Pub Date : 2025-11-04DOI: 10.1109/JRFID.2025.3628985
Clemens Korn;Joerg Robert
Radio Frequency Identification (RFID) is a widely used technology for identifying and locating objects equipped with low-cost RFID transponders (tags). UHF (Ultra High Frequency) RFID operates in frequency bands around 900 MHz and supports communication distances of up to 15 m between the reader and the tag. Reliable motion detection is therefore a highly relevant feature in modern logistics – for example, to determine whether a tag is actually placed on a conveyor belt or merely in its vicinity. A promising approach for accurate motion detection is the use of the Doppler effect. Some state-of-the-art UHF-RFID readers already support Doppler shift measurements. However, their measurement accuracy is insufficient for many applications. In this paper, we propose enhancements for the precise Doppler shift estimation using existing RFID systems – an essential step toward enabling RFID-based motion detection in future logistics. Further, we also derive the theoretical bounds for Doppler-based motion detection in UHF-RFID systems based on the Cramer-Rao Lower Bound. These bounds analyze the influence of tag signal strength, signal duration, and the intervals between multiple tag replies on the performance of motion detection and speed estimation algorithms. In addition, we establish theoretical limits that account for hardware constraints in current UHF-RFID readers. The results of this work provide valuable insights into the limitations of Doppler-based motion detection and support system-level performance optimization. They enable prediction of achievable performance based on reader noise figure, aiding in the design and tuning of RFID systems.
{"title":"Theoretical Bounds for Enhanced Doppler-Based Motion Detection in UHF-RFID Readers","authors":"Clemens Korn;Joerg Robert","doi":"10.1109/JRFID.2025.3628985","DOIUrl":"https://doi.org/10.1109/JRFID.2025.3628985","url":null,"abstract":"Radio Frequency Identification (RFID) is a widely used technology for identifying and locating objects equipped with low-cost RFID transponders (tags). UHF (Ultra High Frequency) RFID operates in frequency bands around 900 MHz and supports communication distances of up to 15 m between the reader and the tag. Reliable motion detection is therefore a highly relevant feature in modern logistics – for example, to determine whether a tag is actually placed on a conveyor belt or merely in its vicinity. A promising approach for accurate motion detection is the use of the Doppler effect. Some state-of-the-art UHF-RFID readers already support Doppler shift measurements. However, their measurement accuracy is insufficient for many applications. In this paper, we propose enhancements for the precise Doppler shift estimation using existing RFID systems – an essential step toward enabling RFID-based motion detection in future logistics. Further, we also derive the theoretical bounds for Doppler-based motion detection in UHF-RFID systems based on the Cramer-Rao Lower Bound. These bounds analyze the influence of tag signal strength, signal duration, and the intervals between multiple tag replies on the performance of motion detection and speed estimation algorithms. In addition, we establish theoretical limits that account for hardware constraints in current UHF-RFID readers. The results of this work provide valuable insights into the limitations of Doppler-based motion detection and support system-level performance optimization. They enable prediction of achievable performance based on reader noise figure, aiding in the design and tuning of RFID systems.","PeriodicalId":73291,"journal":{"name":"IEEE journal of radio frequency identification","volume":"9 ","pages":"883-894"},"PeriodicalIF":3.4,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145560792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-28DOI: 10.1109/JRFID.2025.3626017
Shuai Yang;Ryan Jones;Richard Penty;Michael Crisp
This paper introduces novel sensing applications leveraging tag-to-tag communication. Building on a prior method for inter-tag channel estimation, we explore various proof-of-concept sensing modalities enabled by this technique and compare these to conventional reader to tag measurements. We demonstrate that tag displacement information, including both 1D and 2D localization, can be accurately estimated. Specifically, our approach achieves better than 2.5 cm error in over 90% of the test locations with only a single reader antenna. Furthermore, we investigate the inter-tag channel dependence on angular misalignment of the tags, and show that the inter-tag channel phase is independent of rotation and hence our method is robust to tag angular misalignment. Finally we demonstrate liquid level sensing of a container in the inter-tag channel, showing that the fill level of a bottle can be estimated, independent of its position.
