J.Z. Zhang, F.Q. Yao, H.S. Zhao [references] [full-text] [Download Citations]
Distributed Clustering in Cognitive Radio Ad Hoc Networks Using Soft-Constraint Affinity Propagation

Absence of network infrastructure and heterogeneous spectrum availability in cognitive radio ad hoc networks (CRAHNs) necessitate the self-organization of cognitive radio users (CRs) for efficient spectrum coordination. The cluster-based structure is known to be effective in both guaranteeing system performance and reducing communication overhead in variable network environment. In this paper, we propose a distributed clustering algorithm based on soft-constraint affinity propagation message passing model (DCSCAP). Without dependence on predefined common control channel (CCC), DCSCAP relies on the distributed message passing among CRs through their available channels, making the algorithm applicable for large scale networks. Different from original soft-constraint affinity propagation algorithm, the maximal iterations of message passing is controlled to a relatively small number to accommodate to the dynamic environment of CRAHNs. Based on the accumulated evidence for clustering from the message passing process, clusters are formed with the objective of grouping the CRs with similar spectrum availability into smaller number of clusters while guaranteeing at least one CCC in each cluster. Extensive simulation results demonstrate the preference of DCSCAP compared with existing algorithms in both efficiency and robustness of the clusters.

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Keywords: Cognitive radio ad hoc networks, clustering, soft-constraint affinity propagation, robustness

Z. Fan, D. Guo, B. Zhang [references] [full-text] [Download Citations]
Outage Probability and Power Allocation for Two-Way DF Relay Networks with Relay Selection

In this paper, we investigate the outage probability and power allocation for the two-way decode-and-forward (DF) relay networks with relay selection.~Specially, we consider independent but not necessarily identical distributed Rayleigh fading channels. Firstly, we derive an exact closed form outage probability expression. To shed light on the relation between the outage probability and the power allocation factor, an upper bound for the outage probability is derived, too. We then propose a power allocation scheme in the sense of minimizing this upper bound. Monte Carlo simulations are conducted to show that the derived outage probability expression excellently matches simulation results, and our proposed power allocation scheme performs effectively.

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Keywords: Two-way relay networks, relay selection, decode-and-forward, outage probability, power allocation

Y. B. Li, R. Yang, Y. Lin, F. Ye [references] [full-text] [Download Citations]
The Spectrum Sharing in Cognitive Radio Networks Based on Competitive Price Game

The competitive price game model is used to analyze the spectrum sharing problem in the cognitive radio networks, and the spectrum sharing problem with the constraints of available spectrum resource from primary users is further discussed in this paper. The Rockafeller multiplier method is applied to deal with the constraints of available licensed spectrum resource, and the improved profits function is achieved, which can be used to measure the impact of shared spectrum price strategies on the system profit. However, in the competitive spectrum sharing problem of practical cognitive radio network, primary users have to determine price of the shared spectrum without the acknowledgement of the other primary user’s price strategies. Thus a fast gradient iterative calculation method of equilibrium price is proposed, only with acknowledgement of the price strategies of shared spectrum during last cycle. Through the adaptive iteration at the direction with largest gradient of improved profit function, the equilibrium price strategies can be achieved rapidly. It can also avoid the predefinition of adjustment factor according to the parameters of communication system in conventional linear iteration method. Simulation results show that the proposed competitive price spectrum sharing model can be applied in the cognitive radio networks with constraints of available licensed spectrum, and it has better convergence performance.

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Keywords: Cognitive radio, spectrum sharing, game theory, competitive price model

Z. Zhang, Q. Wu, J. Wang [references] [full-text] [Download Citations]
Energy-efficient Power Allocation Strategy in Cognitive Relay Networks

Cognitive radio and cooperative technique are two essential techniques for the future generation green communication paradigm owing to its inherent advantages of adaptability and cognition. Typically, previous studies on power allocation in the cognitive relay networks often concentrate on two goals independently: the first goal is to minimize the transmit power to reduce energy consumption, as depicted in strategy 1; the second goal is to maximize the transmit rate, as depicted in strategy 2. In this paper, we shift our focus to energy-efficient-oriented design, that is, green power allocation between source and relay. Therefore, we present a novel power allocation strategy considering the two goals jointly, as depicted in strategy 3, and compare the proposed strategy with two previous strategies. Specifically, because the strategy 3 is nonlinear, we use the Lagrange dual method to solve it effectively. Finally, the numerical results are presented to validate our theoretical results through theory simulation and Monte Carlo simulation. Numerical performance results show that the proposed strategy works better than that of the two previous strategies from the viewpoints of energy-efficient.

