eng
Shahed University
Journal of Communication Engineering
2322-4088
2322-3936
2017-07-01
6
2
99
109
10.22070/jce.2017.1488.
566
Mitigating Node Capture Attack in Random Key Distribution Schemes through Key Deletion
Mohammad Ehdaie
mohammad@ehdaie.ir
1
Nikos Alexiou
2
Mahmoud Ahmadian
3
Mohammad Reza Aref
4
Panos Papadimitratos
papadim@kth.se
5
Parsa Sharif Research Center
KTH
K.N.Toosi
Sharif
KTH
Random Key Distribution (RKD) schemes have been widely accepted to enable low-cost 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 special-purpose 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.
http://jce.shahed.ac.ir/article_566_2c207f74582edc201a6c1ea66ef6d57f.pdf
Wireless Sensor Networks
Random Key Distribution
Node Capture
Key Deletion
eng
Shahed University
Journal of Communication Engineering
2322-4088
2322-3936
2017-07-01
6
2
110
117
10.22070/jce.2017.2228.1035
551
A compact stacked Quasi-fractal microstrip antenna for RFID applications
sina rezaee ahvanouee
sinarezaee91@yahoo.com
1
javad Ghalibafan
jghalibafan@shahroodut.ac.ir
2
shahrood university
shahrood university
In this paper, we propose a new compact quasi-fractal 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 quasi-fractal 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 radio-frequency identification systems.
http://jce.shahed.ac.ir/article_551_4b308fbe8112e940381a7ccc1325e4b4.pdf
compact stacked microstrip antenna
quasi-fractal shaped antenna
RFID applications
eng
Shahed University
Journal of Communication Engineering
2322-4088
2322-3936
2017-07-01
6
2
118
130
10.22070/jce.2017.2262.1040
555
Compensation of Doppler Effect in Direct Acquisition of Global Positioning System using Segmented Zero Padding
Hossein Amiri
hossein756@yahoo.com
1
Hossein Khaleghi Bizaki
bizaki@yahoo.com
2
Malek Ashtar University of Technology
Malek Ashtar University of Technology
Because of the very high chip rate of global positioning system (GPS), P-code 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.
http://jce.shahed.ac.ir/article_555_66567a27238b71fecd7d48eaf5863e57.pdf
Segment Zero Padding (SZP), Zero Padding (ZP), Direct Average Method (DAM), Probability of Detection, Average Acquisition Time
Global Positioning System (GPS)
eng
Shahed University
Journal of Communication Engineering
2322-4088
2322-3936
2017-07-01
6
2
131
140
10.22070/jce.2017.2399.1045
544
Physical Optics Calculation of Electromagnetic Scattering From Haack Series Nose Cone
Vahid Mohtashami
v.mohtashami@um.ac.ir
1
Zohreh Asadi
a.asadi1990@gmail.com
2
Ferdowsi University of Mashhad
Department of Electrical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
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 closed-form expression for computing physical optics integral. Then the ray-surface 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 ray-cylinder intersection test has a simple analytical solution, which results in fast rejection of missed rays.
http://jce.shahed.ac.ir/article_544_8343a0f74b5a48095bc5b6ec64e6bc84.pdf
Bounding volume
Haack series
intersection test
mesh generation
physical optics
eng
Shahed University
Journal of Communication Engineering
2322-4088
2322-3936
2017-07-01
6
2
141
150
10.22070/jce.2017.1826.1029
553
Evaluation Performance of OFDM Mutlicarrier Modulation over Rayleigh and RicianStandard Channels Using WPT-OFDM Modulations
saeed Ghazi-Maghrebi
s_ghazi2002@yahoo.com
1
farbayan Khordadpour-Deylamani
farbaian_khordadpoor@yahoo.com
2
Department of Communications, Collage of Electrical Engineering, Yadegar-e- Imam Khomeini (RAH) Shahr-e-Rey Branch, Islamic Azad University
Islamic Azad University
Last years, Wavelet Packet Modulation (WPM) or Wavelet Packet Transform based Orthogonal Frequency Division Multiplexing (WPT-OFDM) 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 inter-symbol and inter-carrier 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 FFT-OFDM and WPT-OFDM 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 WPT-OFDM in contrast with FFT-OFDM 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.
http://jce.shahed.ac.ir/article_553_e1a6628bc42ddaf87832c4798da6ad9c.pdf
FFT-OFDM
FEQ
Overlap FEQ
F1 channel
P1 channel and WPT-OFDM
eng
Shahed University
Journal of Communication Engineering
2322-4088
2322-3936
2017-07-01
6
2
151
162
10.22070/jce.2017.2342.1042
554
CPW-Fed Circularly Polarized Slot ANTENNA with Elliptical-Shaped Patch for UWB Applications
Yashar Zehforoosh
yashar.zehforoosh@gmail.com
1
sabriyeh mirzaei
mirzaei_sabriyeh@ymail.com
2
IAU Urmia branch
Department of Electrical Engineering, Urmia Branch, Islamic Azad University, Urmia, Iran;
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 circular-shaped slits is applied to opposite corners of the slot for enhancing the impedance matching and realizes bandwidth of 134.43% across 2.98-15.20 GHz for VSWR≤2. Furthermore this structure exhibits axial ration bandwidth (ARBW) of 36.22% across 4.43-6.39 GHz by embedding two inverted-L 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 ultra-wideband (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.
http://jce.shahed.ac.ir/article_554_fcd1de61bb70efe9912462d8d7113ea1.pdf
Slot antenna
CPW-fed
ultra-wideband antenna
Circular polarization