Browsing by Author "Gokdogan, Bengisu Yalcinkaya"

Now showing 1 - 6 of 6

Citation - WoS: 1
Citation - Scopus: 1
Blockage Loss and Shadow Fading Behavior of Millimeter-Wave Signals Due To Human Bodies at 28 Ghz
(Wiley, 2024) Benzaghta, Mohamed; Gokdogan, Bengisu Yalcinkaya; Coruk, Remziye Busra; Kara, Ali
As the millimeter-wave (mm-Wave) spectrum is considered to be an essential enabler to the fifth generation (5G) wireless communication systems. Human movements are one of the most significant factors that cause transient blockage in indoor mm-wave channels. In this letter, human blockage measurements and shadow fading statistics due to human body movements in an indoor office environment are reported for the 28 GHz band. The effect of human bodies on the channel is measured for several scenarios including a variety of population and using diverse antenna heights. The reported shadow fading statistics include both the duration and the depth of the blockage fade, and accordingly, we propose several empirical models that cater for such blockage events. The findings reported in this letter could improve the modeling of indoor radio channels at 28 GHz bands by considering the presence of humans, as well as their movements.
Citation - Scopus: 1
A Hybrid-Flipped Classroom Approach: Students' Perception and Performance Assessment
(Univ Nac Colombia, Fac ingenieria, 2023) Gokdogan, Bengisu Yalcinkaya; Coruk, Remziye Busra; Benzaghta, Mohamed; Kara, Ali
This study presents an improved hybrid-flipped classroom (hybrid-FC) education method based on technology-enhanced learning (TEL) along with diluted classes for a course on probability and random processes in engineering. The proposed system was implemented with the participation of two student groups who alternated weekly between attending face-to-face activities and fully online classes as a sanitary measure during the pandemic. The education model was combined with the flipped classroom (FC) approach in order to improve the quality of learning and address the negative effects of remote education. Before the lessons, the students studied the course material, filled a question form, and then took a low- stake online quiz. Then, the students attended a session where the questions reported in the forms were discussed, and they took an online problem-solving session followed by an individual quiz. Class sessions were available to both online and face-to-face students, as well as in the form of video recordings for anyone who missed lessons. Qualitatively and quantitatively, the proposed education method proved to be more effective and comprehensive than conventional online methodologies. The students' performances were evaluated via quizzes and exams measuring the achievement of the course learning outcomes ( CLOs). Weekly pre/post-tests were applied to examine the students' progress in each topic. Midterm and final exams were planned to measure the level of success for all course topics. Additionally, the students' perception was assessed with questionnaires and face-to-face interviews. A performance assessment showed an apparent increase in the success rate, and the students' perception was found to be positive.
Citation - WoS: 3
Citation - Scopus: 3
Modeling and Measurement of Human Body Blockage Loss at 28 Ghz
(Taylor & Francis Ltd, 2023) Benzaghta, Mohamed; Gokdogan, Bengisu Yalcinkaya; Coruk, Remziye Busra; Kara, Ali
Millimeter-wave (mm-Wave) spectrum is an essential enabler to the fifth generation (5G) wireless technology. Humans are one of the most noticeable blockers that cause temporal variation in indoor radio channels. This paper presents human blockage measurements at 28 GHz, with several humans of different sizes. The effect of the crossing orientations of the human bodies is investigated for three different transmitter heights. A human blockage model based on the Fresnel diffraction scheme is shown to be applicable in estimating the human blockage loss in indoor radio links considering various body sizes, different crossing orientations, and different transmitter heights. The findings reported in this paper could help improve indoor radio channel models at 28 GHz bands for 5G technologies considering the presence of human body blockages.
Citation - WoS: 4
Citation - Scopus: 6
On the Classification of Modulation Schemes Using Higher Order Statistics and Support Vector Machines
(Springer, 2022) Coruk, Remziye Busra; Gokdogan, Bengisu Yalcinkaya; Benzaghta, Mohamed; Kara, Ali
The recognition of modulation schemes in military and civilian applications is a major task for intelligent receiving systems. Various Automatic Modulation Classification (AMC) algorithms have been developed for this purpose in the literature. However, classification with low computational complexity as well as reasonable processing time is still a challenge. In this paper, a feature-based approach along with various classifiers is employed based on statistical features as well as higher-order moments and cumulants. An over-the-air (OTA) recorded dataset consisting of four analog and ten digital modulation schemes are used for testing the proposed method at 0-20 dB SNR. The overall accuracy for quadratic Support Vector Machine (SVM) is found to be as high as 98% at 10 dB. The comparison of the results with other AMC papers published in the literature indicates that the proposed method present higher accuracy, especially for realistic channel induced OTA dataset.
Citation - WoS: 2
Citation - Scopus: 2
Radar Cross Section Studies of Low Signature UAVs in X-Band: Simulation, Measurement and Performance Evaluation
(IEEE, 2024) Unalir, Dizdar; Gokdogan, Bengisu Yalcinkaya; Aydin, Elif
In this study, the effectiveness of a radar cross section (RCS) reduction method based on a proposed shaping technique for four-legged unmanned aerial vehicles (UAV) has been proven with simulation tools and experimental measurements in X-Band. Simulative RCS values were obtained with CST and HFSS electromagnetic calculation tools, and the advantages of these tools compared to each other were examined. Experimental measurements were carried out in a laboratory environment with a vector network analyzer (VNA) and confirmed with simulation results. The effects of frequency, polarization and aspect angle factors on RCS were examined. It has been shown that with the proposed measurement method, low-cost and easily applicable RCS analysis can be performed in X-Band, one of the frequency bands frequently used in the defense industry. With the proposed shaping method, RCS reduction in the range of 5-10 dBsm was achieved.
Citation - Scopus: 2
Uav Detection and Ranging With 77-81 Ghz Fmcw Radar
(Ieee, 2022) Doganay, Bengisu; Arslan, Mustafa; Demir, Efe Can; Coruk, Remziye Busra; Gokdogan, Bengisu Yalcinkaya; Aydin, Elif
In this study, detection of unmanned aerial vehicles (UAV), determination of radar cross-section (RCS) values, and range estimation were performed using a commercial off-the-shelf (COTS) millimeter-wave Frequency Modulated Continuous Wave (mmWave FMCW) radar system in the 77-81 GHz frequency band. The measurements were carried out in a laboratory environment using a single transceiver antenna without the need for an anechoic chamber. RCS values of different vertically and horizontally positioned UAVs were measured experimentally along the 360 degrees aspect angle, and the simulated results obtained from computational tool were compared with the experimental results. The measurement and simulation results, together with the range estimation, matched with high accuracy.