{"title":"Applications in Localization and Sensing Leveraging Inter-Tag Channel Estimation","authors":"Shuai Yang;Ryan Jones;Richard Penty;Michael Crisp","doi":"10.1109/JRFID.2025.3626017","DOIUrl":"https://doi.org/10.1109/JRFID.2025.3626017","url":null,"abstract":"This paper introduces novel sensing applications leveraging tag-to-tag communication. Building on a prior method for inter-tag channel estimation, we explore various proof-of-concept sensing modalities enabled by this technique and compare these to conventional reader to tag measurements. We demonstrate that tag displacement information, including both 1D and 2D localization, can be accurately estimated. Specifically, our approach achieves better than 2.5 cm error in over 90% of the test locations with only a single reader antenna. Furthermore, we investigate the inter-tag channel dependence on angular misalignment of the tags, and show that the inter-tag channel phase is independent of rotation and hence our method is robust to tag angular misalignment. Finally we demonstrate liquid level sensing of a container in the inter-tag channel, showing that the fill level of a bottle can be estimated, independent of its position.","PeriodicalId":73291,"journal":{"name":"IEEE journal of radio frequency identification","volume":"9 ","pages":"874-882"},"PeriodicalIF":3.4,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145510153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-16DOI: 10.1109/JRFID.2025.3622467
Yuheng He;Chinaza Ogbonna;Sree Adinarayana Dasari;Seung Yoon Lee;Luke A. Beardslee;Nima Ghalichechian
We present the design, simulation, fabrication, and measurement results of a biodegradable sensor for postoperative monitoring. The proposed sensor is composed of a modified split-ring resonator (SRR) loaded with interdigitated capacitors (IDCs). The sensor operates at around 3.2 GHz in free space and around 2 GHz in liquid solution. The designed sensor can resolve the sensing film thickness of $6.2~mu $ m. The sensitivity is extracted to be 4.2% in free space and 1.8% in the phantom box. A 2-tag configuration is developed to calibrate for the uncertain operating frequency when implanted. Additionally, both wired and wireless measurements are developed to fully characterize the sensor performance. Lastly, we demonstrated that the backscattering measurement data, quantified as resonance frequency in a laboratory environment, matches well with the simulation results. This work demonstrates the potential of using a wireless solution for microwave thickness sensing in next-generation biodegradable devices.
{"title":"A Bioresorbable Backscatter Sensor Facilitated by IDCs Loaded SRR for pH Monitoring","authors":"Yuheng He;Chinaza Ogbonna;Sree Adinarayana Dasari;Seung Yoon Lee;Luke A. Beardslee;Nima Ghalichechian","doi":"10.1109/JRFID.2025.3622467","DOIUrl":"https://doi.org/10.1109/JRFID.2025.3622467","url":null,"abstract":"We present the design, simulation, fabrication, and measurement results of a biodegradable sensor for postoperative monitoring. The proposed sensor is composed of a modified split-ring resonator (SRR) loaded with interdigitated capacitors (IDCs). The sensor operates at around 3.2 GHz in free space and around 2 GHz in liquid solution. The designed sensor can resolve the sensing film thickness of <inline-formula> <tex-math>$6.2~mu $ </tex-math></inline-formula>m. The sensitivity is extracted to be 4.2% in free space and 1.8% in the phantom box. A 2-tag configuration is developed to calibrate for the uncertain operating frequency when implanted. Additionally, both wired and wireless measurements are developed to fully characterize the sensor performance. Lastly, we demonstrated that the backscattering measurement data, quantified as resonance frequency in a laboratory environment, matches well with the simulation results. This work demonstrates the potential of using a wireless solution for microwave thickness sensing in next-generation biodegradable devices.","PeriodicalId":73291,"journal":{"name":"IEEE journal of radio frequency identification","volume":"9 ","pages":"865-873"},"PeriodicalIF":3.4,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145510154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-13DOI: 10.1109/JRFID.2025.3620894
Marek Jahnke;Ben Palmer;Enrico Stoll;Ulf Kulau
LiFi for intra-satellite communication offers immense advantages like flexible AIT or reduced complexity (harness). However, high bandwidths and redundancies are equally required. Modulation methods that make use of the broad spectrum of light are Color Space Based Modulations (CSBMs). However, this requires precise knowledge of the transceivers and environments, as previous methods usually map to the CIE 1931 color scheme. But for intra-satellite communication, various assumptions can be made that favor the use of CSBM within the satellite. This paper presents an automated procedure that generates the symbols for CSBM. In order to ensure high reliability while using the entire color space for the symbols, a method based on cuboids is presented, which guarantees an overlap-free mapping between Transmit- and Signal-Space. In addition, the implementation of a Receiver based on an Field Programmable Gate Array (FPGA) is presented and real world measurements are conducted in detail to show the automatic symbol generation and the evaluation of symbol detection capabilities for communication.
