Pub Date : 2025-12-01DOI: 10.1016/j.phycom.2025.102906
Doaa S. Ibrahim, Fadhil S. Hasan
In this paper, a joint permutation index and code index modulations differential chaos shift keying-based ambient backscatter communication (JPCIM-DCSK-AmBC) is proposed to improve the system performance and data rate. The JPCIM-DCSK-AmBC signal in the proposed system is transmitted using a backscatter device, with multiple bits encoded in a radio frequency (RF) source symbol via joint permutation index and a modulation technique based on code indexing. The information bits are split into two blocks of and bits, where bits are utilized for permutation index and bits are utilized for code index bits. The analytic bit error rate (BER) of the JPCIM-DCSK-AmBC over a flat fading channel is derived and verified with the simulation results. The experimental results demonstrate that the suggested system has lower error rate and higher throughput than conventional methods.
{"title":"A high data rate ambient backscatter DCSK communication system based on joint permutation index and code index modulations","authors":"Doaa S. Ibrahim, Fadhil S. Hasan","doi":"10.1016/j.phycom.2025.102906","DOIUrl":"10.1016/j.phycom.2025.102906","url":null,"abstract":"<div><div>In this paper, a joint permutation index and code index modulations differential chaos shift keying-based ambient backscatter communication (JPCIM-DCSK-AmBC) is proposed to improve the system performance and data rate. The JPCIM-DCSK-AmBC signal in the proposed system is transmitted using a backscatter device, with multiple bits encoded in a radio frequency (RF) source symbol via joint permutation index and a modulation technique based on code indexing. The information bits are split into two blocks of <span><math><msub><mi>m</mi><mi>p</mi></msub></math></span> and <span><math><mrow><msub><mi>m</mi><mi>c</mi></msub><mspace></mspace></mrow></math></span>bits, where <span><math><msub><mi>m</mi><mi>p</mi></msub></math></span> bits are utilized for permutation index and <span><math><msub><mi>m</mi><mi>c</mi></msub></math></span> bits are utilized for code index bits. The analytic bit error rate (BER) of the JPCIM-DCSK-AmBC over a flat fading channel is derived and verified with the simulation results. The experimental results demonstrate that the suggested system has lower error rate and higher throughput than conventional methods.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"73 ","pages":"Article 102906"},"PeriodicalIF":2.2,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145623675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-30DOI: 10.1016/j.phycom.2025.102933
Siva Kumar T, Jeyakumar P
Efficient beam tracking is essential for stable high-throughput communication in ultra-wideband terahertz (THz) massive MIMO systems. However, existing reinforcement learning (RL)-based methods often overlook temporal channel variations and beam squint effects inherent to wideband THz links. To address this, we propose a Hybrid Long Short-Term Memory–Actor-Critic (LSTM–A2C) framework that integrates temporal prediction and spatial decision-making for adaptive beam tracking in 6G THz systems. The LSTM captures beam dynamics over time, while the Actor–Critic learner adjusts beamforming vectors in real time under mobility and hardware impairments. Simulations under realistic THz conditions (with phase noise, ADC quantization, and beam squint) show that LSTM–A2C achieves 15–25 % higher tracking accuracy and 30–40 % lower error compared to DQN, PPO, and EKF methods. It also delivers 3.5 bps/Hz spectral efficiency at 10 dB SNR, 2.1 bits/Joule energy efficiency, and a fairness index of 0.99 in multi-user settings. The reward curve shows faster convergence ( ≈ 200 epochs), validating the proposed framework’s efficiency.
