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31,377 Article Results

Performance Investigation of OFDM-FSO System under Diverse Weather Conditions of Bangladesh

10.11591/ijece.v8i5.pp3722-3731
Maliha Sultana , Agnila Barua , Jobaida Akhtar , Mohammad Istiaque Reja
Free space optical (FSO) communication systems which are deployed for last mile access, being considered as a suitable alternative technology for optical fiber networks. It is one of the emerging technologies for broadband wireless connectivity which has also been receiving growing attention due to high data rate transmission capability with low installation cost and license free spectrum. However, the widespread use of FSO technology has been hampered by the randomly time varying characteristics of propagation path mainly due to atmospheric turbulence, sensitivity to diverse weather conditions and the nonlinear responsivity of laser diode. This paper presents the performance investigation of an OFDM-FSO system over atmospheric turbulence channels under diverse weather conditions of Bangladesh. The channel is modeled with gamma-gamma distribution using 16-QAM modulation format and 4×4 multiple transceiver FSO system. All possible challenges are imposed on the system performance such as atmospheric attenuation, turbulence, pointing error, geometric loss etc. The refractive index structure parameter and atmospheric attenuation coefficient for different weather conditions are calculated by using the data, collected from Bangladesh Meteorological Department. The acquired results can be fruitful for scheming, forecasting and assessing the OFDM-FSO system’s ability to transmit wireless services over turbulent FSO links under actual conditions of Bangladesh.
Volume: 8
Issue: 5
Page: 3722-3731
Publish at: 2018-10-01

Enhanced RSA Cryptosystem based on Multiplicity of Public and Private Keys

10.11591/ijece.v8i5.pp3949-3953
Ahmed Eskander Mezher
Security is one of the most important concern to the information and data sharing for companies, banks, organizations and government facilities. RSA is a public cryptographic algorithm that is designed specifically for authentication and data encryption. One of the most powerful reasons makes RSA more secure is that the avoidance of key exchange in the encryption and decryption processes. Standard RSA algorithm depends on the key length only to protect systems. However, RSA key is broken from time to another due to the development of computers hardware such as high speed processors and advanced technology. RSA developers have increased a key length or size of a key periodically to maintain a high security and privacy to systems that are protected by the RSA. In this paper, a method has been designed and implemented to strengthen the RSA algorithm by using multiple public and private keys. Therefore, in this method the security of RSA not only depends on the key size, but also relies on the multiplicity of public and private keys.
Volume: 8
Issue: 5
Page: 3949-3953
Publish at: 2018-10-01

Nonlinear Control of an Active Magnetic Bearing with Output Constraint

10.11591/ijece.v8i5.pp3666-3677
Danh Huy Nguyen , Tung Lam Nguyen , Manh Linh Nguyen , Huy Phuong Nguyen
In this paper, an appropriate control strategy is proposed to handle the nonlinear dynamics ofan active magnetic bearing (AMB). The goal of the control design is to drive the AMB rotor to the origin with improved transient response. In order to achieve this task, back stepping control technique with a barrier Lyapunov function are employed to keep the tracking error trajectory inside a predefined zone to avoid possible mechanical contact between rotor and stator. Besides, a speed observer is also used since information about rotor speed is not always available. The stability of the closed-loop system is proven. The effectiveness of the proposed control strategy is verified by numerical simulations.
Volume: 8
Issue: 5
Page: 3666-3677
Publish at: 2018-10-01

An Enhancement Role and Attribute Based Access Control Mechanism in Big Data

10.11591/ijece.v8i5.pp3187-3193
M Meneka , K. Meenakshisundaram
To be able to leverage big data to achieve enhanced strategic insight and make informed decision, an efficient access control mechanism is needed for ensuring end to end security of such information asset. Attribute Based Access Control (ABAC), Role Based Access Control (RBAC) and Event Based Access Control (EBAC) are widely used access control mechanisms. The ABAC system is much more complex in terms of policy reviews, hence analyzing the policy and reviewing or changing user permission are quite complex task. RBAC system is labor intensive and time consuming to build a model instance and it lacks flexibility to efficiently adapt to changing user’s, objects and security policies. EBAC model considered only the events to allocate access controls. Yet these mechanisms have limitations and offer feature complimentary to each other. So in this paper, Event-Role-Attribute based fine grained Access Control mechanism is proposed, it provide a flexible boundary which effectively adapt to changing user’s, objects and security policies based on the event. The flexible boundary is achieved by using temporal and environment state of an event. It improves the big data security and overcomes the disadvantages of the ABAC and RBAC mechanisms. The experiments are conducted to prove the effectiveness of the proposed Event-Role-Attribute based Access Control mechanism over ABAC and RBAC in terms of computational overhead.
Volume: 8
Issue: 5
Page: 3187-3193
Publish at: 2018-10-01

