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Dynamic event-triggered leader-follower consensus of nonlinear multi-agent systems under directed weighted topology
Wu Yue, Chen Xiangyong, Qiu Jianlong, Hu Shunwei, Zhao Feng
The Journal of China Universities of Posts and Telecommunications    2023, 30 (6): 3-10.   DOI: 10.19682/j.cnki.1005-8885.2023.1019
Abstract902)      PDF(pc) (1536KB)(318)       Save
This paper studies the dynamic event-triggered leader-follower consensus of nonlinear multi-agent systems (MASs) under directed weighted graph containing a directed spanning tree, and also considers the effects of disturbances and leader of non-zero control inputs in the system. Firstly, a novel distributed control protocol is designed for uncertain disturbances and leader of non-zero control inputs in MASs. Secondly, a novel dynamic event-triggered control ( DETC) strategy is proposed, which eliminates the need for continuous communication between agents and reduces communication resources between agents. By introducing dynamic thresholds, the complexity of excluding Zeno behavior within the system is reduced. Finally, the effectiveness of the proposed theory is validated through numerical simulation.
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Joint global constraint and Fisher discrimination based multi-layer dictionary learning for image classification
Hong PENG yaozong liu
The Journal of China Universities of Posts and Telecommunications    2023, 30 (5): 1-10.   DOI: 10.19682/j.cnki.1005-8885.2023.0010
Abstract634)      PDF(pc) (890KB)(255)       Save

    A multi-layer dictionary learning algorithm that joints global constraints and Fisher discrimination (JGCFD-MDL) for image classification tasks was proposed. The algorithm reveals the manifold structure of the data by learning the global constraint dictionary and introduces the Fisher discriminative constraint dictionary to minimize the intra-class dispersion of samples and increase the inter-class dispersion. To further quantify the abstract features that characterize the data, a multi-layer dictionary learning framework is constructed to obtain high-level complex semantic structures and improve image classification performance. Finally, the algorithm is verified on the multi-label dataset of court costumes in the Ming Dynasty and Qing Dynasty, and better performance is obtained. Experiments show that compared with the local similarity algorithm, the average precision is improved by 3.34% . Compared with the single-layer dictionary learning algorithm, the one-error is improved by 1.00% , and the average precision is improved by 0.54% . Experiments also show that it has better performance on general datasets.

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Node interdependent percolation of multiplex hypergraph with weak interdependence
Zhang Junjie, Liu Caixia, Liu Shuxin, Zang Weifei, Li Qian
The Journal of China Universities of Posts and Telecommunications    2023, 30 (6): 49-59.   DOI: 10.19682/j.cnki.1005-8885.2023.1016
Abstract842)      PDF(pc) (3049KB)(172)       Save
In recent years, there has been considerable attention and research on the higher-order interactions that are prevalent in various real-world networks. Hypergraphs, especially in the study of complex systems, are proved effective in capturing these interactions. To better characterize the model in reality, this paper proposes a theoretical model of node interdependent percolation in multiplex hypergraphs, considering “ weak ” interdependence. The proposed model includes pairwise and higher-order interactions, where the removal of nodes triggers cascading failures. However, interdependent nodes connected to failed nodes experience partial loss of connections due to “ weak” interdependence, reflecting the self-sustaining capabilities of real-world systems. Percolation theory is applied to the analysis to investigate the properties of the percolation threshold and phase transition. Both analysis and simulation results show that as the strength of interdependence between nodes weakens, the network transitions from a discontinuous to a continuous phase, thereby increasing its robustness.
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Distributed consensus of Lurie multi-agent systems under directed topology: a contraction approach
Zhang Xiaojiao, Wu Xiang
The Journal of China Universities of Posts and Telecommunications    2023, 30 (6): 11-21.   DOI: 10.19682/j.cnki.1005-8885.2023.1018
Abstract778)      PDF(pc) (3622KB)(170)       Save
This paper is devoted to investigate the consensus problems for the multi-agent systems with Lurie nonlinear dynamics in directed topology. Under some assumptions, some sufficient conditions for the systems reaching leaderless consensus and tracking consensus are established by using contraction analysis theory. Compared with the existing results, there is no need to formulate the multi-agent networks in compact form. These conditions are only related to the individual agent in lower-dimensional case and the communication topology of the network. Additionally, a generalized nonlinear function is introduced. Finally, three numerical examples are demonstrated to illustrate the effectiveness of the theoretical results.
