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  Subjects -> COMPUTER SCIENCE (Total: 2011 journals)
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COMPUTER SCIENCE (1172 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 872 Journals sorted alphabetically
3D Printing and Additive Manufacturing     Full-text available via subscription   (Followers: 15)
Abakós     Open Access   (Followers: 4)
ACM Computing Surveys     Hybrid Journal   (Followers: 24)
ACM Journal on Computing and Cultural Heritage     Hybrid Journal   (Followers: 9)
ACM Journal on Emerging Technologies in Computing Systems     Hybrid Journal   (Followers: 13)
ACM Transactions on Accessible Computing (TACCESS)     Hybrid Journal   (Followers: 4)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 16)
ACM Transactions on Applied Perception (TAP)     Hybrid Journal   (Followers: 6)
ACM Transactions on Architecture and Code Optimization (TACO)     Hybrid Journal   (Followers: 9)
ACM Transactions on Autonomous and Adaptive Systems (TAAS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Computation Theory (TOCT)     Hybrid Journal   (Followers: 12)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 3)
ACM Transactions on Computer Systems (TOCS)     Hybrid Journal   (Followers: 18)
ACM Transactions on Computer-Human Interaction     Hybrid Journal   (Followers: 15)
ACM Transactions on Computing Education (TOCE)     Hybrid Journal   (Followers: 6)
ACM Transactions on Design Automation of Electronic Systems (TODAES)     Hybrid Journal   (Followers: 2)
ACM Transactions on Economics and Computation     Hybrid Journal  
ACM Transactions on Embedded Computing Systems (TECS)     Hybrid Journal   (Followers: 4)
ACM Transactions on Information Systems (TOIS)     Hybrid Journal   (Followers: 21)
ACM Transactions on Intelligent Systems and Technology (TIST)     Hybrid Journal   (Followers: 8)
ACM Transactions on Interactive Intelligent Systems (TiiS)     Hybrid Journal   (Followers: 4)
ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP)     Hybrid Journal   (Followers: 10)
ACM Transactions on Reconfigurable Technology and Systems (TRETS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Sensor Networks (TOSN)     Hybrid Journal   (Followers: 9)
ACM Transactions on Speech and Language Processing (TSLP)     Hybrid Journal   (Followers: 10)
ACM Transactions on Storage     Hybrid Journal  
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 25)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Ad Hoc Networks     Hybrid Journal   (Followers: 11)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26)
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advances in Adaptive Data Analysis     Hybrid Journal   (Followers: 7)
Advances in Artificial Intelligence     Open Access   (Followers: 16)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 6)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 18)
Advances in Computer Science : an International Journal     Open Access   (Followers: 15)
Advances in Computing     Open Access   (Followers: 2)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 52)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 11)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 27)
Advances in Human-Computer Interaction     Open Access   (Followers: 21)
Advances in Materials Sciences     Open Access   (Followers: 16)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Remote Sensing     Open Access   (Followers: 40)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Advances in Technology Innovation     Open Access   (Followers: 4)
AEU - International Journal of Electronics and Communications     Hybrid Journal   (Followers: 8)
African Journal of Information and Communication     Open Access   (Followers: 8)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
Air, Soil & Water Research     Open Access   (Followers: 9)
AIS Transactions on Human-Computer Interaction     Open Access   (Followers: 6)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1)
Algorithms     Open Access   (Followers: 11)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 5)
American Journal of Computational Mathematics     Open Access   (Followers: 4)
American Journal of Information Systems     Open Access   (Followers: 5)
American Journal of Sensor Technology     Open Access   (Followers: 4)
Anais da Academia Brasileira de Ciências     Open Access   (Followers: 2)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 7)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Animation Practice, Process & Production     Hybrid Journal   (Followers: 5)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 11)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 12)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Software Engineering     Hybrid Journal   (Followers: 13)
Annual Reviews in Control     Hybrid Journal   (Followers: 6)
Anuario Americanista Europeo     Open Access  
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applied and Computational Harmonic Analysis     Full-text available via subscription   (Followers: 1)
Applied Artificial Intelligence: An International Journal     Hybrid Journal   (Followers: 13)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Clinical Informatics     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Computer Systems     Open Access   (Followers: 2)
Applied Informatics     Open Access  
Applied Mathematics and Computation     Hybrid Journal   (Followers: 33)
Applied Medical Informatics     Open Access   (Followers: 10)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Soft Computing     Hybrid Journal   (Followers: 15)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 5)
Architectural Theory Review     Hybrid Journal   (Followers: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 5)
Archive of Numerical Software     Open Access  
Archives and Museum Informatics     Hybrid Journal   (Followers: 136)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Artifact     Hybrid Journal   (Followers: 2)
Artificial Life     Hybrid Journal   (Followers: 7)
Asia Pacific Journal on Computational Engineering     Open Access  
Asia-Pacific Journal of Information Technology and Multimedia     Open Access   (Followers: 1)
Asian Journal of Computer Science and Information Technology     Open Access  
Asian Journal of Control     Hybrid Journal  
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
Australian Educational Computing     Open Access   (Followers: 1)
Automatic Control and Computer Sciences     Hybrid Journal   (Followers: 4)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Automatica     Hybrid Journal   (Followers: 11)
Automation in Construction     Hybrid Journal   (Followers: 6)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Basin Research     Hybrid Journal   (Followers: 5)
Behaviour & Information Technology     Hybrid Journal   (Followers: 52)
Biodiversity Information Science and Standards     Open Access  
Bioinformatics     Hybrid Journal   (Followers: 285)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 18)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 34)
Briefings in Bioinformatics     Hybrid Journal   (Followers: 47)
British Journal of Educational Technology     Hybrid Journal   (Followers: 137)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
c't Magazin fuer Computertechnik     Full-text available via subscription   (Followers: 2)
CALCOLO     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Journal of Electrical and Computer Engineering     Full-text available via subscription   (Followers: 14)
Capturing Intelligence     Full-text available via subscription  
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cell Communication and Signaling     Open Access   (Followers: 2)
Central European Journal of Computer Science     Hybrid Journal   (Followers: 5)
CERN IdeaSquare Journal of Experimental Innovation     Open Access   (Followers: 1)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
ChemSusChem     Hybrid Journal   (Followers: 7)
China Communications     Full-text available via subscription   (Followers: 7)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
CIN Computers Informatics Nursing     Full-text available via subscription   (Followers: 11)
Circuits and Systems     Open Access   (Followers: 15)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
CLEI Electronic Journal     Open Access  
Clin-Alert     Hybrid Journal   (Followers: 1)
Cluster Computing     Hybrid Journal   (Followers: 1)
Cognitive Computation     Hybrid Journal   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Communication Methods and Measures     Hybrid Journal   (Followers: 12)
Communication Theory     Hybrid Journal   (Followers: 20)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Algebra     Hybrid Journal   (Followers: 3)
Communications in Partial Differential Equations     Hybrid Journal   (Followers: 3)
Communications of the ACM     Full-text available via subscription   (Followers: 55)
Communications of the Association for Information Systems     Open Access   (Followers: 18)
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering     Hybrid Journal   (Followers: 3)
Complex & Intelligent Systems     Open Access   (Followers: 1)
Complex Adaptive Systems Modeling     Open Access  
Complex Analysis and Operator Theory     Hybrid Journal   (Followers: 2)
Complexity     Hybrid Journal   (Followers: 6)
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Computación y Sistemas     Open Access  
Computation     Open Access  
Computational and Applied Mathematics     Hybrid Journal   (Followers: 2)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2)
Computational and Mathematical Organization Theory     Hybrid Journal   (Followers: 2)
Computational and Structural Biotechnology Journal     Open Access   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Astrophysics and Cosmology     Open Access   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computational Cognitive Science     Open Access   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Condensed Matter     Open Access  
Computational Ecology and Software     Open Access   (Followers: 9)
Computational Economics     Hybrid Journal   (Followers: 9)
Computational Geosciences     Hybrid Journal   (Followers: 15)
Computational Linguistics     Open Access   (Followers: 22)
Computational Management Science     Hybrid Journal  
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 4)
Computational Methods and Function Theory     Hybrid Journal  
Computational Molecular Bioscience     Open Access   (Followers: 2)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Particle Mechanics     Hybrid Journal   (Followers: 1)
