pwc-archive/papers-with-abstracts huggingface dataset:
Exploiting Pinching-Antenna Systems in Multicast Communications
Authors: Shan Shan, Chongjun Ouyang, Yong Li, Yuanwei Liu
Date: 2025-05-31 00:00:00

The pinching-antenna system (PASS) reconfigures wireless links through pinching beamforming, in which the activated locations of pinching antennas (PAs) along dielectric waveguides are optimized. This article investigates the application of PASS in multicast communication systems, where pinching beamforming is designed to maximize the multicast rate. i) In the single-waveguide scenario, a closed-form solution for the optimal activated location is derived under the assumption of a single PA and linearly distributed users. Based on this, a closed-form expression for the achievable multicast rate is obtained and proven to be larger than that of conventional fixed-location antenna systems. For the general multiple-PA case with arbitrary user distributions, an element-wise alternating optimization (AO) algorithm is proposed to design the pinching beamformer. ii) In the multiple-waveguide scenario, an AO-based method is developed to jointly optimize the transmit and pinching beamformers. Specifically, the transmit beamformer is updated using a majorization-minimization (MM) framework together with second-order cone programming (SOCP), while the pinching beamformer is optimized via element-wise sequential refinement. Numerical results are provided to demonstrate that: i) PASS achieves significantly higher multicast rates than conventional fixed-location antenna systems, particularly when the number of users and spatial coverage increase; ii) increasing the number of PAs further improves the multicast performance of PASS.
Joint Activity Detection and Channel Estimation for Massive Connectivity: Where Message Passing Meets Score-Based Generative Priors
Authors: Chang Cai, Wenjun Jiang, Xiaojun Yuan, Ying-Jun Angela Zhang
Date: 2025-05-31 00:00:00
Tasks: Action Detection, Activity Detection, Bayesian Inference

Massive connectivity supports the sporadic access of a vast number of devices without requiring prior permission from the base station (BS). In such scenarios, the BS must perform joint activity detection and channel estimation (JADCE) prior to data reception. Message passing algorithms have emerged as a prominent solution for JADCE under a Bayesian inference framework. The existing message passing algorithms, however, typically rely on some hand-crafted and overly simplistic priors of the wireless channel, leading to significant channel estimation errors and reduced activity detection accuracy. In this paper, we focus on the problem of JADCE in a multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) grant-free random access network. We propose to incorporate a more accurate channel prior learned by score-based generative models into message passing, so as to push towards the performance limit of JADCE. Specifically, we develop a novel turbo message passing (TMP) framework that models the entire channel matrix as a super node, rather than factorizing it element-wise. This design enables the seamless integration of score-based generative models as a minimum mean-squared error (MMSE) denoiser. The variance of the denoiser, which is essential in message passing, can also be learned through score-based generative models. Our approach, termed score-based TMP for JADCE (STMP-JADCE), takes full advantages of the powerful generative prior and, meanwhile, benefits from the fast convergence speed of message passing. Numerical simulations show that STMP-JADCE drastically enhances the activity detection and channel estimation performance compared to the state-of-the-art baseline algorithms.
Integrated Sensing, Computing and Semantic Communication for Vehicular Networks
Authors: Yinchao Yang, Zhaohui Yang, Chongwen Huang, Wei Xu, Zhaoyang Zhang, Dusit Niyato, Mohammad Shikh-Bahaei
Date: 2025-05-31 00:00:00
Tasks: Autonomous Vehicles, Semantic Communication

This paper introduces a novel framework for integrated sensing, computing, and semantic communication (ISCSC) within vehicular networks comprising a roadside unit (RSU) and multiple autonomous vehicles. Both the RSU and the vehicles are equipped with local knowledge bases to facilitate semantic communication. The framework incorporates a secure communication design to ensure that messages intended for specific vehicles are protected against interception. In this model, an extended Kalman filter (EKF) is employed by the RSU to accurately track all vehicles. We formulate a joint optimization problem that balances maximizing the probabilistically constrained semantic secrecy rate for each vehicle while minimizing the sum of the posterior Cram\'er-Rao bound (PCRB), subject to the RSU's computing capabilities. This non-convex optimization problem is addressed using Bernstein-type inequality (BTI) and alternating optimization (AO) techniques. Simulation results validate the effectiveness of the proposed framework, demonstrating its advantages in reliable sensing, high data throughput, and secure communication.
Second-Order Characterization of Micro Doppler Radar Signatures of Drone Swarms
Authors: Anders Malthe Westerkam, Alba Spliid Damkjær, Rasmus Erik Villadsen, Magnus Ørum Bastrup Poulsen, Troels Pedersen
Date: 2025-05-31 00:00:00