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SNR-adaptive deep joint source-channel coding scheme for imagesemantic transmission with convolutional block attention module
Yang Yujia, Liu Yiming, Zhang Wenjia, Zhang Zhi
The Journal of China Universities of Posts and Telecommunications    2024, 31 (1): 1-11.   DOI: 10.19682/j.cnki.1005-8885.2024.2001
Abstract835)      PDF(pc) (2443KB)(167)       Save
With the development of deep learning (DL), joint source-channel coding (JSCC) solutions for end-to-end transmission have gained a lot of attention. Adaptive deep JSCC schemes support dynamically adjusting the rate according to different channel conditions during transmission, enhancing robustness in dynamic wireless environment. However, most of the existing adaptive JSCC schemes only consider different channel conditions, ignoring the different feature importance in the image processing and transmission. The uniform compression of different features in the image may result in the compromise of critical image details, particularly in low signal-to-noise ratio (SNR) scenarios. To address the above issues, in this paper, a dual attention mechanism is introduced and an SNR-adaptive deep JSCC mechanism with a convolutional block attention module (CBAM) is proposed, in which matrix operations are applied to features in spatial and channel dimensions respectively. The proposedsolution concatenates the pooling feature with the SNR level and passes it sequentially through the channel attention network and spatial attention network to obtain the importance evaluation result. Experiments show that the proposed solution outperforms other baseline schemes in terms of peak SNR (PSNR) and structural similarity (SSIM), particularly in low SNR scenarios or when dealing with complex image content.
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Linear-quadratic optimal control for time-varying descriptor systems via space decompositions
Lv Pengchao, Huang Junjie, Liu Bo
The Journal of China Universities of Posts and Telecommunications    2023, 30 (6): 38-48.   DOI: 10.19682/j.cnki.1005-8885.2023.1011
Abstract858)      PDF(pc) (1663KB)(152)       Save
This paper aims at solving the linear-quadratic optimal control problems ( LQOCP) for time-varying descriptor systems in a real Hilbert space. By using the Moore-Penrose inverse theory and space decomposition technique, the descriptor system can be rewritten as a new differential-algebraic equation (DAE), and then some novel sufficient conditions for the solvability of LQOCP are obtained. Especially, the methods proposed in this work are simpler and easier to verify and compute, and can solve LQOCP without the range inclusion condition. In addition, some  numerical examples are shown to verify the results obtained.
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Review of reader antennas for UHF RFID systems
Niu Yaohui, Li Xiuping, Zhao Wenyu
The Journal of China Universities of Posts and Telecommunications    2023, 30 (5): 72-92.   DOI: 10.19682/j.cnki.1005-8885.2023.0008
Abstract215)      PDF(pc) (5205KB)(150)       Save
   Radio-frequency identification (RFID) antennas are critical components in wireless communication networks for the Internet of things (IoT). The RFID systems make it possible to realize the dynamic interconnection of various things. To better summarize the operating principles of the RFID antennas and associate antennas with specific complex applications, a review of RFID systems and antennas is necessary. In this paper, a review of reader antennas for ultra-high frequency ( UHF) RFID systems is presented, and the categories of RFID systems are summarized for the first time. The antennas are classified according to the reading region and operating principle. The reading region determines the most crucial performance that should be concentrated on when designing an antenna, while the operating principle affects the current distribution on the surface of the antenna, and further the electromagnetic radiation. By the summary of the RFID systems and antennas, the understanding of future researchers on the operating principles of the RFID antennas could be facilitated, which can be helpful in the advanced design and implementation of RFID antennas. In addition, taking engineering requirements into account, the future prospective of RFID applications is discussed, as well as the challenges to be addressed.
