Browsing by Author "Benzaghta, Mohamed"

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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; Electrical-Electronics Engineering; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
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 - 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; Electrical-Electronics Engineering; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
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.
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; Electrical-Electronics Engineering; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
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: 26
Citation - Scopus: 33
Massive Mimo Systems for 5g: a Systematic Mapping Study on Antenna Design Challenges and Channel Estimation Open Issues
(inst Engineering Technology-iet, 2021) Benzaghta, Mohamed; Rabie, Khaled M.; 01. Atılım University
The next generation of mobile networks (5G) is expected to achieve high data rates, reduce latency, as well as improve the spectral and energy efficiency of wireless communication systems. Several technologies are being explored to be used in 5G systems. One of the main promising technologies that is seen to be the enabler of 5G is massive multiple-input multiple-output (mMIMO) systems. Numerous studies have indicated the utility of mMIMO in upcoming wireless networks. However, there are several challenges that needs to be unravelled. In this paper, the latest progress of research on challenges in mMIMO systems is tracked, in the context of mutual coupling, antenna selection, pilot contamination and feedback overhead. The results of a systematic mapping study performed on 63 selected primary studies, published between the year 2017 till the second quarter of 2020, are presented. The main objective of this secondary study is to identify the challenges regarding antenna design and channel estimation, give an overview on the state-of-the-art solutions proposed in the literature, and finally, discuss emerging open research issues that need to be considered before the implementation of mMIMO systems in 5G networks.
Milimetre Dalga Bandında Bina İçi İnsan Yoğun Ortamlarda Sinyal Seviyesi Değişkenliğinin Ölçümü ve Modellenmesi
(2021) Benzaghta, Mohamed; Kara, Ali; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
Milimetre dalga spektrumu, beşinci nesil (5G) kablosuz teknoloji için en temel bileşendir. Milimetre dalga bandındaki radyo kanallarında insan vücudu önemli kesinti sebebi ve sinyal değişkenliği nedenidir. Bu tez çalışmasında, 28 GHz bandında 3 farklı insan modeli ile insan vücudunun sinyal kesintisine ve zayıflamasına etkisine yönelik ölçümler sunulmaktadır. Ayrıca farklı alıcı-verici anten yüksekliklerine göre insan vücudu yerleşiminin etkisi de incelenmektedir. Farklı boyutlarda insan vücutları ve yerleşimleri ile anten yükseklikleri dikkate alınarak Fresnel kırınım modelinin en iyi çalışan model olduğu gösterilmektedir. Ayrıca Fresnel kırınım modeli ile Geometrik Kırınım Teorisi (GKT) modellerini de kıyaslanmakta, öncekinin daha doğru ve gerçeklenmesi basit olduğu gösterilmektedir. İlave olarak tez çalışmasında, insan yoğunluğunun milimetre dalga yayılımında kesinti süresi ve derinliğine yönelik istatistiklerde ölçümler yoluyla çıkarılmaktadır. Bu kapsamda, 3 ve 6 kişinin bir ofis ortamında olağan günlük hareket rotaları dikkate alınarak radyo linkini kesmesine yönelik istatistikler ilk defa bu tez çalışmasında sunulmaktadır.
Citation - WoS: 1
Citation - Scopus: 2
A Miniaturized Multi-Layer Microstrip Antenna for Linear Wireless Sensor Network Monitoring Systems
(Gazi Univ, 2022) Kara, Ali; Aydın, Elif; Benzaghta, Mohamed; Er, Burak; Bilgin, Gulsima; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
This article presents a sub-GHz ISM band microstrip patch antenna based on the use of multi-layer compact structure, which overcomes the shortcomings of typical microstrip antennas such as low gain and high resonant frequency. The antenna was simulated using an electromagnetic simulator, ANSYS HFSS, and fabricated on two different substrates: RT Duroid 5880 and FR4 epoxy with a compact size of 100 x 100 x 8 mm3 (0.29λ × 0.29λ × 0.02λ). The simulated results of the antenna were then compared with the measured ones, and the two were observed to have a reasonable agreement. The proposed antenna operates in the sub-GHz license-free ISM band (862-875 MHz), with a gain value of 2.92 dB. Two prototypes of the proposed antenna were fabricated and used in a Linear Wireless Sensor Networks (LWSNs) monitoring system. Results show that the proposed antenna is a good candidate for those types of LWSNs systems.