We investigate the second-order characteristics of the radar return signal from a swarm of rotor drones. We consider the case of a swarm of identical drones, with each a number of rotors comprised of a number of rotor blades. By considering the orientation and speed of each rotor as stochastic variables, we derive expressions for the autocorrelation function (ACF) and power spectral density (PSD). The ACF and PSD are in the form of an infinite series with coefficients that drop to zero at a predictable limit. Thus in practical applications, the series may be truncated. As a special case, we show that for deterministic rotor speed, the ACF can be expressed in closed form. We further investigate how system parameters (Blade length, Rotor speed, number of blades, and number of drones) influence the derived expressions for the ACF and PSD.
The Coupling Effect of Sensing Targets on the Environment for 3GPP ISAC Channels: Observation, Modeling, and Validation
Authors: Yameng Liu, Jianhua Zhang, Yuxiang Zhang, Hongbo Xing, Yifeng Xiong, Zhiqiang Yuan, Guangyi Liu
Date: 2025-05-31 00:00:00
Tasks: Blocking, Integrated sensing and communication, ISAC

Integrated Sensing And Communication (ISAC) has been identified as a key 6G application by ITU and 3GPP, with standardization efforts already underway. Sensing tasks, such as target localization, demand more precise characterization of the sensing target (ST) in ISAC channel modeling. The ST couples complexly with environmental scatterers, potentially blocking some multipaths and generating new ones, resulting in power variations compared to the original channel. To accurately model this effect, this paper proposes a coupled ISAC channel model based on measurements and validates it through similarity analysis between simulated and measured channels. In this work, we first conduct ISAC channel measurements in an indoor factory scenario at 105 GHz, where the multipath power variations caused by the ST's interaction with the environment are clearly observed. Then, we propose an ISAC channel modeling framework that incorporates two novel parameters: the Blockage-Region Coupling Factor (BR-CF) and the Forward-Scattering (FS)-CF, which characterize the spatial region and intensity of the coupling effect, respectively. Finally, the proposed model is validated through similarity comparison with measured data, demonstrating higher accuracy for both LoS and NLoS scenarios compared to the non-coupled model. This realistic ISAC channel model provides an effective framework for capturing the ST-environment coupling effect, supporting the design and evaluation of ISAC technologies.
Attention-Aided MMSE for OFDM Channel Estimation: Learning Linear Filters with Attention
Authors: TaeJun Ha, Chaehyun Jung, Hyeonuk Kim, Jeongwoo Park, Jeonghun Park
Date: 2025-05-31 00:00:00

In orthogonal frequency division multiplexing (OFDM), accurate channel estimation is crucial. Classical signal processing based approaches, such as minimum mean-squared error (MMSE) estimation, often require second-order statistics that are difficult to obtain in practice. Recent deep neural networks based methods have been introduced to address this; yet they often suffer from high complexity. This paper proposes an Attention-aided MMSE (A-MMSE), a novel model-based DNN framework that learns the optimal MMSE filter via the Attention Transformer. Once trained, the A-MMSE estimates the channel through a single linear operation for channel estimation, eliminating nonlinear activations during inference and thus reducing computational complexity. To enhance the learning efficiency of the A-MMSE, we develop a two-stage Attention encoder, designed to effectively capture the channel correlation structure. Additionally, a rank-adaptive extension of the proposed A-MMSE allows flexible trade-offs between complexity and channel estimation accuracy. Extensive simulations with 3GPP TDL channel models demonstrate that the proposed A-MMSE consistently outperforms other baseline methods in terms of normalized MSE across a wide range of SNR conditions. In particular, the A-MMSE and its rank-adaptive extension establish a new frontier in the performance complexity trade-off, redefining the standard for practical channel estimation methods.
Transient Error Analysis of the LMS and RLS Algorithm for Graph Signal Estimation
Authors: Haiquan Zhao, Chengjin Li
Date: 2025-05-31 00:00:00
Tasks: Mathematical Induction

