Journal of Communication Engineering
http://jce.shahed.ac.ir/
Journal of Communication Engineeringendaily1Wed, 01 Jul 2020 00:00:00 +0430Wed, 01 Jul 2020 00:00:00 +0430Performance analysis of the LTE handover decision events for the high speed railway application
http://jce.shahed.ac.ir/article_3248.html
Providing high quality mobile internet service to passengers of high speed railway (HSR) has a key role to its market share. The LTE radio network has been raised as candidate for providing high data rate for this purpose. However, in the LTE radio network, handover (HO) becomes an important challenge at high moving speeds. The 3GPP standard body, has introduced several events for LTE HO decision making. To date, there has not been an analytical model to compare these events for using in HSR system. We have mathematically analyzed these events to compare their performances in which the effect of speed has also been considered. The results has been validated by comparison with simulation which shows close matching. The analytical model can be used for introducing new modified events which specially will be designed for HSR system.Integration of WSN and RFID networks, and redundant data filtering
http://jce.shahed.ac.ir/article_3314.html
Abstract- Radio frequency identification (RFID) and wireless sensor networks (WSNs) are two important and widely applied wireless technologies with limitless future potential. RFID is used to detect object location, while WSN is used for environmental sensing and monitoring. The integration of RFID and WSN not only provides identity and location but also facilitates environmental condition sensing. However, RFID data contains excessive duplication, which results in time delay and increased energy consumption, resulting in wastage of various network resources. This paper proposes a hybrid network designed by the integration of WSN and RFID and consisting of seven types of nodes. In this architecture, the entire network is divided into clusters and this clustering is obtained by particle swarm optimization. In addition, it also proposes an algorithm to overcome the issue of redundant data on this hybrid network. Simulation results show that the proposed algorithm reduces both data redundancy and processing time compared to existing algorithms.Temperature-Aware Routing in Wireless Body Area Network Based on Meta-Heuristic Clustering Method
http://jce.shahed.ac.ir/article_3276.html
Wireless body area networks (WBANs) are a kind of wireless sensor network created in order to make more acceptable utilization of the hospital resources, detect medical signs or symptoms earlier, and consequently decline the costs of medical care. As a majority of the wireless networks, it has no infra-structure, and thus sensor nodes embedded in the body enjoy small level of energy. Therefore, initial termination of the wireless node energy on the basis of the message transmission in the network may interrupt the entire network process. Also, increasing the temperature of the sensor node due to sending and receiving information, can cause an increase in normal body temperature and disrupt the body's functioning process. In this article, a temperature-aware routing in the wireless body area network based on meta-heuristic clustering method is presented. In this method, in order to find the appropriate cluster head to transfer data to the root, network parameters are examined in the form of membership function of the ant colony optimization meta-heuristic method. The simulation outputs indicate the greater ability of this new method in comparison to other available techniques under the same conditions.Complete Performance Analysis of Underwater VLC Diffusion Adaptive Networks
http://jce.shahed.ac.ir/article_3234.html
In this paper, we simulated a diffusion adaptive network in the underwater environment. The communication method between the nodes of this network is assumed to be the visible light communication technology (VLC) which in the underwater condition is known as the UVLC. The links between the nodes in this case are contaminated with the optical noise and turbulence. These contaminations are modeled with the proper statistical distributions depending on the underwater conditions. The optical turbulence modeling link coefficients are shown to be following the Log-normal distribution which its mean and variance are directly dependent on the temperature and the salinity of the simulated water and the assumed distance between the diffusion network nodes. The performance of the diffusion network in using UVLC technology is then analyzed both with simulations and theoretical calculations and the results are presented using the steady-state error metrics. Our analysis showed that the diffusion network can be implemented underwater with the VLC technology providing that the distance between the network nodes is less than 10 meters. Also, in order to guarantee the convergence of the adaptive network, the water salinity level and temperature must not exceed the values that are presented in our simulations.Ultra-Compact Ultra-Wideband Bandpass Filter Based on Multi Mode Resonator Concept
http://jce.shahed.ac.ir/article_3249.html
