pwc-archive/papers-with-abstracts huggingface dataset:
The Role of Text-to-Image Models in Advanced Style Transfer Applications: A Case Study with DALL-E 3
Authors: Ebubechukwu Ike
Date: 2024-12-04 00:00:00
Tasks: Diversity, Image Stylization, SSIM, Style Transfer

While DALL-E 3 has gained popularity for its ability to generate creative and complex images from textual descriptions, its application in the domain of style transfer remains slightly underexplored. This project investigates the integration of DALL-E 3 with traditional neural style transfer techniques to assess the impact of generated style images on the quality of the final output. DALL-E 3 was employed to generate style images based on the descriptions provided and combine these with the Magenta Arbitrary Image Stylization model. This integration is evaluated through metrics such as the Structural Similarity Index Measure (SSIM) and Peak Signal-to-Noise Ratio (PSNR), as well as processing time assessments. The findings reveal that DALL-E 3 significantly enhances the diversity and artistic quality of stylized images. Although this improvement comes with a slight increase in style transfer time, the data shows that this trade-off is worthwhile because the overall processing time with DALL-E 3 is about 2.5 seconds faster than traditional methods, making it both an efficient and visually superior option.
$ρ$-NeRF: Leveraging Attenuation Priors in Neural Radiance Field for 3D Computed Tomography Reconstruction
Authors: Li Zhou, Changsheng Fang, Bahareh Morovati, Yongtong Liu, Shuo Han, Yongshun Xu, Hengyong Yu
Date: 2024-12-03 00:00:00
Tasks: Computed Tomography (CT), CT Reconstruction, NeRF, Novel View Synthesis

This paper introduces $\rho$-NeRF, a self-supervised approach that sets a new standard in novel view synthesis (NVS) and computed tomography (CT) reconstruction by modeling a continuous volumetric radiance field enriched with physics-based attenuation priors. The $\rho$-NeRF represents a three-dimensional (3D) volume through a fully-connected neural network that takes a single continuous four-dimensional (4D) coordinate, spatial location $(x, y, z)$ and an initialized attenuation value ($\rho$), and outputs the attenuation coefficient at that position. By querying these 4D coordinates along X-ray paths, the classic forward projection technique is applied to integrate attenuation data across the 3D space. By matching and refining pre-initialized attenuation values derived from traditional reconstruction algorithms like Feldkamp-Davis-Kress algorithm (FDK) or conjugate gradient least squares (CGLS), the enriched schema delivers superior fidelity in both projection synthesis and image recognition.
RIS-Aided Covert Communications with Statistical CSI: A Multiport Network Theory Approach
Authors: Andrea Abrardo, Giulio Bartoli
Date: 2024-12-12 00:00:00

A novel framework for covert communications aided by Reconfigurable Intelligent Surfaces (RIS) is proposed. In this general framework, the use of multiport network theory for modelling the RIS consider various aspects that traditional RIS models in communication theory often overlook, including mutual coupling between elements and the impact of structural scattering. Moreover, the transmitter has only limited knowledge about the channels of the warden and the intended receiver. The proposed approach is validated through numerical results, demonstrating that communication with the legitimate user is successfully achieved while satisfying the covertness constraint.
Fronthaul Compression and Beamforming Optimization for Secure Cell-free ISAC Systems
Authors: Seongjun Kim, Seongah Jeong
Date: 2024-12-12 00:00:00
Tasks: ISAC

This letter aims to provide sensing capabilities for a potential eavesdropper, while simultaneously enabling the secure communications with the legitimate users in a cell-free multipleinput multiple-output system with limited fronthaul links. In order to maximize the sensing performance, the joint design of fronthaul compression and beamforming is proposed considering the constraints on the finite fronthaul-capacity links and the maximum power along with the worst-case secrecy rate requirements. To this end, we propose an algorithmic solution based on the minorization-maximization method and semidefinite programming relaxation techniques, whose performance superiority is verified via simulations compared to the reference schemes such as distributed sensing and random beamforming.
WiFo: Wireless Foundation Model for Channel Prediction
Authors: Boxun Liu, Shijian Gao, Xuanyu Liu, Xiang Cheng, Liuqing Yang
Date: 2024-12-12 00:00:00
Tasks: model, Multi-Task Learning, Prediction, Zero-shot Generalization

