2017
6
2
0
0
Mitigating Node Capture Attack in Random Key Distribution Schemes through Key Deletion
2
2
Random Key Distribution (RKD) schemes have been widely accepted to enable lowcost secure communications in Wireless Sensor Networks (WSNs). However, efficiency of secure link establishment comes with the risk of compromised communications between benign nodes by adversaries who physically capture sensor nodes. The challenge is to enhance resilience of WSN against node capture, while maintaining the flexibility and low cost features of RKD schemes. We address this problem by proposing an effective technique, namely KDel, which dont require any specialpurpose hardware or expensive computations. We demonstrate that our approach significantly increases the resilience of RKD schemes against node capture at the cost of a little communications, while maintaining network connectivity at the same level. Moreover, our scheme is generally applicable as it can improve the resilience of any RKD scheme.
1

99
109


Mohammad
Ehdaie
Parsa Sharif Research Center
Parsa Sharif Research Center
Iran
mohammad@ehdaie.ir


Nikos
Alexiou
KTH
KTH
Iran


Mahmoud
Ahmadian
K.N.Toosi
K.N.Toosi
Iran


Mohammad Reza
Aref
Sharif
Sharif
Iran


Panos
Papadimitratos
KTH
KTH
Iran
papadim@kth.se
Wireless Sensor Networks
Random Key Distribution
Node Capture
Key Deletion
A compact stacked Quasifractal microstrip antenna for RFID applications
2
2
In this paper, we propose a new compact quasifractal shaped microstrip antenna that consists of a hexagonal patch as the main radiator and a complementary stacked patch as the parasitic element. The overall surface of the proposed quasifractal patch is about 55% lower than the conventional hexagonal patch. Using of stacked technique, the gain reduction of compression technique is almost compensated for the proposed antenna while the total gain is reduced only about 1 dBi. Experimental results show that the operation frequency of the microstrip antenna is about 2.5 GHz which covers the microwave frequency band of radiofrequency identification systems.
1

110
117


sina
rezaee ahvanouee
shahrood university
shahrood university
Iran
sinarezaee91@yahoo.com


javad
Ghalibafan
shahrood university
shahrood university
Iran
jghalibafan@shahroodut.ac.ir
compact stacked microstrip antenna
quasifractal shaped antenna
RFID applications
Compensation of Doppler Effect in Direct Acquisition of Global Positioning System using Segmented Zero Padding
2
2
Because of the very high chip rate of global positioning system (GPS), Pcode acquisition at GPS receiver will be challenging. A variety of methods for increasing the probability of detection and reducing the average time of acquisition have been provided, among which the method of Zero Padding (ZP) is the most essential and the most widely used. The method using the Fast Fourier Transform (FFT), searches phase codes of the uncertainty region in a parallel method to find the desired code for correct acquisition. ZP method is sensitive to Doppler frequency so that the increase in Doppler frequency drastically reduces the probability of detection and consequently the average time of acquisition increases. The presented method in this paper, that called Segmented Zero Padding (SZP), reduces the Doppler effects on probability of detection at the acquisition of GPS receiver. Also, it will be shown that using the proposed algorithm proper mean acquisition time at high Doppler frequencies is achievable. Based on the comparisons made in this paper, we prove that the proposed algorithm in comparison to ZP algorithm, maintains the capability of parallel search and finally has a lower average acquisition time.
1

118
130


Hossein
Amiri
Malek Ashtar University of Technology
Malek Ashtar University of Technology
Iran
hossein756@yahoo.com


Hossein
Khaleghi Bizaki
Malek Ashtar University of Technology
Malek Ashtar University of Technology
Iran
bizaki@yahoo.com
Segment Zero Padding (SZP), Zero Padding (ZP), Direct Average Method (DAM), Probability of Detection, Average Acquisition Time
Global Positioning System (GPS)
Physical Optics Calculation of Electromagnetic Scattering From Haack Series Nose Cone
2
2
In this paper, the physical optics method is used to study the problem of electromagnetic scattering from Haack series nose cone. First, a meshing scheme is introduced which approximates the curvature of the surface by piecewise linear functions in both axial and rotational directions. This results in planar quadrilateral patches and enables efficient determination of the illuminated region and application of closedform expression for computing physical optics integral. Then the raysurface intersections are obtained using the implicit surface equation of Haack series nose cone. The equation obtained by the intersection test does not have analytical solution. Hence, the Steffensen's method is applied to solve this equation numerically. To find the initial point for Steffensen method's iterations, a bounding cylinder is used. It provides high precision evaluation of initial point, fast convergence and short computation time. Moreover, if the ray does not intersect the bounding volume, it certainly misses the bounded object and hence does not need to be tested in the Steffensen's method. The raycylinder intersection test has a simple analytical solution, which results in fast rejection of missed rays.
1

