Abdelmajid Badri

Performance Analysis of Hybrid Codecs G.711 and G.729 over Signaling Protocols H.323 and SIP

Due to the rapid growth of the internet, customers request more applications over internet such as telephony and video. VoIP (Voice over Internet Protocol) is an emerging technology for voice communication which deploys many techniques to produce a high-quality service. Signaling is one of success keys of Voice over IP; the two most promised approaches in this case are H.323 and SIP. This paper draws a comparison between the four combinations of H.323 and SIP (Session Initiation Protocol), G .711 and G.729 (each combination includes one protocol and one hybrid codec) using a powerful network simulation tool (OPNET Modeler) which enables network simulation by employing various protocols. The combination H.323 and G.729 proved to be the most appropriate one in the connection process.

Design and optimization of an inset fed circular microstrip patch antenna using DGS structure for applications in the millimeter wave band

In this paper we present a performance comparison of an inset fed circular microstrip patch antenna designed to operate at milimeterwave frequencies, with and without a DGS (defected ground plane structure). The parameters such as gain, directivity, return loss and bandwidth are notably improved in our proposed prototype. Also a comparison is made with other previously published works [1]. The proposed antenna operates in the EHF band at frequency of 30 GHz and HFSSv15 software based on Finite elements is used for result simulations.

Automatic speaker identification by using the neural network

Automatic speaker identification ASI is to determine the identity of an individual among a group of known people. From the recorded voice samples, it must determine which speaker spoke of the base. In this paper we are interested at the classification phase of the ASI system and we presented how to implement the multilayer perceptrons (MLP) and radial basis functions (RBF) Neural Network in the classification step of the ASI system, and a performance comparison study between the MLP and RBF to support the classification activity, by estimating the probability density functions required by Bayesian classifiers within a system of ASI. Advantages and disadvantages of each method are discussed and the effects introduced by the speakers number for the ASI system complexity were taken into account. During the various experiments, the Japanese vowels database and the Numenta Speakers database are used to validate our comparative study of RBF and MLP.

Directivity enhancement of aperture coupled microstrip patch antenna using two layers dielectric superstrate

Electromagnetic Band-Gap (EBG) structures are popular and efficient techniques for microwave applications; they are periodic metallic or dielectric materials. EBG may be combined with microstrip patch antenna to increase the directivity, the radiation efficiency and/or to suppress surface waves, to reduce the side lobes of the radiation pattern and to increase the bandwidth. In this paper, we study the influence of Unidimensionnel Electromagnetic Band Gap structure (1D-EBG) on the performances of an aperture coupled rectangular patch antenna. This 1D-EBG is chosen as two similar dielectric layers disposed above the patch. The return loss, radiation pattern, and directivity are studied using HFSS software. The simulation results show that the gain, directivity and S11 parameter of the antenna with dielectric superstrate layers are increased at X band (8-12GHz). Compared with the patch feed with the same aperture size but without dielectric layers, the performance of the proposed antenna is improved obviously.

A web-based spatial decision support system for effective monitoring and routing problem

This paper presents an integrated framework of Geographic Information System (GIS) and a Relational Database Management System (RDBMS) equipped with interactive communication capabilities. The model integrates the design of the database and the management of implementation of the monitoring system which includes the operations of query and analysis using the web and desktop applications. This study aims to apply techniques of analysis of the road network in a GIS to collect geographic data on the monitoring station and the roads. The information on road infrastructure is not only useful for locating monitoring stations, but it is also important to guide a station to follow the shortest path to achieve the objectives of management and routing. Optimal routes based on the minimum cost are identified using Dijkstras algorithm. The results show that it is possible to use an effective method of GIS to integrate multiple data sets and learn advanced information. The need for such a framework and requirements for the orientation of monitoring stations in the event of a road accident are studied and the architecture of this framework is discussed. The proposed system should be a tool comprehensible, well structured, efficient and scalable which facilitates the location of road accidents and the orientation of the monitoring stations in response to these accidents. Simulated test cases have been carried out for network of Mohammedia City in Morocco.

Efficient Combination of Color, Texture and Shape Descriptor, Using SLIC Segmentation for Image Retrieval

In this article we present a novel method of extraction and combination descriptor to represent image. First we extract a descriptor shape (HOG) from entire image, and in second we applied method of segmentation and then we extract the color and texture descriptor from each segment in order to have a local and global aspect for each image. These characteristics will be concatenate, stored and compared to those of the image query using the Euclidean distance. The performance of this system is evaluated with a precision factor. The results experimental show a good performance.

LTE mobile positioning and tracking simulator using Kalman filter

In the past few years the mobile networks telecommunication field has known a huge progress in term of developing new standards to enhance the quality of service (LTE, LTE-A, 5G Ω). Positioning techniques in LTE (Long Term Evolution) network are gaining more interest since the majority of mobile communication operators are deploying their 4G Solution all over the world. In this paper, we investigate the optimal mobile position tracking mean: the Kalman filter when integrated in the localization process. We present, also, a tool based on Matlab/Simulink, for simulating the LTE positioning reference signal (PRS) generation, transmission and reception in a realistic propagation environment. The received signal at mobile station will be proceeded to obtain the time difference of arrival estimates which are used to calculate the handset position and tracking the Mobile User (MU) in a noisy environment. The main purpose of this paper is to design and build a free realistic simulator for LTE positioning dedicated to academic researches.

Directive Beam-Steering Patch Array Antenna Using Simple Phase Shifter

Beam-steering antennas are the ideal solution for a variety of system applications, it is most commonly achieved through using phased arrays, where phase shifters are used to control the relative of the main-beam. In this paper, a low-cost directive beam-steering phased array (DBS-PA) antenna using switched line phase shifters is demonstrated. The proposed DBS-PA antenna has four micro-strip patch antennas, three power dividers and four phase shifters printed on the same Rogers RT-Durroid substrate with a dielectric constant of 2.2 with dimensions of 8 × 3.5 cm. The phased array antenna has a directivity of 11.92 dBi and the main beam direction can be switched between the angles of ±25° with a 3 dB beam-width of 23°. All design and simulations have been carried out using Ansoft HFSS software tool. The frequency considered for the operation is 10 GHz.

Comparative study of the Least Mean Square and Normalized Least Mean Square adaptive filters for positioning purposes

Positioning techniques based on cellular networks are gaining more attention thanks to their accuracy and availability in multiple environment compared to GPS signal which face a big difficulty to reach them. Those techniques can be enhanced with adaptive filtering process, In this paper we will try to introduce the chosen positioning method to work with then apply two different type of filters to compare their performances.

Enhanced mobile positioning technique for UMTS users in both outdoor and Indoor environments

Mobile positioning by cellular networks has received growing attention and several researches are carried out to enhance positioning algorithms and techniques that will be able to give better performance at multiple environments (outdoors/indoors). In this paper, we are interested in UTDOA (uplink time difference of arrival) approach to determine the location of a Mobile Station within an acceptable accuracy and respect of emergency cases in both areas (Indoor/Outdoor). The enhancement of this method is performed with adaptive filtering, with MATLAB software, using two different algorithm to show the advantages of the chosen one, and its efficiency in emergency calls even with legacy phones.