An ultra-compact ultra-wide band (UWB) bandpass filter (BPF) with a very sharp rejection for the high-speed wireless communication applications is proposed. Thefunctional basis of the proposed structure is based on the multi-mode resonator (MMR)technique. The suggested ultra-wideband filter is realized by using two doublet parallelcoupling lines, two symmetrical open stubs and tri-section step-impedance open stubswhich are located at the center of the configuration. In order to analyze the suggestedconfiguration, the even-mode and odd-mode methods have been utilized because of theproposed UWB BPF is a symmetrical structure. Five modes which are including threeeven modes and two odd modes have been placed within the UWB band. By changing thedimensions of the tri-section step-impedance open stubs and two symmetrical open stubs,the resonant modes of the constructed MMR can be tuned. These two parts have beenmainly applied to adjust the resonant modes into desired passband. Changing thedimensions of the two symmetrical open stubs affects both the even and odd modes. Butthe tri-section step-impedance open stubs can only specially control the even-moderesonant frequencies, whereas the odd-mode ones are fixed. Consequently, the centerfrequency and the bandwidth of the proposed configuration can be simply adjusted.Experimental verification is provided and a reasonable agreement between simulated andmeasured results has been achieved. The proposed UWB BPF has a passband covers 3.55to 10.65 GHz and the measured 3 dB fractional bandwidth (FBW) is about 100%.Planar Multibeam Array Antenna with Rotman Lens Beamformer for 5GHz Band Wireless Applications
http://jce.shahed.ac.ir/article_3394.html
A planar multi-beam array with a co-planar Rotman lens beamformer is introduced for wireless applications. The array consists of 8 linear series-fed subarrays with proximity-coupled patch elements. The Rotman lens feeds the subarrays through coupling slots. To reduce beam squinting, the subarrays are fed from the center. The coupling slot feeds each arm of a subarray 180&deg; out of phase. To compensate out-of phase feeding, two feeding arms of each subarray are designed in the opposite direction. Also, cross-polar radiation is reduced significantly. In order to reduce the size of radiating patches to fit within array cell size, they are formed by four sub-patches with indentions and are fed by microstrip line from feed layer with two matching sections to improve the bandwidth. Measured results of the array structure in terms of the S-parameter of beam ports and radiation patterns are presented.Survey of Effective of Combinatorial Design Schemes in Wireless Sensor Networks Security
http://jce.shahed.ac.ir/article_3425.html
Abstract- Wireless sensor networks (WSNs) are made up of thousands of small sensor nodes that are capable of detecting, calculating, and transferring data via networks. Although there are certain resource limits, wireless transmission is still an effective way to transport information. The secure transfer of data is critical in a WSN. Key management techniques have been established for the purposes of security. Key pre-distribution is one of the key management methods used to assign keys to the devices before deploying them in the wireless sensor networks. The challenges of these schemes include memory consumption due to limited device resources, scalability, connectivity, and resilience against node capture attacks. Combinatorial designs with neutrality characteristics, which are based on mathematical structure and impose low computational overhead and communication overhead, are used in key pre-distribution and information security of wireless sensor networks. In this paper, some key pre-distribution methods based on the combinatorial designs are reviewed. Finally, the comparison of performance parameters is illustrated in tables. Suggestions to improve future research are considered as well.An Optimized Method for Outsourcing and Computational Offloading In Resources Allocation to IoT Users In Fog computing
http://jce.shahed.ac.ir/article_3463.html
Fog computing is a method for improving cloud computations performance attempts to expand the Internet of things processes and distribute cloud services in the network edge. This paper proposes a real-time outsourcing and offloading mechanism to optimize the cache and CPU consumption in resource allocation to IoT users in a fog-based processing environment. Based on this mechanism, the computations that require heavy processing are moved to the network edge, and computations with lower processing needs are processed inside user devices. According to the simulation results, the average users' average service latency in the proposed method SPA-(Offloading) for 200 users has been improved in the range of 0.8 to 0.6. In addition, the profits of cloud and fog service providers for 220 users are higher than other methods. Also, the average system cost performance was evaluated, which is better than the other methods. The results show that this mechanism improves cache consumption, processing time, and optimal resource allocation to IoT users.Dual-Band Printed Dipole Antenna Using Rectangular-Shaped Resonators for 2.4/5.5 GHz WLAN Applications
http://jce.shahed.ac.ir/article_3449.html
A new design of a dual-band printed dipole antenna with integrated balun is presented in this study. The antenna in simple form is composed of a printed dipole, integrated balun, a &Gamma;-shaped feed, and a square-shaped ground plane, which achieves a fundamental resonance at 2.4 GHz frequency. A pair of rectangular-shaped resonators are positioned on two sides of the &Gamma;-shaped feed in the second designing step innovatively to accomplish the additional resonance at 5.5 GHz as the second frequency band of the WLAN. Two electromagnetically coupling mechanisms prepared between the &Gamma;-shaped feed and dipole arms, and rectangular-shaped resonators, which lead to creating two operating frequency bands. An equivalent circuit and a parametric study presented to explain the antenna performance in this work. Experiments approve that the proposed dual-band antenna has two impedance bandwidths of 14.1% (2.23-2.57 GHz) and 25.7% (4.83-6.26 GHz) with average gains of 12.10 dBi and 6.36 dBi over the first and second frequency bands, respectively, which is cover the 2.4/5.5 GHz WLAN frequency bands successfully.Localization of Nodes in Wireless Sensor Networks using a Combination of Krill Herd Algorithm with Ant Colony Optimization