Channel prediction permits to acquire channel state information (CSI) without signaling overhead. However, almost all existing channel prediction methods necessitate the deployment of a dedicated model to accommodate a specific configuration. Leveraging the powerful modeling and multi-task learning capabilities of foundation models, we propose the first space-time-frequency (STF) wireless foundation model (WiFo) to address time-frequency channel prediction tasks in a one-for-all manner. Specifically, WiFo is initially pre-trained over massive and extensive diverse CSI datasets. Then, the model will be instantly used for channel prediction under various CSI configurations without any fine-tuning. We propose a masked autoencoder (MAE)-based network structure for WiFo to handle heterogeneous STF CSI data, and design several mask reconstruction tasks for self-supervised pre-training to capture the inherent 3D variations of CSI. To fully unleash its predictive power, we build a large-scale heterogeneous simulated CSI dataset consisting of 160K CSI samples for pre-training. Simulations validate its superior unified learning performance across multiple datasets and demonstrate its state-of-the-art (SOTA) zero-shot generalization performance via comparisons with other full-shot baselines.
Fully Bayesian Wideband Direction-of-Arrival Estimation and Detection via RJMCMC
Authors: Kyurae Kim, Philip T. Clemson, James P. Reilly, Jason F. Ralph, Simon Maskell
Date: 2024-12-12 00:00:00
Tasks: Direction of Arrival Estimation

We propose a fully Bayesian approach to wideband, or broadband, direction-of-arrival (DoA) estimation and signal detection. Unlike previous works in wideband DoA estimation and detection, where the signals were modeled in the time-frequency domain, we directly model the time-domain representation and treat the non-causal part of the source signal as latent variables. Furthermore, our Bayesian model allows for closed-form marginalization of the latent source signals by leveraging conjugacy. To further speed up computation, we exploit the sparse ``stripe matrix structure'' of the considered system, which stems from the circulant matrix representation of linear time-invariant (LTI) systems. This drastically reduces the time complexity of computing the likelihood from $\mathcal{O}(N^3 k^3)$ to $\mathcal{O}(N k^3)$, where $N$ is the number of samples received by the array and $k$ is the number of sources. These computational improvements allow for efficient posterior inference through reversible jump Markov chain Monte Carlo (RJMCMC). We use the non-reversible extension of RJMCMC (NRJMCMC), which often achieves lower autocorrelation and faster convergence than the conventional reversible variant. Detection, estimation, and reconstruction of the latent source signals can then all be performed in a fully Bayesian manner through the samples drawn using NRJMCMC. We evaluate the detection performance of the procedure by comparing against generalized likelihood ratio testing (GLRT) and information criteria.
Experimental Analysis and Modeling of Penetration Loss for Building Materials in FR1 and FR3 bands
Authors: Enrui Liu, Pan Tang, Tao Jiang, Jianhua Zhang
Date: 2024-12-11 00:00:00

This study focuses on analysis and modeling of the penetration loss of typical building materials in the FR1 (450 MHz-6 GHz) and FR3 (7-24 GHz) bands based on experimental measurements. Firstly, we measure the penetration loss characteristics of four different typical building materials from 4 to 16 GHz, including wood, glass, foam and concrete, by using a penetration loss measurement platform based on the vector network analyzer (VNA). Next, we analyze the frequency dependence and thickness dependence of penetration loss. Finally, the linear model is applied to fit the curve of the measured penetration loss, and new model parameters for the penetration loss of different building materials are given, which are compared with that in the third generation partnership project (3GPP) technical report (TR) 38.901. The analysis results and new model parameters may provides insight into understanding propagation characteristics in FR1 and FR3 bands and 3GPP channel model standardisation.
An SDR-Based Monostatic Wi-Fi System with Analog Self-Interference Cancellation for Sensing
Authors: Andreas Toftegaard Kristensen, Alexios Balatsoukas-Stimming, Andreas Burg
Date: 2024-12-11 00:00:00