{"title":"Hybrid LSTM-actor-critic framework for temporal-spatial wideband beam tracking in 6G THz massive MIMO","authors":"Siva Kumar T, Jeyakumar P","doi":"10.1016/j.phycom.2025.102933","DOIUrl":"10.1016/j.phycom.2025.102933","url":null,"abstract":"<div><div>Efficient beam tracking is essential for stable high-throughput communication in ultra-wideband terahertz (THz) massive MIMO systems. However, existing reinforcement learning (RL)-based methods often overlook temporal channel variations and beam squint effects inherent to wideband THz links. To address this, we propose a Hybrid Long Short-Term Memory–Actor-Critic (LSTM–A2C) framework that integrates temporal prediction and spatial decision-making for adaptive beam tracking in 6G THz systems. The LSTM captures beam dynamics over time, while the Actor–Critic learner adjusts beamforming vectors in real time under mobility and hardware impairments. Simulations under realistic THz conditions (with phase noise, ADC quantization, and beam squint) show that LSTM–A2C achieves 15–25 % higher tracking accuracy and 30–40 % lower error compared to DQN, PPO, and EKF methods. It also delivers 3.5 bps/Hz spectral efficiency at 10 dB SNR, 2.1 bits/Joule energy efficiency, and a fairness index of 0.99 in multi-user settings. The reward curve shows faster convergence ( ≈ 200 epochs), validating the proposed framework’s efficiency.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"74 ","pages":"Article 102933"},"PeriodicalIF":2.2,"publicationDate":"2025-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145748481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-30DOI: 10.1016/j.phycom.2025.102946
Sunil Narayan Thool, Devendra Chack
The advancement of Probabilistic Constellation Shaping (PCS) is pivotal for high-capacity optical communication systems and the forthcoming 6 G era. PCS aims to approach the Shannon limit, optimising signal efficiency and performance. However, phase noise from continuous-wave (CW) lasers significantly impacts system performance, especially in terms of bit error rate (BER). This paper introduces and evaluates phase noise estimation and correction using the Viterbi & Viterbi (V&V) algorithm at a 50 Gbaud symbol rate in dual-polarised high-capacity optical systems employing higher-order Quadrature Amplitude Modulation (QAM) schemes, such as 64-QAM and 256-QAM PCS. A comparative analysis with the Blind Phase Search (BPS) algorithm demonstrates the V&V algorithm’s ability to maintain BER of 10–5 and 10–4 for 64-QAM and 256-QAM PCS, respectively, under CW laser linewidth of 1 MHz. Extensive numerical results demonstrate that the V&V algorithm consistently meets the other analytical parameter requirements of the optical link under CW laser linewidths ranging from 10 kHz to 1 MHz. The implemented system design emphasises the V&V algorithm’s robustness in handling phase noise, highlighting its potential to enhance reliability and performance in high-capacity optical communication systems. The findings underscore the potential of our approach to meet the forthcoming requirements of optical links.
{"title":"Phase noise mitigation in higher order probabilistic constellation shaping for high-capacity optical communications","authors":"Sunil Narayan Thool, Devendra Chack","doi":"10.1016/j.phycom.2025.102946","DOIUrl":"10.1016/j.phycom.2025.102946","url":null,"abstract":"<div><div>The advancement of Probabilistic Constellation Shaping (PCS) is pivotal for high-capacity optical communication systems and the forthcoming 6 G era. PCS aims to approach the Shannon limit, optimising signal efficiency and performance. However, phase noise from continuous-wave (CW) lasers significantly impacts system performance, especially in terms of bit error rate (BER). This paper introduces and evaluates phase noise estimation and correction using the Viterbi & Viterbi (V&V) algorithm at a 50 Gbaud symbol rate in dual-polarised high-capacity optical systems employing higher-order Quadrature Amplitude Modulation (QAM) schemes, such as 64-QAM and 256-QAM PCS. A comparative analysis with the Blind Phase Search (BPS) algorithm demonstrates the V&V algorithm’s ability to maintain BER of 10<sup>–5</sup> and 10<sup>–4</sup> for 64-QAM and 256-QAM PCS, respectively, under CW laser linewidth of 1 MHz. Extensive numerical results demonstrate that the V&V algorithm consistently meets the other analytical parameter requirements of the optical link under CW laser linewidths ranging from 10 kHz to 1 MHz. The implemented system design emphasises the V&V algorithm’s robustness in handling phase noise, highlighting its potential to enhance reliability and performance in high-capacity optical communication systems. The findings underscore the potential of our approach to meet the forthcoming requirements of optical links.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"74 ","pages":"Article 102946"},"PeriodicalIF":2.2,"publicationDate":"2025-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-30DOI: 10.1016/j.phycom.2025.102944
