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Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications, 2007 International Symposium on

Date 16-17 Aug. 2007

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Displaying Results 1 - 25 of 378
  • A Dynamic Resource Allocation Scheme Based on Soft Frequency Reuse for OFDMA Systems

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    In this paper, we present a dynamic resource allocation algorithm, termed Dynamic Major group Allocation (DMA), based on Soft Frequency Reuse (SFR) which is an efficient method to mitigate inter-cell interference (ICI) in Orthogonal Frequency Division Multiple Access (OFDMA) systems. DMA defines the method that Radio Network Controller (RNC) orthogonally assigns resource to Cell Edge Users (CEU) in neighboring cells (or sectors) firstly, and then each cell allocal.es its residual resource to Cell Center Users (CCU) according to PF scheduling. Simulation results demonstrate that the proposed DMA algorithm carries superior throughput performance of CEU over the traditional two-level resource allocation scheme (TLA) which simply combines SFR with PF. View full abstract»

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  • Study on the Scattering Property of the Impedance Terminated Dipole Array with Finite Reflector by FDTD Method

    Page(s): 1003 - 1007
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1160 KB) |  | HTML iconHTML  

    The scattering characteristics of the planar array composed of impedance terminated dipoles and a finite reflector are studied by finite difference time domain (FDTD) method. The current distribution on the dipoles and the radar cross section (RCS) of the array are calculated and analyzed. It is seen that the array with resistor terminated dipole tends to give lower RCS. View full abstract»

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  • The Decrease of the Radar Cross Section of Hypersonic Model

    Page(s): 1008 - 1010
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1741 KB) |  | HTML iconHTML  

    To research the effect of plasma, the radar cross section (RCS) of a hypersonic model is measured in our light gas gun. The spectrum of the received signal and one-dimensional radar image of the model are given. According to this experiment, three-dimensional (3-D) finite-difference time-domain (FDTD) simulations are performed for calculating microwave scattering from a plasma-cloaked conducting model. View full abstract»

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  • Transient Simulation of Lossy and Nonuniform Multi-Conductor Transmission Lines by Time Domain Finite Element

    Page(s): 1011 - 1016
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2063 KB) |  | HTML iconHTML  

    A new method - time domain finite element (TDFF) - for the transient simulation of lossy and nonuniform multi-conductor transmission lines (MTL) is presented. The method is based on the integral transformation of the telegrapher's equations, combined with recursive convolution method to get the discrete time and space model for frequency-dependent transmission lines. No special technique is required to ensure the stability of the method as in the case of frequency domain moment-matching methods. At last, several numerical experiments show that TDFE-based modeling leads to high accuracy as well as high efficiency. View full abstract»

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  • Tuned S-shaped Resonators

    Page(s): 1017 - 1019
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (547 KB) |  | HTML iconHTML  

    Tunable metamaterials are important for designing of microwave devices. Tuning methods for S- shaped resonators (metamaterial) have been presented in this paper. Simulation results, obtained from FEM based simulator, have been included and are compared with untuned counterpart. Changes in transmission pass bands are observed as a result of tuning. View full abstract»

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  • Analysis on UWB Ambipolar Multi-pulse Position Modulation

    Page(s): 102 - 105
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3448 KB) |  | HTML iconHTML  

    A new UWB (ultra-wideband) modulation scheme called L-ary UWB-TH-AMPPM (Time hopping Ambipolar multi-pulse position modulation) was proposed to get a better UWB communication performance, and the ECWC (extending constant weight code) was introduced to construct the AMPPM signal. The comparison between AMPPM, SPPM (single pulse position modulation) and BPPM (biorthogonal pulse position modulation) was given in four aspects which are data rate, power efficiency, bandwidth efficiency and probability of symbol error respectively. Theory analysis and numerical results show that when the ECWC is chosen rightly, MPPM can achieve better UWB communication performance than both of the SPPM and BPPM under the same condition. View full abstract»

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  • Using Support Vector Machine Regression for Measuring Electromagnetic Parameters of Magnetic Materials

    Page(s): 1020 - 1022
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1749 KB) |  | HTML iconHTML  