Wireless sensing offers an alternative to wearables for contactless monitoring of human activity and vital signs. However, most existing systems use bistatic setups, which suffer from phase imperfections due to unsynchronized clocks. Monostatic systems overcome this issue, but are hindered by strong self-interference (SI) that require effective cancellation. We present a monostatic Wi-Fi sensing system that uses an auxiliary transmit RF chain to achieve SI cancellation levels of 40 dB, comparable to existing solutions with custom cancellation hardware. We demonstrate that the cancellation filter weights, fine-tuned using least-mean squares, can be directly repurposed for target sensing. Moreover, we achieve stable SI cancellation over 30 minutes in an office environment without fine-tuning, enabling traditional vital sign monitoring using channel estimates derived from baseband samples without the adaptation of the cancellation affecting the sensing channel -- a significant limitation in prior work. Experimental results confirm the detection of small, slow-moving targets, representative for breathing chest movements, at distances up to 10 meters in non-line-of-sight conditions.
COST INTERACT Whitepaper on Signal Processing for Communications, Localization, and Intergrated Sensing and Communication
Authors: Alister Burr, Ana Garcia Armada, Carsten Smeenk, Yang Miao
Date: 2024-12-11 00:00:00

The upcoming next generation of wireless communication is anticipated to revolutionize the conventional functionalities of the network by adding sensing and localization capabilities, low-power communication, wireless brain computer interactions, massive robotics and autonomous systems connection. Furthermore, the key performance indicators expected for the 6G of mobile communications promise challenging operating conditions, such as user data rates of 1 Tbps, end-to-end latency of less than 1 ms, and vehicle speeds of 1000 km per hour. This evolution needs new techniques, not only to improve communications, but also to provide localization and sensing with an efficient use of the radio resources. The goal of INTERACT Working Group 2 is to design novel physical layer technologies that can meet these KPI, by combining the data information from statistical learning with the theoretical knowledge of the transmitted signal structure. Waveforms and coding, advanced multiple-input multiple-output and all the required signal processing, in sub-6-GHz, millimeter-wave bands and upper-mid-band, are considered while aiming at designing these new communications, positioning and localization techniques. This White Paper summarizes our main approaches and contributions.
On the Joint Beamforming Design for Large-scale Downlink RIS-assisted Multiuser MIMO Systems
Authors: Eduard E. Bahingayi, Nemanja Stefan Perović, Le-Nam Tran
Date: 2024-12-11 00:00:00

Reconfigurable intelligent surfaces (RISs) have huge potential to improve spectral and energy efficiency in future wireless systems at a minimal cost. However, early prototype results indicate that deploying hundreds or thousands of reflective elements is necessary for significant performance gains. Motivated by this, our study focuses on \emph{large-scale } RIS-assisted multi-user (MU) multiple-input multiple-output (MIMO) systems. In this context, we propose an efficient algorithm to jointly design the precoders at the base station (BS) and the phase shifts at the RIS to maximize the weighted sum rate (WSR). In particular, leveraging an equivalent lower-dimensional reformulation of the WSR maximization problem, we derive a closed-form solution to optimize the precoders using the successive convex approximation (SCA) framework. While the equivalent reformulation proves to be efficient for the precoder optimization, we offer numerical insights into why the original formulation of the WSR optimization problem is better suited for the phase shift optimization. Subsequently, we develop a scaled projected gradient method (SPGM) and a novel line search procedure to optimize RIS phase shifts. Notably, we show that the complexity of the proposed method \emph{scales linearly with the number of BS antennas and RIS reflective elements}. Extensive numerical experiments demonstrate that the proposed algorithm significantly reduces both time and computational complexity while achieving higher WSR compared to baseline algorithms.
Parameter Estimation based Automatic Modulation Recognition for Radio Frequency Signal
Authors: Shuo Wang, Kuojun Yang, Zelin Ji, Qinchuan Zhang, Huiqing Pan
Date: 2024-12-11 00:00:00
Tasks: Automatic Modulation Recognition, parameter estimation