{"title":"Implementation and Evaluation of CSBM for Intra-Satellite Communication With Cuboid-Based Signal-Space Generated Symbols","authors":"Marek Jahnke;Ben Palmer;Enrico Stoll;Ulf Kulau","doi":"10.1109/JRFID.2025.3620894","DOIUrl":"https://doi.org/10.1109/JRFID.2025.3620894","url":null,"abstract":"LiFi for intra-satellite communication offers immense advantages like flexible AIT or reduced complexity (harness). However, high bandwidths and redundancies are equally required. Modulation methods that make use of the broad spectrum of light are Color Space Based Modulations (CSBMs). However, this requires precise knowledge of the transceivers and environments, as previous methods usually map to the CIE 1931 color scheme. But for intra-satellite communication, various assumptions can be made that favor the use of CSBM within the satellite. This paper presents an automated procedure that generates the symbols for CSBM. In order to ensure high reliability while using the entire color space for the symbols, a method based on cuboids is presented, which guarantees an overlap-free mapping between Transmit- and Signal-Space. In addition, the implementation of a Receiver based on an Field Programmable Gate Array (FPGA) is presented and real world measurements are conducted in detail to show the automatic symbol generation and the evaluation of symbol detection capabilities for communication.","PeriodicalId":73291,"journal":{"name":"IEEE journal of radio frequency identification","volume":"9 ","pages":"852-864"},"PeriodicalIF":3.4,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145352086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A limitation to the practical use of chipless tags is due to the short reading distance, the small number of bits to be used for identification and the stability of the response. For sensor tag a further limitation is the sensitivity. In this work we present a design method and a model of a chipless sensor tag for crack mouth opening displacement that allow to improve these limitations. The sensor tag has been realized and measured confirming the design characteristics. It, based on the spectral signature, has 6 spectral lines (‘bits’) for identification, 1 spectral line for the sensor with adjustable sensitivity. In the experimental measurements it resulted readable from a distance of around 40 cm, from a direction of ± 15° with respect to boresight and with a sensitivity of around 29MHz/mm.