An Efficient Filtering Technique for Denoising Colour Images

10.11591/ijece.v8i5.pp3604-3608
K. Arun Sai , K. Ravi
Single-sensor digital cameras capture image with the aid of masking the sensor surface along a colour filter array(CFA) such that every sensor pixel solely samples certain of three primary colour values i.e., R (red)，G (green) and B (blue). To get a full-colour image, an interpolation method commonly referred in conformity with CFA demosaicking is required to estimate the other two contributions for producing a full-colour image. But, the clutter in imaging sensors not only corrupts the colour filter array but also introduces artifacts at some stage in the colour interpolation step and affects the characteristics of image. To acquire high quality full-colour image, a kind of viable and effective interpolation algorithm based over gradient is used. This technique can remove the noise effectively by retaining image border and detail data clearly.
Volume: 8
Issue: 5
Page: 3604-3608
Publish at: 2018-10-01

Experimental Analysis of Web Browser Sessions Using Live Forensics Method

10.11591/ijece.v8i5.pp2951-2958
Rusydi Umar , Anton Yudhana , Muhammad Nur Faiz
In today's digital era almost every aspect of life requires the internet, one way to access the internet is through a web browser. For security reasons, one developed is private mode. Unfortunately, some users using this feature do it for cybercrime. The use of this feature is to minimize the discovery of digital evidence. The standard investigative techniques of NIST need to be developed to uncover an ever-varied cybercrime. Live Forensics is an investigative development model for obtaining evidence of computer usage. This research provides a solution in forensic investigation effectively and efficiently by using live forensics. This paper proposes a framework for web browser analysis. Live Forensics allows investigators to obtain data from RAM that contains computer usage sessions. 
Volume: 8
Issue: 5
Page: 2951-2958
Publish at: 2018-10-01

Performance Enhancement of MIMO-OFDM using Redundant Residue Number System

10.11591/ijece.v8i5.pp3902-3912
M. I. Youssef , A. E. Emam , M. Abd Elghany
Telecommunication industry requires high capacity networks with high data rates which are achieved through utilization of Multiple-Input-Multiple-Output (MIMO) communication along with Orthogonal Frequency Division Multiplexing (OFDM) system. Still, the communication channel suffers from noise, interference or distortion due to hardware design limitations, and channel environment, and to combat these challenges, and achieve enhanced performance; various error control techniques are implemented to enable the receiver to detect any possible received errors and correct it and thus; for a certain transmitted signal power the system would have lower Bit Error Rate (BER). The provided research focuses on Redundant Residue Number System (RRNS) coding as a Forward Error Correction (FEC) scheme that improves the performance of MIMO-OFDM based wireless communications in comparison with current methods as Low-Density Parity Check (LDPC) coders at the transmitter side or equalizers at receiver side. The Bit Error Rate (BER) performance over the system was measured using MATLAB tool for different simulated channel conditions, including the effect of signal amplitude reduction and multipath delay spreading. Simulation results had shown that RRNS coding scheme provides an enhancement in system performance over conventional error detection and correction coding schemes by utilizing the distinct features of Residue Number System (RNS).
Volume: 8
Issue: 5
Page: 3902-3912
Publish at: 2018-10-01

BB84 with Both Several Cloning and Intercept-resend Attacks

10.11591/ijece.v8i5.pp2988-2993
Mustapha Dehmani , El Mehdi Salmani , Hamid Ez-Zahraouy , Abdelilah Benyoussef
The goal of the protocol QKD BB84 is to allow a transmitter and a receiver which uses a quantum channel to exchange their keys and to detect the presence of eavesdropping attacks. In the present research, we investigate the effect of several eavesdroppers with both intercept-resend and cloning attacks. We will propose the different possible cases of the positioning of the eavesdroppers and their strategies of attacks; also we will calculate the mutual information for each case. The explicit expressions of the mutual information and quantum error clearly show that the security of the exchanged information depends on the numbers of the eavesdroppers and their attacks parameters on the quantum channel.
Volume: 8
Issue: 5
Page: 2988-2993
Publish at: 2018-10-01