Recently, the proposal of the least mean square (LMS) and recursive least squares (RLS) algorithm for graph signal processing (GSP) provides excellent solutions for processing signals defined on irregular structures such as sensor networks. The existing work has completed the steady state error analysis of the GSP LMS algorithm and GSP RLS algorithm in Gaussian noise scenarios, and a range of values for the step size of the GSP LMS algorithm has also been given. Meanwhile, the transient error analysis of the GSP LMS algorithm and GSP RLS algorithm is also important and challenging. Completing the above work will help to quantitatively analyze the performance of the graph signal adaptive estimation algorithm at transient moments, which is what this paper is working on. By using formula derivation and mathematical induction, the transient errors expressions of the GSP LMS and GSP RLS algorithm are given in this paper. Based on the Brazilian temperature datasets, the related simulation experiments are executed, which strongly demonstrate the correctness of our proposed theoretical analysis
A Family of Robust Generalized Adaptive Filters and Application for Time-series Prediction
Authors: Yi Peng, Haiquan Zhao, Jinhui Hu
Date: 2025-05-31 00:00:00
Tasks: Time Series, Time Series Prediction

The continuous development of new adaptive filters (AFs) based on novel cost functions (CFs) is driven by the demands of various application scenarios and noise environments. However, these algorithms typically demonstrate optimal performance only in specific conditions. In the event of the noise change, the performance of these AFs often declines, rendering simple parameter adjustments ineffective. Instead, a modification of the CF is necessary. To address this issue, the robust generalized adaptive AF (RGA-AF) with strong adaptability and flexibility is proposed in this paper. The flexibility of the RGA-AF's CF allows for smooth adaptation to varying noise environments through parameter adjustments, ensuring optimal filtering performance in diverse scenarios. Moreover, we introduce several fundamental properties of negative RGA (NRGA) entropy and present the negative asymmetric RGA-AF (NAR-GA-AF) and kernel recursive NRGA-AF (KRNRGA-AF). These AFs address asymmetric noise distribution and nonlinear filtering issues, respectively. Simulations of linear system identification and time-series prediction for Chua's circuit under different noise environments demonstrate the superiority of the proposed algorithms in comparison to existing techniques.
Physics-based Generative Models for Geometrically Consistent and Interpretable Wireless Channel Synthesis
Authors: Satyavrat Wagle, Akshay Malhotra, Shahab Hamidi-Rad, Aditya Sant, David J. Love, Christopher G. Brinton
Date: 2025-05-31 00:00:00

In recent years, machine learning (ML) methods have become increasingly popular in wireless communication systems for several applications. A critical bottleneck for designing ML systems for wireless communications is the availability of realistic wireless channel datasets, which are extremely resource-intensive to produce. To this end, the generation of realistic wireless channels plays a key role in the subsequent design of effective ML algorithms for wireless communication systems. Generative models have been proposed to synthesize channel matrices, but outputs produced by such methods may not correspond to geometrically viable channels and do not provide any insight into the scenario being generated. In this work, we aim to address both these issues by integrating established parametric, physics-based geometric channel (PPGC) modeling frameworks with generative methods to produce realistic channel matrices with interpretable representations in the parameter domain. We show that generative models converge to prohibitively suboptimal stationary points when learning the underlying prior directly over the parameters due to the non-convex PPGC model. To address this limitation, we propose a linearized reformulation of the problem to ensure smooth gradient flow during generative model training, while also providing insights into the underlying physical environment. We evaluate our model against prior baselines by comparing the generated, scenario-specific samples in terms of the 2-Wasserstein distance and through its utility when used for downstream compression tasks.
Neural Network-based Information-Theoretic Transceivers for High-Order Modulation Schemes
Authors: Ngoc Long Pham, Tri Nhu Do
Date: 2025-05-31 00:00:00
Tasks: Computational Efficiency