Yang Wu , Yu Zhang , Wenyue Zhu
This paper addresses the exacerbated pilot contamination challenge in cell-free massive MIMO (CF-mMIMO) systems for unmanned aerial vehicle (UAV) communications, where strong line-of-sight (LOS) air-to-ground channels intensify interference compared to terrestrial users. The inherent mutual coupling (MC) effects in multi-antenna access points further degrade pilot decontamination (PDC) performance. To address this, we propose a novel structured tensor decomposition-based method, termed two-stage PDC (TPDC), which relies on dual pilot transmission. The first processing stage strategically manages intra-group pilot contamination to construct a low-rank third-order tensor, during which the trilinear alternating least squares (TALS) technique is implemented to decompose three factor matrices corresponding to MC-induced angular, delay, and Doppler domains. The second processing stage resolves UAV-and-multipath mismatch through the coordinated transmission of distinct intra-group pilots combined with K-means clustering. Our proposed framework uniquely incorporates Vandermonde structures within factor matrices, enabling accurate channel estimation under relaxed pilot orthogonality constraints. We further derive the Cramér-Rao lower bound (CRLB) for channel parameters. Numerical results reveal that the proposed TPDC algorithm achieves mean square error (MSE) performance near the CRLB and outperforms conventional ALS and structured CANDECOMP/PARAFAC (CP) decomposition methods.
{"title":"Structured tensor decomposition-based two-stage pilot decontamination for UAV communications in cell-free massive MIMO systems with mutual coupling","authors":"Yang Wu , Yu Zhang , Wenyue Zhu","doi":"10.1016/j.phycom.2025.102944","DOIUrl":"10.1016/j.phycom.2025.102944","url":null,"abstract":"<div><div>This paper addresses the exacerbated pilot contamination challenge in cell-free massive MIMO (CF-mMIMO) systems for unmanned aerial vehicle (UAV) communications, where strong line-of-sight (LOS) air-to-ground channels intensify interference compared to terrestrial users. The inherent mutual coupling (MC) effects in multi-antenna access points further degrade pilot decontamination (PDC) performance. To address this, we propose a novel structured tensor decomposition-based method, termed two-stage PDC (TPDC), which relies on dual pilot transmission. The first processing stage strategically manages intra-group pilot contamination to construct a low-rank third-order tensor, during which the trilinear alternating least squares (TALS) technique is implemented to decompose three factor matrices corresponding to MC-induced angular, delay, and Doppler domains. The second processing stage resolves UAV-and-multipath mismatch through the coordinated transmission of distinct intra-group pilots combined with K-means clustering. Our proposed framework uniquely incorporates Vandermonde structures within factor matrices, enabling accurate channel estimation under relaxed pilot orthogonality constraints. We further derive the Cramér-Rao lower bound (CRLB) for channel parameters. Numerical results reveal that the proposed TPDC algorithm achieves mean square error (MSE) performance near the CRLB and outperforms conventional ALS and structured CANDECOMP/PARAFAC (CP) decomposition methods.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"74 ","pages":"Article 102944"},"PeriodicalIF":2.2,"publicationDate":"2025-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-28DOI: 10.1016/j.phycom.2025.102942
Shibao Li , Qishuai Guan , Yunwu Zhang , Xuerong Cui , Huajun Song , Zhaozhi Gu , Lianghai Li
With the rapid advancement of wireless communication technologies, achieving high reliability, low latency, and energy efficiency remains a critical challenge. Unmanned Aerial Vehicle-mounted Reconfigurable Intelligent Surfaces (UAV-RIS) leverage both the reconfigurability of RIS and the mobility of UAVs to enhance air-to-ground link quality. This paper investigates the joint optimization of UAV trajectory, base station (BS) beamforming, and RIS phase control in UAV-RIS-assisted systems. A density-aware positioning algorithm is first introduced to optimize the UAV trajectory and improve link robustness. Building upon this, a gradient-based adaptive meta-learning (GAML) framework is developed to jointly optimize BS beamforming and RIS phase shifts without extensive pre-training, thereby enhancing adaptability in time-varying channels. The proposed GAML scheme avoids explicit non-convex optimization and significantly reduces computational complexity. Furthermore, the integration of adaptive network structures enhances gradient propagation and mitigates vanishing gradients. Simulation results show that GAML outperforms existing learning-based and random phase methods, achieving up to 14.25% improvement in weighted sum rate (WSR), demonstrating its superior adaptability and efficiency.