    A new method is proposed for electromagnetic parameters (permittivity and permeability) measurement. The microstrip transmission-line is used as measure structure, and supported vector machine (SVM) is introduced to extract actual permittivity and permeability of magnetic materials. Experiment results show that both permittivity and permeability of magnetic materials can be extracted accurately. View full abstract»

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  • A Fast and Accurate Frequency Acquisition Method

    Page(s): 1023 - 1026
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (970 KB) |  | HTML iconHTML  

    To aim at short-time pilot pulse carrier- frequency synchronization, a ,fast and accurate acquisition method is proposed. The method employs phase deduction frequency estimator (PDFE) and digital down conversion loop to perform initial and accurate frequency acquisition. The PDFE estimation accuracy exceeds Prony' s method. Its estimation error normalized variance approaches the Cramer-Rao bound of real sinusoid signal at high signal-to-noise ratio. A Simulink simulation model of accurate frequency acquisition loop was established to verify the acquisition accuracy. An example is given, the maximum acquisition error is not more than 2.2 Hz at input SNR above 13 dB. View full abstract»

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  • A Fast Demodulating Method for Frequency Shift Signal Based on Fractal Box Dimensions Theory

    Page(s): 1027 - 1030
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (7526 KB) |  | HTML iconHTML  

    According to the practical requirement of railway site, a method for demodulating frequency shift signal based on fractal box dimensions theory is proposed in this paper. In view of that the frequency shift signal is FSK signal whose phase is continuous phase and fractal dimension approaches 1, according to the corresponding relationship between the computation process of fractal dimension of frequency shift signal and the derivatives of the signal under different fractal scales, making use of the difference between the derivatives of the upper and lower frequency of the signal to obtain the modulating frequency. Experiment results show that this method is characteristic of accurate computation, easy implementation, good realtimeness, etc., providing a new scheme for analyzing and demodulating railway frequency signal. View full abstract»

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  • A High Resolution Spatial Smoothing Algorithm

    Page(s): 1031 - 1034
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB) |  | HTML iconHTML  

    A high resolution spatial smoothing algorithm which takes cross correlation to the autocorrelation matrixes of subarray output is proposed to increase the angular resolution of conventional spatial smoothing techniques. The formula for the algorithm is derived, and the performance of the algorithm is also analyzed. Simulation results demonstrate that the improved algorithm possesses a better resolving ability and a lower SNR threshold than the conventional spatial smoothing technique and the subarray cross correlation spatial smoothing technique for DOA estimation of coherent signals. View full abstract»

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  • A New 2-D DOA Estimation Algorithm for Noncircular Signals

    Page(s): 1035 - 1038
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB) |  | HTML iconHTML  

    A novel 2D direction finding algorithm for noncircular signals using two parallel linear arrays called extended rank reduction (ERARE) algorithm is presented in this paper. The proposed method needs only 1D search for joint azimuth and elevation estimation. The 2D angles estimated by ERARE are paired automatically. The estimation precision of 2D angles by ERARE algorithm is better than the DOA matrix (DOAM) algorithm which is also a 2D direction finding algorithm with dual parallel subarrays. View full abstract»

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  • A New Method for m-sequence and Gold-sequence Generator Polynomial Estimation

    Page(s): 1039 - 1044
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (439 KB) |  | HTML iconHTML  

    A finite field discrete Fourier transform is used for studying the properties of linear feedback shift register (LFSR) sequence with period (q1-1)/n, and the elation of sequence' s linear complexity and the nonzero-points in frequency-domain is given in this paper. Then a new algorithm is introduced to estimate the generator polynomial and initial state of m-sequence and gold-sequence. Based on the principle of FFT, a fast algorithm is also explored. View full abstract»

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  • A novel call admission control for multimedia network

    Page(s): 1045 - 1047
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1797 KB) |  | HTML iconHTML  

    Modern network is expected to support multimedia traffic, therefore how to guarantee the QoS of multimedia network is the emerging technology. CAC (call admission control) plays an important role in the QoS guarantee of multimedia network. Noticing that many CAC schemes aim to satisfying QoS requirement and upgrading network utilization, but they ignore the fairness principle in network. Directly and simple using these CAC schemes, it will appear the phenomenon of unbalance that the narrow band calls block the broad band calls. So, this paper proposes a fair call admission control scheme by introducing call hold control. Numerical results show that the new scheme not only realizes the balancing accessing machinery to all calls, but also decrease CBP (call block probability) and improves network utilization. View full abstract»