Computational Research     Open Access   (Followers: 1)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computational Science and Techniques     Open Access  
Computational Statistics     Hybrid Journal   (Followers: 14)
Computational Statistics & Data Analysis     Hybrid Journal   (Followers: 30)
Computer     Full-text available via subscription   (Followers: 91)
Computer Aided Surgery     Hybrid Journal   (Followers: 5)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 8)
Computer Communications     Hybrid Journal   (Followers: 10)
Computer Engineering and Applications Journal     Open Access   (Followers: 5)
Computer Journal     Hybrid Journal   (Followers: 9)
Computer Methods in Applied Mechanics and Engineering     Hybrid Journal   (Followers: 22)
Computer Methods in Biomechanics and Biomedical Engineering     Hybrid Journal   (Followers: 12)
Computer Methods in the Geosciences     Full-text available via subscription   (Followers: 2)
Computer Music Journal     Hybrid Journal   (Followers: 18)
Computer Physics Communications     Hybrid Journal   (Followers: 6)
Computer Science - Research and Development     Hybrid Journal   (Followers: 8)
Computer Science and Engineering     Open Access   (Followers: 19)
Computer Science and Information Technology     Open Access   (Followers: 13)
Computer Science Education     Hybrid Journal   (Followers: 14)
Computer Science Journal     Open Access   (Followers: 22)

        1 2 3 4 5 6 | Last

Journal Cover AEU - International Journal of Electronics and Communications
  [SJR: 0.318]   [H-I: 36]   [8 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1434-8411
   Published by Elsevier Homepage  [3123 journals]
  • Improved spectrum sensing and achieved throughput of multiband cognitive
           radio systems under probabilistic spectrum access
    • Authors: Mohammad Karimi; Seyed Mohammad Sajad Sadough
      Pages: 8 - 16
      Abstract: Publication date: March 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 86
      Author(s): Mohammad Karimi, Seyed Mohammad Sajad Sadough
      We investigate wideband spectrum sensing for multiband cognitive radio (CR) to opportunistically detect spectrum holes without causing harmful interference to licensed (primary) subchannels. In classical wideband energy detection, primary subchannels are absolutely classified into vacant or occupied according to the measured energy. CR signal transmission is then performed over all vacant subchannels. In this paper, we first introduce a probabilistic spectrum access method, which assigns a probability for CR signal transmission over each primary subchannel. More precisely, in our proposed method, each primary subchannel is likely to be classified into vacant or occupied via the definition of a spectrum access probability for CR transmission, in contrast to absolute sub-channel classification used in classical methods. Second, we derive the secondary information rates achieved by the proposed spectrum sensing method and compare it to those provided by classical wideband spectrum sensing. Third, we perform optimal power allocation to maximize the CR achievable rates constrained on the total power and interference introduced to the primary network. Numerical results indicate that the proposed spectrum access outperforms the classically-used spectrum sensing in terms of secondary achievable data rates.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.012
      Issue No: Vol. 86 (2018)
  • Realization of dielectric loaded waveguide filter with substrate
           integrated waveguide technique based on incorporation of two substrates
           with different relative permittivity
    • Authors: Hassan Aghayari; Javad Nourinia; Changiz Ghobadi; Bahman Mohammadi
      Pages: 17 - 24
      Abstract: Publication date: March 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 86
      Author(s): Hassan Aghayari, Javad Nourinia, Changiz Ghobadi, Bahman Mohammadi
      In this paper a new structure based on substrate integrated waveguide (SIW), called incorporated substrate integrated waveguide (ISIW), has been used to implement the dielectric loaded waveguide filter in planar structure. Conventional waveguide filter and dielectric loaded waveguide filter have been realized with SIW and ISIW technique, respectively. The use of ISIW structure has reduced the size of the filter, required precision in designing process and the cost of manufacturing process, at the cost of increasing the losses. Thus, while the size of filter and the cost of manufacturing process reduce significantly, there is no need to build the particular dielectric material as resonator and integration with other microstrip devices will be much easier too. Two different excitation mechanism have been considered to cancel the spurious response in the desired frequency band. The SIW and ISIW filters have been fabricated and fairly compared with waveguide filters. Advantages and disadvantages of ISIW structure have been scrutinized in detail. Good agreement between the simulated and measured frequency response of proposed filters has been shown.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.008
      Issue No: Vol. 86 (2018)
  • Analysis of Load Frequency Control in a restructured multi-area power
           system with the Kalman filter and the LQR controller
    • Authors: Seyed Hamid Shahalami; Davoud Farsi
      Pages: 25 - 46
      Abstract: Publication date: March 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 86
      Author(s): Seyed Hamid Shahalami, Davoud Farsi
      The performance of power systems in restructured environments has become increasingly more complex due to the technical limitations and traditional requirements. To this end, electrical power systems act independently in the generation, transmission and distribution of electricity, leading to restructuring and deregulation. On the one hand, technical requirements for transmission lines and renewable energies will contribute to HVDC transmission. On the other hand, one of the main goals of the Automatic Generation Control (AGC) is to manage Load Frequency Control (LFC) in a multi-area power system. In order to examine the internal and intrinsic stability, the Linear Quadratic Regulator (LQR) control method was used but since neither all the state variables were available nor their measurements were noise-free, the LQR controller was used with the Kalman filter (KF) for the real-time control for solving the LFC problem. Finally in the section on the simulation, a comparison was made using MATLAB, between two multi-area power systems consisting of thermal and hydroelectric generation units, one of which with the HVDC transmission lines and the other one without them, in terms of frequency stability. Moreover, the simulation results indicated that the introduced control method led to the improved LFC performance in a multi-area power system with HVDC transmission links.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.011
      Issue No: Vol. 86 (2018)
  • Performance of antenna selection schemes in dual hop full-duplex
           decode-and-forward relaying over Nakagami-m fading channels
    • Authors: Mesut Toka; Oğuz Kucur
      Pages: 92 - 102
      Abstract: Publication date: March 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 86
      Author(s): Mesut Toka, Oğuz Kucur
      In this paper, we investigate the outage performance of several antenna selection (AS) schemes in dual hop full-duplex (FD) multiple-input multiple-output (MIMO) relay networks in which the relay adopts decode-and-forward (DF) protocol over Nakagami-m fading channels. In the network, the source (S), destination (D) and relay (R) are assumed to be equipped with multiple antennas. We assume that the line-of-sight component between S and D cannot be established due to the poor fading environment conditions. For signal transmission-reception during the training period, only a single antenna at each node is selected according to selection techniques, and then with the help of an error-free feedback channel the selected antenna index is sent to the related node. Outage probability (OP) expressions related to AS schemes are obtained in closed forms and asymptotic OPs are also derived in order to get more meaningful insights into OP and diversity behaviour. The theoretical results are verified by Monte Carlo simulations. We show that performance of the FD relay can be significantly improved by using selection techniques compared to half-duplex (HD), especially at low signal-to-noise ratio (SNR) region. In addition, results show that the performance floor level meaning zero diversity at high SNR region, which is also confirmed by asymptotic analysis and is an inherent disadvantage of FD relay, can be decreased. Moreover, it is shown that the FD relay with AS schemes outperforms HD as the target rate increases for a certain value of SNR and residual self-interference power.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.018
      Issue No: Vol. 86 (2018)
  • An approach to essentially improve current efficiency for bulk-driven OTA
    • Authors: Xiao Zhao; Qisheng Zhang; Yongqing Wang; Liyuan Dong
      Pages: 103 - 107
      Abstract: Publication date: March 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 86
      Author(s): Xiao Zhao, Qisheng Zhang, Yongqing Wang, Liyuan Dong
      An approach to essentially improve the current efficiency for the bulk-driven circuits is presented. By employing an auxiliary amplifier cross-coupled to the gate of bulk-driven flipped voltage follower and input differential pairs, it achieves not only the gain-bandwidth improved, but also the slew rate significantly enhanced, which leads to a great boost in current efficiency. To validate our introduced method, the conventional and the proposed bulk-driven amplifiers are both designed under the CSMC 0.18  μ m technology. Simulation results demonstrate that bulk-driven amplifier based on the proposed method achieves an 8 times slew rate and a 4 times bandwidth improvement with only a negligible increase in power consumption.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.028
      Issue No: Vol. 86 (2018)
  • A sub-wavelength polarization insensitive X-band absorber based on
           interleaved concept
    • Authors: Seyed Vahid Masumina; Javad Nourinia; Changiz Ghobadi; Mohsen Karamirad; Bahman Mohammadi
      Pages: 108 - 116
      Abstract: Publication date: March 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 86
      Author(s): Seyed Vahid Masumina, Javad Nourinia, Changiz Ghobadi, Mohsen Karamirad, Bahman Mohammadi