http://jce.shahed.ac.ir/article_3623.html
Abstract- The industrial revolution and the spread of electronic technologies and wireless communications have led to the production of small smart sensors with low consumption and low-cost benefits. Sensor nodes work as autonomous systems with low cost, small size, and wireless communication media but work with low resources. The most significant item in the operation of Wireless Sensor Networks (WSNs) is finding the spatial information of objects, including retrieval and identification of events, routing according to geometric position, monitoring and tracking. Localization in WSNs divides into two range-based and range-free categories. In this paper, to overcome the weaknesses of DV-Hop, a hybrid model based on the Krill Herd Algorithm and Ant Colony Optimization called KHAACO was proposed for locating unknown nodes. The aim of this study is to provide an approach for estimating the location of sensor nodes with minimal error and using KHAACO to estimate the location of unknown nodes and using the motion characteristics of other krill, foraging, and spatial dispersion of the KHA and optimizing it with ACO. The evaluation of the hybrid model in the MATLAB environment has been done based on error criteria and energy consumption. The results showed that the hybrid model compared to DV-Hop, DV-Hop-ACO, and DV-Hop-PSO reduced the Localization error. The value of reduction of localization error for 90 anchor nodes and 450 sensor nodes was equal to 9.95%.The Presentation of Adaptive Beam-Forming Algorithms GSC-LMS in Indoor and Outdoor Scenarios
http://jce.shahed.ac.ir/article_3601.html
In this paper, we investigate the multiple-input multiple-output systems (MIMO) and the co-channel interference cancelation in these systems. In recent years, the usages of array antennas in the receiver/ transmitter or both have greatly increased in telecommunication systems. Due to the increasing transmission data rate and the decreasing error rate, the MIMO systems in wireless communication systems are very important. In the third, fourth, and fifth generations of wireless communications in order to increase the network capacity and spectrum efficiency, the same frequency channel is allocated to different users. This leads to co-channel interference for the users with the same frequency channel. Thus, it is essential to eliminate inter-channel interference in telecommunication networks. In this paper, an adaptive algorithm is evaluated to eliminate the co-channel interference in MIMO systems. We also investigate the algorithm in indoor and outdoor environments using the Wiener model, with direct and indirect channels using the Rayleigh and Rice fading models and calculate the error probability in different conditions. In order to improve the performance of the system in uplink transmission, auxiliary antennas and linear arrays of antennas at the receiver are used. The results of the proposed algorithm are simulated and compared with the previous conventional methods.A Survey of DV-Hop Localization Methods in Wireless Sensor Networks
http://jce.shahed.ac.ir/article_3434.html
Wireless Sensor Networks (WSNs) are used to observation and monitor events in different environments. The successful operation of WSNs depends on locating the sensor nodes. The location of the nodes must be available to detect the occurrence of events and receive packets sent by nodes. Therefore, a key step in the design phase of WSNs is to determine localization algorithms. One of the known algorithms for locating unknown nodes is the DV-Hop algorithm. DV-Hop localization algorithm is a classic range free localization algorithm in WSNs. This algorithm operates based on distance and number of steps and uses beacon nodes to detect the location of unknown nodes. But positioning error is one of the main problems in DV-Hop. Researchers have used a variety of methods to correct positioning errors. In this paper, we divide the methods used to improve DV-Hop into four categories (meta-heuristic algorithms, RSSI, Distance Vector, and Weighted Centroid Localization (WCL)). Each method, based on its own performance has capabilities and features that help reduce DV-Hop error. This paper covers all DV-Hop literature in Elsevier, Springer, IEEE and Other Journals. Based on the performed studies on different methods in order to improve DV-Hop, we came to the conclusion that the distance vector method is more efficient. Using distance vector to improve DV-Hop is equal to 38%. The distance vector method includes more accurate localization information by varying the distance and number of steps.A comparative study of precoding techniques for PAPR reduction of OFDM signals
http://jce.shahed.ac.ir/article_3669.html