Neural network (NN)-based end-to-end (E2E) communication systems, in which each system component may consist of a portion of a neural network, have been investigated as potential tools for developing artificial intelligence (Al)-native E2E systems. In this paper, we propose an NN-based bitwise receiver that improves computational efficiency while maintaining performance comparable to baseline demappers. Building on this foundation, we introduce a novel symbol-wise autoencoder (AE)-based E2E system that jointly optimizes the transmitter and receiver at the physical layer. We evaluate the proposed NN-based receiver using bit-error rate (BER) analysis to confirm that the numerical BER achieved by NN-based receivers or transceivers is accurate. Results demonstrate that the AE-based system outperforms baseline architectures, particularly for higher-order modulation schemes. We further show that the training signal-to-noise ratio (SNR) significantly affects the performance of the systems when inference is conducted at different SNR levels.
Feature Fusion and Knowledge-Distilled Multi-Modal Multi-Target Detection
Authors: Ngoc Tuyen Do, Tri Nhu Do
Date: 2025-05-31 00:00:00
Tasks: Domain Adaptation, Knowledge Distillation

In the surveillance and defense domain, multi-target detection and classification (MTD) is considered essential yet challenging due to heterogeneous inputs from diverse data sources and the computational complexity of algorithms designed for resource-constrained embedded devices, particularly for Al-based solutions. To address these challenges, we propose a feature fusion and knowledge-distilled framework for multi-modal MTD that leverages data fusion to enhance accuracy and employs knowledge distillation for improved domain adaptation. Specifically, our approach utilizes both RGB and thermal image inputs within a novel fusion-based multi-modal model, coupled with a distillation training pipeline. We formulate the problem as a posterior probability optimization task, which is solved through a multi-stage training pipeline supported by a composite loss function. This loss function effectively transfers knowledge from a teacher model to a student model. Experimental results demonstrate that our student model achieves approximately 95% of the teacher model's mean Average Precision while reducing inference time by approximately 50%, underscoring its suitability for practical MTD deployment scenarios.
Single-layer Circular SIW Filtenna With Beam Scanning Capability for 5G Millimeter Wave Communication Applications
Authors: Jiawang Li
Date: 2025-05-31 00:00:00

In this communication, two novel low-cost single-layer filtering antennas (filtennas) are proposed for millimeter wave (mmWave) applications. The proposed filtennas consists of a compact circular substrate integrated waveguide (SIW) cavity, a metal post close to the center of the cavity for power feeding, a metal post in the center for modes controlling, and a slot for radiating power. In the passband, the fundamental TM010 mode and the TM110 mode in the circular SIW cavity are excited by the feeding post. In addition, thanks to the high-pass characteristics of the cavity, it exhibits more than 20 dB suppression in the lower frequency band. There are three radiation nulls in Filtenna 1 and one radiation null in Filtenna 2 in the upper band which increase the suppression level as high as 18 dB. As a proof of concept, the proposed filtennas are fabricated and measured. It is shown that the Filtenna 1 can achieve simulated and measured -10 dB impedance fractional bandwidth (FBW) of 7.1% (27.14 - 29.13 GHz) and 8.6% (27.62 - 30.11 GHz), respectively. While filtenna 2 can achieve simulated and measured -10 dB FBW of 7.4% (27.86 - 29.99 GHz) and 10.1% (28.11 - 31.09 GHz), respectively. The filtennas features stable radiation patterns with an average gain of 5.0 dBi. The lower and upper sideband suppression levels for both filtennas exceed 18 dB. These filtennas are good candidates for 5G mmWave applications, as they simultaneously provide beam scanning and filtering capability with a low cost, and single layer structure.
Power-of-Two (PoT) Weights in Large Language Models (LLMs)
Authors: Mahmoud Elgenedy
Date: 2025-05-31 00:00:00
Tasks: Quantization

Complexity of Neural Networks is increasing rapidly due to the massive increase in model parameters. Specifically, in Large Language Models (LLMs), the number of model parameters has grown exponentially in the past few years, for example, from 1.5 billion parameters in GPT2 to 175 billion in GPT3. This raises a significant challenge for implementation, especially for Edge devices where memory and processing power are very limited. In this work, we investigate reducing LLM complexity with special type of quantization, power of two (PoT), for linear layers weights and transformer tables. PoT not only provides memory reduction but more importantly provides significant computational reduction through converting multiplication to bit shifting. We obtained preliminary results of PoT quantization on Nano-GPT implementation using Shakespeare dataset. We then extended results to 124-M GPT-2 model. The PoT quantization results are shown to be very promising with cross entropy loss degradation $\approx$[1.3-0.88] with number of bits range [4-6] to represent power levels.
The Impact of Uniform Circular Array on Near-field ISAC
Authors: Na Xue, Xidong Mu, Yue Chen, Yuanwei Liu
Date: 2025-05-30 00:00:00
Tasks: Integrated sensing and communication, ISAC

