• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.384-388
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• 2004

In this paper, we analyses transmission performance of synchronization pattern for over the air rekeying in aerial tactical link of LINK16, when it is given by symbol error rate, in respect of pattern detection probability and false alarm probability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.304-306
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• 2016

In this letter, we investigate the performance of coherent free-space optical(FSO) systems under pulsed noise jamming conditions. In particular, we derive the average bit error probability of the coherent FSO systems with the pulsed noise jamming in a closed-form. Also, we derive the optimal fraction of symbol time of the jammer. We confirm the derived average error probability expressions by the exactly matching Monte-Carlo simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1283-1288
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• 2007

An equalization technique for OFDM systems in tine variant fading environment is described. Time variant channels lead to interchannel interference which increases the bit mr rate. A frequency domain equalizer using pilot symbols is proposed. The equalizer decreases the interchannel interference affecting the error performance. The effectiveness of the proposed technique is analyzed via computer simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.273-279
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• 2007

I evaluate the BER performance of OFDM systems in frequency selective Doppler time variant fading channels, considering the pilot patterns for channel estimation. The performance of the systems is degraded due to channel estimation error. For the reduction of performance degradation in acceptable level, the optimum distance of pilot symbols in pilot pattern is 5 subcarriers in frequency domain and 6 OFDM block in time domain.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.4B
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• pp.427-436
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• 2001

RS product codes are widely used in digital storage systems. There are lots of decoding strategies for product code for short-length RS codes. Unfortunately many of them cannot be applied to long-length RS product codes because of the complexity of decoder. This paper proposes new decoding strategies which can be used in long length RS product codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12C
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• pp.965-970
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• 2010

In the NAND flash memory storing two bits per cell, data is discriminated among four levels of electrical charges. We refer to these four levels as E, P1, P2, and P3 from the low voltage. In the statistics, many errors occur when E and P3 are stored at the next cells. Therefore, we propose a coding scheme for avoiding E-P3 or P3-E data patterns. We investigate two modulation codes for 9/10 code (9 bit input and 5 symbol codeword) and 11/12 code (11 bit input and 6 symbol codeword).

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.9-14
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• 2013

In this paper, we propose a low complexity bilateral search SIC for OFDM in fast time-varying channels. Due to the possibility of error propagation in SIC, symbol detection ordering within the block of symbols has a significant effect on the overall performance. In this paper, the first symbol to be detected is determined based on CSEP values, and then the next symbol to be detected is selected according to the updated CSEP while bilaterally searching from the boundary of the detected symbol group. Through computer simulations, we show that the proposed method has performance improvements with almost the same computation complexity over the conventional methods in the high SNR region. It has a performance approaching the MFB, known as the performance upper bound, within 2dB at the BER of $10^{-5}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.2
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• pp.246-252
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• 2012

STBC is a technique where a multiple antenna signals are transmitted. With this technique, antenna diversity can be achieved. The performance of STBC OFDM system using pilot symbol for the channel estimation is analyzed. IEEE 802.16e standards suggest that the BER performance of STBC system can be improved using channel state information. Pilot symbol is used for the channel estimation in OFDM systems. However, imperfect channel estimates in this systems degrade the performance. The performance of this STBC OFDM systems using channel state information, gauged by the average bit error rate, is analyzed considering the channel estimation error.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4C
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• pp.453-459
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• 2009

Due to its capability to resist jamming signals, chirp spread spectrum (CSS) technique has attracted much attention in the field of wireless communications. However, there has been little rigorous analysis for the performance of CSS systems in the presence of jamming signals. In this paper, thus, we present analytic results on the performance of a CSS system: specifically, symbol error rate (SER) expressions are derived for a CSS M-ary phase shift keying (MPSK) system in the presence of broadband and tone jamming signals, respectively. The numerical results show that the empirical SER closely agree with the analytic result.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.294-301
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• 2013

OFDM technique uses multiple sub-carriers for the data transmission. Therefore, bit error rate increases because of inter-carrier interference caused by nonlinear high power amplifier and carrier frequency offset. Wireless OFDM transmission over multi path fading channels is characterized by small transmission gain in multiple sub-carrier frequency interval. Therefore bit error rate increases because of burst errors. Inter-leaver and convolution error control coding are effective for the reduction of this burst error. Pilot symbol is used for the channel estimation in OFDM systems. However, imperfect channel estimates in this systems degrade the performance. The performance of this convolution coding OFDM systems using inter-leaver, gauged by the bit error rate, is analyzed considering the nonlinear high power amplifier, carrier frequency offset and channel estimation error.