate the theoretical analysis results, with experimental data confirming the full practical feasibility of our attack on such an RSA variant system.

关键词： RSA system Generalized Implicit Factorization Problem Coppersmith's method LLL algorithm

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Multipath Smart Preloading Algorithms in Short Video Peer-to-Peer CDN Transmission Architecture

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IEEE NETWORK 2024年第3期38卷 285-291页

作者： Wei, Dehui Zhang, Jiao Li, Haozhe Xue, Zhichen Peng, Yajie Han, Rui BUPT State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China Purple Mt Labs Nanjing 211111 Peoples R China ByteDance Ltd Beijing 100085 Peoples R China

The rapid growth of short video users has brought high traffic costs to content providers. Saving Content Distribution Network (CDN) costs while maintaining users' playback Quality of Experience (QoE) is a significant problem for major short video platforms like Douyin (the Chinese counterpart of TikTok). Two commonly utilized cost-saving methods: PCDN (peer-to-peer CDN, fetching data from multiple low-cost but low-bandwidth edge devices with a multipath transmission protocol) and preloading control (minimizing unnecessary future playing data by downloading videos in segmented data ranges), each may hurt users' experience respectively. Worse still, both methods combined have a synergistic negative effect over QoE. In this paper, we focus on experiences, algorithms, and prospects to solve this cost-QoE dilemma. We first introduce Douyin's current PCDN multipath architecture and then review learning-based preloading techniques. Second, based on Reinforcement Learning (RL), we propose a Multipath-aware Smart Preloading algorithm, which consists of three schemes: one to decide the best size of the next range of preloaded data, another to design a water level valve algorithm that prioritizes preloading between currently playing video's unfinished data and the next video's beginning data, and the last one to determine the bitrate level of the next video. Douyin's anonymous user feedback shows our Smart Preloading algorithm reduces traffic waste by $\sim 26$ % while ensuring QoE. Third, we analyze and outlook the future of video systems, including trends in PCDN and other open issues.

关键词： Streaming media Costs Quality of experience Computer architecture Bit rate Servers Reinforcement learning Videos Smart devices Peer-to-peer computing Telecommunication traffic Multipath channels Content distribution networks Preloading Reinforcement Learning PCDN Multipath transmission Short video

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Diffuse Scattering Analysis of Indoor Propagation Channel at Terahertz Frequency 25

Diffuse Scattering Analysis of Indoor Propagation Channel at...

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IEEE Wireless Communications and networking Conference (IEEE WCNC)

作者： Guo, Gan Yang, Xiaoli Zhou, Yi Ma, Nan BUPT State Key Lab Networking & Switching Technol Beijing Peoples R China China Telecommun Technol Lab CAICT Beijing Peoples R China

ISBN: (纸本)9798350303582;9798350303599

To derive reliable channel models for future terahertz (THz) indoor communication systems, accurate propagation mechanisms of electromagnetic waves are essential. In this paper, we focus on the diffuse scattering in the THz bands, which has often been overlooked in previous work. We present a parameterized model for the diffuse scattering of different materials at 180GHz by measuring the diffuse scattering power spectrum in indoor propagation environment. New contributions representing diffuse scattering are added to the traditional specular rays in ray tracing simulation. The impact of this enrichment on the simulated indoor propagation channel is analyzed by comparing simulations taking into account or not the diffuse scattering. The simulation results demonstrate that the small-scale parameters of the channel are significantly modified when taking into account the diffuse scattering phenomenon. This means that considering the diffuse scattering component is particularly important for establishing a more realistic THz channel model.

关键词： THz Diffuse scattering Channel characteristics Channel model

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Unsupervised Network Traffic Classification Based on Multi-source Synergistic Distribution Alignment

Unsupervised Network Traffic Classification Based on Multi-s...

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IEEE Conference on Global Communications (IEEE GLOBECOM) - Intelligent Communications for Shared Prosperity

作者： Gao, Bowen Yang, Yang Gao, Zhipeng Yu, Peng Lyu, Rui Chen, Shaoyin Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing Peoples R China

ISBN: (纸本)9798350310900

Network traffic classification is a key technology in network communication management, which is of great significance for building intelligent communication and so on. Due to the difficult and time-consuming process of network traffic labeling, it is difficult to obtain any labeled traffic data in some special networks. At the same time, in a real network environment, there are multiple network traffic domains, and the data distribution of each network traffic domain is different, making it extremely difficult to train a network traffic classification model that performs well on multiple traffic domains simultaneously. Therefore, this paper proposes a network traffic classification method in unsupervised scenarios, aiming to study how to learn traffic knowledge from multiple source traffic domains and achieve accurate classification of unlabeled network traffic without labeled traffic data in the target traffic domain. This paper divides three traffic domains from the data set, namely VPN, nonVPN and nonTor. And three traffic classification tasks of unsupervised multi-source domain are constructed. The accuracy of traffic classification tasks in the source traffic domain is nonTor and nonVPN, and the target traffic domain is VPN reaches 89.76%. The source traffic domain is VPN and nonTor,the accuracy of the classification task is 91.73% when the target traffic domain is nonVPN, and 90.35% when the source traffic domain is VPN and nonVPN, and the target traffic domain is nonTor. Experimental results show the effectiveness of the network traffic classification algorithm proposed in this paper.

关键词： unsupervised network traffic classification dynamic multi-scale fusion convolution synergistic distribution alignment multi-source decision related certainty weighting

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