Papers by Hosam Mohamed Elocla
TCP congestion avoidance model with congestive loss
Proceedings. 2004 12th IEEE International Conference on Networks (ICON 2004) (IEEE Cat. No.04EX955)
Abstract This paper presents a model for the TCP congestion avoidance algorithm in networks with ... more Abstract This paper presents a model for the TCP congestion avoidance algorithm in networks with only congestive loss. The model predicts the congestion window evolution, throughput and packet loss rate of sustained TCP flows. In other TCP models, packet loss ...
On indirect method of RCS calculation of conducting targets in random media
IEEE Antennas and Propagation Society Symposium, 2004., 2004
One of the random medium effects is the enhancement in radar cross-section (RCS) of targets, and ... more One of the random medium effects is the enhancement in radar cross-section (RCS) of targets, and it can be explained by the coherent addition of doubly scattered waves. In several earlier studies (Tateiba, M. and Tomita, E., 1992; El-Ocla, H. and Tateiba, 2001, 2002, 2003), we have proved that the spatial coherence length (SCL) of waves around the target in a random medium, together with the target configuration, affects the RCS and backscattering enhancement, apart from the polarization of the incident waves. This conclusion is important in radar detection and remote sensing applications. These results need a lot of computation time if we use our method directly. We propose an indirect estimate for the RCS by using a beam wave incident on a conducting target in free space. This method presents an approximate solution to the scattering problem in a random medium. This indirect estimate reduces the processing time that is so important in radar detection, especially in real time applications. H-wave scattering is quite different from E-wave scattering, especially in the resonance region, because of waves creeping along objects. Therefore, we need to analyze the scattering for both polarizations. The time factor is assumed and suppressed. This method is applicable for low and high frequency ranges.
IEEE Transactions on Antennas and Propagation, 2013
In this paper a three-dimensional (3-D) numerical technique based on the finite difference freque... more In this paper a three-dimensional (3-D) numerical technique based on the finite difference frequency domain (FDFD) is implemented to calculate the scattering from arbitrary shaped objects embedded in a continuous random medium. The total field/scattered field (TF/SF) algorithm is integrated with the FDFD to minimize the memory consumption and speed up the calculations. For validation purposes, the radar cross-section of a 2-D conducting cylinder in random medium is calculated using the FDFD technique and compared to previously published data based on the current generator method. An upgrade to a 3-D solver was then inspired once the idea of using the multi-grid technique was introduced to accelerate the convergence rate of the BICGSTAB iterative solver. Thus, allowing the FDFD technique to become a robust method to solve the scattering problem from large targets embedded in random medium. Therefore, using the introduced simulating scheme, one can easily elucidate any scattering information out of real life targets surrounded by random environmental effects.
European Transactions on Telecommunications, 2008
Several data-link control (DLC) protocol procedures have been proposed in order to provide reliab... more Several data-link control (DLC) protocol procedures have been proposed in order to provide reliable data transmission over powerless radio links. However, many quality of service (QoS) issues still need to be achieved such as balance between cell transfer delay (CTD) and cell loss rate (CLR), absence of cell delay variation (CDV) and network traffic utilisation. The main problem with wireless ATM is how to overcome the unreliability of the wireless link in order to maintain QoS requirements especially for variable bit rate (VBR) application. Here, we propose a model that provides QoS support for ATM virtual connections (VC) and solves the unreliability problem of the wireless ATM through an efficient DLC protocol for bursty VBR traffic. This model mainly concerns with enhancing QoS to gain error-free wireless transmission and regulating VBR Traffic.
Influence of Incident Waves on Resonance in Backscattering from Targets in Random Media
Electromagnetics, 2013
Abstract The main concern of this study is the effect of incident wave properties on the resonanc... more Abstract The main concern of this study is the effect of incident wave properties on the resonance that occurs when the target size is close to the wavelength. In doing that, the laser radar cross-section of a conducting target is calculated using a boundary value method with a beam wave incidence and H-wave polarization. Therefore, the effect of creeping waves, produced with H-wave incidence, on the backscattering enhancement would be clarified. A comparison with a similar scattering problem using a plane wave incidence is considered.