      In this paper, a miniaturized absorber realized on interleaved structure across X-band is reported. The presented absorber has been designed based on the concept of complementary interleaved Brigid’s cross. Results show that the structure rejects 9.88 GHz with absorption rate of almost 99%. Moreover, the absorber is polarization independent, as it maintains stability against TE- and TM-polarizations. The results from waveguide simulator and space wave measurements provide an efficient absorber at sub-wavelength spacing.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.013
      Issue No: Vol. 86 (2018)
  • Tri-layer linearly-polarized discrete lens antenna operating in X-band,
           design & characterization
    • Authors: Hamza Kaouach; Mohamed Ali Belaid
      Pages: 117 - 124
      Abstract: Publication date: March 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 86
      Author(s): Hamza Kaouach, Mohamed Ali Belaid
      This research work presents the design and characterization of planar discrete lens antennas (TA Transmit-Array antennas) based on a simple tri-layer elementary cell operating in the 10-GHz band. The structure of the proposed elementary cell allows 1-bit and 2-bit phase quantization and easy fabrication with a simple printed-circuit board. The linear/circular polarization can be generated with 1-bit/2-bit configuration. The elementary cell consists of two C-slot loaded patch antennas interconnected by a metalized via hole. The simulation of the elementary cell has been validated by the measurement that confirmed a good accord in terms of return loss (10 dB-bandwidth is equal to 9%) and insertion loss (0.35 dB at 10 GHz). The linearly-polarized transmit-array achieves a maximum directivity of 25.1 dBi and a gain of 22.7 dBi. The 1-dB gain bandwidth is up to 9.6% around 9.8 GHz with 56.3% of radiation efficiency. Beam-steering up to 30° is achieved by tilting the focal source.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.032
      Issue No: Vol. 86 (2018)
  • A Miniaturized inductive – Loaded narrow strip wide band-notched
           ultra-wideband monopole antenna with dual-mode resonator
    • Authors: Hefilia Asokan; Srivatsun Gopalakrishnan
      Pages: 125 - 132
      Abstract: Publication date: March 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 86
      Author(s): Hefilia Asokan, Srivatsun Gopalakrishnan
      A new miniaturized ultra-wideband (UWB) monopole antenna with a broad band, sharp roll-off frequency notch function is presented. A narrow, stepped impedance strip is the radiating element of the antenna similar to conventional narrowband antennas, in order to retain the conventional antenna characteristics such as polarization purity, omnidirectional radiation pattern, etc. The strip is split to create multiple closed resonances and inductors are loaded in series to achieve wide bandwidth. The split portions are inserted one over the other to make the antenna very compact. A new compact dual mode wide band parasitic resonator placed along the feed line, rejects the frequency band ranging from 5.15 to 5.825 GHz which has been allocated for IEEE 802.11a and High Performance Radio Local Area Network (HIPERLAN). The designed antenna was fabricated and the results were measured in an anechoic chamber. The measured results show the ultra-wideband resonance with reflection coefficient values below −10 dB over 3–10.5 GHz with a sharp roll off notch band.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.024
      Issue No: Vol. 86 (2018)
  • A novel planar four-way power divider with large dividing ratio
    • Authors: Xiao Yang; XuChun Zhang; ZhenHeng Liao
      Pages: 1 - 6
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Xiao Yang, XuChun Zhang, ZhenHeng Liao
      In this paper, a novel planar four-way power divider with symmetrical simple structure based on microstrip line is presented, and it’s design formulas are deduced. It can achieve arbitrary power dividing ratio, ideal matched ports, ideal isolation between four ports, and the largest power dividing ratio can be 33:1 when the port impedance is 50 Ω and the maximum ring-line impedance is 120 Ω. The relative phase difference of four output ports are 0, π / 2 , π , π / 2 respectively. The structure has ideal matched ports and isolation between four ports. It is suitable for high-power application. Finally, an experimental prototype with power dividing ratio 5.76:5.76:1:1 is simulated and measured respectively. The measured results validate the proposed method.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.028
      Issue No: Vol. 85 (2018)
  • A novel center of mass method for estimation of center frequency and
           spectral edges in CR using filter banks
    • Authors: S. Chris Prema; K.S. Dasgupta
      Pages: 7 - 11
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): S. Chris Prema, K.S. Dasgupta
      In this paper, we propose a novel multistage DFT based polyphase filter bank technique using center of mass approach for estimating center frequency, detecting spectral edges and identifying spectral holes in wideband cognitive radio (CR) for efficient utilization of radio frequency spectrum. Spectral holes are identified by measuring energy at the output of individual subband of filter banks. Accuracy of spectral holes detection depends on frequency resolution of subbands and can be increased with an increase in number of DFT points, however, at the expense of computational complexity. In order to reduce complexity our algorithm starts with a coarser spectral resolution in the first stage. If a primary user appears over more than one subband, center frequency can be estimated in the first stage using proposed approach. However, if the primary user appears exclusively within a single subband, center frequency can be estimated at the second stage. For center frequency estimation, we propose a novel center of mass approach to achieve better precision, where mass is related to energy and distance is related to frequency. Exhaustive simulation results show that center frequency estimation using proposed multistage polyphase filter bank based on center of mass reduces computational complexity and has higher precision compared to conventional filter bank methods.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.11.030
      Issue No: Vol. 85 (2018)
  • Throughput optimization using availability analysis based spectrum sensing
           for a cognitive radio
    • Authors: Srijibendu Bagchi; Jawad Yaseen Siddiqui
      Pages: 12 - 22
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Srijibendu Bagchi, Jawad Yaseen Siddiqui
      Recently, cognitive radio has been projected to facilitate the utilization of vacant licensed frequency bands through dynamic spectrum access. Availability analysis of frequency bands may be considered necessary to avoid wastage of time to sense already occupied bands. In this article, we propose availability analysis by modeling the trend of state transition of a frequency band from occupied to vacant or vice versa as a two-state Semi-Markov Process. The state transition rates are treated as random variables and their estimates are found by Bayesian approach. We start the analysis with different prior distributions and find out respective posterior distributions of the state transition rates. Subsequently, Bayes’ risk has been calculated using several loss functions and estimates are found out by minimizing it. Average availability is then calculated over a time horizon that consists of a number of time frames. Each frame is divided into sensing and transmission slots. Initially, a frame length has been calculated under constant false alarm and detection rates to maximize the achievable throughput. Next, the sensing time in a frame has been calculated under constant detection rate and average availability for maximizing the achievable throughput. Numerical results are provided to substantiate the findings.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.024
      Issue No: Vol. 85 (2018)
  • A 5.7–6.0 GHz CMOS PLL with low phase noise and
           −68 dBc reference spur
    • Authors: Xiaoqiang Li; Jingwei Zhang; Yuanzhi Zhang; Wenshen Wang; Huimin Liu; Chao Lu
      Pages: 23 - 31
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Xiaoqiang Li, Jingwei Zhang, Yuanzhi Zhang, Wenshen Wang, Huimin Liu, Chao Lu
      This paper presents a 5.7–6.0 GHz Phase-Locked Loop (PLL) design using a 130 nm 2P6M CMOS process. We propose to suppress reference spur through reducing the current mismatch in charge pump (CP), controlling the delay time in phase frequency detector (PFD), and using a smaller VCO gain (KVCO). With a reference frequency of 32.768 MHz, chip measurement results show that the frequency tuning range is 5.7–6.0 GHz, the reference spur is −68 dBc, the phase noise levels are −109 dBc/Hz and −135 dBc/Hz at 1 MHz and 10 MHz offset respectively for 5.835 GHz. Compared with existing designs in the literature, this work’s reference spur is improved by at least 17% and its phase noise is the lowest. Under a 1.5 V supply voltage, the power dissipation with an output buffer of the PLL is 12 mW.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.025
      Issue No: Vol. 85 (2018)
  • QoS-data rate optimization for fast fading interference alignment X
    • Authors: P.G. Sudheesh; Maurizio Magarini; P. Muthuchidambaranathan
      Pages: 32 - 38
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): P.G. Sudheesh, Maurizio Magarini, P. Muthuchidambaranathan
      Quality of service (QoS) and high data rate are two main parameters that drive the research in wireless communication. Perfect Channel State Information (CSI) at both transmitter and receiver sides is an important condition for achieving QoS and high data rate. But, achieving perfect CSI in mobile transmitters/receivers under fast fading is challenging. That is, frequent CSI updating is required to satisfy QoS requirements under fast fading scenario. In this paper, we consider a multiple transmitter-receiver system, called X network, that has data flow in all the channels. Interference alignment (IA) is a practical solution to achieve maximum capacity in an X network. The present contribution explores the performance of the system with a mobile receiver (or transmitter) that employs CSI estimation using pilot symbols, and further optimize the performance so as to cater both bit error rate (BER) and data rate requirements. Using Monte-Carlo simulations, a novel algorithm is proposed to calculate optimal pilot overhead in M × 2 X network or 2 × M X network by setting an upper bound on BER. With simulation results we show that the optimal overhead varies with Doppler frequency and Signal-to-Noise Ratio (SNR).

