Ahmed S. Elkorany

Energy Efficient Intra Cluster Transmission in Grid Clustering Protocol for Wireless Sensor Networks

Clustering based routing protocols have a pivotal role in wireless sensor networks (WSN) due to efficient energy consumption of limited power sensor node that is the prime challenge in WSN. Intra-cluster transmission and cluster size have great impact on balancing energy consumption within cluster and network. However, they play minor role in traditional routing protocols. In this paper, authors will offer mathematical analysis to provide judging metric that define energy efficient intra-cluster transmission. This metric is called threshold distance which is exploited in determining optimum cluster size. Based on the optimum cluster size, centralized energy aware grid clustering protocol (CEAG) will be proposed. Mat lab simulator will be utilized for appreciating the proposed protocol. The simulation results manifested that CEAG attains maximum network life tie and throughput in comparison with the existing protocols such as LEACH, K-LEACH, Energy-LEACH, DCHS and MOD-LEACH.

UWB integrated microstrip patch antenna with unsymmetrical opposite slots

A new ultra wide band (UWB) probe fed microstrip patch antenna (MPA) with two unsymmetrical opposite slots is proposed. In this paper, two opposite slots with dimensions L1×W1 and L2×W2 were entrenched in radiating edges of patch. The dielectric substrate has dimensions 100×100 mm2 and optimized height of 4mm. A parametric study of slots dimensions, dielectric material type and substrate thickness has been carried out to enhance the impedance bandwidth of the proposed antenna. The antenna performance has been characterized in terms of reflection coefficient (S11) and radiation characteristics. Among different dielectric materials, FR4 epoxy with thickness of 4mm resulted in an impedance bandwidth of 4.8 to 10.6 GHz. The peak gain varies from 4.5 dB to 7.5 dB over the operating frequency range. The antenna was simulated using Ansys HFSS v13 based on Finite element method. This antenna is a suitable candidate for variety of UWB wireless and broadband applications.

Efficient Technique for Sidelobe Suppression and PAPR Reduction in OFDM-Based Cognitive Radios

Orthogonal Frequency Division Multiplexing (OFDM) is a transceiver technology able to achieve spectrally efficient and high data rate wireless transmissions. It is also able to transmit in a non-contiguous (NC) fashion by utilizing several separate spectral whitespaces. Cognitive radio (CR) is an efficient solution for solving the spectrum scarcity problem, while OFDM based CR system, i.e. NC OFDM system is used as modulation scheme. NC-OFDM has two significant problems, high peak to average power ratio (PAPR) and high sidelobe power, which cause out of band radiation and interference with primary users (PU). Many solutions were proposed for solving either of these problems while in this paper, an efficient technique for reducing both PAPR and sidelobe power is proposed. This technique is based on using the Advanced Cancelation Carriers combined with signal set expansion and gives an efficient reduction for both PAPR and sidelobe power. A modified version is also proposed which reduces the transmitted power and decreases the complexity but gives a little reduction for PAPR. Simulation results cover the PAPR and sidelobe reduction for both the proposed technique and its modified version for comparison purposes.

Two proposed approaches for minimization of both sidelobe and PAPR in Cognitive Radio network

Cognitive Radio (CR) is considered an important solution for the spectrum scarcity problem. Orthogonal Frequency Division Multiplexing (OFDM) based cognitive radio system, i. e. Non-Contiguous (NC) OFDM system used as modulation scheme. NC-OFDM has two main problems, high Peak to Average Power Ratio (PAPR) and high sidelobe power, which cause interference with Primary Users (PUs). Many solutions were proposed to solve these problems. In this paper, two techniques to reduce both PAPR and sidelobe are proposed. Instead of usingSelective Mapping (SLM) with Multiple Choice Sequences(MCS) alone, first proposed technique suggests adding extra interleaver on the input data to achieve more reduction on PAPR. The second proposed technique is based on the phase shift adjustment in SLM. Simulation results show that the two proposed techniques improve both the PAPR and Sidelobe power. The proposed technique with adding interleaver is more complex than the phase shift adjustment technique.

Hybrid gray wolf optimizer–artificial neural network classification approach for magnetic resonance brain images

Automated and accurate classification of magnetic resonance images (MRIs) of the brain has great importance for medical analysis and interpretation. This paper presents a hybrid optimized classification method to classify the brain tumor by classifying the given magnetic resonance brain image as normal or abnormal. The proposed system implements a gray wolf optimizer (GWO) combined with a supervised artificial neural network (ANN) classifier to achieve enhanced MRI classification accuracy via selecting the optimal parameters of ANN. The introduced GWO-ANN classification system performance is compared to the traditional neural network (NN) classifier using receiver operating characteristic analysis. Experimental results obviously indicate that the presented system achieves a high classification rate and performs much better than the traditional NN classifier.