{"title":"Joint beamforming and phase optimization for UAV-RIS systems by gradient-based adaptive meta-learning","authors":"Shibao Li , Qishuai Guan , Yunwu Zhang , Xuerong Cui , Huajun Song , Zhaozhi Gu , Lianghai Li","doi":"10.1016/j.phycom.2025.102942","DOIUrl":"10.1016/j.phycom.2025.102942","url":null,"abstract":"<div><div>With the rapid advancement of wireless communication technologies, achieving high reliability, low latency, and energy efficiency remains a critical challenge. Unmanned Aerial Vehicle-mounted Reconfigurable Intelligent Surfaces (UAV-RIS) leverage both the reconfigurability of RIS and the mobility of UAVs to enhance air-to-ground link quality. This paper investigates the joint optimization of UAV trajectory, base station (BS) beamforming, and RIS phase control in UAV-RIS-assisted systems. A density-aware positioning algorithm is first introduced to optimize the UAV trajectory and improve link robustness. Building upon this, a gradient-based adaptive meta-learning (GAML) framework is developed to jointly optimize BS beamforming and RIS phase shifts without extensive pre-training, thereby enhancing adaptability in time-varying channels. The proposed GAML scheme avoids explicit non-convex optimization and significantly reduces computational complexity. Furthermore, the integration of adaptive network structures enhances gradient propagation and mitigates vanishing gradients. Simulation results show that GAML outperforms existing learning-based and random phase methods, achieving up to 14.25% improvement in weighted sum rate (WSR), demonstrating its superior adaptability and efficiency.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"74 ","pages":"Article 102942"},"PeriodicalIF":2.2,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To address the real-time and robustness challenges of resource allocation under rapidly time-varying channels in high-mobility scenarios, this paper proposes an MHA-augmented scheme within a centralized-training–decentralized-execution architecture for mixed V2I/V2V services. First, we adopt a bounded V2V normalized completion rate as a physically meaningful reliability metric. Second, we embed a Multi-Head Attention layer at the front end of the DDQN Q-network: local observations from each link are linearly projected into Query, Key and Value vectors, and multiple attention heads compute in parallel to produce a set of weighted contextual features. This enables agents to dynamically focus on the interference links most severely affected by Doppler shifts. In addition, we incorporate Prioritized Experience Replay together with importance-sampling correction and priority clipping to control sampling bias and to accelerate learning from critical, Doppler- or blockage-induced extreme samples. Simulation results indicate that the proposed hybrid MHA-enhanced scheme increases average V2I throughput by about 9.7%, while still retaining an approximately 5% advantage in high-density, high-speed scenarios. Concurrently, end-to-end V2V transmission success probability improves by roughly 7.8% on average and attains an average gain of about 9.2% at the peak speed of 30 m/s. These experiments validate the complementary effects of MHA and PER under strong Doppler perturbations and demonstrate the effectiveness of the proposed method in multicriteria trade-offs and engineering-level deployment. https://github.com/HX-hx206/V2XX.git.