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.029
      Issue No: Vol. 85 (2018)
  • Miniature high gain slot-fed rectangular dielectric resonator antenna for
           IoT RF energy harvesting
    • Authors: Alphonsos A Masius; Yan Chiew Wong; Kok Tee Lau
      Pages: 39 - 46
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Alphonsos A Masius, Yan Chiew Wong, Kok Tee Lau
      Radio-frequency (RF) energy harvesting is a promising candidate for alternative power source that can reduce the dependencies on batteries. However, its power density is very low which makes it crucial to have a high gain antenna to increase the power received by the system. This study presents the design of miniature high gain dielectric resonator antenna for RF energy harvesting application with high figure of merit to increase the power received. Numerical approximation is used to assist the antenna design and modelling. The design focused on three parameters which are the width, length, and height of the dielectric resonator. The performance, electric field density, and the radiation patterns of the dielectric resonator antenna have been observed by varying the design parameters. The effect of air gap to the performance is investigated and it is found that 8.11–13% gain improvement and up to 36% improvement in impedance matching is achieved through incorporating thin air gap between the dielectric resonator. Soda-lime glass with relative permittivity 7.75 is used which allows miniaturization and transparency. Experimental results show reasonable agreement to the simulations. The work shows highest antenna gain with smallest size with high FOM at 5 GHz ISM band compared to previous works.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.023
      Issue No: Vol. 85 (2018)
  • Triangular quad-port multi-polarized UWB MIMO antenna with enhanced
           isolation using neutralization ring
    • Authors: Ahmet Kayabasi; Abdurrahim Toktas; Enes Yigit; Kadir Sabanci
      Pages: 47 - 53
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Ahmet Kayabasi, Abdurrahim Toktas, Enes Yigit, Kadir Sabanci
      In this study, a quad-port multi-polarized ultra-wideband (UWB) multiple input multiple output (MIMO) antenna system with a new isolation technique is designed for wireless devices. The antenna structure consists of four triangular monopole elements and neutralization ring (NR) structures. The monopoles are back-to-back positioned in symmetrical and orthogonal arrangement. Therefore, they radiate towards four directions without interference, and thus the diversity performance is improved. A novel NR is formed by combining a rectangular ring and a straight line to reduce the mutual coupling due to interoperation of the elements. Each triangular monopole is fed by 50 Ohm microstrip transmission line (MTL) with a thin strip line for ensuring impedance matching. Antenna performance in terms of impedance bandwidth, current distribution, radiation pattern, peak gain and envelope correlation coefficient (ECC) is also investigated. The MIMO antenna system has 3.1–17.3 GHz impedance bandwidth, 1–5 dBi peak gain variation, less than 0.1 ECC. The results indicate that the proposed antenna has the characteristics of larger UWB bandwidth, high isolation by the NR structure, multi-polarization, uniform gain and quasi-omnidirectional pattern.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.027
      Issue No: Vol. 85 (2018)
  • Energy efficiency and spectral efficiency tradeoff in downlink OFDMA
           systems with imperfect CSI
    • Authors: Fei Liu; Qinghai Yang; Qingsu He; Kyung Sup Kwak
      Pages: 54 - 58
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Fei Liu, Qinghai Yang, Qingsu He, Kyung Sup Kwak
      In this paper, we investigate the tradeoff between energy efficiency (EE) and spectral efficiency (SE) in downlink orthogonal frequency division multiplexing access (OFDMA) systems, whilst considering the channel estimation cost and the corresponding effect of imperfect channel state information (CSI) on SE and EE. The problem is formulated as a multi-objective optimization to determine the optimal pilot transmission power, data transmission power and subcarrier assignment, and then transformed into a single-objective optimization problem, which is a non-convex mixed-integer nonlinear programming (NCMINP) and NP-hard. To address it, we propose an efficient algorithm by adopting alternating optimization and convex optimization methods in lower power region as well as approximate conversion and branch-and-bound methods in high power region. Simulation results analyze and validate the performance of EE-SE tradeoff.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.015
      Issue No: Vol. 85 (2018)
  • Relay selection for SWIPT: Performance analysis of optimization problems
           and the trade-off between ergodic capacity and energy harvesting
    • Authors: Hoang-Sy Nguyen; Thanh-Sang Nguyen; Miroslav Voznak
      Pages: 59 - 67
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Hoang-Sy Nguyen, Thanh-Sang Nguyen, Miroslav Voznak
      In this paper, we focus on the optimal relay selection (RS) and ergodic capacity of an energy harvesting (EH) amplify-and-forward (AF) multi-relay network, where multiple relays cooperate with the source node and the destination node. We begin the work with the optimization of a single relay. In the first step, after the average end-to-end signal-to-noise ratio (SNR) is obtained, the high end-to-end SNR is approximated to achieve the PDF and CDF, and we jointly optimize time switching (TS) and power splitting (PS) ratios by using Alternate Convex Search algorithm, second derivatives and Hessian matrices. Following that, closed-form expressions for the outage probability and throughput in both delay-restricted and delay-tolerant transmission mode in the high SNR regime are derived. Most importantly, we achieve not only ergodic capacity in the considered EH multi-relay network but also the trade-off between it and the average EH. Our theoretical results are proved by numerical simulations, in which delay-tolerant throughput outperforms delay-restricted throughput thanks to the change of number of relays. In addition, the data rate can be significantly enhanced thanks to the achievement of optimal TS and PS ratios.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.012
      Issue No: Vol. 85 (2018)
  • Secrecy analysis of MRT/RAS system under Nakagami-m fading channels in the
           presence of imperfect channel state information
    • Authors: Rajiv Kumar; Sudakar Singh Chauhan
      Pages: 68 - 73
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Rajiv Kumar, Sudakar Singh Chauhan
      In this paper, we investigate the secrecy performance of a multiple-input multiple-output (MIMO) system in the presence of channel estimation error (CEE) and feedback delay (FD) under Nakagami-m fading channel. In specific, the legitimate transmitter uses maximum ratio transmission (MRT), in which all the antennas are used to transmit the signals. Whereas, both the legitimate receiver and eavesdropper uses receive antenna selection (RAS) scheme, in which single antenna is used to receive the largest SNR at receive end. We derive the exact closed form expressions of the average secrecy capacity (ASC) and secrecy outage probability (SOP) with imperfect channel state information (ICSI).

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.034
      Issue No: Vol. 85 (2018)
  • Optimization of energy efficiency for cognitive radio with partial RF
           energy harvesting
    • Authors: Jianxin Guo; Hang Hu; Xinyu Da; Jian Liu; Wei Li
      Pages: 74 - 77
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Jianxin Guo, Hang Hu, Xinyu Da, Jian Liu, Wei Li
      The cognitive radio (CR) with energy harvesting is a potential technology to improve both the spectrum efficiency (SE) and the energy efficiency (EE). In this letter, we consider that the secondary users can harvest radio frequency (RF) energy from primary signal and its own signal. The goal is to maximize the energy efficiency of the CR system subject to sufficient protection to the primary user and the power constraint. An efficient algorithm is proposed to optimize the sensing time and the power of the secondary transmitter. Simulation results show that the EE is further improved by using the proposed mechanism.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.030
      Issue No: Vol. 85 (2018)
  • Compact microstrip lowpass filter using meandered unequal T-shaped
           resonator with ultra-wide rejection band
    • Authors: Farzin Shama; Mohsen Hayati; Milad Ekhteraei
      Pages: 78 - 83
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Farzin Shama, Mohsen Hayati, Milad Ekhteraei
      In this paper, a compact lowpass filter (LPF) with ultra-wide rejection band has been presented. In fact, a novel meandered semi-hairpin resonator has been used and the stopband characteristics have been improved by using a combinatorial suppressing unit. The suppressing unit contains a combination between T-shaped and semi-circular patches, which are loaded symmetrically to the designed resonator. For the proposed LPF, the-3 dB cut-off frequency has been adjusted to 2.2 GHz. After simulations, the proposed LPF has been fabricated and tested. The experimental results validated that the rejection bandwidth is expanded from 2.471 GHz to 28.62 GHz with corresponding attenuation level of −20 dB. The transition band is only 0.271 GHz from 2.2 GHz to 2.471 GHz with corresponding attenuation levels of −3 dB to −20 dB, respectively. In addition, the measured maximum insertion loss and return loss in the passband, from DC to 2.04 GHz (93% of the passband region) are 0.2 dB and 17 dB, respectively.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.038