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Keywords: Cognitive relay networks (CRN); energy-efficient (EE); secondary user (SU); primary user (PU)

H. Xiao, H. Shao, K. Yang, F. Yang, W. Wang [references] [full-text] [Download Citations]
Multiple Timescale Energy Scheduling for Wireless Communication with Energy Harvesting Devices

The primary challenge in wireless communication with energy harvesting devices is to efficiently utilize the harvesting energy such that the data packet transmission could be supported. This challenge stems from not only QoS requirement imposed by the wireless communication application, but also the energy harvesting dynamics and the limited battery capacity. Traditional solar predictable energy harvesting models are perturbed by prediction errors, which could deteriorate the energy management algorithms based on this models. To cope with these issues, we first propose in this paper a non-homogenous Markov chain model based on experimental data, which can accurately describe the solar energy harvesting process in contrast to traditional predictable energy models. Due to different timescale between the energy harvesting process and the wireless data transmission process, we propose a general framework of multiple timescale Markov decision process (MMDP) model to formulate the joint energy scheduling and transmission control problem under different timescales. We then derive the optimal control policies via a joint dynamic programming and value iteration approach. Extensive simulations are carried out to study the performances of the proposed schemes.

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Keywords: Energy scheduling, energy harvesting, multiple timescale Markov decision process, transmission control, wireless communication

Y. Liu, Z. Tan [references] [full-text] [Download Citations]
Carrier Frequency Offset Estimation for OFDM Systems using Repetitive Patterns

This paper deals with Carrier Frequency Offset (CFO) estimation for OFDM systems using repetitive patterns in the training symbol. A theoretical comparison based on Cramer Rao Bounds (CRB) for two kinds of CFO estimation methods has been presented in this paper. Through the comparison, it is shown that the performance of CFO estimation can be improved by exploiting the repetition property and the exact training symbol rather than exploiting the repetition property only. The selection of Q (number of repetition patterns) is discussed for both situations as well. Moreover, for exploiting the repetition and the exact training symbol, a new numerical procedure for the Maximum-Likelihood (ML) estimation is designed in this paper to save computational complexity. Analysis and numerical result are also given, demonstrating the conclusions in this paper.

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Keywords: OFDM, CFO, repetitive patterns

B. Nikolic, B. Dimitrijevic, N. Milosevic, G.T. Djordjevic [references] [full-text] [Download Citations]
Performance Improvement of QPSK Signal Predetection EGC Diversity Receiver

This paper proposes a modification of quadrature phase-shift-keying (QPSK) signal diversity reception with predetection equal gain combiner (EGC). The EGC combining is realized by using the constant modulus algorithm (CMA). Carrier synchronization is performed by the phase locked loop (PLL). Comparative analysis of the modified and ordinary diversity receiver in the presence of carrier frequency offset in the additive white Gaussian noise (AWGN) channel, as well as in Rician fading channel is shown. The proposed diversity receiver allows significant frequency offset compared to the diversity receiver that uses only PLL, and the error probability of the proposed receiver is very close to the error probability of the receiver with only PLL and zero frequency offset. The functionality of the proposed diversity receiver, as well as its properties is experimentally verified on a system based on universal software radio peripheral (USRP) hardware. The performed comparison confirms the expected behavior of the system.

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19. DE LAMARE, R. C., HAARDT, M., SAMPAIO-NETO, R. Blind adaptive constrained reduced-rank parameter estimation based on constant modulus design for CDMA interference suppression. IEEE Transactions on Signal Processing, 2008, vol. 52, no. 6, p. 2470–2482.
20. DE LAMARE, R. C., SAMPAIO-NETO, R. Low-complexity variable step-size mechanisms for stochastic gradient algorithms in minimum variance CDMA receivers. IEEE Transactions on Signal Processing, 2006, vol. 54, no. 6, p. 2302–2317.
21. WANG, L., CAI, Y., DE LAMARE, R. C. Low-complexity adaptive step size constrained constant modulus SG-based algorithms for blind adaptive beamforming. In Proc. IEEE International Conference on Acoustics, Speech and Signal Processing. Las Vegas (NV, USA), 2008, p. 2593–2596.
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Keywords: Equal gain combiner, constant modulus algorithm, phase locked loop, adaptive filtering

M. Modarresi, S. M.-S. Sadough [references] [full-text] [Download Citations]
Improved Design and Implementation of Variational Bayesian Iterative Receivers

It was recently shown that detection performance can be significantly improved if the statistics of channel estimation errors are available and properly used at the receiver. Although deriving the statistics of channel estimation errors is rather straightforward for pilot-only channel estimation methods, it is not the case for semi-blind receivers such as variational Bayesian (VB) receivers. We have shown in a recent contribution that by a modified formulation of the VB formalism, one can reduce the impact of channel uncertainty on the decoder performance. In this paper, we propose different practical VB receiver implementation techniques that lead to further performance improvement. The adequacy of the proposed receiver design compared to classically-used VB receivers is demonstrated by simulations for orthogonal frequency-division multiplexing (OFDM) systems.

