أحمد حسن العجيلي بن لابيش

عضو هيئة تدريس - قسم الحاسوب-مدرسة العلوم الأساسية - الأكاديمية الليبية للدراسات العليا


عضو هيئة تدريس قار

المؤهل العلمي: دكتوراه

الدرجة العلمية: أستاذ مساعد

التخصص: شبكات - علوم حاسوب

قسم علوم الحاسوب - مدرسة العلوم الأساسية

المنشورات العلمية
Double Knife-Edge Diffraction Model for Analyzing Human Body Shadowing Effects in Fifth Generation Wireless Systems
Conference paper

This paper addresses the critical challenge of human-induced signal attenuation in millimeter-wave (mmWave) communications, a key concern for fifth-generation (5G) network reliability in indoor environments. Our study introduces a simplified model to quantify the impact of human body blockage on indoor communication links at a frequency of 32.5 GHz., a frequency relevant to 5G systems. The influence of nearby scattering objects is investigated through experimental measurements involving a human body. Key wave propagation phenomena, including diffraction, are considered for each scattering object. The Double Knife-Edge Diffraction (DKED) model is used to estimate the attenuation caused by the human body (to estimate blockage losses). Through controlled experiments with human subjects, we systematically analyze how scattering objects and body positioning influence signal propagation. The model's performance is validated by comparing simulation results with experimental data. The findings show that the proposed model effectively predicts signal attenuation in indoor environments, providing valuable insights for future studies on human presence effects in fifth-generation (5G) communication systems. Keywords: 5G, DKED, diffraction, human shadowing, millimeter-wave, blockage.

Ahmed Hassen ELjeealy Ben Alabish, (05-2025), 10th International Conference on Control Engineering &Information Technology (CEIT-2025) Proceedings Book Series –PBS- Vol 23, pp.145-151: (CEIT-2025), 145-151

Impact of Human Body on Knife-Edge Diffraction in Wireless Communication
Conference paper

-This paper examines the effect of human body blockage on signal propagation (millimeter-wave (mmWave) signal propagation) in indoor environments links at 32.5 GHz (a critical frequency for fifth-generation (5G) network), with a particular focus on the diffraction effects caused by the human body, where diffraction is one of the important wave propagation mechanisms. In this study, measurements were taken to assess the effect of the human body as it moves between the transmitter and the receiver. To predict the signal attenuation, the principles of Fresnel diffraction were utilized, particularly emphasizing complex Fresnel integrals. Our results show that the received power varies significantly based on the person’s position, as diffraction loss highly depends on the body’s location. This study enhances our understanding of how human-induced diffraction, is critical for designing more reliable wireless networks. As the findings demonstrate that the proposed model effectively predicts signal attenuation in indoor environments and emphasizes the importance of accounting for human interference when optimizing communication systems, thus supporting the effective deployment of 5G technology. 

Ahmed Hassen ELjeealy Ben Alabish, (05-2025), 10th International Conference on Control Engineering &Information Technology (CEIT-2025) Proceedings Book Series –PBS- Vol 23, pp.162-169: (CEIT-2025), 162-169

An Enhancement Log Normal Shadowing Model to Estimate 5G Propagation Path Loss for the Indoor Environment
Conference paper

This paper presents a comprehensive study of modelling human body blockage (the most critical challenges in fifth-generation (5G)) effects on indoor millimetre wave (mmWave) communication links at 32.5 GHz, a key frequency for 5G networks. Through controlled experiments in a laboratory environment, we analyse signal attenuation as a human subject obstructs the line-of-sight (LOS) path between transmitter and receiver, recording received power at incremental positions. To model the observed phenomena, we propose a hybrid framework integrating deterministic and statistical components: (1) a modified Double Knife-Edge Diffraction (DKED) model with Gaussian-shaped blockage attenuation (20.8 dB peak at full blockage) and reflection-induced signal enhancement (−15.0 dB peak from nearby objects), and (2) a log-normal shadowing component (σ = 11.8 dB) capturing environmental randomness. Our results reveal strong agreement between simulations and measurements, achieving a mean absolute error of 3.2 dB and a correlation coefficient R² = 0.89. The analysis demonstrates that human-induced diffraction dominates near the LOS centre, while multipath reflections significantly alter signal strength at peripheral positions. We further derive practical guidelines for 5G network design, recommending a 44.4 dB link budget safety margin to account for combined blockage and shadowing effects. This work advances indoor mmWaves channel modelling by unifying physics-based diffraction analysis with empirical reflection characterization, the framework achieves strong experimental validation and offers actionable insights for 5G network design. Keywords— mmWaves, blockage, DKED, attenuation, shadowing  