131
140


Vahid
Mohtashami
Ferdowsi University of Mashhad
Ferdowsi University of Mashhad
Iran
v.mohtashami@um.ac.ir


Zohreh
Asadi
Department of Electrical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Department of Electrical Engineering, Faculty
Iran
a.asadi1990@gmail.com
Bounding volume
Haack series
intersection test
mesh generation
physical optics
Evaluation Performance of OFDM Mutlicarrier Modulation over Rayleigh and RicianStandard Channels Using WPTOFDM Modulations
2
2
Last years, Wavelet Packet Modulation (WPM) or Wavelet Packet Transform based Orthogonal Frequency Division Multiplexing (WPTOFDM) have been introduced to wired and wireless communication fields as efficient Multicarrier Modulation (MCM) techniques. The wavelets have interesting features such as flexibility, compatibility and localization in both time and frequency domains with no need to use rectangular window function. As a result, the transmitted signal is naturally less sensitive to intersymbol and intercarrier interferences (ISI and ICI). Also, it is possible to implement OFDM modulation without adding cyclic prefix (CP) and it is enough only to use time domain or overlap frequency domain equalization (TEQ or overlap FEQ) in order to shorten the effective channel impulse response length with the purpose of avoiding the ISI and decreasing the ICI. In this paper, we compare BER performance for FFTOFDM and WPTOFDM in the presence of two types of channels defined by ETSI (i.e. Rayleigh P1 and Rician F1 channels). In our simulation Haar, Daubechies6, Symlet5 and Coiflet5 wavelets and overlap frequency domain equalization (overlap FEQ) are used for WPTOFDM in contrast with FFTOFDM which uses FEQ equalization. Simulation results show that the performance of OFDM will be improved by using WPT transform and due to no need of CP, the power/bandwidth efficiency of OFDM modulation will be improved as well.
1

141
150


saeed
GhaziMaghrebi
Department of Communications, Collage of Electrical Engineering, Yadegare Imam Khomeini (RAH) ShahreRey Branch, Islamic Azad University
Department of Communications, Collage of
Iran
s_ghazi2002@yahoo.com


farbayan
KhordadpourDeylamani
Islamic Azad University
Islamic Azad University
Iran
farbaian_khordadpoor@yahoo.com
FFTOFDM
FEQ
Overlap FEQ
F1 channel
P1 channel and WPTOFDM
CPWFed Circularly Polarized Slot ANTENNA with EllipticalShaped Patch for UWB Applications
2
2
A new design of coplanar waveguide (CPW)fed antenna with circular polarization (CP) and excellent impedance matching is presented. In this design a pair of circularshaped slits is applied to opposite corners of the slot for enhancing the impedance matching and realizes bandwidth of 134.43% across 2.9815.20 GHz for VSWR≤2. Furthermore this structure exhibits axial ration bandwidth (ARBW) of 36.22% across 4.436.39 GHz by embedding two invertedL shaped ground arms in the slot. The total dimension of the proposed antenna is 25×25×0.8 mm3. This new design has advantages of, supporting the ultrawideband (UWB) systems and covering the WLAN spectrums with 3dB CP radiation and VSWR≤2 simultaneously. The numerical and experimental results of the antenna explain the superiority of the proposed antenna performance with comparison to recent similar works.
1

151
162


Yashar
Zehforoosh
IAU Urmia branch
IAU Urmia branch
Iran
yashar.zehforoosh@gmail.com


sabriyeh
mirzaei
Department of Electrical Engineering, Urmia Branch, Islamic Azad University, Urmia, Iran;
Department of Electrical Engineering, Urmia
Iran
mirzaei_sabriyeh@ymail.com
Slot antenna
CPWfed
ultrawideband antenna
circular polarization