{"title":"A Crack Mouth Opening Displacement Gauge Based on Van-Atta UWB Cross-Pol Chipless Tag Technology","authors":"Alessandro Di-Carlofelice;Emidio Di-Giampaolo;Piero Tognolatti","doi":"10.1109/JRFID.2025.3617957","DOIUrl":"https://doi.org/10.1109/JRFID.2025.3617957","url":null,"abstract":"A limitation to the practical use of chipless tags is due to the short reading distance, the small number of bits to be used for identification and the stability of the response. For sensor tag a further limitation is the sensitivity. In this work we present a design method and a model of a chipless sensor tag for crack mouth opening displacement that allow to improve these limitations. The sensor tag has been realized and measured confirming the design characteristics. It, based on the spectral signature, has 6 spectral lines (‘bits’) for identification, 1 spectral line for the sensor with adjustable sensitivity. In the experimental measurements it resulted readable from a distance of around 40 cm, from a direction of ± 15° with respect to boresight and with a sensitivity of around 29MHz/mm.","PeriodicalId":73291,"journal":{"name":"IEEE journal of radio frequency identification","volume":"9 ","pages":"841-851"},"PeriodicalIF":3.4,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145352118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article investigates the secrecy performance of a non-linear energy-harvesting backscatter communication (BackCom) network in the presence of direct link and reconfigurable intelligent surface (RIS) interference. The network comprises a source, multiple passive tags, an RIS, and a legitimate reader, with an eavesdropper attempting to intercept the communication. We analyze a tag selection scheme based on long-short-term memory (LSTM) to address the challenge of selecting tags under the influence of direct link and the RIS interference. The nonideal behavior of the RIS is exploited to enhance secrecy performance by modeling RIS phase errors using Von Mises and uniform distributions. Because of interference from the direct link and the RIS being common to all tags, the secrecy rates of different tags are correlated. The LSTM-based scheme effectively captures this correlation and perfectly matches the conventional selection scheme on low and high tag counts. The secrecy outage probability (SOP) achieved using the LSTM outperforms other machine learning techniques, such as $k$ -nearest neighbors ($k$ -NN), decision trees (DT), and support vector machines (SVM). We also demonstrate the impact of RIS elements, phase error parameters, and the number of tags on the SOP in the considered RIS-aided BackCom network.
{"title":"Deep Learning-Based Secure Tag Selection in BackCom Network With RIS-Induced Interference","authors":"Yasin Khan;Shalini Tripathi;Ankit Dubey;Sudhir Kumar;Sunish Kumar Orappanpara Soman","doi":"10.1109/JRFID.2025.3611299","DOIUrl":"https://doi.org/10.1109/JRFID.2025.3611299","url":null,"abstract":"This article investigates the secrecy performance of a non-linear energy-harvesting backscatter communication (BackCom) network in the presence of direct link and reconfigurable intelligent surface (RIS) interference. The network comprises a source, multiple passive tags, an RIS, and a legitimate reader, with an eavesdropper attempting to intercept the communication. We analyze a tag selection scheme based on long-short-term memory (LSTM) to address the challenge of selecting tags under the influence of direct link and the RIS interference. The nonideal behavior of the RIS is exploited to enhance secrecy performance by modeling RIS phase errors using Von Mises and uniform distributions. Because of interference from the direct link and the RIS being common to all tags, the secrecy rates of different tags are correlated. The LSTM-based scheme effectively captures this correlation and perfectly matches the conventional selection scheme on low and high tag counts. The secrecy outage probability (SOP) achieved using the LSTM outperforms other machine learning techniques, such as <inline-formula> <tex-math>$k$ </tex-math></inline-formula>-nearest neighbors (<inline-formula> <tex-math>$k$ </tex-math></inline-formula>-NN), decision trees (DT), and support vector machines (SVM). We also demonstrate the impact of RIS elements, phase error parameters, and the number of tags on the SOP in the considered RIS-aided BackCom network.","PeriodicalId":73291,"journal":{"name":"IEEE journal of radio frequency identification","volume":"9 ","pages":"797-806"},"PeriodicalIF":3.4,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-10DOI: 10.1109/JRFID.2025.3608617
Nadeem Rather;Roy B. V. B. Simorangkir;Dinesh R. Gawade;John L. Buckley;Brendan O’Flynn;Salvatore Tedesco
This paper presents a comprehensive design and implementation approach for robust detection of depolarizing chipless RFID (CRFID) tags. Depolarizing tags are advantageous compared to co-polar CRFID tags due to their improved performance on RF-lossy materials. This work introduces the application of deep learning (DL) regression modelling to a specialised dataset of depolarised Radar Cross Section (RCS) measurements of a custom 3-bit CRFID tag, acquired through an extensive robot-based data acquisition method. A dataset of 12,600 depolarised Electromagnetic (EM) RCS signatures were collected using an automated data acquisition system to train and validate a 1-dimensional Convolutional Neural Network (1D CNN) architecture. A novel hybrid 1D CNN with Bi-LSTM and attention mechanism architecture was also implemented to visualize the model attention and improve detection performance. We present, for the first time reported in literature, a comprehensive design and AI implementation approach for reliably detecting identification (ID) information from depolarized signals. Also, we report the first instance of describing the impact of surface permittivity variations, tag deformations, tilt angles, and read ranges, all integrated into model training for enhanced robustness in detecting ID information. The developed models facilitate real-time identification and recording of objects, enhancing IoT applications in varied environments. It was observed that both models were able to generalize well to given data, with Model-1 achieving a low RMSE of 0.040 (0.66%) on an unseen test dataset. However, the hybrid model reduced the error further by 27.5% with a test RMSE of 0.029 (0.48%).
