• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1295-1303
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• 2010

In this paper, an effective method has been proposed for selection of white Gaussian noise(WGN) band for radio background noise measurement system under broad band noise environment. MMN which comes from industrial devices and equipment mostly happens in the shape of broad band noise mostly like impulsive noise and this is the main reason for increasing level in the present radio noise measurements. The existing method based on singular value decomposition has weak point that it cannot give good performance for the broad band signal because it uses signal's white property. The proposed method overcomes such a weakness of singular value decomposition based method by using signal's Gaussian property based method in parallel. Moreover, this proposed method hires a modelling based method which uses parameter estimation algorithm like maximum likelihood estimation(MLE) and gives more accurate result than the method using amplitude probability distribution(APD) graph. Experiment results under the natural environment has done to verify feasibility of the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3A
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• pp.272-280
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• 2009

Measurement of the background radio noise is very important process being used in survey of radio noise environment, calculating the threshold level for the frequency occupancy measurement and so forth. First step of background radio noise measurement is to select the sample sub-band which is mostly dominated by the background white Gaussian noise (WGN) within the target band. The second step is to carry out the main measurement of radio noise on this selected sample sub-band for the representative value of the noise power. In this paper, a method for selection of sample sub-band for the effective background radio noise measurement using SVD is proposed under the assumption that background radio noise is WGN. The performance of the proposed method is compared with that of the APD method which is widely used for the same purpose. Simulation results are shown to demonstrate the high performance of the proposed method in comparison with the existing APD method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1202-1207
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• 2006

In this paper we analyze the performance improvement of the M-ary FSK systems for low power and low data rate applications. This contribution presents a unified analysis of its MRC diversity, uncoded and performance in A WGN, m=2, m=3, Rayleigh and one sided Gaussian fading channels using optimum noncoherent demodulation with Reed-Solomon(RS) codes. The results of this paper should be useful as benchmarks of obtainable performance and as a reference for validating the results of simulation studies when slow fading models are applicable.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.1
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• pp.23-31
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• 1993

This paper aims to analyse the performance of coded frequency hopping /spread spectrum mul~ tiple access system by employing the channel with mixture of A WGN, partial band jamming, fading and user interference. In this approach, a special consideration is focused on the effect of the partial hit. That is, the interfering signals that are present for a small fraction of the hop dur~ ation did not cause hit. The results of analysis showed that the frequency hit changed linearly according to the varying degree of frequency overlap. And this effect did not change the type of error probability distri~ bution.

• The Journal of the Acoustical Society of Korea
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• v.33 no.1
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• pp.54-59
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• 2014

Identification of RTF (Relative Transfer Function) between sensors is essential to multichannel speech enhancement system. In this paper, we present an approach for estimating the relative transfer function of speech signal. This method adapts a CASA (Computational Auditory Scene Analysis) technique to the conventional OM-LSA (Optimally-Modified Log-Spectral Amplitude) based approach. Evaluation of the proposed approach is performed under simulated stationary and nonstationary WGN (White Gaussian Noise). Experimental results confirm advantages of the proposed approach.

• Journal of information and communication convergence engineering
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• v.4 no.2
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• pp.71-74
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• 2006

A basic access method about IEEE 802.11 MAC layer protocol using IEEE 802.11 wireless LANs is the DCF thatis based on the CSMA/CA. But, cause of IEEE 802.11 MAC layer uses original backoff algorithm (exponential backoff method), when collision occurred, the size of contention windows increases the double size Also, a time of packet transmission delay increases and efficienty is decreased by original backoff scheme. In this paper, we have analyzed TCP packet transmission time of IEEE 802.11 MAC DCF protocol for wireless LANs a proposed enhanced backoff algorithm. It is considered the transmission time of transmission control protocol (TCP) packet on the orthogonal frequency division multiplexing (OFDM) in additive white gaussian noise (A WGN) and Rician fading channel. From the results, a proposed enhanced backoff algorithm produces a better performance improvement than an original backoff in wireless LAN environment. Also, in OFDM/quadrature phase shift keying channel (QPSK), we can achieve that the transmission time in wireless channel decreases as the TCP packet size increases and based on the data collected, we can infer the correlation between packet size and the transmission time, allowing for an inference of the optimal packet size in the TCP layer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.1014-1020
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• 2008

Storage devices such as memories are widely used in various electronic products. They require high-density memory and currently the data has been stored in multi-level format, that results in high error rate. In this paper, we apply error correction schemes that are widely used in communication system to the storage devices for satisfying low bit error rate and high code rate. In A WGN channel with average BER $10^{-5}$ and $5{\times}10^{-6}$, we study error correction schemes for 4-1evel cell to achieve target code rate 0.99 and target BER $10^{-11}$ and $10^{-13}$, respectively. Since block codes may perform better than the concatenated codes for high code rate, and it is important to use less degraded inner code even when many bits are punctured. The performance of concatenated codes using general feedforward systematic convolutional codes are worse than the block code only scheme. The simulation results show that RSC codes must be used as inner codes to achieve good performance of punctured convolutional codes for high code rate.

• Journal of Broadcast Engineering
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• v.9 no.4 s.25
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• pp.371-383
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• 2004

In this paper we consider technological requirements to broadcast digital television signals using single frequency networks (SFN) in the Advanced Television Systems Committee (ATSC) transmission systems and propose equalization digital on-channel repeater (EDOCR) that overcomes the limitations of conventional digital on-channel repeaters (DOCRs). Since there are no forward error correction (FEC) decoder and encoder, the EDOCR does not have an ambiguity problem. In addition, since an adaptive equalizer in the EDOCR removes multi-path signals, additive white Gaussian noise (A WGN), and feedback signal due to low antenna isolation, the EDOCR may have good output signal quality with high power.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.868-882
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• 2009

In this paper, channel model and wireless link performance analysis for the short-range wireless communication system applications in the terahertz frequency which is currently interested in many countries will be described. In order to realize high data rates above 10 Gbps, the more wide bandwidths will be required than the currently available bandwidths of millimeter-wave frequencies, therefore, the carrier frequencies will be pushed to THz range to obtain larger bandwidths. From the THz atmospheric propagation characteristics based on ITU-R P.676-7, the available bandwidths were calculated to be 68, 48 and 45 GHz at the center frequencies of 220, 300 and 350 GHz, respectively. With these larger bandwidths, it was shown from the simulation that higher data rate above 10 Gbps can be achieved using lower order modulation schemes which have spectral efficiency of below 1. The indoor propagation delay spread characteristics were analyzed using a simplified PDP model with respect to building materials. The RMS delay spread was calculated to be 9.23 ns in a room size of $6\;m(L){\times}5\;m(W){\times}2.5\;m(H)$ for the concrete plaster with TE polarization, which is a similar result of below 10 ns from the Ray-Tracing simulation in the reference paper. The indoor wireless link performance analysis results showed that receiver sensitivity was $-56{\sim}-46\;dBm$ over bandwidth of $5{\sim}50\;GHz$ and antenna gain was calculated to be $26.6{\sim}31.6\;dBi$ at link distance of 10m under the BPSK modulation scheme. The maximum achievable data rates were estimated to be 30, 16 and 12 Gbps at the carrier frequencies of 220, 300 and 350 GHz, respectively, under the A WGN and LOS conditions, where it was assumed that the output power of the transmitter is -15 dBm and link distance of 1 m with BER of $10^{-12}$. If the output power of transmitter is increased, the more higher data rate can be achieved than the above results.