• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1802-1811
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• 2016

A novel battery SOH estimation algorithm based on outlier detection has been presented. The Battery state of health (SOH) is one of the most important parameters that describes the usability state of the power battery system. Firstly, a battery system model with lifetime fading characteristic was established, and the battery characteristic parameters were acquired from the lifetime fading process. Then, the outlier detection method based on angular distribution was used to identify the outliers among the battery behaviors. Lastly, the functional relationship between battery SOH and the outlier distribution was obtained by polynomial fitting method. The experimental results show that the algorithm can identify the outliers accurately, and the absolute error between the SOH estimation value and true value is less than 3%.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.1047-1048
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• 2006

In this paper, we present an iterative phase offset estimation algorithm based on a space-time block code and turbo coded system. External single phase estimator receives soft information from the turbo decoder and estimates phase offset with LMS algorithm. The estimated phase offset value is used for space-time decoder. Simulation results show the phase estimation gain in a flat fading channel.

• ETRI Journal
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• v.41 no.4
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• pp.426-436
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• 2019

In time division duplex (TDD)-based multiuser massive multiple input multiple output (MIMO) systems, the uplink channel is estimated and the results are used in downlink for signal detection. Owing to noisy uplink channel estimation, the downlink channel should also be estimated for accurate signal detection. Therefore, recently, a blind method was developed, which assumes the use of a linear high-power amplifier (HPA) in the base station (BS). In this study, we extend this method to a scenario with a nonlinear HPA in the BS, where the Bussgang decomposition is used for HPA modeling. In the proposed method, the average power of the received signal for each user is a function of channel gain, large-scale fading, and nonlinear distortion variance. Therefore, the channel gain is estimated, which is required for signal detection. The performance of the proposed method is analyzed theoretically. The simulation results show superior performance of the proposed method compared to that of the other methods in the literature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2C
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• pp.234-241
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• 2009

TETRA Enhanced Data Service (TEDS), which is an upgrade version of narrow-band ETSI TETRA Release 1 system, can support high speed packet data services in frequency selected fading channel. The performance of M-QAM transceivers employed in the TEDS is significantly affected by the accuracy of channel estimation. In this paper, we consider the design of a decision-directed channel estimation scheme robust to fast fading by estimating the channel by means of a per-survivor processing (PSP) method. The performance of the proposed channel estimation scheme is verified by computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.43-50
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• 2005

In this paper, we present an improved channel estimation method for orthogonal frequency division multipexing systems using pilot symbol assisted modulation(PSAM). Conventional linear minimum mean square error(LMMSE) channel estimation method uses only pilot symbols for channel estimation. So, as the fading channel varies rapidly, the system performance is degraded. The basic idea of the proposed scheme is that we firstly estimate channel coefficients at the middle point between two pilot symbols and then compute the channel attenuation by using LMMSE method. Superior performance achieved with the proposed method is illustrated by simulation experiments with the Doppler frequency of 36Hz and 185Hz in comparison with conventional LMMSE channel estimator.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.145-147
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• 2017

Tracking filter plays a key role in accurate estimation and prediction of maneuvering vessel's dynamics. The third-order ${\alpha}-{\beta}-{\gamma}$ filter is one of the special cases of the general solution provided by the Kalman filter. Fading memory algorithm performs a better performance in numerous of ${\alpha}-{\beta}-{\gamma}$ filter algorithms. This study aims to optimize the fourth-order fading memory algorithm ${\alpha}-{\beta}-{\gamma}-{\eta}$ filter, which is extended form ${\alpha}-{\beta}-{\gamma}$ filter, to get much more accurate position of high dynamic target on the condition that the own ship is also high dynamic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5C
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• pp.506-513
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• 2003

Most existing space-time coding (STC) schemes have been developed for flat fading channels. To obtain antenna diversity gain, they rely on channel state information (CSI) required at the receiver through channel estimation techniques. This paper proposes a new decision feedback decoding scheme for Alamouti-based space-time block coding (STBC) transmission over time-selective fading channels. In wireless channels, time-selective fading effects arise mainly due to Doppler shift and carrier frequency offset, Modelling the time-selective fading channels as the first-order Gauss-Markov processes, we use recursive algorithms such as Kalman filtering, LMS and RLS algorithms for channel tracking. The proposed scheme consists of the symbol decoding stage and channel tracking algorithms. Computer simulations confirm that the proposed scheme shows the better performance and robustness to time-selectivity.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.5
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• pp.492-502
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• 2021

In electronic warfare, source enumeration and direction-of-arrival estimation are important. The source enumeration method based on eigenvalues of covariance matrix from received is one of the most used methods. However, there are some drawbacks such as accuracy less than 100 % at high SNR, poor performance at low SNR and reduction of maximum number of estimating sources. We suggested new method based on eigenvalues gaps, which is named AREG(Accumulated Ratio of Eigenvalues Gaps). Meanwhile, FGML(Fast Gridless Maximum Likelihood) which reconstructs the covariance matrix was suggested by Wu et al., and it improves performance of the existing source enumeration methods without modification of algorithms. In this paper, first, we combine AREG with FGML to improve the performance. Second, we compare the performance of source enumeration and direction-of-arrival estimation methods in Rayleigh fading. Third, we suggest new method named REG(Ratio of Eigenvalues Gaps) to reduce performance degradation in Rayleigh Fading environment of AREG.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.4
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• pp.277-284
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• 2020

The remaining range between missile and target can be used to calculate the guidance command as well as to determine the explosion time of the warhead. Since the range, however, is not directly measured by on-board sensors of the missile, it is usually estimated by filter-based techniques using angle-only measurements. Conventional filter-based techniques are complex and require huge computation. In this paper, we propose a range estimation algorithm based on the geometrical triangulation principle for two points of missiles and a target. The proposed algorithm has a simple structure but the accuracy is largely dependent on the measurement errors. To improve the accuracy of estimation, Digital Fading Memory Filter (DFMF) is applied. The performance of the proposed algorithm is analyzed through numerical simulations.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.77-80
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• 2002

In this paper, we analyze a physical layer of W-CDMA .system and design a transmitter and receiver by using ADS (Advanced Design System). Also, we simulated a link level performance with different channel estimation algorithm in Jakes fading channel environment. For the channel estimator, we used the WMSA(Weighted Multi-Slot Averaging) algorithm, EGE(Equal Gain Estimation) algorithm and SSE(Symbol-to-Symbol Estimation) algorithm. This study will be useful in the analysis and design of W-CDMA system.