      Issue No: Vol. 85 (2018)
  • A broadband circularly polarized antenna of square-ring patch for UHF RFID
           reader applications
    • Authors: Jwo-Shiun Sun; Chia-Hao Wu
      Pages: 84 - 90
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Jwo-Shiun Sun, Chia-Hao Wu
      A circularly polarized, broad bandwidth, square-ring patch antenna for radio-frequency identification (RFID) is proposed. The antenna has a dimension of 100 × 100 × 22.9 mm3. By using a Wilkinson power divider and a patch-antenna structure, a measured 3-dB axial-ratio bandwidth of approximately 140 MHz (16.47%), an impedance bandwidth of 136 MHz (15.81%), and a measured peak gain of approximately 6.8 dBic are being achieved. The operating band of the proposed antenna is suitable for China (840–846 MHz), Europe (865–868 MHz) and the United States (902–928 MHz) ultra-high frequency (UHF) RFID applications.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.033
      Issue No: Vol. 85 (2018)
  • A novel SOI-MESFET with symmetrical oxide boxes at both sides of gate and
           extended drift region into the buried oxide
    • Authors: Ali Naderi; Fatemeh Heirani
      Pages: 91 - 98
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Ali Naderi, Fatemeh Heirani
      In this paper a novel structure for silicon on insulator metal semiconductor field effect transistors (SOI MESFETs) is proposed. The proposed structure contains two symmetrical oxide boxes at both sides of gate metal and extended drift region into the buried oxide which is named SO-ED-SOI-MESFET. SO-ED stands for symmetrical oxide boxes and extended drift region. DC and radio frequency characteristics of the SO-ED are analyzed by 2-D numerical simulation and compared with conventional SOI MESFET (C-SOI MESFET) characteristics. The obtained results demonstrate the superiorities of the proposed structure over C-SOI MESFET including increased breakdown voltage, higher driving current and improved RF characteristics. The extended drift region improves the current capability by increasing the effective channel thickness. The oxide region boosts the breakdown voltage due to its high tolerable electric field. Also, RF performance of the device is enhanced because of modified gate-source and gate-drain capacitances in the proposed structure. Unilateral power gain, maximum available gain and current gain experience 63, 52 and 63.5% improvement by applying the proposed structure, respectively. Thus the proposed structure can be considered as a proper candidate for using in high power and high frequency applications.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.001
      Issue No: Vol. 85 (2018)
  • A quad-band antenna for multi-band radio frequency energy harvesting
    • Authors: Sachin Agrawal; Manoj Singh Parihar; Pravin Neminath Kondekar
      Pages: 99 - 107
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Sachin Agrawal, Manoj Singh Parihar, Pravin Neminath Kondekar
      In this paper, a compact planar CPW-fed antenna operating over the four frequency bands is proposed for RF energy harvesting applications. The proposed antenna includes five radiating elements and a stepped ground plane, occupies a total area of 48 × 42 mm2. By virtue of stepped ground plane, the antenna exhibits a better impedance match compared to the antenna with the full ground plane. The measured S 11 better than −10 dB is obtained at the frequency bands GSM-900, GSM-1800, Wi-Fi 2.1 GHz and Bluetooth (2.4 GHz), showing its suitability for RF energy harvesting application. For this to be feasible, the developed antenna is matched with the rectifier at four desired frequencies using a compact quad-band matching network. The merit of the proposed rectifier circuit is it can be extended for n number of frequency the band by using only 3n-1 number of lumped elements. To validate the design method experimentally, a prototype of a dual-band rectifier is also fabricated. The measured result demonstrates that the proposed dual-band rectifier circuit achieved the peak efficiency of 42 % and 38 % for 0.9 and 2.1 GHz, respectively at a load impedance of 4.7 k Ω .

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.035
      Issue No: Vol. 85 (2018)
  • Analytical solutions of electrical circuits described by fractional
           conformable derivatives in Liouville-Caputo sense
    • Authors: V.F. Morales-Delgado; J.F. Gómez-Aguilar; M.A. Taneco-Hernandez
      Pages: 108 - 117
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): V.F. Morales-Delgado, J.F. Gómez-Aguilar, M.A. Taneco-Hernandez
      In this paper, new analytical solutions for the RL, LC and RLC electric circuits considering conformable and β -derivatives of type Liouville-Caputo were analyzed. These solutions were obtained by iterating conformable and β -integrals. The fractional derivatives considered have properties similar to the classical fractional integrals and derivatives. Due to these operators depend on two parameters, we obtain a better detection of the memory. Novel fractional conformable β -derivatives in the Riemann-Liouville and the Liouville-Caputo sense are obtained. Numerical simulations of alternative models are presented for evaluating the effectiveness of these representations. Different source terms are introduced in the fractional conformable differential equations in Liouville-Caputo sense.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.031
      Issue No: Vol. 85 (2018)
  • An anti-noise modem for visible light communication systems using the
           improved M-ary position phase shift keying
    • Authors: Pu Miao; Lenan Wu; Zhimin Chen
      Pages: 126 - 133
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 85
      Author(s): Pu Miao, Lenan Wu, Zhimin Chen
      In this paper, we propose an anti-noise modem based on the improved M-ary position phase shift keying (MPPSK) for visible light communication (VLC) systems. The line spectral interferences in the original MPPSK are theoretically analyzed and approximately mitigated by adopting a set of improved waveform samples. Then, within one symbol duration, the peak envelopes of the received signals are captured at each of synchronization bit with a quantity of sampling offsets to improve the proportion of the reliable data tones. In addition, a novel demodulation scheme using an amplitude-position detector based on soft decision is proposed to recover the MPPSK symbols, which can minimize the contamination influence of channel noise on symbol decision. With this scheme, the false alarm error and wrong slot error caused by the multipath fading in VLC channel can be effectively corrected and the bit error rate (BER) performance of the system is significantly improved. Simulation results demonstrate that the proposed scheme reduce the required signal-to-noise ratio (SNR) at least by 2 dB for BER = 10−4, which show the feasibility and validity of this anti-noise modem.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2017.12.039
      Issue No: Vol. 85 (2018)
  • An Offset CPW-Fed Triple-Band Circularly Polarized Printed Antenna for
           Multiband Wireless Applications
    • Authors: Ashok Kumar; Venuka Sankhla; Jitendra Kumar Deegwal; Arjun Kumar
      Abstract: Publication date: Available online 3 February 2018
      Source:AEU - International Journal of Electronics and Communications
      Author(s): Ashok Kumar, Venuka Sankhla, Jitendra Kumar Deegwal, Arjun Kumar
      An offset coplanar waveguide (CPW)-fed triple-band circularly polarized tilted asymmetrical E-shaped printed antenna for multiband wireless applications is presented in this paper. The antenna mainly consists of a tilted asymmetrical E-shaped patch and excite by a 50 Ω offset CPW feed line using a transformer for impedance matching to generate wide quad operating bands. By properly embedding rectangular slots in the tilted asymmetrical E-shaped patch and triangular stubs loaded modified CPW ground plane, the antenna reveals triple-band circular polarization (CP) features. Numerical analysis and experimental validation of the antenna structure have been carried out and results are presented. The mechanism of triple-band CP operation, analysis of surface current distributions, design procedure and parametric study of the design is discussed in details. It is well suited for the application of UMTS-2100, 3.5/5.5 GHz WiMAX, 5.2/5.8 GHz WLAN, ITS, downlink of X-band satellite communication, and ITU 8 GHz bands.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.02.002
  • Non-Orthogonal Multiple Access Protocol for Overlay Cognitive Radio
           Networks Using Spatial Modulation and Antenna Selection
    • Authors: Said Emam; M.E. Çelebi
      Abstract: Publication date: Available online 3 February 2018
      Source:AEU - International Journal of Electronics and Communications
      Author(s): Said Emam, M.E. Çelebi
      In this paper we propose a novel spectrum sharing protocol for overlay cognitive radio networks using non-orthogonal multiple access (NOMA), spatial modulation (SM) and antenna selection (AS). The proposed protocol allows a secondary transmitter (ST) to transmit simultaneously to both a primary receiver (PR) and a secondary receiver (SR) using SM. The usage of NOMA and SM will increase the spectral efficiency for both PR and SR with reduced detection complexity than the case without NOMA in which the detectors are required to jointly detect both SM symbols at each receiver. The application of AS at ST with regards to PR provides higher quality transmission for PR without affecting the performance of SR. The performance of the proposed protocol is investigated by derivations of upper bounds on the average symbol error probabilities at PR and SR and by Monte Carlo simulations. Analytical and simulation results show that the proposed protocol offers efficient spectrum utilization over spectrum sharing protocols proposed recently that uses SM – to convey the primary data to PR through the amplitude phase modulation technique and the secondary data to SR through the index of the active antenna.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.02.006