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11. SADOUGH, S. M. S., MODARRESI, M. Improved iterative Joint detection and estimation through variational bayesian inference. International Journal of Electronics and Communications - AE¨U, 2012, vol. 66, no. 5, p. 380 - 383.
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13. MAGNIEZ, P., MUQUET, B., DUHAMEL, P., BUZENAC, V., DECOURVILLE, M. Optimal decoding of bit-Interleaved modulations: Theoritical aspects and practical algorithms. In Proceedings of International Symposium on Turbo Codes and Related Topics. Brest (France), 2003, p. 169 - 172.
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Keywords: VBEM algorithm, joint iterative data detection and channel estimation, channel estimation errors, OFDM

Y. Wang, A. Liu, D. Guo, X. Liu [references] [full-text] [Download Citations]
Reduced-complexity Non-data-aided Timing Recovery for PAM-based M-ary CPM Receivers

Continuous phase modulation (CPM) is a widely used modulation scheme in communication systems. However, difficulties arise with the design of CPM receivers, due to the nonlinear nature of CPM. One popular solution is to linearize CPM with pulse amplitude modulation (PAM) representation. In this paper, a reduced-complexity non-data-aided (NDA) timing recovery method for PAM-based M-ary CPM receivers is proposed. The proposed method is based on the PAM representation and maximum likelihood principle. The merits of the proposed method are twofold. On one hand, the proposed method is reduced-complexity in nature for PAM-based CPM receivers, i.e., it shares the match filter bank with PAM-based detectors. On the other hand, it is shown that the performance of the proposed method is better than the existing method with some modulation schemes. Therefore, the proposed method provides an important synchronization component for PAM-based M-ary CPM receivers.

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4. PERRINS, E., RICE, M. PAM representation of ternary CPM. IEEE Transactions on Communications, 2008, vol. 56, no. 12, p. 2020 - 2024.
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19. CHANDRAN, P., PERRINS, E. Symbol timing recovery for CPM with correlated data symbols. IEEE Transactions on Communications, 2009, vol. 57, no. 5, p. 1265 - 1270.
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Keywords: Continuous phase modulation, pulse amplitude modulation representation, timing recovery, non-data-aided, reduced-complexity

M. Blaha, J. Machac [references] [full-text] [Download Citations]
Planar Resonators for Metamaterials

This paper presents the results of an investigation into a combination of electric and magnetic planar resonators in order to design the building element of a volumetric metamaterial showing simultaneously negative electric and magnetic polarizabilities under irradiation by an electromagnetic wave. Two combinations of particular planar resonators are taken into consideration. These planar resonators are an electric dipole, a split ring resonator and a double H-shaped resonator. The response of the single resonant particle composed of a resonator with an electric response and a resonator with a magnetic response is strongly anisotropic. Proper spatial arrangement of these particles can make the response isotropic. This is obtained by proper placement of six planar resonators on the surface of a cube that now represents a metamaterial unit cell. The cells are distributed in space with 3D periodicity.

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5. HOLLOWAY, C. L., KUESTER, E. F., BAKER-JARVIS, J., KABOS, P. A double negative (DNG) composite medium composed of magnetodielectric spherical particles embedded in a matrix. IEEE Trans. Antennas Propag., 2003, vol. 51, no. 10, p. 2596-2603.
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7. ZEDLER, M., CALOZ, C., RUSSER, P. A 3-D isotropic lefthanded metamaterial based on the rotated transmission-line matrix (TLM) scheme. IEEE Transaction on Microwave Theory and Techniques, 2007, vol. 55, p. 2930-2941
8. IYER, A., ELEFTHERIADES, G. A three-dimensional isotropic transmission-line metamaterial topology for free-space excitation. Applied Physics Letters, 2008, vol. 92, no. 26, 261106, 3 pages.
9. HUDLICKA, M., MACHAC, J. Triple wire medium for use in isotropic metamaterials. In Proceedings of the 37th European Microwave Conference. Munich (Germany), October 2007, CDROM, p. 628-631.
10. BLAHA, M., MACHAC, J., RYTIR, M. A double H-shaped resonator and its use as an isotropic ENG metamaterial. International Journal on Microwave and Wireless Technologies, Aug. 2009, vol. 1, no. 4, p. 315-321.
11. HRABAR, S., BENIC, L., BARTOLIC, J. Simple experimental determination of complex permittivity or complex permeability of SNG metamaterials. In Proceedings of the 36th European Microwave Conference. Manchester (UK), 2006, p. 1395-1398.
12. NICHOLSON, K. J., GHORBANI, K. Design, manufacture and measurement of a metamaterial with tunable negative-refractive index region. In APMC 2009. Asia Pacific Microwave Conference. Singapore, 2009, p. 1231-1233.
13. BECVAR, V., BLAHA, M., MACHAC, J. Planar resonator with negative electric and magnetic polarizabilities. In Proceedings of the 21st International Conference Radioelektronika. Brno (Czech Rep.), April 2011, p.147-150.
14. KRUPKA, J., GWAREK, W., KWIETNIEWSKI, N., HARTNETT, J. G. Measurements of planar metal–dielectric structures using split-post dielectric resonators. IEEE Transactions on Microwave Theory and Techniques, 2010, vol. 58, no. 12, p. 3511-3518.
15. JELINEK, L., BAENA, J. D., MARQUES, R., ZEHENTNER, J. Direct polarizability extraction method. In Proceedings of the 36th European Microwave Conference. Manchester (UK), 2006, CDROM, p. 983-986.
16. TRETYAKOV, S. Analytical Modelling in Applied Electromagnetics. Boston, London: Artech House, 2003.
17. MACHAC J., PROTIVA P., ZEHENTNER J. Isotropic epsilonnegative particles. In Proceedings of the 2007 IEEE MTT-S International Microwave Symposium. Honolulu (Hi., USA), June 2007, TH4D-03, CD ROM.
18. SCHURING, D., MOCK, J. J., SMITH, D. R. Electric-fieldcoupled resonators for negative permittivity metamaterials. Applied Phys. Letters, 2006, vol. 88, p. 041109-1 to 041109-3.
19. PADILLA, W. J., ARONSSON, M. T., HIGSTRETE, C., LEE, M., TAYLOR, A. J., AVERITT, R. D. Electrically resonant terahertz metamaterials: Theoretical and experimental investigations. Physical Review B, 2007, vol. 75, p. 04102-1 to 04102-4.
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Keywords: Metamaterial, negative electric polarizability, negative magnetic polarizability, isotropic response, planar resonator.