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Performance analysis of different coding schemes for wideband vehicle-to-vehicle MIMO systems
Liang Xiaolin, Rong Zhanyi, Cao Wangbin, Liu Shuaiqi, Zhao Xiongwen
The Journal of China Universities of Posts and Telecommunications    2023, 30 (6): 89-98.   DOI: 10.19682/j.cnki.1005-8885.2023.1017
Abstract779)      PDF(pc) (2637KB)(143)       Save
The signal is subjected to lots of interferences in vehicle-to-vehicle (V2V) channel propagation, resulting in receiving error codes. Two-dimensional (2D) and three-dimensional (3D) geometrical channel models are used to depict the wideband V2V multiple-input multiple-output (MIMO) channels. Using the channel model, Turbo code and low-density parity-check (LDPC) code are investigated for wideband V2V MIMO system, and the encoding and the decoding schemes are investigated. The bit error rate (BER), channel capacity and outage probability of wideband V2V MIMO system using Turbo code and LDPC code are analyzed at different typical speeds. The results show that the performance of wideband V2V MIMO system using Turbo code outperform that using LDPC code. The performance is affected by transmitting and receiving speeds with the same coding scheme. And the channel capacity of the 3D channel is larger than that of 2D channel.
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Black-box membership inference attacks based on shadow model
Han Zhen, Zhou Wen'an, Han Xiaoxuan, Wu Jie
The Journal of China Universities of Posts and Telecommunications    2024, 31 (4): 1-16.   DOI: 10.19682/j.cnki.1005-8885.2024.1016
Abstract290)      PDF(pc) (3603KB)(140)       Save
Membership inference attacks on machine learning models have drawn significant attention. While current  research primarily utilizes shadow modeling techniques, which require knowledge of the target model and training  data, practical scenarios involve black-box access to the target model with no available information. Limited  training data further complicate the implementation of these attacks. In this paper, we experimentally compare  common data enhancement schemes and propose a data synthesis framework based on the variational autoencoder  generative adversarial network (VAE-GAN) to extend the training data for shadow models. Meanwhile, this paper  proposes a shadow model training algorithm based on adversarial training to improve the shadow model's ability to  mimic the predicted behavior of the target model when the target model's information is unknown. By conducting  attack experiments on different models under the black-box access setting, this paper verifies the effectiveness of the  VAE-GAN-based data synthesis framework for improving the accuracy of membership inference attack.  Furthermore, we verify that the shadow model, trained by using the adversarial training approach, effectively  improves the degree of mimicking the predicted behavior of the target model. Compared with existing research  methods, the method proposed in this paper achieves a 2% improvement in attack accuracy and delivers better  attack performance.
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Superjunction 4H-SiC trench-gate IGBT with an integrated clamping PN diode
The Journal of China Universities of Posts and Telecommunications    2024, 31 (2): 3-9.   DOI: 10.19682/j.cnki.1005-8885.2024.0001
Abstract281)      PDF(pc) (4079KB)(137)       Save

In this paper, a novel superjunction 4H-silicon carbide (4H-SiC) trench-gate insulated-gate bipolar transistor (IGBT) featuring an integrated clamping PN diode between the P-shield and emitter (TSD-IGBT) is designed and theoretically studied. The heavily doping superjunction layer contributes to a low specific on-resistance, excellent electric field distribution, and quasi-unipolar drift current. The anode of the clamping diode is in floating contact with the P-shield. In the on-state, the potential of the P-shield is raised to the turn-on voltage of the clamping diode, which prevents the hole extraction below the N-type carrier storage layer (NCSL). Additionally, during the turn-off transient, once the clamping diode is turned on, it also promotes an additional hole extraction path. Furthermore, the potential dropped at the semiconductor near the trench-gate oxide is effectively reduced in the off-state.