  • Microstrip Bandpass Filters using Coupled Feed Lines for Third and Fourth
           Generation Communications
    • Authors: Amirhossein Ghaderi; Alireza Golestanifar; Farzin Shama
      Abstract: Publication date: Available online 3 February 2018
      Source:AEU - International Journal of Electronics and Communications
      Author(s): Amirhossein Ghaderi, Alireza Golestanifar, Farzin Shama
      In this paper, two compact tuneable bandpass filters (BPFs) based on the coupled feed lines are introduced. To approach a compact size, the coupled feed lines are bended. To design a high performance single-band bandpass filter (BPF), coupled feed lines are loaded by T-shaped stubs (as main resonators) and rectangular stubs (as suppressor stubs). Also, the mechanism of coupled feed lines combining with T-shaped open stubs is analyzed to show a tunable passband. The dual-band BPF includes two big radial-stubs, two small radial-stubs, two T-shaped structures and spiral coupled feed lines. The LC model of big radial-stubs is analyzed to compute the equation of transmission zero using its transfer function. The passband frequency of single-band BPF resonates at 2.12 GHz (3G) with corresponded insertion loss of 0.83 dB. Also, for dual-band BPF, the measured insertion-losses of first and second passbands are close to 0.8 and 1.1 dB, respectively. The frequency responses of BPFs are easily adjusted by altering the physical dimensions, demonstrating a adjustable performance. To verify the correct operation of circuits, the proffered filters are implemented and tested.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.02.007
  • A Miniaturized Lowpass Bandpass Diplexer with high Isolation
    • Authors: Hossein Heshmati; Sobhan Roshani
      Abstract: Publication date: Available online 3 February 2018
      Source:AEU - International Journal of Electronics and Communications
      Author(s): Hossein Heshmati, Sobhan Roshani
      A new compact and wide band lowpass-bandpass diplexer with simple structure is designed and fabricated in this paper. T shaped and Z shaped resonators are used in the lowpass channel and two coupled open stubs are used in the bandpass channel. The designed diplexer has 3 dB cutoff frequency of 1GHz in the lowpass channel and operating frequency of 2.4GHz in the bandpass channel. The obtained insertion losses in the lowpass and bandpass channels are 0.25 dB and 0.58 dB, respectively. The obtained isolation between the two output ports is better than 35 dB. The overall size of the fabricated lowpass bandpass diplexer is obtained 45.6mm× 28.6mm, which shows good miniaturization, compared with other similar diplexers.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.02.004
  • Isolation and Gain Enhancement of Patch Antennas using EMNZ Superstrate
    • Authors: Prakash Kumar Panda; Debalina Ghosh
      Abstract: Publication date: Available online 2 February 2018
      Source:AEU - International Journal of Electronics and Communications
      Author(s): Prakash Kumar Panda, Debalina Ghosh
      A system comprising of multiple antennas demonstrate performance degradation due to the adverse effects of mutual coupling. This work describes an isolation enhancement technique using an epsilon-and-mu-near-zero (EMNZ) metamaterial as superstrate. The method is demonstrated for closely packed H-plane microstrip patch antennas. The EMNZ superstrate is placed at a height of 10 mm (equivalent to λ 0 / 12 ) above the antennas which have an edge to edge separation of 4mm (equivalent to λ 0 / 30 ). The EMNZ superstrate enhances the isolation to -30dB at the resonant frequency. At the same time metamaterial demonstrates NZRI (near zero refractive index) properties due to which the directivity of the antennas is enhanced. Additionally, the generation of cavity effect due to the placement of the superstrate leads to an increase in the gain and efficiency of the antenna by 3.4dBi and 20% respectively. The overall design is very compact and can be easily incorporated in a multi antenna system.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.037
  • A 12-bit 100MS/s Pipelined ADC without Using Front-End SHA
    • Authors: H. Imanpoor; M. Mehranpouy; P. Torkzadeh; A. Jannesari
      Abstract: Publication date: Available online 2 February 2018
      Source:AEU - International Journal of Electronics and Communications
      Author(s): H. Imanpoor, M. Mehranpouy, P. Torkzadeh, A. Jannesari
      This paper presents a model and a novel architecture of a low-power pipelined analog-to-digital converter (ADC) without using front-end Sample and Hold Amplifier (SHA) stage. The Modeling of all ADC building blocks along with their non-ideal effects have been implemented in MATLAB SIMULINK environment and the main transistor level circuits have been implemented in H-SPICE environment using 180-nm TSMC CMOS Technology. The maximum DNL and INL amounts are equal to ± 0.9 LSB and ± 2.3 LSB, respectively. Applying a 33.1MHz with 1.4 V p - p (-6dBFS) input signal, achieved SNDR is 61dB resulting in 9.8Bits ENOB with total power consumption of 42mW.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.027
  • Ku Band Pattern Reconfigurable Substrate Integrated Waveguide Leaky Wave
           Horn Antenna
    • Authors: Tanvi Agrawal; Shweta Srivastava
      Abstract: Publication date: Available online 2 February 2018
      Source:AEU - International Journal of Electronics and Communications
      Author(s): Tanvi Agrawal, Shweta Srivastava
      A dual band substrate integrated waveguide H plane sectoral horn antenna with reconfigurable radiation characteristics has been proposed in this paper. Designed antenna acts as a perfect broadside radiator at 16.1 GHz and perfect endfire radiator at 14.4 GHz frequency. Broadside radiation has been achieved by etching rectangular slots in the flared section of horn exhibiting a gain of 8.87 dBi. To achieve perfect endfire radiation, dielectric loading is done at the edge of horn and at this frequency antenna shows a gain of 11.3 dBi. The horn and the loaded dielectric are integrated by using the same single substrate resulting in easy fabrication and low cost. The proposed design has been fabricated and measured results are in good agreement with the simulated results.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.022
  • A Fully Integrated RSSI and an Ultra-Low Power SAR ADC for 5.8GHz DSRC ETC
    • Authors: Meijuan Zhang; Ruifeng Liu; Yuanzhi Zhang; Wenshen Wang; Huimin Liu; Chao Lu
      Abstract: Publication date: Available online 2 February 2018
      Source:AEU - International Journal of Electronics and Communications
      Author(s): Meijuan Zhang, Ruifeng Liu, Yuanzhi Zhang, Wenshen Wang, Huimin Liu, Chao Lu
      This study presents a monolithic received signal strength indicator (RSSI) and an ultra-low power SAR ADC for 5.8GHz DSRC transceiver in China electronic toll collection systems. In order to meet the stringent requirement of wide input range for the transceiver, two RSSIs collaborate with auxiliary ADC circuits to provide the digitalized received signal strength to the digital baseband of a transceiver. The RSSI design achieves fast transient response and low power consumption with a small die area by using internal active low-pass filters instead of external passive ones. The proposed design has been fabricated using a 0.13µm 2P6M CMOS technology. Measurement results show that the overall input dynamic range is 86dB with an accuracy of ±1.72dB and a transient response of less than 2µs. Compared with the state-of-the-art designs in the literature, the overall input range and transient settling time are improved by at least 14.6%, and 300%, respectively.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.01.020
    • Authors: Deniz Ustun; Ali Akdagli
      Abstract: Publication date: Available online 2 February 2018
      Source:AEU - International Journal of Electronics and Communications
      Author(s): Deniz Ustun, Ali Akdagli
      In this study, a novel UWB antenna with dual band–rejection is designed by using a new hybrid optimization algorithm based artificial bee colony algorithm (ABC) and differential evolution (DE). The hybrid performance of ABC and DE (H–ABCDE) is tested on well–known benchmark functions. To show its performance on a design problem, an optimization interface (OI) which simultaneously communicates with H–ABCDE and an electromagnetic simulation tool is developed. Hence OI integrating H–ABCDE and HyperLynx® 3D EM is used to design and optimize an antenna. A low profile UWB monopole antenna operating over the frequency range of 2.9–13.0 GHz is then designed through OI. In order to achieve band–rejection operation, various slits and strips have been loaded on the antenna. It thus rejects the dual–band of 3.3–3.6 GHz and 5.15–5.825 GHz corresponds to the operation bands of WLAN and WiMAX. Furthermore, the optimized antenna is prototyped to investigate the measurement performance and it is compared with several designs in the literature. Therefore, H–ABCDE can successfully adapt to the extended electromagnetic problem as well as engineering optimization tasks.