M. Gokten [references] [full-text] [Download Citations]
Efficient Analysis of Ferrite Loaded Waveguides Using the MRFD Method

A full wave two-dimensional Multiresolution Frequency Domain formulation for efficient analysis of the dispersion characteristics of ferrite loaded waveguide structures is developed and presented. It has been concluded that the proposed formulation, which takes advantage of the compactly supported wavelet bases to expand electric and magnetic fields, allows coarser discretization compared to conventional Finite Difference Frequency Domain (FDFD) scheme. The efficiency and accuracy of the newly developed formulation, in comparison to FDFD method, is demonstrated by solving the dispersion characteristics of fully and partially ferrite loaded waveguide structures.

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Keywords: Multiresolution analysis, Finite Difference Method, MRFD, ferrite loaded waveguide, frequency domain

K. N. Abdul Rani, M. F. Abdul Malek, N. Siew-Chin [references] [full-text] [Download Citations]
Nature-inspired Cuckoo Search Algorithm for Side Lobe Suppression in a Symmetric Linear Antenna Array

In this paper, we proposed a newly modified cuckoo search (MCS) algorithm integrated with the Roulette wheel selection operator and the inertia weight controlling the search ability towards synthesizing symmetric linear array geometry with minimum side lobe level (SLL) and/or nulls control. The basic cuckoo search (CS) algorithm is primarily based on the natural obligate brood parasitic behavior of some cuckoo species in combination with the Levy flight behavior of some birds and fruit flies. The CS metaheuristic approach is straightforward and capable of solving effectively general N-dimensional, linear and nonlinear optimization problems. The array geometry synthesis is first formulated as an optimization problem with the goal of SLL suppression and/or null prescribed placement in certain directions, and then solved by the newly MCS algorithm for the optimum element or isotropic radiator locations in the azimuth-plane or xy-plane. The study also focuses on the four internal parameters of MCS algorithm specifically on their implicit effects in the array synthesis. The optimal inter-element spacing solutions obtained by the MCS-optimizer are validated through comparisons with the standard CS-optimizer and the conventional array within the uniform and the Dolph-Chebyshev envelope patterns using MATLABTM. Finally, we also compared the fine-tuned MCS algorithm with two popular evolutionary algorithm (EA) techniques include particle swarm optimization (PSO) and genetic algorithms (GA).

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6. NIK ABD MALIK, N. N., ESA, M., SYED YUSOF, S. K., MARIMUTHU, J. Suppression of antenna's radiation side lobes using particle swarm optimization. In Progress in Electromagnetics Research Symposium. Moscow (Russia), 2009.
7. KHODIER, M. M., CHRISTODOULOU, C. G. Linear array geometry synthesis with minimum side lobe level and null control using particle swarm optimization. IEEE Trans. Antennas Propag., Aug. 2005, vol. 53, p. 2674-2679.
8. GAVIRIA, N., MELDE, K. L., MCNEILL, K. M., RODRIGUEZ, J. J. Development of array distributions for smart antennas with low side lobes, interference-nulling, and effective radiated voltage constraints. In IEEE Antennas and Propagation Society International Symposium. Albuquerque (NM, USA), 2006, p. 3323-3326.
9. CENGIZ, Y., TOKAT, H. Linear antenna array design with use of genetic, memetic and tabu search optimization algorithms. Progress in Electromagnetics Research C, 2008, vol. 1, p. 63-72.
10. LEE, K. C. Frequency-domain analyses of nonlinearly loaded antenna arrays using simulated annealing algorithms. Progress in Electromagnetics Research, 2005, vol. 53, p. 271-281.
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Keywords: Modified cuckoo search, side lobe suppression, null control, linear array, isotropic radiator, Dolph-Chebyshev.