Automatic modulation recognition (AMR) critically contributes to spectrum sensing, dynamic spectrum access, and intelligent communications in cognitive radio systems. The introduction of deep learning has greatly improved the accuracy of AMR. However, current automatic identification methods require the input of key parameters such as the carrier frequency, which is necessary to convert the radio frequency (RF) to a base-band signal before it can be used for identification. In addition, the high complexity of deep learning models leads to high computational effort and long recognition times of existing methods, which are difficult to implement in demodulation system deployments. To address the above issues, in this paper, we first use power spectrum analysis to estimate the carrier frequency and signal bandwidth, which realizes the effective conversion from RF signals to base-band signals. This paper chooses the long short-term memory (LSTM) network as the model for automatic identification, which has low implementation complexity while maintaining high accuracy. Finally, by training the LSTM with actual sampling data combined with parameter estimation (PE), the method proposed in this paper can guarantee more than 90% format recognition accuracy.
5G NR monostatic positioning with array impairments: Data-and-model-driven framework and experiment results
Authors: Shengheng Liu, Hao Wang, Mengguan Pan, Peng Liu, Yahui Ma, Yongming Huang
Date: 2024-12-11 00:00:00

In this article, we present an intelligent framework for 5G new radio (NR) indoor positioning under a monostatic configuration. The primary objective is to estimate both the angle of arrival and time of arrival simultaneously. This requires capturing the pertinent information from both the antenna and subcarrier dimensions of the receive signals. To tackle the challenges posed by the intricacy of the high-dimensional information matrix, coupled with the impact of irregular array errors, we design a deep learning scheme. Recognizing that the phase difference between any two subcarriers and antennas encodes spatial information of the target, we contend that the transformer network is better suited for this problem compared to the convolutional neural network which excels in local feature extraction. To further enhance the network's fitting capability, we integrate the transformer with a model-based multiple-signal-classification (MUSIC) region decision mechanism. Numerical results and field tests demonstrate the effectiveness of the proposed framework in accurately calibrating the irregular angle-dependent array error and improving positioning accuracy.
Active Sampling and Gaussian Reconstruction for Radio Frequency Radiance Field
Authors: Chi-Shiang Gau, Xingyu Chen, Tara Javidi, Xinyu Zhang
Date: 2024-12-11 00:00:00

Radio-frequency (RF) Radiance Field reconstruction is a challenging problem. The difficulty lies in the interactions between the propagating signal and objects, such as reflections and diffraction, which are hard to model precisely, especially when the shapes and materials of the objects are unknown. Previously, a neural network-based method was proposed to reconstruct the RF Radiance Field, showing promising results. However, this neural network-based method has some limitations: it requires a large number of samples for training and is computationally expensive. Additionally, the neural network only provides the predicted mean of the RF Radiance Field and does not offer an uncertainty model. In this work, we propose a training-free Gaussian reconstruction method for RF Radiance Field. Our method demonstrates that the required number of samples is significantly smaller compared to the neural network-based approach. Furthermore, we introduce an uncertainty model that provides confidence estimates for predictions at any selected position in the scene. We also combine the Gaussian reconstruction method with active sampling, which further reduces the number of samples needed to achieve the same performance. Finally, we explore the potential benefits of our method in a quasi-dynamic setting, showcasing its ability to adapt to changes in the scene without requiring the entire process to be repeated.
Streamlined Swift Allocation Strategies for Radio Stripe Networks
Authors: Filipe Conceição, Marco Gomes, Vitor Silva, Rui Dinis
Date: 2024-12-10 00:00:00