Orthogonal frequency division multiplexing (OFDM) is an attractive approach for multi-channel transmission. Due to some advantages such as high spectral efficiency, simplicity in channel equalization, and robustness to the fading channel, the OFDM technique has been generally used in many wireless communication devices. Besides these advantages, the OFDM systems usually experience a high peak-to-average power ratio (PAPR). As a result of the high PAPR, the OFDM signal is clipped during the passing via a non-linear power amplifier. The precoding techniques decrease the autocorrelation of the input data symbols to mitigate the high PAPR. In this paper, we compare WHMT, VLMT, DCMT, DHMT, DFMT, ZCMT, and CVMT precoding approaches in terms of autocorrelation and PAPR reduction performance. We demonstrate that the serial combinations of both ZCMT and CVMT precoding matrices with the IFFT matrix cancel the impact of each other when their dimensions are the same. In this case, a sparse matrix is produced and hence the PAPR of the OFDM signal is remarkably reduced. This issue is proved by the mathematical calculations and verified by the simulation results. It is also presented that DFMT, ZCMT, and CVMT precoding schemes have almost the same PAPR reduction performance and they are the best among their counterparts.BER/Sum-Rate Analysis for Composition of Non-orthogonal LDM and Orthogonal eMBMS in CDTV Broadcasting
http://jce.shahed.ac.ir/article_3671.html
In this research, performance analysis for the composition of non-orthogonal and orthogonal cellular digital television broadcasting is investigated. A downlink multi-carrier layered division multiplexing (LDM) superimposed with an evolved multimedia broadcast multicast service (eMBMS). We define two broadcast service providers (BSP), which offer different radio access technology (RAT). The BER and Sum-Rate efficiency are selected as our criteria. The proposed downlink composition framework can work without a subscriber identity module (SIM card) uplink and internet protocol (IP). Mathematical analysis, based on the exact closed-form expressions, is consistent with the theory of the proposed composition LDM/eMBMS. Evaluation and performance are done based on the Monte Carlo iterative methodology. The results show that the BER and Sum-Rate performance of a composition framework outperforms compared with LDM/eMBMS individually system.Extraction of Electromagnetic Scattering from Random Rough Surfaces in Complex Environments using Numerical Methods
http://jce.shahed.ac.ir/article_3799.html
In this study, we present a comprehensive overview of the exact and approximate models and methods that are available to measure the dispersion of random rough surfaces. We investigated the structural implementation of such surfaces in the finite-difference time-domain (FDTD) simulation environment and introduced a method for error reduction in simulated environments with such surfaces to improve the accuracy of near-path scattering of random rough surfaces. For this aim, a new adsorbent consisting of two types of adsorbents with distinct properties is proposed. During different tests in environments with the random rough surfaces and more complex environments with abnormal dispersers, the superiority, and higher performance of the proposed adsorbents are verified and then, properties of the adsorbents are investigated. Next, two dimensional random rough surfaces are analyzed to investigate electromagnetic scattering. To determine the electromagnetic scattering field, surface height's and slope's joint probability density function is calculated and utilized after generating a two-dimensional rough surface. The ray-tracing base model is exploited, and then the Monte-Carlo technique is hired to convert an infinite integration form into the form of finite integration.FDFD based measurement of permittivity using an open-ended coaxial probe
http://jce.shahed.ac.ir/article_3825.html
In this paper, 2D-FDFD method is applied for measuring electrical properties of dielectric materials using an open-ended coaxial probe. A SMA connector with flange is used as the coaxial probe and the reflection coefficient from probe aperture in contact with dielectric is measured by a vector network analyzer. To convert the aperture-plane reflection coefficient to dielectric permittivity, first, the coaxial probe is modeled by the 2D-FDFD method and then the genetic algorithm is employed to solve the inverse problem. The accuracy of the proposed method is investigated by measuring the dielectric properties of three known materials. The mean absolute percentage errors are below 10% and the maximum absolute percentage error is below 12%. Thus, good agreement between measured and actual values are observed.Modify the Injection Probe Equivalent Models by Considering the Shield Slot and Ferrite Permittivity Capacitors
http://jce.shahed.ac.ir/article_3852.html
Explicit and hybrid equivalent models of bulk current injection probe are reviewed, these models don&rsquo;t take slot and ferrite dielectric constant capacitive effects into account, which caused the appearance of negative values in the real part of ferrite permeability spectra when extracting it from measured input impedance of the probe. In this paper, these capacitances are calculated using CST Electrostatic Solver, then its effect on the probe equivalent series impedance, voltage transfer ratio, and the core predicted permeability are evaluated. The evaluation shows that introducing these capacitances cancels the abnormal negative permeability resulting in the model, without affecting the model validation.A GaAs-Based LNA with less than 1-dB measured NF for X-Band Communication Systems
http://jce.shahed.ac.ir/article_3857.html