Adaptation Meta-Cognitive as an Educational Tool: Animated Puzzle

10.11591/ijeecs.v12.i1.pp319-325
Ida Syakirah Sudin , Suzana Ahmad , Marina Ismail , Norizan Mat Diah
Students need to be equipped with high order thinking skill in order to prepare them with future world. Eventhough variety of programs on teaching high order thinking skills has been implemented formally in schools in Malaysia and also placed in the school curriculum, the results are not to the satisfactory.  This research is proposing a suitable educational tool which can  increase higher thinking skills among students. Keeping in mind that learning is a conceptualized multidimensional development involving three components: cognitive learning achievement, meta-cognition and motivation, an educational game with Meta-cognitive activity is proposed.  An animated puzzle game that adapts acitivities that enables to nurture meta-cognitive skills has been developed and tested.  Heuristic testing and functionality testing has been done towards the project prototype and positive results has been obtained.  An enhancement of prototype will embark a new perspective of educational mechanism and could improve students higher order thinking skills capability.
Volume: 12
Issue: 1
Page: 319-325
Publish at: 2018-10-01

Selection of Learning Materials Based on Students’ Behaviors in 3DMUVLE

10.12928/telkomnika.v16i5.7994
Rasim; Bandung Institute of Technolog Rasim , Yusep; Bandung Institute of Technology Rosmansyah , Armein Z.R.; Bandung Institute of Technology Langi , Munir; Universitas Pendidikan Indonesia Munir
Learning in 3-dimensional virtual environments has been widely used as a complement to traditional learning. Multi User Virtual Learning Environment in 3 Dimensions (3DMUVLE) provides many benefits and can support lifelong learning. In its implementation, this learning has not supported personal learning. This study aims to build a 3DMUVLE with personalized materials based on students' models. The system development model uses the Linear Sequence model by integrating MOODLE, SLOODLE and OPENSIM. Student's model in this research is Myer Briggs Type Indicator (MBTI) and determination of type uses fuzzy logic. The results of this study are 16 types of students and each type consists of 3 levels: low, medium and high. Each level has a specific learning material. The implication of this research is the level of MBTI type so that the learning material is more specific.
Volume: 16
Issue: 5
Page: 2127-2136
Publish at: 2018-10-01

Effects of the Computer Mediated Communication Interaction on Vocabulary Improvement

10.12928/telkomnika.v16i5.10195
Siamak; Flinders University Mirzaei , Ashkan Farrokh; Unisa University Hayati
This study examined the effect of CMC interaction on Iranian EFL learners’ vocabulary improvement. The study was carried out on the basis of a comparative design and tried to compare CMC with face to-face interactions in the Iranian EFL learners in order to see whether the learners’ lexical knowledge improved by the CMC interaction. Participants of the study were advanced learners studying in a language institute. The Oxford placement test was used to determine the Iranian EFL learners’ proficiency level and ensure a homogeneous sample. Then, the participants were randomly assigned to one control group (face-to-face interaction) and one experimental group (CMC interaction) in order to compare the effect of CMC on the learners’ vocabulary improvement. The learners took a pre-test to select 12 target lexical items, treatment activity to perform information-gap task, and two immediate and delayed post-tests for assessing the acquisition of new lexical items. Yahoo Messenger was used to provide the chat communication. The research provided evidence that there was a significant relationship between the use of CMC interaction and face-to-face interaction with regard to improvement in the learners’ vocabulary learning. The result indicated that the learners’ vocabulary learning improved more in CMC interaction in comparison to face-to-face interaction. In addition, there was a significant difference in negotiating the meaning of new lexical items through CMC interaction in comparison to face-to-face interaction. Moreover, the results indicated that in terms of signal, the CMC interaction outperformed face-to-face group.
Volume: 16
Issue: 5
Page: 2217-2225
Publish at: 2018-10-01

Modelling of Time Efficiency in Heterogeneous and Adhoc Networks

10.11591/ijeecs.v12.i1.pp147-154
Yatendra Singh Bhandari , Yashwant Singh Chauhan , Priti Dimri
Heterogeneous Networks are bunch of homogeneous networks base stations grouped together. The term introduced in this research paper Time Efficiency (Te) gives out the information on the heterogeneous networks where most of the data flows in and out. In this paper, a model for evaluating Time Efficiency in heterogeneous network is developed. The common goals of different base stations in a heterogeneous network are towards coverage of area and capability improvement. Base stations in a homogeneous network differs in transmitted power, achievable rate of data, area covered, density of a base station, energy efficiency and time efficiency. To find out the area of most data flow in certain period, Time efficiency can be used as a major factor. 
Volume: 12
Issue: 1
Page: 147-154
Publish at: 2018-10-01