N. Zakaria, S. K. A. Rahim, T. S. Ooi, K. G. Tan, A. W. Reza, M. S. A. Rani [references] [full-text] [Download Citations]
Design of Stacked Microstrip Dual-band Circular Polarized Antenna

This study introduces a new design of dual-band circular polarized (CP) microstrip antenna for ISM band applications (2.45 GHz and 5.8 GHz). The proposed dual-band CP microstrip antenna with compact design has achieved design intention of having return loss of < −10 dB and axial ratio of < 3 dB for both frequencies of 2.45 GHz and 5.8 GHz. The antenna has been successfully designed, fabricated, simulated, and measured and it shows the advantages of good dual-band and CP performances. Thus, the obtained results confirm satisfactory performance and good agreement.

1. YANG, K. P., WONG, K. L. Dual-band circularly-polarized square microstrip antenna. IEEE Transactions on Antennas and Propagation, 2001, vol. 49, p. 377-382.
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9. OOI, T. S., RAHIM, S. K. A., KOH, B. P. 2.45 GHz and 5.8 GHz compact dual-band circularly polarized patch antenna. Journal of Electromagnetic Waves and Applications, 2010, vol. 24, no. 11-12, p. 1473-1482.
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12. KE, S.-Y. A dual-band microstrip antenna for precise GPS applications. WHAMPOA – An Interdisciplinary Journal (Department of Electrical Engineering, R.O.C. Military Academy, Taiwan), 2007.
13. CHANG, T.-N., NI, G.-Y. Dual-band circular polarized antenna with a quad-EMC structure. Microwave and Optical Technology Letters, 2007, vol. 49, no. 3, p. 645-647.
14. YANG, S., FENG, Q. Y., DONG, B. Broadband stacked annular ring patch antenna for CP operation. In International Conference on E-Business and Information System Security. Wuhan (China), May 2009, p. 1-3.
15. THIAGARAJAH, S., BORHANUDDIN, M. A., HABAEBI, M. H. Circular polarized active microstrip antenna for commercial GPS application. In Proceedings of TENCON. Kuala Lumpur (Malaysia), 2000, vol. 1, p. 109 – 114.
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Keywords: Microstrip antenna, patch antenna, circular polarized

R. K. Maharjan, B. Shrestha, N. Y. Kim [references] [full-text] [Download Citations]
Microstrip Cross-coupled Interdigital SIR Based Bandpass Filter

A simple and compact 4.9 GHz bandpass filter for C-band applications is proposed. This paper presents a novel microstrip cross-coupled interdigital half-wavelength stepped impedance resonator (SIR) based bandpass filter (BPF).The designed structure is similar to that of a combination of two parallel interdigital capacitors. The scattering parameters of the structure are measured using vector network analyzer (VNA). The self generated capacitive and inductive reactances within the interdigital resonators exhibited in a resonance frequency of 4.9 GHz. The resonant frequency and bandwidth of the capacitive cross-coupled resonator is directly optimized from the physical arrangement of the resonators. The measured insertion loss (S21) and return loss (S11) were 0.3 dB and 28 dB, respectively, at resonance frequency which were almost close to the simulation results.

1. POZAR, D. M. Microwave Engineering. 3rd edition. New York, 2004.
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13. SHRESTHA, B., MAHARJAN, R. K., CHO, S., YOON, K. C., KIM, N. Y. A low-phase noise oscillator using spurline resonator for I-band application. In Asia-Pacific Microwave Conference, APMC-2010. Yokohama (Japan), 2010, p. 469-472.
14. HONG, J. S., LANCASTER, M. J. Microstrip Filters for RF/Microwave Applications. A Wiley-Interscience Publication, John Wiley & Sons, Inc. 2001.
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Keywords: Bandpass filter, interdigital resonator, stepped impedance resonator (SIR), half wavelength SIR resonator

W. Jaikla, S. Siripongdee, P. Suwanjan [references] [full-text] [Download Citations]
MISO Current-mode Biquad Filter with Independent Control of Pole Frequency and Quality Factor

This article presents a three-inputs single-output biquadratic filter performing completely standard functions: low-pass, high-pass, band-pass, band-reject and all-pass functions, based on current controlled current conveyor transconductance amplifier (CCCCTA). The quality factor and pole frequency can be electronically/independently tuned via the input bias current. The proposed circuit uses 2 CCCCTAs and 2 grounded capacitors without external any resistors which is very suitable to further develop into an integrated circuit. The filter does not require double input current signal. Each function response can be selected by suitably selecting input signals with digital method. Moreover, the circuit possesses high output impedance which would be an ideal choice for current-mode cascading. The PSPICE simulation results are included to verify the workability of the proposed filter. The given results agree well with the theoretical anticipation.