This paper proposes the use of an access point (AP) selection scheme to improve the total uplink (UL) spectral efficiency (SE) of a radio stripe (RS) network. This scheme optimizes the allocation matrix between the total number of APs' antennas and users' equipment (UEs) while considering two state-of-the-art and two newly proposed equalization approaches: centralized maximum ratio combining (CMRC), centralized optimal sequence linear processing (COSLP), sequential MRC (SMRC), and parallel MRC (PMRC). The optimization problem is solved through a low-complexity and adaptive genetic algorithm (GA) which aims to output an efficient solution for the AP-UE association matrix. We evaluate the proposed schemes in several network scenarios in terms of SE performance, convergence speed, computational complexity, and fronthaul signalling capacity requirements. The COSLP exhibits the best SE performance at the expense of high computational complexity and fronthaul signalling. The SMRC and PMRC are efficient solutions alternatives to the CMRC, improving its computational complexity and convergence speed. Additionally, we assess the adaptability of the MRC schemes for two different instances of network change: when a new randomly located UE must connect to the RS network and when a random UE is removed from it. We have found that in some cases, by reusing the allocation matrix from the original instance as an initial solution, the SMRC and/or the PMRC can significantly boost the optimization performance of the GA-based AP selection scheme.
Multi-Modal Environmental Sensing Based Path Loss Prediction for V2I Communications
Authors: Kai Wang, Li Yu, Jianhua Zhang, Yixuan Tian, Eryu Guo, Guangyi Liu
Date: 2024-12-10 00:00:00

The stability and reliability of wireless data transmission in vehicular networks face significant challenges due to the high dynamics of path loss caused by the complexity of rapidly changing environments. This paper proposes a multi-modal environmental sensing-based path loss prediction architecture (MES-PLA) for V2I communications. First, we establish a multi-modal environment data and channel joint acquisition platform to generate a spatio-temporally synchronized and aligned dataset of environmental and channel data. Then we designed a multi-modal feature extraction and fusion network (MFEF-Net) for multi-modal environmental sensing data. MFEF-Net extracts features from RGB images, point cloud data, and GPS information, and integrates them with an attention mechanism to effectively leverage the strengths of each modality. The simulation results demonstrate that the Root Mean Square Error (RMSE) of MES-PLA is 2.20 dB, indicating a notable improvement in prediction accuracy compared to single-modal sensing data input. Moreover, MES-PLA exhibits enhanced stability under varying illumination conditions compared to single-modal methods.
A Software-Defined and Distributed Wi-Fi Channel-State Information Acquisition Testbed
Authors: Frederik Zumegen, Christoph Studer
Date: 2024-12-10 00:00:00

We propose a software-defined testbed for Wi-Fi channel-state information (CSI) acquisition. This testbed features distributed software-defined radios (SDRs) and a custom IEEE 802.11a software stack that enables the passive collection of CSI data from commercial off-the-shelf (COTS) devices that connect to an existing Wi-Fi network. Unlike commodity Wi-Fi sniffers or channel sounders, our software-defined testbed enables a quick exploration of advanced CSI estimation algorithms in real-world scenarios from naturally-generated Wi-Fi traffic. We explore the effectiveness of two advanced algorithms that denoise CSI estimates, and we demonstrate that CSI-based positioning of COTS Wi-Fi devices with a multilayer perceptron is feasible in an indoor office/lab space in which people are moving.
GSM: A GNN-based Space-MIMO Framework for Direct-to-Cell Communications
Authors: Sai Xu, Yanan Du, Gaojie Chen, Rahim Tafazolli
Date: 2024-12-10 00:00:00
Tasks: Graph Neural Network

This paper proposes a graph neural network (GNN)-based space multiple-input multiple-output (MIMO) framework, named GSM, for direct-to-cell communications, aiming to achieve distributed coordinated beamforming for low Earth orbit (LEO) satellites. Firstly, a system model for LEO multi-satellite communications is established, where multiple LEO satellites collaborate to perform distributed beamforming and communicate with terrestrial user terminals coherently. Based on the system model, a weighted sum rate maximization problem is formulated. Secondly, a GNN-based method is developed to address the optimization problem. Particularly, the adopted neural network is composed of multiple identical GNNs, which are trained together and then deployed individually on each LEO satellite. Finally, the trained GNN is quantized and deployed on a field-programmable gate array (FPGA) to accelerate the inference by customizing the microarchitecture. Simulation results demonstrate that the proposed GNN scheme outperforms the benchmark ones including maximum ratio transmission, zero forcing and minimum mean square error. Furthermore, experimental results show that the FPGA-based accelerator achieves remarkably low inference latency, ranging from 3.863 to 5.883 ms under a 10-ns target clock period with 8-bit fixed-point data representation.