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; Electrical-Electronics Engineering; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
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; Electrical-Electronics Engineering; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 06. School Of Engineering; 01. Atılım University
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: 6
Citation - Scopus: 6
Opportunities and Challenges Inrcsmeasurement of 9-Mm Bullet Model With77 Ghzmmwavecotsradar Systems
(Wiley, 2020) Ahmed, Badar-ud-din; Kara, Ali; Zencir, Ertan; Benzaghta, Mohamed; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
This article indicates a thus far unexplored area of applied research and development to the application and system engineers and researchers from broad engineering backgrounds. Results of a study are presented for measurement of calibrated Radar Cross Section (RCS) of a 9-mm bullet (projectile) model by using a commercial-of-the-shelf (COTS) millimeter wave Frequency Modulated Continuous Wave (FMCW) radar system operating in 77 to 81 GHz frequency range. The calibrated RCS variation against the aspect angle is measured experimentally, analyzed, and compared with the simulation results which shows fair matching between the two. The opportunities and challenges attached with the use of such COTS systems for development of Hostile Fire Indication (HFI) systems are discussed. This bullet type and this mmwave frequency has not been thus far studied and reported in literature. This may motivate interested individuals/entities to try to measure (at acceptable accuracy before anechoic chamber measurements) RCS of similar low-size objects by using such low-cost COTS platforms.
Yansımaları Kullanarak Emisyon Kaynaklarının Yer Tespiti
(2021) Tabakcıoğlu, Mehmet Barış; Benzaghta, Mohamed; Imran, Md Abdullah Al; Taş, Sümeyra; Kara, Ali; Maiga, Bamoye; Dalveren, Yaser; 01. Atılım University
Bu projede, deniz yüzeyi ve çevresindeki girinti çıktının çok olduğu bölgeler (kıyılar, koylar, adaların yoğun bölgeler vb.) başta olmak üzere, yansımaların olduğu tüm (askeri/sivil) operasyonel ortamlarda, yansımaların kullanılması suretiyle bir temas alıcısı (geniş bant pasif alıcı) tarafından emisyon kaynaklarının konumlarının tespit edilmesine yönelik yöntem ve araçlar geliştirilmiştir. Geliştirilen yöntemde, öncelikli olarak pürüzlü/düzensiz (rough and irregular) araziler üzerindeki saçılma merkezlerinin kestirimi yapılmaktadır. Bunu yapabilmek için, sayısal harita bilgileri bilinen ve yöntemin çalıştırılması öngörülen bölgelerde (örneğin, Ege Denizi ve çevresi), temas alıcısında var olan ölçüm yeteneklerinin de yardımıyla, emisyon kaynağına (radar vericisi) yönelik parametreler (darbe genişliği, hüzme açısı gibi) kullanılarak yansıma olan muhtemel bölgelerin sınırları belirlenmektedir. Ardından, muhtemel saçılma merkezleri belirlenerek, arazi kesitleri üzerinde radyo yayılım kayıpları, yüksek frekanslı teknikler (GTD/UTD) ve dalga yayılım etkileri (yansıma, kırınım) kullanan bir ışın izleme algoritmasıyla hesaplanmaktadır. Ayrıca, geliştirilen ışık izleme algoritması ile, saçılma merkezlerinin çok yollu yayılımın kaynağı olma olasılıkları da hesaplanabilmektedir. Geliştirilen yöntemin sonraki aşamasında, saçılma merkezleri yer tespit/konumlamada kullanılmak üzere yapay sensör olarak belirlenmektedir. Belirlenen yapay sensörler, çoklu sensör uygulaması için literatürde bilinen bir Varış Zaman Farkı (VZF: Time Difference of Arrival-TDOA) konumlama tekniğinde kullanılmaktadır. Yöntemin son aşamasında ise TDOA tekniği ile elde edilen pozisyonlar ile saçılma merkezlerinin çok yollu yayılımın kaynağı olma olasılıkları ağırlıklı ortalama alma yönteminde kullanılarak emisyon kaynağının konumu/pozisyonu kestirilmektedir. Bu şekilde, temas alıcısı ile birlikte yansımaların yapay sensör olarak kullanılması suretiyle, tek bir alıcı ile sabit emisyon kaynaklarının konumlanması yapılabilmektedir. Geliştirilen yöntemin kestirim doğruluğu ve uygulanabilirliği yüksek çözünürlüklü (DTED2) sayısal harita verileri ile gerçekçi senaryolar üzerinde benzetimler yapılarak değerlendirilmiştir. Elde edilen sonuçlar, geliştirilen yer tespit yönteminin elektronik harp uygulamalarında genel olarak uygulanabilir olduğunu doğrulamaktadır.