Ahmed Hassen ELjeealy Ben Alabish, (05-2025), 10th International Conference on Control Engineering &Information Technology (CEIT-2025) Proceedings Book Series –PBS- Vol 23, pp.179-186: (CEIT-2025), 179-186

Evaluating the Accuracy of DKED and Fresnel Diffraction Models for Human Body Blockage in Indoor 5G Band Communications
Conference paper

This paper investigates human-induced signal attenuation in indoor mm-wave communications at 32.5 GHz, a critical concern for 5G systems. Two distinct diffraction-based models are applied to the same indoor scenario to assess human blockage effects: one employs the Double Knife-Edge Diffraction (DKED) approach, and the other uses Fresnel diffraction principles with complex Fresnel integrals. Controlled experiments with a human subject moving between a transmitter (TX) and a receiver (RX) reveal that the DKED model consistently underestimates the received power by 2 6 dB, while the Fresnel diffraction approach underestimates it by 2–5 dB Based on the comparative results, the DKED model demonstrates higher accuracy in predicting signal attenuation, offering valuable insights for improving indoor 5G network performance

Ahmed Hassen ELjeealy Ben Alabish, (05-2025), Academy journal for Basic and Applied Sciences (AJBAS): Academy journal for Basic and Applied Sciences (AJBAS), 70-75

Measurement System and its Suitability for Examining Indoor Millimeter Wave Propagation at (28–33GHz)
Conference paper

The purpose of this study is to determine the suitability of system measurements on indoor radio wave propagation at (28–33GHz) which might be used by 5G communication.

Ahmed Ben Alabish, Abduelbaset Mustafa Alia Goweder, (05-2021), IEEEAccess: 2021 IEEE 1st International Maghreb Meeting of the Conference on Sciences and Techniques of Automatic Control and Computer Engineering MI-STA, 1-4

DKED modelling of Human body blockage of 5G system link at 32 GHz
Conference paper

This paper is the continuation of a research carried out by Alabish et.al, which depicts the scattering objects effects on a blocked indoor wireless 5G link by a human body using a simple approach. Some measurement were made on the scattering effects due to having an object close to the link in this case it is a human body. In this paper, more measurements were conducted at 32 GHz. The double knife-edge diffraction (DKED) model was used in order to foresee the attenuation due to human body. To test the prediction precision of the model, simulation was then compared with measurements. The obtained results indicate that the assumed simple models for the indoor links performed well.

Ahmed Hassen ELjeealy Ben Alabish, (05-2021), IEEEAccess: 2021 IEEE 1st International Maghreb Meeting of the Conference on Sciences and Techniques of Automatic Control and Computer Engineering MI-STA, 1-4

Characterizing the effects of human body blockage and scattering objects for 31and 33 GHz indoor 5G link
Conference paper

This paper is concerned with studying the effects of human body blockage as well as surrounding objects scattering effects for an indoor 31 and 33 GHz link utilizing the Double Knife Edge Diffraction (DKED) model for diffraction effect on received signal.

Ahmed Hassen ELjeealy Ben Alabish, (05-2021), IEEEAccess: 2021 IEEE 1st International Maghreb Meeting of the Conference on Sciences and Techniques of Automatic Control and Computer Engineering MI-STA, 1-4

A Simplified Model for Characterizing the Effects of Scattering Objects and Human Body Blocking Indoor Links at 28 GHzIEEE Access
Journal Article

This paper presents a simple approach to characterize the effects of scattering objects around indoor links at 28 GHz while the link is fully blocked by a human body. The effects of scattering objects nearby the link were studied by conducting measurements with a metallic re ector and the human body.

Ahmed Ben Alabish, (05-2019), IEEEAccess: IEEE, 1109 (29), 1-10

An Experimental Study towards Examining Human Body Movements in Indoor Wave Propagation at 18–22 GHz
Conference paper

This paper presents some initial studies for characterizing effects of human body movements on short range indoor links at 18-22 GHz. Firstly, measurement system is described, and then, calibration measurements along with initial results of the impact of human body movement on the channel are presented for some scenarios. 

Ahmed Hassen ELjeealy Ben Alabish, (06-2018), International Symposium on Networks, Computers and Communications (ISNCC): IEEE, 1-4

A Universal Lexical Steganography Technique International Journal of Computer and Communication Engineering
Journal Article

 In this paper, English language will be used as an instance of natural languages as we will be concerned with the set of all natural language texts. this research tries to employ a set of all synonyms as a way to hide secret message inside a natural language text. 

Ahmed Hassen ELjeealy Ben Alabish, Abduelbaset Mustafa Alia Goweder, (01-2013), International Journal of Computer and Communication Engineering: IJCCE, 2 (159), 153-157