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2. BAJER, J., LAHIRI, A., BIOLEK, D. Current-mode CCII+ based oscillator circuits using a conventional and a modified Wienbridge with all capacitors grounded. Radioengineering, 2011, vol. 20, no. 1, p. 245 - 250.
3. LI, Y. Current-mode sixth-order elliptic band-pass filter using MCDTAs. Radioengineering, 2011, vol. 20, no. 3, p. 645 - 649.
4. JAIKLA, W., NOPPAKARN, A., LAWANWISUT, S. New gain controllable resistor-less current-mode first order allpass filter and its application. Radioengineering, 2012, vol. 21, no. 1, p. 312 to 316.
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6. IBRAHIM, M. A., MINAEI, S., KUNTMAN, H. A. A 22.5 MHz current-mode KHN-biquad using differential voltage current conveyor and grounded passive elements. International Journal of Electronics and Communication (AEU), 2005, vol. 59, no. 5, p. 311 - 318.
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9. SIRIPRUCHYANUN, M., JAIKLA, W. Electronically controllable current-mode universal biquad filter using single DOCCCDTA. Circuits, Systems & Signal Processing, 2008, vol. 27, no. 1, p. 113 - 122.
10. HORNG, J-W. Current-mode universal biquadratic filter with five inputs and one output using tree ICCIIs. Indian Journal of Pure & Applied Physics, 2011, vol. 49, p. 214 - 217.
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12. LEE, C.-N. Multiple-mode OTA-C universal biquad filters. Circuits, Systems & Signal Processing, 2010, vol. 29, no. 2, p. 263 to 274.
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14. SENANI, R., ABDALLA, K. K., BHASKAR, D. R. A state variable method for the realization of universal current-mode biquads. Circuits and Systems, 2011, vol. 2, no. 4, p. 286 - 292.
15. PANDEY, N., PAUL, S. K. VM and CM universal filters based on single DVCCTA. Active and Passive Electronic Components, 2011, Article ID 929507.
16. SINGH, S. V. MAHESHWARI, S., CHAUHAN, D. S. Electronical-ly tunable current-mode SIMO/MISO universal biquad filter using MO-CCCCTAs. International Journal of Recent Trends in Engineering and Technology, 2010, vol. 3, no. 3, p. 65 - 70.
17. CHUNHUA, W., HAIGUANG, L., YAN, Z. Universal currentmode filter with multiple inputs and one output using MOCCII and MO-CCCA. International Journal of Electronics and Communication (AEU), 2009, vol. 63, no. 6, p. 448 - 453.
18. OZCAN, S., KUNTMAN, H., ÇIÇEKOGLU, O. A novel multiinput single-output filter with reduced number of passive elements using single current conveyor. In Proceedings of the 43rd IEEE Midwest Symposium on Circuits and Systems. Lansing (MI, USA), 2000, p. 1030 - 1032.
19. SAWANGAROM, V., DUMAWIPATA, T., TANGSRIRAT, W., SURAKAMPONTORN, W. Cascadable three-input single-output current-mode universal filter using CDBAs. In The 2007 ECTI International Conference, 2007, p. 53 - 56.
20. CHANNUMSIN, O., PUKKALANUN, T., TANGSRIRAT, W. Universal current-mode biquad with minimum components. In Proceedings of the 2011 International MultiConference of Engineering and Computer Scientists, IMECS 20011. Hong Kong (China), 2011, p. 1012 - 1015.
21. TANGSRIRAT, W., SURAKAMPONTORN W. Electronically tunable current-mode universal filter employing only plus-type current-controlled conveyors and grounded capacitors. Circuits, Systems & Signal and Processing, 2006, vol. 27, no. 6, p. 701 - 713.
22. TANGSRIRAT, W. Cascadable current-controlled current-mode universal filters using CDTAs and grounded capacitors. Journal of Active and Passive Electronic Devices, 2009, vol. 4, p. 135 - 145.
23. TANGSRIRAT, W., DUMAWIPATA, T. SURAKAMPONTORN, W. Multiple-input single-output current-mode multifunction filter using current differencing transconductance amplifiers. International Journal of Electronics and Communication (AEU), 2007, vol. 61, no. 4, p. 209 - 214.
24. TANGSRIRAT, W., PUKKALANUN, T. Structural generation of two integrator loop filters using CDTAs and grounded capacitors. International Journal of Circuit Theory and Applications, 2011, vol. 39, no. 1, p. 31 - 45.
25. HORNG, J.-W. High output impedance current-mode universal biquadratic filters with five inputs using multi-output CCIIs. Microelectronics Journal, 2011, doi:10.1016/j.mejo.2011.02.007.
26. PANDEY, N., PAUL, S. K. Multi-input single-output universal current mode biquad. Journal of Active and Passive Electronic Devices, 2006. vol. 1, no. 3 - 4, p. 229 - 240.
27. KUMNGERN, M. Multiple-input single-output current-mode universal filter using translinear current conveyors. Journal of Electrical and Electronics Engineering Research, 2011, vol. 3, no. 9, p. 162 - 170.
28. PROMMEE, P. ANGKEAW, K. SOMDUNYAKANOK, M. DEJHAN, K. CMOS-based near zero-offset multiple inputs max– min circuits and its applications. Analog Integrated Circuits and Signal Processing, 2009, vol. 61, no. 1, p. 93 - 105.