      PubDate: 2018-02-05T14:10:19Z
      DOI: 10.1016/j.aeue.2018.02.001
  • Design of miniaturised CMOS bandpass filters for ultra-wideband
    • Authors: Abdelhalim A. Saadi; Mustapha C.E. Yagoub; Abdelhalim Slimane; Rachida Touhami
      Pages: 1 - 7
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Abdelhalim A. Saadi, Mustapha C.E. Yagoub, Abdelhalim Slimane, Rachida Touhami
      In this paper, a set of ultra-compact CMOS bandpass filters are proposed for ultra-wideband (UWB) applications. For this aim, a comparative study was first performed enabling to deduce that Chebyshev-inverse and Hourglass filtering functions can be the most suitable for UWB operation. The impact of the latter functions on the easiness of implementation in integrated passive device (IPD) technologies and filtering performance was investigated, where the designed filters were implemented in 0.18-µm CMOS technology. Finally, the issue of in-band interference has been addressed by rejecting the wireless local area network (WLAN) signals. The performance of the proposed UWB filters were validated through post layout simulation, and good fulfilling with UWB specifications was noted while depicting a compact size, smaller than 0.6 mm2, which is very miniaturised compared with relevant works mentioned in the state of the art.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.013
      Issue No: Vol. 84 (2017)
  • Covariance matrix based fast smoothed sparse DOA estimation with partly
           calibrated array
    • Authors: Jing Liu; Weidong Zhou; Defeng (David) Huang; Filbert H. Juwono
      Pages: 8 - 12
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Jing Liu, Weidong Zhou, Defeng (David) Huang, Filbert H. Juwono
      To solve the problem of direction-of-arrival (DOA) estimation for partly calibrated array, a new gain-phase error matrix estimation scheme and a smoothed sparse signal reconstruction method tailored for the complex-valued covariance matrix are proposed. In the proposed method, DOA estimation is achieved by employing the structure of the covariance matrix for the error matrix estimation and the complex-valued gradient matrix based fast non-convexity data reconstruction. The proposed method has much faster computational speed than other sparse DOA estimation methods with partly calibrated array. In addition, simulation results show that it performs well and is independent of the errors.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.10.026
      Issue No: Vol. 84 (2017)
  • Cyclic frequency distinction and its application in modulation parameter
           estimation: An adaptive approach
    • Authors: Fatemeh Rahimzadeh; Kamal Shahtalebi; Farzad Parvaresh
      Pages: 13 - 20
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Fatemeh Rahimzadeh, Kamal Shahtalebi, Farzad Parvaresh
      Cyclic frequency detection of cyclostationary signals and its application in modulation parameters estimation is the aim of this paper. A simple frequency shifted (FRESH) model is structured. The normalized least mean square (NLMS) algorithm is engaged to estimate the unknown weights of the considered model. The norm of the parameter estimate is related to the model accuracy. A high (low) value indicates that the FRESH structure is based on an accurate (inaccurate) cyclic frequency and the weight estimate of the NLMS algorithm converges to a nonzero (zero) vector. Accordingly for two given values which only one of them is the true cyclic frequency of the received signal, two FRESH structures are considered and simultaneously two NLMS algorithms are executed. If the norm of the weight estimate of the first algorithm exceeds the resulted norm of the second one, according to the proposed method, the first given value is the true cyclic frequency and vice versa. The method is used to estimate the modulation parameters of three different problems: chip rate estimation of a spread spectrum signal, carrier frequency and bit rate estimation of BPSK and QPSK signals, and symbol rate estimation of OFDM signals.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.003
      Issue No: Vol. 84 (2017)
  • The dual-band reentrant power splitter
    • Authors: V.V. Atuchin; A.P. Gorbachev; V.A. Khrustalev; N.V. Tarasenko
      Pages: 21 - 26
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): V.V. Atuchin, A.P. Gorbachev, V.A. Khrustalev, N.V. Tarasenko
      A novel configuration of the microwave dual-band power splitter is presented in this paper. The proposed power splitter is based on the reentrant structure in which the metallic body with a floating potential is asymmetrical. As a result, two adjacent work bands are created, leading to quasi-flat maximum responses and that improves the weight, compatibility and cost of the splitter. The general TEM circuit model for the proposed splitter, in terms of a series multi-port connection, is designed and used to determine the initial electrical parameters. An experimental printed unit has been manufactured using conventional printed circuit implementation. The measured S-parameters show an acceptable agreement with analytical and full-wave simulations and that paves the way for a variety of applications.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.007
      Issue No: Vol. 84 (2017)
  • Design of an asymmetric capped biconical antenna for constant beam
           direction over a desired range of frequencies
    • Authors: Javad Ghalibafan; Seyed Mohammad Hashemi
      Pages: 27 - 33
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Javad Ghalibafan, Seyed Mohammad Hashemi
      In this paper a new wideband biconical antenna with shaped radiation pattern is presented. This biconical antenna has two different elements. Each element consists of a simple cone and an annular cap playing a role as shaping of E-plane radiation pattern. By introducing several geometric features, the beam shaping behavior of the proposed antenna over a desired range of frequencies is investigated. To improve the impedance matching, decrease the feeding cable effect on the antenna performance and simplify the fabrication process, a coaxial cable is embedded in antenna feed port. The simulated and measured results show a wideband impedance bandwidth (387 MHz–7.13 GHz), constant beam direction in E-plane over a desired range of frequencies and omnidirectional H-plane pattern for the proposed antenna.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.017
      Issue No: Vol. 84 (2017)
  • On the cellular spectral efficiency of MC-CDMA systems with MMSE multiuser
           detector employing fractional and soft frequency reuse
    • Authors: Henry Carvajal Mora; Nathaly Orozco Garzón; Celso de Almeida
      Pages: 34 - 45
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Henry Carvajal Mora, Nathaly Orozco Garzón, Celso de Almeida
      In this paper, an approach to evaluate the cellular spectral efficiency of the uplink of MC-CDMA systems employing fractional frequency reuse (FFR) and soft frequency reuse (SFR) is proposed. For this, an algorithm to calculate the cell coverage radius assuming the use of adaptive modulation is proposed. Then, expressions to evaluate the mean spectral efficiency of the cellular system are derived, which are function of the cell coverage radius, the number of users and the spreading factor. The analysis proposed in this paper allows to find operating scenarios that maximize the cellular spectral efficiency at the same time that a certain quality of service based on a target bit error rate (BER) is guaranteed for MC-CDMA systems. Specifically, this analysis considers the uplink of MC-CDMA systems employing a minimum-mean-square error (MMSE) multiuser detector and an antenna array at the base stations. Additionally, the presence of own-cell and co-cell interference is assumed in the channel model.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.011
      Issue No: Vol. 84 (2017)
  • Node-power-based MAC protocol with adaptive listening period for wireless
           sensor networks
    • Authors: Khalil F. Ramadan; M.I. Dessouky; Mohammed Abd-Elnaby; Fathi E. Abd El-Samie
      Pages: 46 - 56
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Khalil F. Ramadan, M.I. Dessouky, Mohammed Abd-Elnaby, Fathi E. Abd El-Samie
      One of the major challenges during initiation of Wireless Sensor Networks (WSNs) is the energy conservation. Knowing that the transceiver is the main source of energy dissipation, we have to design a suitable protocol at the Medium Access Control (MAC) layer to maximize the network lifetime. We are interested in reducing the energy consumption in such networks with very little degradation in the delay profile. In this paper, a Node-power-based MAC protocol with adaptive listening period for WSNs is presented. The proposed protocol alleviates the problems of unfair distribution of power among nodes in the original Sensor-MAC (S-MAC) and Multi-Layer MAC (ML-MAC) protocols. Simulation results show that the proposed MAC protocol provides an enhanced performance compared to both the S-MAC and ML-MAC protocols. The simulation results show also that the proposed MAC protocol consumes less energy than those consumed by both the S-MAC and ML-MAC protocols. The proposed protocol saves about 61.1% of the energy consumed by the S-MAC protocol. It also achieves 17% energy saving as compared to the ML-MAC protocol in the non-coherent mode. Moreover, in the coherent mode, the proposed protocol saves 73% and 23.1% of the energy consumed by the S-MAC and ML-MAC protocols, respectively.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.10.034
      Issue No: Vol. 84 (2017)
  • Wave diffraction by a right-angled interface between resistive half and
           whole planes
    • Authors: Yusuf Ziya Umul
      Pages: 57 - 61
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Yusuf Ziya Umul
      The interaction phenomenon of electromagnetic plane waves by a right angled interface between whole and half screens with different resistivities is studied. The construction, under examination, is considered in order to model various corner discontinuities between transmissive surfaces for indoor wireless communications. First of all, the initial waves, which occur in the absence of the diffracting edge, are determined. Then the scattered geometrical optics fields are obtained by subtracting the initial waves from the total geometrical optics fields. The diffracted field is constructed directly from the scattered geometrical optics wave by a new method. The resultant field expressions are examined numerically.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.015
      Issue No: Vol. 84 (2017)
  • Miniaturization of substrate integrated waveguide filters using novel
           compact metamaterial unit-cells based on SIR technique
    • Authors: Mostafa Danaeian; Kambiz Afrooz; Ahmad Hakimi
      Pages: 62 - 73
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Mostafa Danaeian, Kambiz Afrooz, Ahmad Hakimi