In communication systems, Low-Noise Amplifiers (LNAs) with low noise performance are essential components. This work introduces a LNA for radio frequency front-end receivers with a frequency range of 8&ndash;9.6 GHz. The planned LNA contains a two-stage high-electron-mobility transistor cascade amplifier with a minimum measured Noise Figure (NF) of 0.8 dB and a peak gain of 25 dB at room temperature. The proposed LNA is based on a GaAs FET transistor (CE3512K2) because of its good low noise performance at microwave frequency bands. The measured results demonstrate that the proposed LNA is perfectly matched over the whole operational frequency spectrum of the input/output ports (|S11| &lt; -10 dB, |S22| &lt;-10 dB). In addition, the suggested LNA draws a current of 20 mA and operates with a +3.6 V and a -3.6 V power supply. The recommended LNA is appropriate for X frequency bands applications.Performance Comparison of the Target Detection Methods in High Speed Platform Forward Looking SAR (HSP-FLSAR)
http://jce.shahed.ac.ir/article_3860.html
Sea target detection in the HSP-FLSAR images has not been addressed so far in the literature. In this paper we carry out a comparative evaluation of existing SAR target detection algorithms in the case of monostatic HSP-FLSAR range Doppler images assuming a platform diving trajectory. To do so, various CFAR methods, including CA-CFAR, SOCA-CFAR, GOCA-CFAR, OS-CFAR, VIE-CFAR, and G0 distribution CFAR algorithms, are used to detect a set of point scatterers in simulated images. The performance of methods is compared based on receiver operating characteristic curves. Simulation results show that OS-CFAR has the best probability of detection for a fixed probability of false alarm. This paper can be a starting point to find better target detection methods in HSP-FLSAR images.Microwave Imaging behind a Drywall using Synthetic Aperture Radar
http://jce.shahed.ac.ir/article_3900.html
We study through a drywall imaging using synthetic aperture radar (SAR) method. Transmission and reflection characteristics of the wall are analyzed by a rigorous coupled-wave analysis (RCWA) method. The Bragg modes are investigated on analytic formulation and reconstructed image. The cutoff frequency for different Bragg modes is calculated and the relative power carried by each of these modes is shown. The Green function of such a periodic structure is derived by representing a line source radiation in the spectral domain. The analytical results are then validated by the numerical FEM results using the COMSOL software and the effect of the number of the Bragg modes is shown. Having numerically calculated backscattered fields of a target behind the wall and the free-space Green function, the SAR image of the target is computed and the image artifacts due to the presence of the wall are addressed. Firstly, we show that the target image is still distorted and not focused even with the background subtraction. Secondly, by properly employing the phase of the wall Green function instead of the free-space Green function, we indicate that the target image is successfully refocused.Steady-State Performance Analysis of Incremental Variable Tap-Length Algorithm in WSNs Under Noisy Links condition
http://jce.shahed.ac.ir/article_3901.html
Recently proposed distributed incremental fractional tap-length (FT) variable-length least mean square (LMS) technique do not consider noisy links errors, which occur during the communication of local estimations between nodes. In this paper, we study the noisy links effect on the performance of this algorithm. We derive a mathematical formulation for the steady-state length at each node. Our derived relationship shows how steady-state tap-length is affected by noisy links. Simulations confirm that there is a good match between the theory and simulated tap-length. Furthermore, the critical result is that, as the noise level increases, the steady-state tap-length decreases compared to the ideal link version. However, in low noise conditions, this length is still larger than the optimal filter length.Energy Efficient Clustering in IOT-Based Wireless Sensor Networks using Whale Optimization Algorithm
http://jce.shahed.ac.ir/article_3902.html
One of the most critical challenges of wireless sensor networks is the limited energy of the nodes, which has tried to manage energy consumption in these networks by using more accurate clustering. So far, many methods have been proposed to increase the accuracy of clustering, which reduces the energy consumption of nodes and thus increases network throughput. In this paper, we propose a method for clustering wireless sensor networks using the whale optimization algorithm, which results in increased throughput in these networks. Although much work has been done in this area in terms of energy, some do not have good throughput. Therefore, in this paper, a clustering method based on the whale optimization algorithm is proposed. Features of this algorithm include easy implementation, providing high- quality solutions, quick convergence, and the ability to escape from local minima. Also, in terms of clustering, in addition to paying attention to energy consumption, has appropriate throughput. In the proposed method, the Euclidean distance is used to assign data to the cluster and determine the cluster centers by the whale optimization algorithm. In other words, concentrated clusters are created. Then, according to the two remaining energy parameters and the distance of the nodes to the centers of the cluster, two clusters are selected. To evaluate the research, we have used MATLAB software and compared the proposed method with one of the latest works. The results show an improvement in throughput and comparable in terms of energy