Keywords: Analog filter, CCCCTA, Current-mode, Multiple input-Single output

N. Schwerg [references] [full-text] [Download Citations]
Symbolical Analysis of RF-Network Problems using Mason’s Rule

We briefly review Mason’s rule for the computation of RF-network problems and show its implementation into the software package freeMASON. This tool solves symbolically Mason’s rule for any wave quantity and allows to derive analytical expressions as well as their functional evaluation. We demonstrate our approach studying the effect of an unbalanced magictee on the RF power distribution to two accelerating cavities.

1. VALUCH, D. High CW Power, Phase and Amplitude Modulator Realized with Fast Ferrite Phase-Shifters. PhD thesis. Bratislava (Slovakia): Slovak University of Technology, 2004.
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Keywords: Mason’s rule, symbolical network analysis, RF power distribution, S-parameters, flow graph

P. Struhovsky, O. Subrt, J. Hospodka, P. Martinek [references] [full-text] [Download Citations]
Developing Model-Based Design Evaluation for Pipelined A/D Converters

This paper deals with a prospective approach of modeling, design evaluation and error determination applied to pipelined A/D converter architecture. In contrast with conventional ADC modeling algorithms targeted to extract the maximum ADC non-linearity error, the innovative approach presented allows to decompose magnitudes of individual error sources from a measured or simulated response of an ADC device. Design Evaluation methodology was successfully applied to Nyquist rate cyclic converters in our works [13]. Now, we extend its principles to pipelined architecture. This qualitative decomposition can significantly contribute to the ADC calibration procedure performed on the production line in term of integral and differential nonlinearity. This is backgrounded by the fact that the knowledge of ADC performance contributors provided by the proposed method helps to adjust the values of on-chip converter components so as to equalize (and possibly minimize) the total non-linearity error. In this paper, the design evaluation procedure is demonstrated on a system design example of pipelined A/D converter. Significant simulation results of each stage of the design evaluation process are given, starting from the INL performance extraction proceeded in a powerful Virtual Testing Environment implemented in Maple™ software and finishing by an error source simulation, modeling of pipelined ADC structure and determination of error source contribution, suitable for a generic process flow.

1. PARENTI, M., VECCHI, G., BONI, A., CHIORBOLI, G., Systematic design and modeling of high-resolution, high-speed pipeline ADCs. Measurement, 2005, vol. 37, no. 4, p. 344 - 351.
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3. YUN, R., QIN, Y., SIGNELL, S. LMS-based calibration of pipelined ADCs including linear and nonlinear errors. In Proc. IEEE Conf. ECCTD. Seville (Spain), 2007, p. 348-351.
4. CHIORBOLI, G., MORANDI, C. Functional simulation of a technique for background calibration of capacitor mismatch errors in pipelined A/D converters. Measurement, 2006, vol. 39, no. 3, p. 204-212.
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6. MALOBERTI, F. Data Converters. Springer, 2007. ISBN 978-0- 387-32485-2, pp. 184-199.
7. SUBRT, O., MARTINEK, P., WEGENER, C. A contribution to advanced extraction methods for static ADC non-linearity. In Proc. IEEE Instrumentation and Measurement Technology Conference Proceedings IMTC. Warsaw (Poland), May 2007, CD.
8. The Institute of Electrical and Electronics Engineers, Inc.: IEEE Standard for Terminology and Test Methods for Analog-to-Digital Converters, IEEE Std. 1241-2000, New York, December 2000.
9. SUBRT, O. Application of SI technique in A/D Conversion and its LEMMA-aided design evaluation. Ph.D. Thesis. CTU Prague, Faculty of Electrical Engineering, December 2005.
10. WEGENER, C., KENNEDY, M. P. Linear model-based error identification and calibration for data converters. In Proc. of Conf. on Design Automation and Test in Europe DATE. Munich (Germany), March 2003, p. 630-635.
11. MICHAELI, L. Modeling of the Analog-Digital Interfaces. TU Kosice, 2001. ISBN 80-968550-1-8(in Slovak).
12. STRUHOVSKY, P., SUBRT, O., HOSPODKA, J., MARTINEK, P. Advanced modeling and design evaluation procedure applied to pipelined A/D converter. In Proc. of the 13th Workshop on ADC Modelling and Testing IWADC. Florence (Italy), September 2008.
13. STRUHOVSKY, P., SUBRT, O., HOSPODKA, J., MARTINEK, P. Developing virtual ADC testing environment in MAPLE. In Proc. of the 10th Workshop on Design and Diagnostics of Electronic Circuits and Systems DDECS. Krakow (Poland), April 2007.