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  • A Novel Frequency-band Coded Orthogonal UWB Chirp Pulse Design for Cognitive NBI Suppression

    Page(s): 1048 - 1051
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (16580 KB) |  | HTML iconHTML  

    In this paper, a novel frequency-band coded orthogonal UWB pulse design method based on Chirp signal is presented. The new approach uses the chirp signals located at different frequency-bands to synthesize the orthogonal pulses by coding with Pseudo Noise sequence in frequency domain. The auto-correlation and cross-correlation property of the proposed chirp pulses are better than those of other conventional pulses. Furthermore, the new method also improves the efficiency of the instantaneous spectrum and energy of the transmitting UWB signal. In addition, by the aid of cognitive radio technology to adjust the chirp envelope and the frequency-sweeping range of each chirp subpulse , it can guarantee the transmitting UWB signal to be matched with the different UWB spectrum regulations and coexistence, interference avoidance with other traditional narrow band systems. And simulation result showed that the proposed pulse could reduce the effect of NBI on UWB system with litter complexity. View full abstract»

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  • A Simple Design Method for Nonuniform Cosine Modulated Filter Banks

    Page(s): 1052 - 1055
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (685 KB) |  | HTML iconHTML  

    Traditional designs for nonuniform filter banks usually involve complicated nonlinear optimization with a large number of parameters. A simple design approach that involves the optimization of only single parameter is presented for the design of nonuniform cosine modulated filter bank, which is derived by combination of filters in uniform cosine modulated filter banks. The prototype filter is formulated as an interpolated FIR filter and is indirectly designed by varying the passband edge of a low-order model filter. A design example is presented to show that very good design can be obtained in spite of the limit of the formulation. View full abstract»

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  • A Technique for Eureka-147 Digital Audio Broadcasting Fine Symbol Timing Offset Estimation

    Page(s): 1056 - 1059
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4343 KB) |  | HTML iconHTML  

    This paper introduces a new algorithm in Ereka-147 digital audio broadcasting (DAB) symbol timing offset estimation. The proposed algorithm performs robust operation and low complication in symbol timing offset estimation. The performance of this algorithm is carried out under AWGN and multipath fading channel. View full abstract»

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  • BER Performance of Position Code Parallel Combinatory Spread Spectrum System

    Page(s): 106 - 110
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2533 KB) |  | HTML iconHTML  

    A novel position code parallel combinatory spread spectrum (PC/PC/SS) communication system is proposed in this paper. PC/PC/SS system can be designed to have higher data transmission capability, even several times compared to ordinary PC/SS system on Gaussian channel. In the proposed system, modulation of position code is applied to each simultaneously transmitting PN sequences. The symbol error rate and average bit error rate performances are analyzed to evaluate the performance of the proposed systems. Furthermore, PC/PC/SS system has excellent secret property than PC/SS and M-ary/SS systems. View full abstract»

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  • A Widely-Linear LMS Algorithm for Adaptive Beamformer

    Page(s): 1060 - 1063
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (810 KB) |  | HTML iconHTML  

    A novel adaptive Array structure using widely-linear weight is proposed in this paper. MMSE law is used to evaluate the performance of the adaptive array. According to the widely-linear structure, the widely-linear LMS algorithm (WL-LMS) is used here, which uses widely-linear model of the received signal rather than linear model estimating the desired signal. This structure provides a unified framework for beamforming in circular and non-circular sources, and can get much less MMSE between the beamforming output and the desired signal. This algorithm has been tested for beamforming using BPSK and narrow-band FM signal. View full abstract»

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  • An Adaptive Demodulation Method for QAM Signals

    Page(s): 1064 - 1067
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1071 KB) |  | HTML iconHTML  

    The paper presents a novel method for demodulating the QAM signals basing on adaptive filtering. The commonly used least mean square (LMS) error adaptive filtering algorithm is employed for studying the demodulating procedure and the performance of the novel adaptive QAM demodulation. The novel adaptive QAM demodulation does not need the adaptive filter completing convergence. Therefore, the sampling rate and processing speed are decelerated. The performance of the method in theory is compared with computer simulating results. It shows that the error rates in simulation agree well with that in theory. Also, it is indicated that the demodulation method has many advantages over conventional ones, such as the powerful anti-noise ability, the small transfer delay, and the convenient implementation with DSP technology. View full abstract»