{"title":"Doppler-aware dynamic resource allocation for V2X communications using Double Deep Q-Network","authors":"Xi Huang , Yingying Yu , Longfei Huang , Wenxun Chen","doi":"10.1016/j.phycom.2025.102923","DOIUrl":"10.1016/j.phycom.2025.102923","url":null,"abstract":"<div><div>To address the real-time and robustness challenges of resource allocation under rapidly time-varying channels in high-mobility scenarios, this paper proposes an MHA-augmented scheme within a centralized-training–decentralized-execution architecture for mixed V2I/V2V services. First, we adopt a bounded V2V normalized completion rate as a physically meaningful reliability metric. Second, we embed a Multi-Head Attention layer at the front end of the DDQN Q-network: local observations from each link are linearly projected into Query, Key and Value vectors, and multiple attention heads compute in parallel to produce a set of weighted contextual features. This enables agents to dynamically focus on the interference links most severely affected by Doppler shifts. In addition, we incorporate Prioritized Experience Replay together with importance-sampling correction and priority clipping to control sampling bias and to accelerate learning from critical, Doppler- or blockage-induced extreme samples. Simulation results indicate that the proposed hybrid MHA-enhanced scheme increases average V2I throughput by about 9.7%, while still retaining an approximately 5% advantage in high-density, high-speed scenarios. Concurrently, end-to-end V2V transmission success probability improves by roughly 7.8% on average and attains an average gain of about 9.2% at the peak speed of 30 m/s. These experiments validate the complementary effects of MHA and PER under strong Doppler perturbations and demonstrate the effectiveness of the proposed method in multicriteria trade-offs and engineering-level deployment. <span><span>https://github.com/HX-hx206/V2XX.git</span><svg><path></path></svg></span>.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"74 ","pages":"Article 102923"},"PeriodicalIF":2.2,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145625378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-25DOI: 10.1016/j.phycom.2025.102926
Kehao Wang, Yufeng Gong, Changzhen Li, Pei Liu
This paper proposes a joint task performance-oriented multiple unmanned aerial vehicle task system (JTP-MUAVTS), in which multiple UAVs are capable of performing reconnaissance, communication, and jamming tasks under constraints of time, power, and terrain. Specifically, we integrate the reconnaissance probability, transmission rate, and jamming-to-signal ratio (JSR) into a unified metric, and then formulate a joint optimization problem under JTP-MUAVTS. Due to the strong coupling and non-convex nature of the problem, we develop an alternating optimization algorithm and employ the block coordinate descent (BCD) method to decompose the original problem into three sub-problems: task allocation, power optimization, and trajectory planning. To achieve a balance between global search ability and convergence efficiency, we propose an Adaptive-Elitist Binary Particle Swarm Optimization algorithm (AE-BPSO). To tackle the non-convexity of the power allocation sub-problem, we adopt the Successive Convex Approximation (SCA) method to obtain sub-optimal solutions. Finally, to satisfy safety and efficiency demands of trajectory planning, the Q-learning algorithm is employed. Simulation results demonstrate that the proposed AE-BPSO algorithm achieves superior performance in terms of maximizing the joint task performance compared with several other intelligent algorithms.
{"title":"Joint optimization of task allocation, power optimization and trajectory planning in multi-UAV system","authors":"Kehao Wang, Yufeng Gong, Changzhen Li, Pei Liu","doi":"10.1016/j.phycom.2025.102926","DOIUrl":"10.1016/j.phycom.2025.102926","url":null,"abstract":"<div><div>This paper proposes a joint task performance-oriented multiple unmanned aerial vehicle task system (JTP-MUAVTS), in which multiple UAVs are capable of performing reconnaissance, communication, and jamming tasks under constraints of time, power, and terrain. Specifically, we integrate the reconnaissance probability, transmission rate, and jamming-to-signal ratio (JSR) into a unified metric, and then formulate a joint optimization problem under JTP-MUAVTS. Due to the strong coupling and non-convex nature of the problem, we develop an alternating optimization algorithm and employ the block coordinate descent (BCD) method to decompose the original problem into three sub-problems: task allocation, power optimization, and trajectory planning. To achieve a balance between global search ability and convergence efficiency, we propose an Adaptive-Elitist Binary Particle Swarm Optimization algorithm (AE-BPSO). To tackle the non-convexity of the power allocation sub-problem, we adopt the Successive Convex Approximation (SCA) method to obtain sub-optimal solutions. Finally, to satisfy safety and efficiency demands of trajectory planning, the Q-learning algorithm is employed. Simulation results demonstrate that the proposed AE-BPSO algorithm achieves superior performance in terms of maximizing the joint task performance compared with several other intelligent algorithms.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"74 ","pages":"Article 102926"},"PeriodicalIF":2.2,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-24DOI: 10.1016/j.phycom.2025.102928
