@article { author = {Ehdaie, Mohammad and Alexiou, Nikolaos and Papadimitratos, Panos}, title = {Random Key Pre-Distribution Techniques against Sybil Attacks}, journal = {Journal of Communication Engineering}, volume = {5}, number = {1}, pages = {1-13}, year = {2016}, publisher = {Shahed University}, issn = {2322-4088}, eissn = {2322-3936}, doi = {10.22070/jce.2016.387}, abstract = {Sybil attacks pose a serious threat for Wireless Sensor Networks (WSN) security. They can create problems in routing, voting schemes, decision making, distributed storage and sensor re-programming. In a Sybil attack, the attacker masquerades as multiple sensor identities that are actually controlled by one or a few existing attacker nodes. Sybil identities are fabricated out of stolen keys, obtained by captured benign nodes. Existing Sybil defensive mechanisms suffer from the restricted sensor network size, or cause excessive resource consumption for the sensor network. In this work we propose a Sybil node detection mechanism, based on Random Key Distribution (RKD) schemes that can cope with large network sizes and minimize the waste of resources. We explain the techniques each node can use in a network running q-composite RKD to detect Sybil identities and restrict their number. Our method requires no trust to other sensors, which is important to defend against the attack.}, keywords = {Random Key Predistribution,Sybil Attack,Wireless Sensor Networks}, url = {https://jce.shahed.ac.ir/article_387.html}, eprint = {https://jce.shahed.ac.ir/article_387_8e439e81efc753ada17f26af594f7df2.pdf} } @article { author = {Daneshjoo, Parisa and Haj Seyed javadi, Hamid and Sharifi, Hamid Reza}, title = {Sink Location Service Based on Fano Plane in Wireless Sensor Networks}, journal = {Journal of Communication Engineering}, volume = {5}, number = {1}, pages = {14-23}, year = {2016}, publisher = {Shahed University}, issn = {2322-4088}, eissn = {2322-3936}, doi = {10.22070/jce.2016.388}, abstract = {Sink location is considered as a basic service in geographic routing in wireless sensor networks. Obtaining the location of sink node by source node using an efficient method with low complexity has always been a challenging issue in research. In this paper, a sink location algorithm based on Fano plane is proposed. The research challenge is how to ensure the intersection of two SLQ (Location Query) and SLA (Sink Location Announcement) routes in at least one point. In the proposed solution, a compound Fano plane has been created in which both SLQ and SLA paths have a point of intersection. Source and destination nodes send data packets to nearby routes and the sensor node at the intersection announces the location of the destination node to the source. Simulation is used to evaluate the proposed algorithm. The results revealed reduction in communication overhead.}, keywords = {Combinatorial Scheme,Fano plane,Sink location,Wireless Sensor Network}, url = {https://jce.shahed.ac.ir/article_388.html}, eprint = {https://jce.shahed.ac.ir/article_388_fb82e30622420750c773739d6e7a7439.pdf} } @article { author = {Seyyedrezaei, Seyyedeh Faezeh and Dadashzadeh, Gholamreza}, title = {Optimal Control of Light Propagation Governed by Eikonal Equation within Inhomogeneous Media Using Computational Adjoint Approach}, journal = {Journal of Communication Engineering}, volume = {5}, number = {1}, pages = {24-37}, year = {2016}, publisher = {Shahed University}, issn = {2322-4088}, eissn = {2322-3936}, doi = {10.22070/jce.2017.1493.}, abstract = {A mathematical model is presented in the present study to control‎ ‎the light propagation in an inhomogeneous media‎. ‎The method is ‎based on the identification of the optimal materials distribution‎ ‎in the media such that the trajectories of light rays follow the‎ ‎desired path‎. ‎The problem is formulated as a distributed parameter ‎identification problem and it is solved by a numerical method‎. ‎The‎ ‎necessary optimality conditions based on Karush-Kuhm-Tucker (KKT) conditions is derived‎ ‎by means of the adjoint approach and a solution algorithm is‎ ‎introduced to find local minimizers of the original problem‎. ‎The‎ ‎original PDE and its corresponding adjoint are discretized by the‎ ‎finite difference method and they are solved efficiently by the‎ ‎fast sweeping approach‎. ‎The main benefits of the presented‎ ‎algorithm is the computational efficiency‎, ‎flexibility and ability‎ ‎to produce isotropic materials distribution with bounded physical‎ ‎properties‎. ‎The presented algorithm can be used for the optimal‎ ‎design of waveguides and invisibility cloaks in the wavelength ‎spectrum of visible light‎. ‎The feasibility of the‎ ‎presented method is studied by a numerical example‎.          }, keywords = {Adjoint method,Eikonal equation,Geometric optics,metamaterial,Transformation optics}, url = {https://jce.shahed.ac.ir/article_428.html}, eprint = {https://jce.shahed.ac.ir/article_428_ecc953e1bffe250d84eaa24d4078742c.pdf} } @article { author = {Zehforoosh, Yashar and Sedghi, Tohid}, title = {An Improved CPW-Fed Printed UWB Antenna With Controllable Band-notched Functions}, journal = {Journal of Communication Engineering}, volume = {5}, number = {1}, pages = {38-49}, year = {2016}, publisher = {Shahed University}, issn = {2322-4088}, eissn = {2322-3936}, doi = {10.22070/jce.2016.386}, abstract = {A newly designed printed slot antenna is presented that incorporates variable two band-notched functions for ultra-wideband (UWB) applications. The two band notches of this coplanar waveguide (CPW) fed antenna are achieved by an M-shaped slot (MSS) embedded in the radiating element and a C-shaped strip (CSS) close to ground plane, therefore two very narrow rejected properties in the wireless local area network (WLAN) band (5.15-5.825 GHz) and worldwide interoperability for microwave access (WiMAX) operation in the (3.3-3.7GHz) are obtained. The rectangular aperture is etched in the square ground plane. It has a determinative role in antenna’s impedance bandwidth (IBW) enhancement; moreover, by adjusting carefully it leads to wide IBW. Based on simulated results it covers the frequency range 2.4–12.9 GHz with VSWR ≤ 2, which corresponds to a fractional bandwidth of 137% excluding the rejected bands. Numerical and measured results are presented to understand its behavior. The volume of the proposed antenna is 25 × 25 × 0.8 mm3.}, keywords = {Slot antenna,ultra-wideband antenna,WLAN,WiMAX,band-notched function}, url = {https://jce.shahed.ac.ir/article_386.html}, eprint = {https://jce.shahed.ac.ir/article_386_f817780481cc720b997068c29450fa45.pdf} } @article { author = {Samieean, Hamid and Ostadzadeh, Saeed Reza and Mirzaie, Amin}, title = {Application of Intelligent Water Drops in Transient Analysis of Single Conductor Overhead Lines Terminated to Grid-Grounded Arrester under Direct Lightning Strikes}, journal = {Journal of Communication Engineering}, volume = {5}, number = {1}, pages = {50-59}, year = {2016}, publisher = {Shahed University}, issn = {2322-4088}, eissn = {2322-3936}, doi = {10.22070/jce.2016.410}, abstract = {In this paper, Intelligent water drop algorithm (IWD) is used to analyze single overhead line connected to grid-grounded arrester. In this approach, at first Norton’s equivalent circuit of the overhead line over lossy soil is computed by method of moments (MoM) and then for the problem under consideration, a nonlinear equivalent circuit in the frequency domain is proposed. Finally applying intelligent water drop algorithm (IWD), nonlinear analysis is efficiently analyzed and transient voltage across the arrester is easily computed. Comparison of the achieved voltage with transient solvers shows good agreement as well as fast run-time.    the achieved voltage with transient solvers shows good agreement as well as fast run-time.}, keywords = {IWD,arrester,lossy soil}, url = {https://jce.shahed.ac.ir/article_410.html}, eprint = {https://jce.shahed.ac.ir/article_410_3e7d21a35d92215f26e49da0e6f981c8.pdf} } @article { author = {rashki, zohreh and seyyed Mahdavi Chabok, Seyyed Javad}, title = {Novel Design of Optical Channel Drop Filter Based on Photonic Crystal Ring Resonators}, journal = {Journal of Communication Engineering}, volume = {5}, number = {1}, pages = {60-70}, year = {2016}, publisher = {Shahed University}, issn = {2322-4088}, eissn = {2322-3936}, doi = {10.22070/jce.2017.1498.}, abstract = {In this paper, a new design of optical channel drop filter based on two- dimensional photonic crystal ring resonators with triangular lattice is proposed. The rods of this structure is silicon with the refractive index 3.46 and the surrounding environment is air with the refractive index of 1.The widest photonic band gap obtained is for filling ratio of r/a = 0.2. The filter’s transmission spectrum is calculated using the two-dimensional (2D) finite-difference time-domain (2D-FDTD) numerical method. The simulation shows 100% dropping efficiency and suitable quality factor at 1519.4 nm wavelength achieved for this filter. Also, in this paper, we investigate parameters which have an effect on resonant wavelength and transmission spectrum in this CDF, such as refractive index of inner rods and whole of dielectric rods of the structure. The overall size of the structure is small that is 14 μm × 14μm which is suitable for photonic integrated circuits (PIC) and optical communication network applications. }, keywords = {Photonic crystal,Ring resonator,Triangular lattice,Optical communication}, url = {https://jce.shahed.ac.ir/article_429.html}, eprint = {https://jce.shahed.ac.ir/article_429_8de77abcf9d674eee763d2cf572c205d.pdf} }