Browsing by Author "Yalcinkaya, Bengisu"

Now showing 1 - 7 of 7

Citation - WoS: 2
Citation - Scopus: 3
An Experimental Study on the Influence of Human Movement in Indoor Radio Channel at 28ghz
(Ieee, 2021) Benzaghta, Mohamed; Coruk, Remziye Busra; Yalcinkaya, Bengisu; Kara, Ali
Human activities around the communication link in an indoor environment have a significant impact on millimeter-wave (mmWave) communication systems, which are used for the new generation of communication networks (5G). Therefore, it is essential to evaluate short range indoor links from the link blockage point of view. This paper presents the propagation measurements in the presence of human activity, for a short range indoor office environment communication link at 28 GHz. During the experimental measurements, the human activity of three and six persons were observed for three different antenna height combinations. The human blockage (shadowing effect) is characterized in terms of the shadowing event duration, temporal fading, as well as overall attenuation. The results reported by this experimental study is believed to be vital in designing future mmWave communication systems that can overcome the deep fades caused by human blockage in short indoor communication links. Yet, this paper constitutes a part of an ongoing research study, further detailed results will be foreseen to present the precise effect of human movements around the propagation link at 28GHz.
From Street Canyons To Corridors: Adapting Urban Propagation Models for an Indoor IQRF Network
(MDPI, 2025) Doyan, Talip Eren; Yalcinkaya, Bengisu; Dogan, Deren; Dalveren, Yaser; Derawi, Mohammad
Among wireless communication technologies underlying Internet of Things (IoT)-based smart buildings, IQRF (Intelligent Connectivity Using Radio Frequency) technology is a promising candidate due to its low power consumption, cost-effectiveness, and wide coverage. However, effectively modeling the propagation characteristics of IQRF in complex indoor environments for simple and accurate network deployment remains challenging, as architectural elements like walls and corners cause substantial signal attenuation and unpredictable propagation behavior. This study investigates the applicability of a site-specific modeling approach, originally developed for urban street canyons, to characterize peer-to-peer (P2P) IQRF links operating at 868 MHz in typical indoor scenarios, including line-of-sight (LoS), one-turn, and two-turn non-line-of-sight (NLoS) configurations. The received signal powers are compared with well-known empirical models, including international telecommunication union radio communication sector (ITU-R) P.1238-9 and WINNER II, and ray-tracing simulations. The results show that while ITU-R P.1238-9 achieves lower prediction error under LoS conditions with a root mean square error (RMSE) of 5.694 dB, the site-specific approach achieves substantially higher accuracy in NLoS scenarios, maintaining RMSE values below 3.9 dB for one- and two-turn links. Furthermore, ray-tracing simulations exhibited notably larger deviations, with RMSE values ranging from 7.522 dB to 16.267 dB and lower correlation with measurements. These results demonstrate the potential of site-specific modeling to provide practical, computationally efficient, and accurate insights for IQRF network deployment planning in smart building environments.
Citation - WoS: 5
Citation - Scopus: 5
Hierarchical Classification of Analog and Digital Modulation Schemes Using Higher-Order Statistics and Support Vector Machines
(Springer, 2024) Yalcinkaya, Bengisu; Coruk, Remziye Busra; Kara, Ali; Tora, Hakan
Automatic modulation classification (AMC) algorithms are crucial for various military and commercial applications. There have been numerous AMC algorithms reported in the literature, most of which focus on synthetic signals with a limited number of modulation types having distinctive constellations. The efficient classification of high-order modulation schemes under real propagation effects using models with low complexity still remains difficult. In this paper, employing quadratic SVM, a feature-based hierarchical classification method is proposed to accurately classify especially higher-order modulation schemes and its performance is investigated using over the air (OTA) collected data. Statistical features, higher-order moments, and higher-order cumulants are utilized as features. Then, the performances of some well-known classifiers are evaluated, and the classifier presenting the best performance is employed in the proposed hierarchical classification model. An OTA dataset containing 17 analog and digital modulation schemes is used to assess the performance of the proposed classification model. With the proposed hierarchical classification algorithm, a significant improvement has been achieved, especially in higher-order modulation schemes. The overall accuracy with the proposed hierarchical structure is 96% after 5 dB signal-to-noise ratio value, approximately a 10% increase is achieved compared to the traditional classification algorithm.