Jingyi Lang, Mengdan Ji
This work investigates multi-user task-oriented semantic communications where bandwidth, transmit power, and edge compute cycles are orchestrated jointly under a passive eavesdropper. We define a system-level task utility that captures semantic importance and downstream inference accuracy, and we place two competing scheduling philosophies: a channel-state-first policy that prioritizes favorable propagation conditions, and a semantic-importance-first policy that prioritizes information units with the highest task value per resource. Building on a drift-plus-penalty framework, we develop an online secrecy-aware orchestration algorithm that relies only on causal state information, enforces latency and secrecy through virtual queues and a conditional value-at-risk controller, and exposes a tunable tradeoff between utility optimality and backlog. Each slot decomposes into weighted water-filling for bandwidth and power, lightweight scoring for compute allocation, and optional artificial noise or rate back-off when secrecy risk rises. We conduct extensive simulations for image classification on the ImageNet-100 benchmark using task-driven semantic encoders over Rayleigh and Rician fading with partial knowledge of the eavesdropper channel. Simulation results demonstrate the superior gains of the semantic-importance-first policy over channel-state-first at comparable delay, and a marked reduction in secrecy-outage events when risk control is enabled.
{"title":"Semantic security-aware multi-user resource allocation: A novel meaning-first scheduling","authors":"Jingyi Lang, Mengdan Ji","doi":"10.1016/j.phycom.2025.102928","DOIUrl":"10.1016/j.phycom.2025.102928","url":null,"abstract":"<div><div>This work investigates multi-user task-oriented semantic communications where bandwidth, transmit power, and edge compute cycles are orchestrated jointly under a passive eavesdropper. We define a system-level task utility that captures semantic importance and downstream inference accuracy, and we place two competing scheduling philosophies: a channel-state-first policy that prioritizes favorable propagation conditions, and a semantic-importance-first policy that prioritizes information units with the highest task value per resource. Building on a drift-plus-penalty framework, we develop an online secrecy-aware orchestration algorithm that relies only on causal state information, enforces latency and secrecy through virtual queues and a conditional value-at-risk controller, and exposes a tunable tradeoff between utility optimality and backlog. Each slot decomposes into weighted water-filling for bandwidth and power, lightweight scoring for compute allocation, and optional artificial noise or rate back-off when secrecy risk rises. We conduct extensive simulations for image classification on the ImageNet-100 benchmark using task-driven semantic encoders over Rayleigh and Rician fading with partial knowledge of the eavesdropper channel. Simulation results demonstrate the superior gains of the semantic-importance-first policy over channel-state-first at comparable delay, and a marked reduction in secrecy-outage events when risk control is enabled.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"74 ","pages":"Article 102928"},"PeriodicalIF":2.2,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145625380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-24DOI: 10.1016/j.phycom.2025.102930
Bin Peng , Changxiang Fan
Frequency estimation of unknown signals is an important problem for many applications, such as optical communication, electroencephalogram (EEG) signal processing and electrocardiograms (ECG) signal processing. In this paper, firstly a novel subspace-based algorithm is proposed to estimate multiple frequencies of signals without a prior knowledge of source number, which is necessary for existing subspace-based methods. Firstly, the fourth-order cumulant is used to construct a specific subspace similar to the covariance matrix. By analyzing the relationship between the constructed matrix and frequency matrix, an orthogonal matrix is constructed and proved to be the subspace orthogonal to the frequency matrix. It avoids the eigenvalue decomposition (EVD), leading to a fast and efficient estimator. Secondly, the effect of the source number in the procedure of constructing propagators is analyzed and an improvement is proposed to get rid of the essential source number, leading to a much greater potential for practical application. At last, some simulations are carried out for verifying the effectiveness of the proposed methods.