Keywords: Pipelined A/D converter, ADC modeling, design evaluation, integral and differential non-linearity, error determination.

D. K. Upadhyay [references] [full-text] [Download Citations]
Class of Recursive Wideband Digital Differentiators and Integrators

New designs of recursive digital differentiators are obtained by optimizing a general fourth-order recursive digital filter over different Nyquist bands. In addition, another design of recursive digital differentiator is also obtained by optimizing the specified pole-zero locations of existing recursive digital differentiator of second-order system. Further, new designs of recursive digital integrators are obtained by inverting the transfer functions of designed recursive digital differentiators with suitable modifications. Thereafter, the zero-reflection approach is discussed and then applied to improve the phase responses of designed recursive digital differentiators and integrators. The beauty of finally obtained recursive digital differentiators and integrators is that they have nearly linear phase responses over wideband and also provide the choice of suitable recursive digital differentiator and integrator according to the importance of accuracy, bandwidth and the system simplicity.

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Keywords: Digital differentiator, digital integrator, linear phase, recursive, wideband

M. S. Khan, M. Grabner, S. S. Muhammad, M. S. Awan, E. Leitgeb, V. Kvicera, R. Nebuloni [references] [full-text] [Download Citations]
Empirical Relations for Optical Attenuation Prediction from Liquid Water Content of Fog

Simultaneous measurements of the liquid water content (LWC) and optical attenuation have been analyzed to predict optical attenuation caused by fog particles. Attenuation has been measured at two different wavelengths, 830 nm and 1550 nm, across co-located links. Five months measured data have been processed to assess power-law empirical models, which estimate optical attenuation from the LWC. The proposed models are compared with other published models and are demonstrated to perform sufficiently well to predict optical attenuation if the LWC values are available.

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Keywords: Free-Space optical links, Liquid water content, Optical attenuation, Drop size distribution, Aerosols.

J. Dedkova, K. Ostanina [references] [full-text] [Download Citations]
Two-dimensional Tissue Image Reconstruction Based on Magnetic Field Data

This paper introduces new possibilities within two-dimensional reconstruction of internal conductivity distribution. In addition to the electric field inside the given object, the injected current causes a magnetic field which can be measured either outside the object by means of a Hall probe or inside the object through magnetic resonance imaging. The Magnetic Resonance method, together with Electrical impedance tomography (MREIT), is well known as a bio-imaging modality providing cross-sectional conductivity images with a good spatial resolution from the measurements of internal magnetic flux density produced by externally injected currents. A new algorithm for the conductivity reconstruction, which utilizes the internal current information with respect to corresponding boundary conditions and the external magnetic field, was developed. A series of computer simulations has been conducted to assess the performance of the proposed algorithm within the process of estimating electrical conductivity changes in the lungs, heart, and brain tissues captured in two-dimensional piecewise homogeneous chest and head models. The reconstructed conductivity distribution using the proposed method is compared with that using a conventional method based on Electrical Impedance Tomography (EIT). The acquired experience is discussed and the direction of further research is proposed.

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Keywords: Impedance tomography, magnetic resonance, image reconstruction, inverse problem, finite element method

A. J. Sporka, O. Polacek, J. Havlik [references] [full-text] [Download Citations]
Segmentation of Speech and Humming in Vocal Input

Non-verbal vocal interaction (NVVI) is an interaction method in which sounds other than speech produced by a human are used, such as humming. NVVI complements traditional speech recognition systems with continuous control. In order to combine the two approaches (e.g. "volume up, mmm") it is necessary to perform a speech/NVVI segmentation of the input sound signal. This paper presents two novel methods of speech and humming segmentation. The first method is based on classification of MFCC and RMS parameters using a neural network (MFCC method), while the other method computes volume changes in the signal (IAC method). The two methods are compared using a corpus collected from 13 speakers. The results indicate that the MFCC method outperforms IAC in terms of accuracy, precision, and recall.

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Keywords: Non-verbal vocal interaction, Speech, MFCC, Neural network, Segmentation, Multi-layer perceptron