• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1995.06a
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• pp.63-67
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• 1995

This paper proposes a new frequency offset correction technique for OFDM receivers on a frequency-selective fading channel. The frequency offset in the OFDM signals is known to introduce an interchannel interference among the multiple subcarriers, which degrades the receiver performance severely. In order to reduce the frequency offset, this paper describes an algorithm with two stages: acquisition and tracking. At both stages the algorithm oversamples the received OFDM signals. At the acquisition stage the frequency offset is reduced to half or less than the intercarrier spacing by matching the sign patterns of even and odd samples. Next, at tracking stage the frequency offset is compensated by a frequency detector which is controlled by the correlation of the even and odd sample sets. From the results, it is found that the proposed algorithm can correct the frequency offset even if the initial offset exceeds one half of th eintercairrers spacing.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.9
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• pp.9-13
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• 2010

In this thesis, we develop and analyze the beamforming algorithm which has two constraints to combat the signal cancellations. Through the simulation results, it is shown that the proposed scheme is more efficient compared with the spatial averaging method for preventing signal cancellation and eliminating interfering signal.

• ETRI Journal
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• v.38 no.1
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• pp.81-89
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• 2016

In this paper, a beam ID preamble (BIDP) technique, where a beam ID is transmitted in the physical layer, is proposed for efficient beam training in millimeter-wave cellular communication systems. To facilitate beam ID detection in a multicell environment with multiple beams, a BIDP is designed such that a beam ID is mapped onto a Zadoff-Chu sequence in association with its cell ID. By analyzing the correlation property of the BIDP, it is shown that multiple beams can be transmitted simultaneously with the proposed technique with minimal interbeam interference in a multicell environment, where beams have different time delays due to propagation delay or multipath channel delay. Through simulation with a spatial channel model, it is shown that the best beam pairs can be found with a significantly reduced processing time of beam training in the proposed technique.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.137-146
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• 2002

In order to remove the intersymbol interference(ISI) phenomenon in data transmission channel, the structure and convergence analysis of the improved multiplication free adaptive digital filter(IMADF) is presented. Under conditions of zero-mean, wide-sense stationary and white Gaussian noise, it is shown that this paper analyze the convergence characteristics of the IMADF with a fractionally-spaced equalizer(FSE). In the experimental results, the convergence characteristics of the IMADF algorithm is almost same as the sign algorithm, but is better than the MADF algorithm. Here, this algorithm has useful characteristics when the correlation of the input signal is highly.

• The Journal of the Acoustical Society of Korea
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• v.20 no.1
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• pp.30-35
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• 2001

The most important characteristic of Emile Bell's sound is a beating. It is modulation phenomenon which appears as a result of interference multiplication in time domain. This modulation phenomenon can be modeled as DSB-SC which suppress carrier and signals distributed both sides. The beatiog wave is observed in Laman distribution signal for polyvinyl speech signal, water vein wave, tide wave. The beating wave is caused by asymmetry Property of the bell.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.286-289
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• 2006

Measurement results are presented for the effects of people moving near and across short-range indoor propagation links at 2.45 GHz (ISM band). Excess loss due to scattering and blockage by human bodies in the vicinity of one terminal were measured for different radio links in an office environment. Statistics on fades due to human body motion are given. Polarization coupling (depolarization) for various radio links was measured, and correlation of polarization components is discussed as a basis for using polarization diversity reception in short-range indoor systems.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.288-298
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• 2016

Proactive relay selection in cognitive radio networks has recently received considerable attention. However, its outage probability analysis is limited to partially-identical fading distributions, uncorrelation among received signal-to-noise ratios (SNRs), and no direct channel. This paper completes this literature deficiency by generalizing the existing analysis for non-identical fading distributions, correlation among received SNRs, and with direct channel. Numerous results demonstrate that relay selection with a direct channel achieves a higher diversity order and superior performance than that without a direct channel at virtually no cost of power and bandwidth. Further, proactive relay selection suffers an error floor at either a large maximum transmit power or large maximum interference power; however, the error floor level can be significantly remedied with an increase in the number of relays.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1239-1242
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• 2002

In this paper, the implementation of MAI(multiple access interference)-cancelled SSMA(spread spectrum multiple access) system using orthogonal carriers was presented. Employing the pseudo periodic spreading codes and orthogonal carriers frequency offset, proposed system have the features no MAI during a certain local time-duration. Spreading signals designed by pseudo periodic method and repetition, have zero correlation duration(ZCD) by orthogonal frequency shift method. The SSMA modem has been designed and implemented using surface-acoustic-wave(SAW) device as the matched filter of receiver. The effects of frequency offset on stability have been evaluated using computer simulation.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1647-1650
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• 2002

In this paper, a class of multi-level spreading codes, i.e., ternary ZCD(zero-correlation duration) spreading codes are introduced. Novel ternary ZCD code sets are generated by carrying out a chip-shift operation of the ternary preferred pairs (TPP) with a ZCD of(0.75N+1)chips. Ternary ZCD codes have superior family size than the binary ZCD codes and they are effective for approximately synchronized (AS) CDMA

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.51-53
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• 2004

In this paper, we are going to propose the new algorithms to detect, classify, discriminate the transient and the reflected signal from noise and thus discriminate the fault section and locale the fault accurately on underground power cable system. Actually, at this system, it's very difficult to discriminate the transient because of the reflected signal including many noises. Therefore, how to solve the noise interference is a big problem. In this paper, authors present a solution based on multiple scales correlation of the transient using stationary wavelet transform. It's simple, quick and straightforward. For applying all algorithms, we just use the signal captured in single end.