{"title":"Improved subspace-based method for estimating frequency of unknown signals","authors":"Bin Peng , Changxiang Fan","doi":"10.1016/j.phycom.2025.102930","DOIUrl":"10.1016/j.phycom.2025.102930","url":null,"abstract":"<div><div>Frequency estimation of unknown signals is an important problem for many applications, such as optical communication, electroencephalogram (EEG) signal processing and electrocardiograms (ECG) signal processing. In this paper, firstly a novel subspace-based algorithm is proposed to estimate multiple frequencies of signals without a prior knowledge of source number, which is necessary for existing subspace-based methods. Firstly, the fourth-order cumulant is used to construct a specific subspace similar to the covariance matrix. By analyzing the relationship between the constructed matrix and frequency matrix, an orthogonal matrix is constructed and proved to be the subspace orthogonal to the frequency matrix. It avoids the eigenvalue decomposition (EVD), leading to a fast and efficient estimator. Secondly, the effect of the source number in the procedure of constructing propagators is analyzed and an improvement is proposed to get rid of the essential source number, leading to a much greater potential for practical application. At last, some simulations are carried out for verifying the effectiveness of the proposed methods.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"74 ","pages":"Article 102930"},"PeriodicalIF":2.2,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-24DOI: 10.1016/j.phycom.2025.102927
Yinuo Zhao , Enyu Li , Xiaofei Zhai , Weidong Yao , Tonghao Wang
The objective of information confrontation is to detect, interfere with and disrupt satellite communications while protecting one’s own communication. In view of the above background, a covert communication system model is proposed in the information confrontation environment. The exact closed-form result of the detection error probability (DEP) of the eavesdropping user is analyzed, and the optimal value of DEP and the optimal decision threshold are also given. Considering the behavior that intelligent eavesdroppers automatically select attacks and eavesdropping, combined with non-orthogonal multiple access (NOMA) technology and the imperfect successive interference cancellation (SIC) technology, the exact closed-form results of the outage probability of legitimate users and the intercept probability of eavesdroppers are derived, and the approximate results are also given in high signal-to-noise ratio (SNR). Finally, the accuracy of the theoretical derivation is verified by Monte Carlo simulation, and the influence of relevant system parameters is discussed concretely in the simulation. The numerical simulation results show that a reasonable selection of system parameters can improve the covert performance and anti-interference ability of the system, thereby achieving more reliable covert communication.
{"title":"Performance analysis of covert communication in the presence of intelligent eavesdroppers","authors":"Yinuo Zhao , Enyu Li , Xiaofei Zhai , Weidong Yao , Tonghao Wang","doi":"10.1016/j.phycom.2025.102927","DOIUrl":"10.1016/j.phycom.2025.102927","url":null,"abstract":"<div><div>The objective of information confrontation is to detect, interfere with and disrupt satellite communications while protecting one’s own communication. In view of the above background, a covert communication system model is proposed in the information confrontation environment. The exact closed-form result of the detection error probability (DEP) of the eavesdropping user is analyzed, and the optimal value of DEP and the optimal decision threshold are also given. Considering the behavior that intelligent eavesdroppers automatically select attacks and eavesdropping, combined with non-orthogonal multiple access (NOMA) technology and the imperfect successive interference cancellation (SIC) technology, the exact closed-form results of the outage probability of legitimate users and the intercept probability of eavesdroppers are derived, and the approximate results are also given in high signal-to-noise ratio (SNR). Finally, the accuracy of the theoretical derivation is verified by Monte Carlo simulation, and the influence of relevant system parameters is discussed concretely in the simulation. The numerical simulation results show that a reasonable selection of system parameters can improve the covert performance and anti-interference ability of the system, thereby achieving more reliable covert communication.</div></div>","PeriodicalId":48707,"journal":{"name":"Physical Communication","volume":"74 ","pages":"Article 102927"},"PeriodicalIF":2.2,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145625379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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