{"title":"Hybrid DCNN-Enabled Depolarizing Chipless RFID: Improving Tag Detection Across Varying Lossy Surfaces and Shapes","authors":"Nadeem Rather;Roy B. V. B. Simorangkir;Dinesh R. Gawade;John L. Buckley;Brendan O’Flynn;Salvatore Tedesco","doi":"10.1109/JRFID.2025.3608617","DOIUrl":"https://doi.org/10.1109/JRFID.2025.3608617","url":null,"abstract":"This paper presents a comprehensive design and implementation approach for robust detection of depolarizing chipless RFID (CRFID) tags. Depolarizing tags are advantageous compared to co-polar CRFID tags due to their improved performance on RF-lossy materials. This work introduces the application of deep learning (DL) regression modelling to a specialised dataset of depolarised Radar Cross Section (RCS) measurements of a custom 3-bit CRFID tag, acquired through an extensive robot-based data acquisition method. A dataset of 12,600 depolarised Electromagnetic (EM) RCS signatures were collected using an automated data acquisition system to train and validate a 1-dimensional Convolutional Neural Network (1D CNN) architecture. A novel hybrid 1D CNN with Bi-LSTM and attention mechanism architecture was also implemented to visualize the model attention and improve detection performance. We present, for the first time reported in literature, a comprehensive design and AI implementation approach for reliably detecting identification (ID) information from depolarized signals. Also, we report the first instance of describing the impact of surface permittivity variations, tag deformations, tilt angles, and read ranges, all integrated into model training for enhanced robustness in detecting ID information. The developed models facilitate real-time identification and recording of objects, enhancing IoT applications in varied environments. It was observed that both models were able to generalize well to given data, with Model-1 achieving a low RMSE of 0.040 (0.66%) on an unseen test dataset. However, the hybrid model reduced the error further by 27.5% with a test RMSE of 0.029 (0.48%).","PeriodicalId":73291,"journal":{"name":"IEEE journal of radio frequency identification","volume":"9 ","pages":"768-778"},"PeriodicalIF":3.4,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11157779","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-03DOI: 10.1109/JRFID.2025.3605595
Lei Zuo;Bihang Lei;Lingshuo Li;Bing Li;Baiqiang Yin;Lifen Yuan
Focusing on the issue of how variations in liquid level height within a container affect the performance of passive ultrahigh frequency (UHF) radio frequency identification (RFID) tags, this study derives a link budget model for a passive UHF RFID system based on RFID operational principles and electromagnetic wave propagation theory. Using power transmission coefficients, the study analyzes how impedance mismatch caused by liquid in the container affects system performance. To validate the theoretical model, a combination of simulations and indoor experiments was employed, establishing segmented models of the tag response signal power (RSSI) as a function of liquid level height in both vertical and horizontal tag orientations. The RSSI of two tags, Alien9662 and Alien9640, was tested in an open indoor environment across varying liquid levels from 0 mm to 140 mm, measuring signal strength variations under different liquid levels. Theoretical analysis and experimental results reveal that when the liquid level changes along the antenna’s bent arm, RSSI decreases significantly (e.g., from –43.4 dBm to –75.6 dBm for the Alien9662 tag in vertical deployment). when the liquid level changes along the small electrical loop, RSSI first increases and then decreases (e.g., from –52.8 dBm to –43.4 dBm for L < 20 mm), exhibiting a nonlinear variation with liquid level height. The RSSI changes observed in both tags align with the segmented models, validating the model’s accuracy. These findings not only provide a theoretical basis for understanding the impact of liquid environments on RFID system performance but also offer a reference for optimizing RFID tag placement in liquid containers, which could support practical applications such as inventory management and liquid level monitoring.