Harmonic Suppression Dual-band Dipole Antenna with Parasitic Elements and a Stub

10.12928/telkomnika.v16i5.9188
A. B.; Universiti Tun Hussein Onn Malaysia Albishti , S A; Universiti Tun Hussein Onn Malaysia Hamzah , S M; Universiti Tun Hussein Onn Malaysia Shah , K N; Universiti Tun Hussein Onn Malaysia Ramli , N; Universiti Tun Hussein Onn Malaysia Abdullah , M S; Universiti Tun Hussein Onn Malaysia Zainal , L; Universiti Tun Hussein Onn Malaysia Audah , A; Universiti Tun Hussein Onn Malaysia Ubin , F C; Universiti Tun Hussein Onn Malaysia Seman , A K; Universiti Tun Hussein Onn Malaysia Anuar , S Z; Universiti Tun Hussein Onn Malaysia Sapuan , R; Universiti Tun Hussein Onn Malaysia Atan , M; Universiti Teknologi Malaysia Esa , N N N Abd; Universiti Teknologi Malaysia Malik
A dual-band harmonic suppression dipole antenna suitable for energy harvesting system is presented in this paper. A linear dipole with two parasitic elements is designed and fabricated with a capability to eliminate the harmonic of higher order modes. At first, the antenna resonates at 900 MHz and 2.7 GHz. Therefore, a parasitic element is added into each of the dipole’s arm to tune the second frequency band to 2.4 GHz to fit into wireless application. However, the presence of two parasitic elements has generated an unwanted harmonic at 4.0 GHz. Thus, a stub has been integrated into the antenna’s terminal (feed line) to suppress the 4.0 GHz frequency. This technique is suitable for developing a multiband antenna with harmonic suppression. The antenna is fabricated on a FR-4 board with the size of 72×152 mm2 which operates efficiently at 0.8 GHz and 2.4 GHz which is suitable for wireless communication applications. The prototype can suppress the undesired harmful harmonics present within the frequency range of 3 to 5 GHz. The antenna has a good potential to be used in a rectenna system with a dual-band frequency operation but with better performance. Simulation and measurement results obtained are in a good agreement, which have confirmed the proposed design concept.
Volume: 16
Issue: 5
Page: 1918-1922
Publish at: 2018-10-01

Optimum Image Filters for Various Types of Noise

10.12928/telkomnika.v16i5.10508
Zayed M.; Al-Ahliyya Amman University Ramadan
In this paper, the quality performance of several filters in restoration of images corrupted with various types of noise has been examined extensively. In particular, Wiener filter, Gaussian filter, median filter and averaging (mean) filter have been used to reduce Gaussian noise, speckle noise, salt and pepper noise and Poisson noise. Many images have been tested, two of which are shown in this paper. Several percentages of noise corrupting the images have been examined in the simulations. The size of the sliding window is the same in the four filters used, namely 5x5 for all the indicated noise percentages. For image quality measurement, two performance measuring indices are used: peak signal-to-noise ratio (PSNR) and structural similarity (SSIM). The simulation results show that the performance of some specific filters in reducing some types of noise are much better than others. It has been illustrated that median filter is more appropriate for eliminating salt and pepper noise. Averaging filter still works well for such type of noise, but of less performance quality than the median filter. Gaussian and Wiener filters outperform other filters in restoring mages corrupted with Poisson and speckle noise.
Volume: 16
Issue: 5
Page: 2458-2464
Publish at: 2018-10-01

An Electromagnetism-like Mechanism Algorithm Approach for Photovoltaic System Optimization

10.11591/ijeecs.v12.i1.pp333-340
Jian Ding Tan , Siaw Paw Koh , Sieh Kiong Tiong , Kharudin Ali , Ying Ying Koay
Solar energy has become one of the most studied topic in the field of renewable energy. In this paper, an artificial intelligent approach is proposed for the optimization of a photovoltaic solar energy harvesting system. An Electromagnetism-Like Mechanism Algorithm (EM) has been developed to search for the hourly optimum tilt angles for photovoltaic panels. In order to investigate the effect of the search step size on the efficiency and overall accuracy of the algorithm, the EM has also been modified into several variants with different search step size settings. Experimental findings show that EM with bigger search lengths has the advantage of reaching a near optimum tilt angle in earlier iterations but less accurate. EM with smaller step lengths, on the other hand, can hit a relatively more optimum tilt angle in the process. During the peak of the power generation at noon, EM with smaller search stes found an optimum tilt angle which yielded additional 3.17W of power compared to a fixed panel. We thus conclude that the proposed EM performs well in optimizing the tilt angle of a photovoltaic solar energy harvesting system.
Volume: 12
Issue: 1
Page: 333-340
Publish at: 2018-10-01
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