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Pointer-prototype fusion network for few-shot named entity recognition
Zhao Haiying, GUO Xuan
The Journal of China Universities of Posts and Telecommunications    2023, 30 (5): 32-41.   DOI: 10.19682/j.cnki.1005-8885.2023.0011
Abstract186)      PDF(pc) (1526KB)(135)       Save

   Few-shot named entity recognition (NER) aims to identify named entities in new domains using a limited amount of annotated data. Previous methods divided this task into entity span detection and entity classification, achieving good results. However these methods are limited by the imbalance between the entity and non-entity categories due to the use of sequence labeling for entity span detection. To this end, a point-proto network ( PPN) combining pointer and prototypical networks was proposed. Specifically, the pointer network generates the position of entities in sentences in the entity span detection stage. The prototypical network builds semantic prototypes of entity types and classifies entities based on their distance from these prototypes in the entity classification stage. Moreover, the low-rank adaptation ( LoRA) fine-tuning method, which involves freezing the pre-trained weights and injecting a trainable decomposition matrix, reduces the parameters that need to be trained and saved. Extensive experiments on the few-shot NER Dataset (Few-NERD) and Cross-Dataset demonstrate the superiority of PPN in this domain.

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3D reconstruction algorithm for movable cultural relics based on salient region optimization
Wang Wenhao , Zhao Haiying
The Journal of China Universities of Posts and Telecommunications    2023, 30 (5): 11-31.   DOI: 10.19682/j.cnki.1005-8885.2023.0012
Abstract335)      PDF(pc) (9159KB)(132)       Save

   How to protect cultural retics is of great significance to the transmission and dissemination of history and culture. Digital 3-dimensional (3D) modeling of cultural relics is an effective way to preserve them. The efficiency and complexity of cultural relic model reconstruction algorithms are significant challenges due to redundant data. To tackle the above issue, a 3D reconstruction algorithm, named COLMAP + LSH, was proposed for movable cultural relics based on salient region optimization. COLMAP + LSH algorithm introduces saliency region detection and locality-sensetive Hashing (LSH) to achieve efficient, accurate, and robust digital 3D modeling of cultural relics. Specifically, 400 cultural model data were collected through offline and online collection. COLMAP + LSH algorithm detects the salient region interactively and reduces the number of images in the salient region by feature diffusion. Additionally, COLMAP + LSH algorithm utilizes LSH to calculate the image selection scores and employs the image selection scores to reduce the redundant image. The experiments on the self-constructed cultural relics dataset show that COLMAP + LSH algorithm can efficiently achieve image feature diffusion and ensure the quality of artifact reconstruction while selecting most of the redundant image data.

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Fairness optimization and power allocation in cognitive NOMA / OMA V2V network with imperfect SIC
Liang Xiaolin, Liu Qianlong, Cao Wangbin, Liu Shuaiqi, Zhao Shuhuan, Zhao Xiongwen
The Journal of China Universities of Posts and Telecommunications    2023, 30 (6): 68-81.   DOI: 10.19682/j.cnki.1005-8885.2023.1020
Abstract772)      PDF(pc) (4592KB)(123)       Save
In order to improve the reliability and resource utilization efficiency of vehicle-to-vehicle (V2V) communication system, in this paper, the fairness optimization and power allocation for the cognitive V2V network that takes into account the realistic three-dimensional (3D) channel are investigated. Large-scale and small-scale fading are considered in the proposed channel model. An adaptive non-orthogonal multiple access ( NOMA) / orthogonal multiple access (OMA) scheme is proposed to reduce the complexity of successive-interference-cancellation (SIC) in decoding and improve spectrum utilization. Also, a fairness index that takes into account each user’s requirements is proposed to indicate the optimal point clearly. In the imperfect SIC, the optimization problem of maximizing user fairness is formulated. Then, a subgradient descent method is proposed to solve the optimization problem with customizable precision. And the computational complexity of the proposed method is analyzed. The achievable rate, outage probability and user fairness are analyzed. The results show that the proposed adaptive NOMA / OMA (A-NOMA / OMA) outperforms both NOMA and OMA. The simulation results are compared with validated analysis to confirm the theoretical analysis.