IEEE Antennas and Wireless Propagation Letters, 2003
This paper discusses an indirect estimate of the radar cross section (RCS) of a conducting cylind... more This paper discusses an indirect estimate of the radar cross section (RCS) of a conducting cylinder with a partially convex cross-section under the condition that the backscattering enhancement occurs in a random medium. Once we evaluate the spatial coherence length (SCL) of incident waves around the cylinder in random medium, we may approximately estimate the RCS from the RCS in free space with beam wave incidence in which the spot size equals the SCL. This method is restricted only to the case where the SCL is larger than the target size.
OLMS: Online Learning Management System for E-Learning
World Journal on Educational Technology: Current Issues
In this paper we introduce a learning management system that provides a management system for cen... more In this paper we introduce a learning management system that provides a management system for centralized control of course content. A secure system to record lectures is implemented as a key feature of this application. This feature would be accessed through web camera and mobile recording. These features are mainly designed for e-learning environment. In addition, we integrate a learning management system with a platform for social activities and student assessment analysis is developed. Users Including students, professors, and administrators are able to manage schedules, lectures, assignments, jobs, events, discussions, and research.
Wireless Networks, 2010
In this paper, we propose and verify a modified version of TCP Reno that we call TCP Congestion C... more In this paper, we propose and verify a modified version of TCP Reno that we call TCP Congestion Control Enhancement for Random Loss (CERL). We compare the performance of TCP CERL, using simulations conducted in ns-2, to the following other TCP variants: TCP Reno, TCP NewReno, TCP Vegas, TCP WestwoodNR and TCP Veno. TCP CERL is a sender-side modification of TCP Reno. It improves the performance of TCP in wireless networks subject to random losses. It utilizes the RTT measurements made throughout the duration of the connection to estimate the queue length of the link, and then estimates the congestion status. By distinguishing random losses from congestion losses based on a dynamically set threshold value, TCP CERL successfully attacks the well-known performance degradation issue of TCP over channels subject to random losses. Unlike other TCP variants, TCP CERL doesn't reduce the congestion window and slow start threshold when random loss is detected. It is very simple to implement, yet provides a significant throughput gain over the other TCP variants mentioned above. In single connection tests,
Effect of H-wave polarization on laser radar detection of partially convex targets in random media
Journal of the Optical Society of America a Optics Image Science and Vision, Jul 1, 2010
A study on the performance of laser radar cross section (LRCS) of conducting targets with large s... more A study on the performance of laser radar cross section (LRCS) of conducting targets with large sizes is investigated numerically in free space and random media. The LRCS is calculated using a boundary value method with beam wave incidence and H-wave polarization. Considered are those elements that contribute to the LRCS problem including random medium strength, target configuration, and beam width. The effect of the creeping waves, stimulated by H-polarization, on the LRCS behavior is manifested. Targets taking large sizes of up to five wavelengths are sufficiently larger than the beam width and are sufficient for considering fairly complex targets. Scatterers are assumed to have analytical partially convex contours with inflection points.
Radar cross-section of partially convex targets of large sizes in continuous random media for E-polarization wave
IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450), 2000
Analysis of backscattering enhancement for partially convex targets in random media for plane and beam wave incidences
IEEE International Geoscience and Remote Sensing Symposium, 2000
Analysis of depolarized electromagnetic waves propagated through random medium by using perturbation method
2014 16th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM), 2014
Backscattering enhancement of partially convex targets of large sizes in continuous random media for e-polarization wave
6th International SYmposium on Antennas, Propagation and EM Theory, 2003. Proceedings. 2003, 2003
Backscattering enhancement of partially convex targets of large sizes in continuous random media for E-polarization wave
2003 46th Midwest Symposium on Circuits and Systems, 2000
2005 IEEE Antennas and Propagation Society International Symposium, 2000
Radar cross-section of conducting targets in random media for circular polarization
Canadian Conference on Electrical and Computer Engineering, 2005., 2000
Indirect method of RCS estimate of conducting target in random medium
Canadian Conference on Electrical and Computer Engineering, 2005., 2000
Radar Cross-Section of Targets using Beam wave incidence for Horizontal Polarization
2006 IEEE Antennas and Propagation Society International Symposium, 2006
Effect of the illumination region of targets on waves scattering in random media with H-polarization
Http Dx Doi Org 10 1080 17455030903108166, Oct 22, 2009
Analysis of Backscattering Enhancement for Complex Targets in Continuous Random Media for H-Wave Incidence(Special Issue on Innovation in Antennas and Propagation for Expanding Radio Systems)
Ieice Transactions on Communications, Sep 1, 2001
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Papers by Hosam Mohamed Elocla