• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8C
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• pp.795-800
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• 2006

In this paper, the minimum mean square error(MSE) convergence of the RBF equalizer is evaluated and compared with the linear equalizer based on the theoretical minimum MSE. The basic idea of comparing these two equalizers comes from the fact that the relationship between the hidden and output layers in the RBF equalizer is also linear. As extensive studies of this research, various channel models are selected, which include linearly separable channel, slightly distorted channel, and severely distorted channel models. In this work, the theoretical minimum MSE for both RBF and linear equalizers were computed, compared and the sensitivity of minimum MSE due to RBF center spreads was analyzed. It was found that RBF based equalizer always produced lower minimum MSE than linear equalizer, and that the minimum MSE value of RBF equalizer was obtained with the center spread which is relatively higher(approximately 2 to 10 times more) than variance of AWGN. This work provides an analytical framework for the practical training of RBF equalizer system.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.1037-1040
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• 1999

This paper investigates a RBF(Radial Basis Function) equalizer for channel equalization. RBF network has an identical structure to the optimal Bayesian symbol-decision equalizer solution. Therefore RBF can be employed to implement the Bayesian equalizer. Proposed algorithm of this paper makes channel states estimation to be unncessary, also makes center number which is needed indivisual channel to be minimum. Bayesian Equalizer has the theorical optimum performance. Proposed Equalizer performance is compared with this Baysian equalizer performance.

• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.76-80
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• 1992

We consider the tapped-delay line (TDL) equalizer with the few calculation quantity and the simplity, the decision feedback equalizer (DFE) with the good property for interference, and lattice equalizer(LE) with high insensitivity to roundoff noise in mobile communication fading channel. The used adaptive algorithm is the LMS algorithm and RLS algorithm. In this paper, we have evaluated the performance of the TDL equalizer, the decision feedback equalizer, and lattice-structured equalizer, for the digital signal corrupted by the impulsive noise and the white gaussian noise under the fading channel environment. From the results of error performance analysis, it is confirmed that lattice-structured equalizer has better performance than DFE equalizer and TDL equalizer.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.69-72
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• 1999

In this paper, an efficient time domain equalization algorithm for discrete wavelet multitone(DWMT) data transmission is developed. In this algorithm, the time domain equalizer(TEQ) consists of two stages, i.e., the channel impulse response shortening equalizer(TEQ-S) in the first stage and the channel frequency flattening equalizer(TEQ-F) in the second stage. TEQ-S reduces the length of transmission channel impulse response to decrease intersymbol interference(ISI) followed by TEQ-F that enhances the channel frequency response characteristics to the level of an ideal channel, hence diminishes the bit error rate. TEQ-S is implemented using the least-squares(LS) method, while TEQ-F is designed by using the least mean-square(LMS) algorithm. Since DWMT system also requires of the frequency domain equalizer in order to further reduce ICI and ISI the hardware complexity is an another concern. However, by adopting an well designed and trained TEQ, the hardware complexity of the whole DWMT system can be greatly reduced.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.2 no.3
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• pp.174-178
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• 2002

This paper discusses a blind equalization technique for FIR channel system, that might be minimum phase or not, in digital communication. The proposed techniques consist of two parts. One is to estimate the original channel coefficients based on fourth-order cumulants of the channel output, the other is to employ RBF neural network to model an inverse system fur the original channel. Here, the estimated channel is used as a reference system to train the RBF. The proposed RBF equalizer provides fast and easy teaming, due to the structural efficiency and excellent recognition-capability of R3F neural network. Throughout the simulation studies, it was found that the proposed blind RBF equalizer performed favorably better than the blind MLP equalizer, while requiring the relatively smaller computation steps in tranining.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.7
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• pp.47-53
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• 2004

In this paper we introduce a complex escalator (ESC) structure-Equalizer and investigate its performance in complex channels in QPSK undulation systems. The proposed complex equalizer has the complete orthogonalization property and is independent of eigenvalue spread ratio (ESR) of channel. The proposed complex ESC equalizer shows as 7 times faster convergence speed as that of the conventional complex TDL equalizer algorithms in a complex channel model for QPSK systems.

• ETRI Journal
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• v.25 no.5
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• pp.379-386
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• 2003

This paper presents the design of a narrow-band channel filter and its group-delay equalizer for a Ka-band satellite transponder. We used an 8th order channel filter for high selectivity with an elliptic-integral function response and an inline configuration. We designed a 2-pole, reflection-type, group-delay equalizer to compensate for the steep variation of the group-delay at the output of the channel filter, keeping the thermal stability at ${\pm}7$ ns of group-delay variation at the band edges over 15-55$^{\circ}C$. We devised a new tuning technique using short-ended dummy cavities and used it for tuning both the filter and equalizer; this removes the necessity of additional tuning after the cavities are assembled. Through measurement, we demonstrate that the group-delay-equalized filter meets the equipment requirements and is appropriate for satellite input multiplexers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.372-378
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• 2002

In this paper, a narrow-band waveguide channel fitter has been designed and realized for Ku band satellite transponder. Group-delay and amplitude variations of the channel filter have been minimized using a 2-pole reflection type equalizer. The channel filter has been designed to have the 8-pole elliptic response for high frequency selectivity. Dual-mode technique has been adopted for reducing mass and volume of the channel filter and equalizer. The channel filter and equalizer have shown good performance for satellite transponder.

• Journal of the Korea Society of Computer and Information
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• v.14 no.7
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• pp.57-64
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• 2009

Based on this article, I have analyzed the OFDM system which applies three types of equalizer forms in the two-path channel of the microwave baseband. The Two-path channel of microwave baseband had been simulated through the Rummler channel. In the Two-path channel, the OFDM system which has three forms of equalizer has been analyzed and the result is, equalizer 1-tab has great improvement in efficiency compared with Pre-FFT 11-tab which has noise power ratio less than 18dB. On the contrary, if the symbol energy to the noise ratio is more than 18dB, the equalizer which applies Pre-FFT 11-tab has greater efficiency compared to the equalizer which applies 1-tab frequency. Last but not least, the OFDM system which applies Dual equalizer has better efficiency compared to the system which has 1-tab frequency and equalizer which applies Pre-FFT 11-tab.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.18-24
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• 2017

The process of transmitting messages through a medium with a limited bandwidth or channel dispersion inevitably involves signal distortion and noise influxes, resulting in the degradation of transmission quality due to the inter-symbol interference and additional noise, which increases the error rate of the received symbols. The main role of the equalizer is to remove the channel distortion and noise from the received signal to recover the transmitted messages. A number of studies on the equalizer composed of a combination of linear filter and error control coding have shown that they played a key role in enhancing the transmission efficiency, which is essential for digital communication. This paper proposes a new algorithm to correct the residual symbol errors in the message signal. In general, equalizer performance improvement algorithms were developed to improve the initial convergence speed or steady-state error. In this paper, however, the equalizer input signal was reconstructed using the equalizer decision symbols and the channel estimates to directly correct the decision errors by analyzing the statistical characteristics of the difference signal between the actual received signal and the reconstructed signal.