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  • An Efficient Timing and Frequency Synchronization Scheme for OFDM based TETRA Systems

    Page(s): 1068 - 1071
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2296 KB) |  | HTML iconHTML  

    An efficient timing and frequency synchronization scheme for orthogonal frequency division multiplexing (OFDM) based TETRA system is present. TETRA specifies its own preamble for timing synchronization and frequency offset estimation. Two correlators are utilized in this paper to make timing more accurately. A frequency offset estimator with adjustable parameter is proposed in time domain. According to the operation condition, set the proper range of the frequency offset estimator so that the best accuracy can be achieved. Simulation result shows that the proposed schemes exhibit good performances in the channel model defined in TETRA. View full abstract»

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  • An improved Second Order Nonstationary Source Separation Algorithm

    Page(s): 1072 - 1075
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1065 KB) |  | HTML iconHTML  

    In this paper, a second order separation algorithm of nonstationary using temporal structure and linear prediction model was proposed. The blind source separation algorithms based on second order statistics can work well when the sources have temporal structure. Our method had a low computation and a loose request for sources independency. It is not sensitive to additive white noise. Simulations showed the better performance of the proposed algorithm. View full abstract»

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  • Blind Adaptive Channel Equalization Based on Affine Projection Algorithm

    Page(s): 1076 - 1079
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1355 KB) |  | HTML iconHTML  

    In this Letter, we address a novel constant modulus algorithm (CMA) based on affine projection algorithm (APA) for blind equalization transmission channel of QPSK systems to deal with inter symbol interference (ISI). Our algorithm is more rapidly convergence, tracking properties and slightly improved steady-state equalization performance than the same category algorithms such as LMS-CMA and NLMS-CMA, and computationally more efficient with similar convergence compared with least squares algorithm (LS-CMA). Simulation results are presented to compare our APA-CMA algorithm with the blind NLMS-CMA and LS-CMA schemes. View full abstract»

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  • DOA Estimation for MC-CDMA System with Antenna Array

    Page(s): 1080 - 1083
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (857 KB) |  | HTML iconHTML  

    In this paper, a direction of arrival (DOA) estimation algorithm is proposed for uplink MC-CDMA system with antenna array. By utilizing the orthogonality of spreading codes and frequency diversity of MC-CDMA the users' signals are separated and enhanced, and the multiple access interference (MAI) is suppressed. After that the conventional subspace based DOA estimation is applied to estimate the DOAs of users' signals. Simulation results show the efficiency of the proposed algorithm. View full abstract»

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  • Doubly Selective Fading Channel Tracking Based on Particle Filter in MIMO-OFDM Systems

    Page(s): 1084 - 1087
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB) |  | HTML iconHTML  

    Time selectivity and frequency selectivity are the main characteristics of wireless communication channels. To track doubly selective fading channels in MIMO-OFDM systems, a novel channel estimation algorithm based on particle filter is proposed. We model the fading channel as an autoregressive (AR) process and encode the transmit signal using space-time block code (STBC) scheme. In the receiver, channel estimation and symbol detection are alternated, and maximum likelihood (ML) scheme is used for symbol detection. Simulation results show that the proposed method has more effective tracking performance than traditional methods based on training symbols and offers much improved spectral efficiency. View full abstract»

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  • Enhanced HARQ Schemes Based on LDPC Coded Irregular Modulation

    Page(s): 1088 - 1092
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (854 KB) |  | HTML iconHTML  

    The bit-interleaved coded irregular modulation (BICIM) was initially proposed for convolutional code and turbo code cases, which applies different signal constellations and mappings within one codeword. We firstly extend this idea to irregular LDPC codes and present an optimized mapping rule for LDPC coded irregular modulation according to the code degree distribution. Furthermore, we apply this optimized LDPC coded irregular modulation to chase combing (CC) HARQ and propose two enhanced HARQ schemes. The improved schemes can efficiently reduce the reliability variances of bits after soft combining. Simulation results show that they can not only achieve better BER performance but also provide a throughput performance enhancement. View full abstract»

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