{"title":"Study on the Influence of Liquid Level Height in Containers on RFID System Performance","authors":"Lei Zuo;Bihang Lei;Lingshuo Li;Bing Li;Baiqiang Yin;Lifen Yuan","doi":"10.1109/JRFID.2025.3605595","DOIUrl":"https://doi.org/10.1109/JRFID.2025.3605595","url":null,"abstract":"Focusing on the issue of how variations in liquid level height within a container affect the performance of passive ultrahigh frequency (UHF) radio frequency identification (RFID) tags, this study derives a link budget model for a passive UHF RFID system based on RFID operational principles and electromagnetic wave propagation theory. Using power transmission coefficients, the study analyzes how impedance mismatch caused by liquid in the container affects system performance. To validate the theoretical model, a combination of simulations and indoor experiments was employed, establishing segmented models of the tag response signal power (RSSI) as a function of liquid level height in both vertical and horizontal tag orientations. The RSSI of two tags, Alien9662 and Alien9640, was tested in an open indoor environment across varying liquid levels from 0 mm to 140 mm, measuring signal strength variations under different liquid levels. Theoretical analysis and experimental results reveal that when the liquid level changes along the antenna’s bent arm, RSSI decreases significantly (e.g., from –43.4 dBm to –75.6 dBm for the Alien9662 tag in vertical deployment). when the liquid level changes along the small electrical loop, RSSI first increases and then decreases (e.g., from –52.8 dBm to –43.4 dBm for L < 20 mm), exhibiting a nonlinear variation with liquid level height. The RSSI changes observed in both tags align with the segmented models, validating the model’s accuracy. These findings not only provide a theoretical basis for understanding the impact of liquid environments on RFID system performance but also offer a reference for optimizing RFID tag placement in liquid containers, which could support practical applications such as inventory management and liquid level monitoring.","PeriodicalId":73291,"journal":{"name":"IEEE journal of radio frequency identification","volume":"9 ","pages":"758-767"},"PeriodicalIF":3.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145090150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-26DOI: 10.1109/JRFID.2025.3602901
Hansaka Aluvihare;Sivakumar Sivasankar;Xianqi Li;Arjuna Madanayake;Sirani M. Perera
True-time-delay (TTD) beamformers can produce wideband squint-free beams in both analog and digital signal domains, unlike frequency-dependent FFT beams. Our previous work showed that TTD beamformers can be efficiently realized using the elements of the delay Vandermonde matrix (DVM), answering the longstanding beam-squint problem. Thus, building on our work on DVM algorithms, we propose a structured neural network (StNN) to realize wideband multi-beam beamformers using structure-imposed weight matrices and submatrices. The structure and sparsity of the weight matrices and submatrices are shown to reduce the computational complexity of the NN significantly. The proposed StNN architecture has $mathcal {O} boldsymbol {(p L M} log boldsymbol M)$ complexity compared to a conventional fully connected L-layers network with $mathcal {O}(M^{2}L)$ complexity, where M is the number of nodes in each layer of the network, p is the number of sub-weight matrices per layer, and $M gt gt p$ . We show numerical simulations in the 24 to 32 GHz range to demonstrate the numerical feasibility of realizing wideband multi-beam beamformers using the proposed StNN architecture. We also show the complexity reduction of the proposed NN and compare that with fully connected NNs, to show the efficiency of the proposed architecture without sacrificing accuracy. The accuracy of the proposed NN architecture was shown in terms of the mean squared error, which is based on an objective function of the weight matrices and beamformed signals of antenna arrays, while also normalizing nodes. The proposed StNN’s robustness was tested against channel impairments by simulating with Rayleigh fading at different signal-to-noise ratios (SNRs). We show that the proposed StNN architecture leads to a low-complexity NN to realize wideband multi-beam beamformers, enabling a path for reconfigurable intelligent systems.