A novel uniform circular array (UCA) based near-field (NF) integrated sensing and communication (ISAC) framework is proposed, where the Cylindrical coordinate is invoked to evaluate the joint positioning performance. The joint squared position error bound (SPEB) of the sensing target (ST) is derived for the coplanar and non-coplanar cases. For the coplanar case, where the ST is located in the coplanar region of the UCA, the approximate Cram{\'e}r-Rao bound (CRB) expressions for the separate angle and distance estimation are given by exploiting the uniform spherical wavefront model. A SPEB minimization problem is formulated with the constraints of communication requirement and power budget, where the closed-form solution to minimize the CRB of the angle is derived. Inspired by the close-form expression, a low complexity vector-based quadratic transformation (VQF) algorithm is proposed by invoking the Rayleigh quotient. For the non-coplanar case, where the ST is located beyond the coplanar region of the UCA, the separate CRBs over three-dimensional coordinates and the joint SPEB approximations are derived. To minimize the SPEB performance, the semi-definite relaxation (SDR) method and extended low-complexity VQF algorithm are proposed. Numerical results validated that i) the Fisher Information Matrix about angle and distance in NF propagation can be approximated as a diagonal matrix with the trinity loss; ii) Compared with the uniform planar array, the UCA achieve better positioning performance when ST located in the coplanar of the antenna array; and iii) the proposed VQF algorithms reach higher solution precision than conventional SDR algorithm with much less computation complexity.
STARS-assisted Near-field ISAC: Sensor Deployment and Beamforming Design
Authors: Na Xue, Xidong Mu, Yue Chen, Yuanwei Liu
Date: 2025-05-30 00:00:00
Tasks: Integrated sensing and communication, ISAC, Position

A simultaneously transmitting and reflecting surface (STARS) assisted near-field (NF) integrated sensing and communication (ISAC) framework is proposed, where the radio sensors are installed on the STARS to directly conduct the distance-domain sensing by exploiting the characteristic spherical wavefront. A new squared position error bound (SPEB) expression is derived to reveal the dependence on beamforming (BF) design and sensor deployment. To balance the trade-off between the SPEB and the sensor deployment cost, a cost function minimization problem, a cost function minimization problem is formulated to jointly optimize the sensor deployment, the active and passive BF, subject to communication and power consumption constraints. For the sensor deployment optimization, a joint sensor deployment algorithm is proposed by invoking the successive convex approximation. Under a specific relationship between the sensor numbers and BF design, we derive the optimal sensor interval in a closed-form expression. For the joint BF optimization, a penalty-based method is invoked. Simulation results validated that the derived SPEB expression is close to the exact SPEB, which reveals the Fisher information Matrix of position estimation in NF can be approximated as a diagonal matrix. Furthermore, the proposed algorithms achieve the best SPEB performance than the benchmark schemes accompanying the lowest deployment cost.
How can AI reduce fall injuries in the workplace?
Authors: Nicholas Cartocci, Antonios E. Gkikakis, Roberto F. Pitzalis, Fabio Pera, Maria Teresa Settino, Darwin G. Caldwell, Jesús Ortiz
Date: 2025-05-30 00:00:00

Fall-caused injuries are common in all types of work environments, including offices. They are the main cause of absences longer than three days, especially for small and medium-sized businesses (SMEs). However, data, data amount, data heterogeneity, and stringent processing time constraints continue to pose challenges to real-time fall detection. This work proposes a new approach based on a recurrent neural network (RNN) for Fall Detection and a Kolmogorov-Arnold Network (KAN) to estimate the time of impact of the fall. The approach is tested on SisFall, a dataset consisting of 2706 Activities of Daily Living (ADLs) and 1798 falls recorded by three sensors. The results show that the proposed approach achieves an average TPR of 82.6% and TNR of 98.4% for fall sequences and 94.4% in ADL. Besides, the Root Mean Squared Error of the estimated time of impact is approximately 160ms.