Concentric Ring Shaped Cellular Configuration for High Altitude Platforms using Particle Swarm Optimization

In this paper a high altitude platform (HAP) based vertical one dimensional (1D) antenna array is used to generate a concentric ring shaped cellular configuration. The geometry and the design of the ring shaped cells are explained. Different types of weights for the linear array, e.g. the DolphChebyshev weights, Hamming weights, and optimized weights by The Particle Swarm Optimization PSO algorithm are used for beamforming of the linear array. Calculations of the link budget are introduced for evaluating the signal to interference ratio SIR of a user in the HAP system. The study of the coverage performance for the three different types of weights is introduced. Results indicate the superior performance of PSO in improving the coverage performance than Dolf-Chebyshev and Hamming windows.

New Simple Flower Shaped Reconfigurable Band-Notched UWB Antenna Using Single Varactor Diode

In this paper, a new flower-shaped microstrip line feed reconfigurable band-notched UWB monopole antenna using single varactor diode is introduced and fabricated. Different notch frequencies can be obtained using different capacitance values. The effect of changing the varactor position is also examined. The flower shape is first optimized to obtain UWB characteristics. Then, a slot is made in the microstrip line to be loaded later with a single varactor diode. A wide range of notch frequencies can be obtained using this simple configuration which covers most of the narrow band coexistence systems. The notch frequency can be lower by increasing the capacitance value. The notch frequency covers the WLAN band when C = 0.8 pF and covers the WiMAX band when the capacitance is changed to 0.7 pF for the same antenna configuration and varactor position. Two prototypes of the proposed antenna using two different single capacitor elements with capacitances 0.6 pF and 1.5 pF are fabricated, and their reflection characteristics are measured and compared with the simulated ones. Notch frequencies at 6.1 GHz and 4.3 GHz are obtained respectively in both simulated and measured antenna structures. The proposed antenna has a directive radiation pattern in E-plane and omnidirectional pattern in Hplane. Also, the gain is suppressed in the notched frequencies. The group delay is nearly stable in the UWB frequency range with very little variations, but it is distorted sharply at the notch frequencies. So, the proposed antenna is a good candidate for the modern UWB systems.

Design of stacked segmented ultra wide band antenna

In this paper, a novel wide band stacked segment microstrip patch antenna (MPA) with two layered RT/Duroid is proposed. Multi-layered stacked patches are designed with rectangular dimensions, and square slots are entrenched with first patch to excite them. A parametric study of dielectric thickness and stacked center is carried out to enhance the impedance bandwidth of the proposed antenna. The antenna performance has been characterized in terms of reflection coefficient (S11), peak gain and radiation characteristics. Among different cases, thickness and locations of stacked center resulted in an impedance bandwidth of 9.3 to 19 GHz. The peak gain varies of 3dB over the operating frequency range. The antenna was simulated using Ansys HFSS v13 (Finite element method) and CST MWS (Finite Integral Method). This stacked antenna can be a suitable candidate for a variety of modern wireless and broadband applications.

Polarimetry radar calibration using trihedral corner reflectors with electromagnetic band gap polarization converters

Polarimetric radar systems need calibration. Trihedral corner reflectors are used for calibration. Conventional techniques cover one side of the reflector with corrugations which are heavy and thick. In this paper an electromagnetic band gap material is designed to cover one side of the reflector. The electric field incident upon the reflector is linearly polarized. The reflected electric field is also linear but perpendicular to the incident field. These materials are low profile, low cost , broad band and simple to construct.

Miniaturization and enhancement performance of passive microwave components using HTS and thin film ferroelectric materials

Passive RF/microwave components (e.g. couplers, and filters) occupy big design area in the RF/microwave circuit and systems, especially when it work at low frequencies. This paper presents using of High Temperature Superconductor HTS for reducing the size of circuit design and maintains good performance, the surface impedance model is investigated and verified, branch-line coupler is designed on Lanthanum Aluminate (LaAlO3) substrate which is more suitable for HTS, the CST Electromagnetic wave simulator is used for design the coupler, all parameters of the designed coupler (Insertion Loss, Return Loss, and Isolation) show good enhancement when compared to previously published result of the coupler made of copper material. Also the size of the HTS coupler is small four times than the coupler made of copper material. A tunable frequency branch-line coupler is designed by using thin film layer of Strontium Titanate(SrTiO3) ferroelectric material, the thin layer is sandwiched between the LAO substrate and HTS microstrip line, the response shows a variation of frequency work with changing applied electric field.