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Performance study of vertical MSM solar-blind photodetectors based on β-Ga 2O 3 thin film
The Journal of China Universities of Posts and Telecommunications    2024, 31 (2): 17-27.   DOI: 10.19682/j.cnki.1005-8885.2024.0006
Abstract280)      PDF(pc) (4363KB)(123)       Save

In this work, β-Ga2O3 thin films were grown on SiO2 substrate by atomic layer deposition (ALD) and annealed in N2 atmosphere to enhance the crystallization quality of the thin films, which were verified from X-rays diffraction (XRD). Based on the grown β-Ga2O3 thin films, vertical metal-semiconductor-metal (MSM) interdigital photodetectors (PDs) were fabricated and investigated. The PDs have an ultralow dark current of 1.92 pA, ultra-high photo-to-dark current ratio (PDCR) of 1.7×106, and ultra-high detectivity of 4.25×1014 Jones at a bias voltage of 10 V under 254 nm deep ultraviolet (DUV). Compared with the horizontal MSM PDs under the same process, the PDCR and detectivity of the fabricated vertical PDs are increased by 1 000 times and 100 times, respectively. In addition, the vertical PDs possess a high responsivity of 34.24 A/W and an external quantμm efficiency of 1.67×104%, and also exhibit robustness and repeatability, which indicate excellent performance. Then the effects of electrode size and external irradiation conditions on the performance of the vertical PDs continued to be investigated.

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GNN-based temporal knowledge reasoning for UAV mission planning systems
Chai Rong, Duan Xiaofang, Wang Lixuan
The Journal of China Universities of Posts and Telecommunications    2024, 31 (1): 12-25.   DOI: 10.19682/j.cnki.1005-8885.2024.2002
Abstract930)      PDF(pc) (2603KB)(120)       Save
Unmanned aerial vehicles (UAVs) are increasingly applied in various mission scenarios for their versatility, scalability and cost-effectiveness. In UAV mission planning systems (UMPSs), an efficient mission planning strategy is essential to meet the requirements of UAV missions. However, rapidly changing environments and unforeseen threats pose challenges to UMPSs, making efficient mission planning difficult. To address these challenges, knowledge graph technology can be utilized to manage the complex relations and constraints among UAVs, missions, and environments. This paper investigates knowledge graph application in UMPSs, exploring its modeling, representation, and storage concepts and methodologies. Subsequently, the construction of a specialized knowledge graph for UMPS is detailed. Furthermore, the paper delves into knowledge reasoning within UMPSs, emphasizing its significance in timely updates in the dynamic environment. A graph neural network (GNN)-based approach is proposed for knowledge reasoning, leveraging GNNs to capture structural information and accurately predict missing entities or relations in the knowledge graph. For relation reasoning, path information is also incorporated to improve the accuracy of inference. To account for the temporal dynamics of the environment in UMPS, the influence of timestamps is captured through the attention mechanism. The effectiveness and applicability of the proposed knowledge reasoning method are verified via simulations.
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Stability and Hopf bifurcation analysis in DCTCP congestion control
Cheng Zunshui, Jiang Jingna, Sun Dongsheng
The Journal of China Universities of Posts and Telecommunications    2023, 30 (6): 30-37.   DOI: 10.19682/j.cnki.1005-8885.2023.1015
Abstract898)      PDF(pc) (3657KB)(115)       Save
Traditional loss-based transports cannot meet the strict requirements of low latency and high throughput in data center networks (DCNs). Thus data center transmission control protocol (DCTCP) is proposed to better manage the congestion control in DCNs. To provide insight into improving the stability of the DCN, this paper focuses on the Hopf bifurcation analysis of a fluid model of DCTCP, and investigates the stability of the network. The round-trip time (RTT), being an effective congestion signal, is selected as the bifurcation parameter. And the network turns unstable and generates periodic solutions when the parameter is larger than the given critical value, which is given by explicit algorithms. The analytical results reveal the existence of Hopf bifurcation. Numerical simulations are performed to make a comparative analysis between the fluid model and the simplified model of DCTCP. The influence of other parameters on the DCN stability is also discussed.