{"title":"A Low-Complexity Structured Neural Network Approach to Intelligently Realize Wideband Multi-Beam Beamformers","authors":"Hansaka Aluvihare;Sivakumar Sivasankar;Xianqi Li;Arjuna Madanayake;Sirani M. Perera","doi":"10.1109/JRFID.2025.3602901","DOIUrl":"https://doi.org/10.1109/JRFID.2025.3602901","url":null,"abstract":"True-time-delay (TTD) beamformers can produce wideband squint-free beams in both analog and digital signal domains, unlike frequency-dependent FFT beams. Our previous work showed that TTD beamformers can be efficiently realized using the elements of the delay Vandermonde matrix (DVM), answering the longstanding beam-squint problem. Thus, building on our work on DVM algorithms, we propose a structured neural network (StNN) to realize wideband multi-beam beamformers using structure-imposed weight matrices and submatrices. The structure and sparsity of the weight matrices and submatrices are shown to reduce the computational complexity of the NN significantly. The proposed StNN architecture has <inline-formula> <tex-math>$mathcal {O} boldsymbol {(p L M} log boldsymbol M)$ </tex-math></inline-formula> complexity compared to a conventional fully connected L-layers network with <inline-formula> <tex-math>$mathcal {O}(M^{2}L)$ </tex-math></inline-formula> complexity, where M is the number of nodes in each layer of the network, p is the number of sub-weight matrices per layer, and <inline-formula> <tex-math>$M gt gt p$ </tex-math></inline-formula>. We show numerical simulations in the 24 to 32 GHz range to demonstrate the numerical feasibility of realizing wideband multi-beam beamformers using the proposed StNN architecture. We also show the complexity reduction of the proposed NN and compare that with fully connected NNs, to show the efficiency of the proposed architecture without sacrificing accuracy. The accuracy of the proposed NN architecture was shown in terms of the mean squared error, which is based on an objective function of the weight matrices and beamformed signals of antenna arrays, while also normalizing nodes. The proposed StNN’s robustness was tested against channel impairments by simulating with Rayleigh fading at different signal-to-noise ratios (SNRs). We show that the proposed StNN architecture leads to a low-complexity NN to realize wideband multi-beam beamformers, enabling a path for reconfigurable intelligent systems.","PeriodicalId":73291,"journal":{"name":"IEEE journal of radio frequency identification","volume":"9 ","pages":"727-738"},"PeriodicalIF":3.4,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145036880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-22DOI: 10.1109/JRFID.2025.3601843
Nesrine Benchoubane;Olfa Ben Yahia;William Ferguson;Gürkan Gür;Sumit Chakravarty;Gregory Falco;Gunes Karabulut Kurt
In the face of adverse environmental conditions and cyber threats, robust communication systems for critical applications such as wildfire management and detection demand secure and resilient architectures. This paper presents a novel framework that considers both adversarial factors, building resilience into a heterogeneous network (HetNet)integrating Low Earth Orbit (LEO) satellite constellation with High-Altitude Platform Ground Stations (HAPGS) and Low-Altitude Platforms (LAPS), tailored to support wildfire management operations. Building upon our previous work on secure-by-component approach for link segment security, we extend protection to the communication layer by securing both Radio Frequency (RF)/Free Space Optics (FSO) management and different links. Through a case study, we quantify how environmental stressors impact secrecy capacity and expose the system to passive adversaries. Key findings demonstrate that atmospheric attenuation and beam misalignment can notably degrade secrecy capacity across both short- and long-range communication links, while high-altitude eavesdroppers face less signal degradation, increasing their interception capability. Moreover, increasing transmit power to counter environmental losses can inadvertently improve eavesdropper reception, thereby reducing overall link confidentiality. Our worknot only highlights the importance of protecting networks from these dual threats but also aligns with the IEEE P3536 Standard for Space System Cybersecurity Design, ensuring resilience and the prevention of mission failures.
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