Low Signature UAVs: Radar Cross Section Analysis, Simulation, and Measurement in X-Band
(Springer London Ltd, 2025) Unalir, Dizdar; Yalcinkaya, Bengisu; Aydin, Elif
The increasing prevalence of unmanned aerial vehicles (UAVs) is driving the development of radar systems capable of detecting them. This hampers the deployment of UAVs in military operations. While radar cross section reduction (RCSR) can be a valuable solution, the research on this subject is inadequate. This paper presents an RCSR approach adopting a shaping technique for UAVs, demonstrating the proposed approach's efficacy through simulations and actual experimental measurements performed in X-Band on a four-legged UAV model. Using electromagnetic computational instruments, the shaping is applied to the designed UAV model with parameter-based simulations, the simulated radar cross section (RCS) values are derived, and the comparative analysis of these instruments is conducted. Experimental measurements are performed in laboratory conditions using a vector network analyzer. Actual measurement results are validated by simulative findings with the examination of the influence of frequency, polarization, and aspect angle on RCS. The demonstrated measuring approach allows cost-effective and easily applicable research on RCS in X-Band, a commonly utilized frequency range in military. An average RCSR of 10 dBsm has been accomplished with the presented shaping approach.
Citation - WoS: 1
Citation - Scopus: 1
Millimeter-Wave Sar Imaging for Sub-Millimeter Defect Detection With Non-Destructive Testing
(Mdpi, 2025) Yalcinkaya, Bengisu; Aydin, Elif; Kara, Ali
This paper introduces a high-resolution 77-81 GHz mmWave Synthetic Aperture Radar (SAR) imaging methodology integrating low-cost hardware with modified radar signal characteristics specifically for NDT applications. The system is optimized to detect minimal defects in materials, including low-reflectivity ones. In contrast to the existing studies, by optimizing key system parameters, including frequency slope, sampling interval, and scanning aperture, high-resolution SAR images are achieved with reduced computational complexity and storage requirements. The experiments demonstrate the effectiveness of the system in detecting optically undetectable minimal surface defects down to 0.4 mm, such as bonded adhesive lines on low-reflectivity materials with 2500 measurement points and sub-millimeter features on metallic targets at a distance of 30 cm. The results show that the proposed system achieves comparable or superior image quality to existing high-cost setups while requiring fewer data points and simpler signal processing. Low-cost, low-complexity, and easy-to-build mmWave SAR imaging is constructed for high-resolution SAR imagery of targets with a focus on detecting defects in low-reflectivity materials. This approach has significant potential for practical NDT applications with a unique emphasis on scalability, cost-effectiveness, and enhanced performance on low-reflectivity materials for industries such as manufacturing, civil engineering, and 3D printing.
Model Enhancement for UAV Stealth in X-Band
(IEEE, 2025) Unalir, Dizdar; Yalcinkaya, Bengisu; Aydin, Elif
With the rapid advancement of technology, radar detection techniques continue to evolve, challenging the effectiveness of traditional unmanned aerial vehicles (UAVs) stealth techniques. As the usage of UAVs in military applications expands, the need for effective radar cross section reduction (RCSR) methods to enhance their stealth capabilities has grown significantly. In this study, we propose an enhancement of a previously developed Low-RCS UAV model, focusing on RCSR with shaping technique in the X-band. For the identification and optimization of the UAV model's highly reflective components, a detailed simulative analysis of the RCS was performed using CST Studio Suite Environment. The modifications are applied to the body and leg components to minimize radar reflections. Simulation results demonstrated that the proposed enhancements significantly reduced RCS values compared to the original Low-RCS UAV model. A total of 13 dBsm reduction in RCS was observed compared to the traditional UAV models. Comparative analysis for different frequencies in X-Band and various aspect angles confirmed the effectiveness of the improved design, validating its potential for stealth applications. The findings can contribute to the research in UAV stealth technology and provide insights into future low-visibility UAV designs.
Citation - WoS: 5
Citation - Scopus: 6
On the Design and Effectiveness of Simulink-Based Educational Material for a Communication Systems Course
(Wiley, 2020) Coruk, R. Busra; Yalcinkaya, Bengisu; Kara, Ali
The methods used in engineering education have gained diversity in parallel with rapidly evolving technology. New technological methods along with the traditional methods have been adopted for undergraduate education. Today, Simulink-based educational materials are used in many fields in engineering education. However, in the literature, the contribution of such educational materials to the learning process has not been measured thoroughly. This study presents a comprehensive measurement method to improve the created course material and show the effectiveness of developed course material in students' success. First, educational material was developed for an undergraduate electrical engineering course: communication systems. A feedback group made up of diverse student learners was employed extensively in the material development phase. Next, the impact of the developed material on the success of the students was examined using both qualitative and quantitative measurement tools including questionnaires, one-to-one interviews, and class and university level anonymous surveys. This also included students' performance regarding laboratory quizzes and achievement of course learning outcomes. Overall, the measurement results show that the course material increased students' success in the course. Moreover, students' general perception of the course material was positive.