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Characteristics and modeling of UAV-vehicle MIMO wideband channels
Liang Xiaolin, Ma Jiaxu, Cao Wangbin, Xu Jianpeng, Liu Shuaiqi, Zhao Xiongwen
The Journal of China Universities of Posts and Telecommunications    2023, 30 (6): 60-67.   DOI: 10.19682/j.cnki.1005-8885.2023.1012
Abstract735)      PDF(pc) (2101KB)(114)       Save
A geometry-based stochastic model ( GBSM) for unmanned aerial vehicle to vehicle ( UAV-V) multiple-input multiple-output (MIMO) wideband channel is proposed to investigate the characteristics of UAV-V channel. Based on the proposed model, a three-dimensional (3D) wideband channel matrix regarding channel numbers, time and delay is constructed. And some important channel characteristics parameters, such as power delay profile (PDP), root mean square ( RMS) delay spread, RMS Doppler spread, channel gain and Doppler power spectral density (PSD) are investigated with different vehicle velocities. It is much simpler and clearer compared with the complex analytical derivations. The results are compared with validated analysis to confirm the theoretical analysis.
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Infrared image enhancement algorithm based on adaptive weighted guided filter
The Journal of China Universities of Posts and Telecommunications    2022, 29 (2): 73-84.   DOI: 10.19682/j.cnki.1005-8885.2022.0003
Abstract575)      PDF(pc) (3254KB)(114)       Save
The physical principle of infrared imaging leads to the low contrast of the whole image, the blurring of contour and edge details, and it is also sensitive to noise. To improve the quality of infrared image and visual effect, an adaptive weighted guided filter (AWGF) for infrared image enhancement algorithm was proposed. The core idea of AWGF algorithm is to propose an adaptive strategy to update the weights of guided filter (GF) parameters, which not only improves the accuracy of regularization parameter estimation in GF theory, but also achieves the purpose of removing infrared image noise and improving its detail contrast. A large number of real infrared images were used to verify AWGF algorithm, and good experimental results were obtained. Compared with other guided filtering algorithms, the halo phenomenon at the edge of infrared images processed by the AWGF algorithm is significantly avoided, and the evaluation parameter values of information entropy (IE), average gradient (AG), and moment of inertia (MI)are relatively high. This shows that the quality of infrared image processed by the AWGF algorithm is better.
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Parameter optimization of complex network based on the change-point identification
Xu Xingtao, Tao Jiagui
The Journal of China Universities of Posts and Telecommunications    2023, 30 (6): 22-29.   DOI: 10.19682/j.cnki.1005-8885.2023.1014
Abstract749)      PDF(pc) (6155KB)(111)       Save
This paper proposes a novel method for the parameter optimization of complex networks established through coarsening and phase space reconstruction. Firstly, we identify the change-points of the time series based on the cumulative sum ( CUSUM) control chart method. Then, we optimize the coarse-graining parameters and phase space embedding dimension based on the evolution analysis of the global topology index ( betweenness) at the mutation point. Finally, we conduct a simulation analysis based on real-time data of Chinese copper spot prices. The results show that the delay of the copper spot prices in Chinese spot market is 1 day, and the optimal embedding dimension of the phase space reconstruction is 3. The acceptance level of the investors towards the small fluctuations in copper spot prices is 0.2 times than the average level of price fluctuations, which means that an average price fluctuation of 0.2 times is the optimal coarse- graining parameter.
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Wireless semantic communication based on semantic matching multiple access and intent bias multiplexing
Ren Chao, He Zongrui, Sun Chen, Li Haojin, Zhang Haijun
The Journal of China Universities of Posts and Telecommunications    2024, 31 (1): 26-36.   DOI: 10.19682/j.cnki.1005-8885.2024.2003
Abstract619)      PDF(pc) (1783KB)(108)       Save
This paper proposes a multi-access and multi-user semantic communication scheme based on semantic matching and intent deviation to address the increasing demand for wireless users and data. The scheme enables flexible management of long frames, allowing each unit of bandwidth to support a higher number of users. By leveraging semantic classification, different users can independently access the network through the transmission of long concatenated sequences without modifying the existing wireless communication architecture. To overcome the potential disadvantage of incomplete semantic database matching leading to semantic intent misunderstanding, the scheme proposes using intent deviation as an advantage. This allows different receivers to interpret the same semantic information differently, enabling multiplexing where one piece of information can serve multiple users with distinct purposes. Simulation results show that at a bit error rate (BER) of 0.1, it is possible to reduce the transmission by approximately 20 semantic basic units.
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