      In this paper, three novel compact metamaterial unit-cells are proposed. The proposed unit-cells are based on the concept of the stepped-impedance resonator (SIR) technique which are used to miniaturize the physical size of the conventional complementary split ring resonators (CSRRs). The proposed metamaterial unit-cells consists of two modified rings so that in these unit-cells, the slot lines in the conventional CSRRs are replaced by the stepped-impedance slot lines. The electrical size of the proposed unit-cells called the SIR-CSRR are larger than the conventional CSRR. To investigate the performance of the proposed SIR-CSRR unit-cells in the size reduction, three substrate integrated waveguide filters loaded by SIR-CSRR unit-cells with different configurations are designed. By loading the SIR-CSRRs on the surface of the waveguide, an additional forward-wave passband propagating below the initial cut-off frequency of the waveguide is produced. Consequently, by using the proposed SIR-CSRR unit-cells instead of the conventional CSRRs, miniaturization with arbitrary ratio are achieved. In order to validate the proposed miniaturization technique, the designed filters are fabricated and measurement results are provided. Good agreement between simulation and measurement results are achieved.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.008
      Issue No: Vol. 84 (2017)
  • Multi-phase low-noise digital ring oscillators with sub-gate-delay
    • Authors: Oussama Elissati; Abdelkarim Cherkaoui; Assia El-Hadbi; Sébastien Rieubon; Laurent Fesquet
      Pages: 74 - 83
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Oussama Elissati, Abdelkarim Cherkaoui, Assia El-Hadbi, Sébastien Rieubon, Laurent Fesquet
      Multi-phase oscillators are often required to generate multiple clock phases with high frequency, high resolution and low-phase noise. This paper deals with self-timed ring oscillators (STROs), which are a promising solution for designing multi-phase clock generators. In STROs, the phase resolution can be adjusted as fin as desired by simply increasing its number of stages without frequency drop, and this resolution is not limited by the gate delay. In addition, different oscillation frequencies can be obtained by the same STRO depending on its initialization. Thanks to this configurability, 1 / N ( - 10 · log ( N ) dB ) phase noise reduction is obtained at the cost of higher power consumption when the number of stages is increased N times, while keeping the same oscillation frequency. Moreover, clock jitter in STROs is reduced to the minimum and unavoidable component due to the white noise. Two test-chips have been designed and fabricated in STMicroelectonics CMOS 65 nm and in AMS 350 nm. Most of the measurements are perfectly in accordance with our theoretical claims.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.022
      Issue No: Vol. 84 (2017)
  • Selection of maximum power transfer region for resonant inductively
           coupled wireless charging system
    • Authors: Durga P. Kar; Sushree S. Biswal; Pradyumna K. Sahoo; Praveen P. Nayak; Satyanarayan Bhuyan
      Pages: 84 - 92
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Durga P. Kar, Sushree S. Biswal, Pradyumna K. Sahoo, Praveen P. Nayak, Satyanarayan Bhuyan
      In order to uphold the maximum power transfer in a resonant inductively coupled wireless power transfer system, an operating region has been proposed based on the coupling coefficient, frequency and electric load. The effectiveness of the proposed condition has been examined both theoretically and experimentally. The obtained results are in well agreement with each other. It has been seen that the operating frequency region is different for different electric loads corresponding to the coupling coefficient between the transmitter and receiver coils of the resonant inductive link. The operating frequency region shifts to lower frequency side for lower value of electric load at larger value of coupling coefficient even maintaining the optimum power transfer. The obtained knowledge reveals the design modus operandi through which an effective wireless charging system can be intended not only for low power device applications but also for high power EV charging.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.023
      Issue No: Vol. 84 (2017)
  • Microstrip Sierpinski fractal carpet for slot antenna with metamaterial
           loads for dual-band wireless application
    • Authors: Gohar Varamini; Asghar Keshtkar; Navid Daryasafar; Mohammed Naser -Moghadasi
      Pages: 93 - 99
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Gohar Varamini, Asghar Keshtkar, Navid Daryasafar, Mohammed Naser -Moghadasi
      The compact microstrip antennas with the dual-band characteristic and reconfigurable qualification have been noticed and investigated in this paper. We have developed the slot microstrip antenna with Sierpinski carpet and Minkowski formations and then the metamaterial loads are placed on this antenna in the slot area. The reflection/transmission method has considered to obtain the permittivity and permeability of the split ring resonator (SRR) as a metamaterial. Finally, we show that by using some junction in the metamaterial layer, we can obtain reconfigurable characteristic. Both antennas have dual-band characteristic where the first antenna has two resonances at 3.2 and 4.5 GHz and in the second antenna by altering the metamaterial layer both resonances are occurring at 3.5 and 5.8 GHz. We show that the antenna has two resonance frequencies that matched with the metamaterial Double Negative (DNG) characteristic. Both antennas are printed on FR-4 also we compared measurement and simulation results together. Aforementioned antennas cover the main wireless, WiMAX and LTE bands with sufficient gain and high efficiency (more than 80% typically) with a bi-directional radiation pattern for the indoor application. Here, the metamaterial is used for controlling the resonances and Sierpinski carpet is developed for matching.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.028
      Issue No: Vol. 84 (2017)
  • Wavelet transform based novel edge detection algorithms for wideband
           spectrum sensing in CRNs
    • Authors: Abhishek Kumar; Seemanti Saha; Rajarshi Bhattacharya
      Pages: 100 - 110
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Abhishek Kumar, Seemanti Saha, Rajarshi Bhattacharya
      The primary task in cognitive radio is to dynamically explore the radio spectrum and reliably detect the co-existing licensed primary transmissions across a wide-band spectrum. This paper focuses on wavelet transform (WT) based wide-band sensing techniques, which identify the edges of the multiple frequency bands simultaneously. Novel edge detection algorithms are proposed based on continuous WT (CWT) and discrete WT (DWT) techniques, applied on wide-band power spectrum. In CWT based spectrum sensing, logarithmic scaling preceded by a thresholding is performed on the CWT coefficients to enhance the small modulus maxima values at the edges, resulting in better detection probability. Since the logarithmic scaling magnifies the spurious edges, the proposed algorithm increases the false alarm probability at high noise variance. To alleviate this problem, DWT based algorithms are proposed, where DWT performs simultaneous denoising and edge detection. To achieve good detection performance at poor SNR scenario, a moving average filtering strategy is adopted at different levels of DWT based algorithms and better performance is achieved even with lower scale value of DWT, thereby reducing the computation time. Comparative studies show that the proposed algorithms outperform the existing WT based edge detection algorithms in the dynamic and frequency selective channels as well.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.024
      Issue No: Vol. 84 (2017)
  • Channel estimation in ACO-OFDM employing different transforms for VLC
    • Authors: Suseela Vappangi; Venkata Mani Vakamulla
      Pages: 111 - 122
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Suseela Vappangi, Venkata Mani Vakamulla
      The pronounced eminency of assuring simultaneous illumination and communication has driven Visible Light Communication (VLC) to gain significant ubiquity in recent times. This paper proposes comb type pilot arrangement based channel estimation for Asymmetrically Clipped Optical OFDM (ACO-OFDM) and different multicarrier transmission systems like Discrete Hartley Transform (DHT)-based ACO-OFDM and Fast-Walsh Hadamard transform (FWHT)-based Hadamard Coded Modulation (HCM) over dispersive VLC channel. Various channel estimation algorithms like Least Square (LS), Minimum Mean Square Error (MMSE), and Interpolation techniques namely Linear, Spline, and Low-Pass are evaluated and compared for the aforesaid systems employing different orders of constellation. Here, an elaborate mathematical analysis is accomplished and Cramer Rao Lower Bound (CRLB) is derived for the channel estimation error. Simulated results emphasize that, ACO-OFDM and DHT-based ACO-OFDM have improved Bit Error Rate (BER) performance than HCM at lower Signal to Noise Ratio (SNR), while at higher SNRs HCM dominates the former. Furthermore, the simulated results evidences that, in all multicarrier systems MMSE algorithm has reducible probability of error than LS because, at higher SNRs LS is more susceptible to noise and Spline Interpolation outperforms both LS and MMSE. The simulated results are validated analytically demonstrating good agreement.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.016
      Issue No: Vol. 84 (2017)
  • Broad-range microstrip patch refflectarray element loaded with multiple
           L-shaped slots
    • Authors: Yeong-Nan Phua; Eng-Hock Lim; Boon-Kuan Chung
      Pages: 123 - 130
      Abstract: Publication date: February 2018
      Source:AEU - International Journal of Electronics and Communications, Volume 84
      Author(s): Yeong-Nan Phua, Eng-Hock Lim, Boon-Kuan Chung
      A single-layer microstrip patch unit element, which is loaded with eight concentric L-shaped slots, is proposed for reflectarray design. In this case, the lengths of the inner and outer slots are varied concurrently to function as the phase-shifting geometrical parameters. The reflection characteristics of the element are analyzed using the waveguide method, and the simulation results have been verified with experiments. A broad reflection phase range of 631.83° with slow gradient has been successfully achieved with the use of the slotted patch with constant size. Parametric analysis has been performed and it is found that the S-curve can be easily fine-tuned by changing some of the design parameters.

      PubDate: 2017-12-13T10:31:10Z
      DOI: 10.1016/j.aeue.2017.11.025
      Issue No: Vol. 84 (2017)
School of Mathematical and Computer Sciences
Heriot-Watt University
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