• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.10
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• pp.1-6
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• 2011

In this paper, the sum-rate and BER performances of MU-MIMO system employing quantized differential feedback technique are analyzed over temporrally correlated channels. Several differential codebooks are assumed in the analysis such as quasi-diagonal codebook, spherical cap codebook, and differential equal gain codebook. The simulation results indicates that the system employing quantized differential feedback technique provides significant performance improvement. The performance improved 0.6bps/Hz at least in terms of sum-rate, and 4dB power gain is provided in terms of average BER.

• Journal of Advanced Navigation Technology
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• v.16 no.5
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• pp.810-816
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• 2012

In this paper, BER(Bit Error Ratio) performances of the TransferJet system, which is the standard of a close proximity inductive wireless communication system, are presented and analyzed. Comparing to other wireless communication systems, the TransferJet system has some advantages such as short communication range(i.e., high security in the wireless communication environments), fewer effects of multipath distortion, and higher transmission rate. In order to demodulate the received signal, either SC(Soft-decision Combining) or HC(Hard-decision Combining) can apply to the despreader and demodulator of the receiver. When the spreading factor is more than 4, the SC scheme approximately has a minimum signal-to-noise ratio gain of 2 dB over the HC scheme. Moreover, from simulation results, we can conclude that the quantization bits of 3 bits are an optimum value for the SC scheme in the TransferJet system since the 3-bit quantization achieves nearly the performance as that attained by double-precision floating-point.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.699-707
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• 2014

Recently, the communication between LED array and camera, called Visual-MIMO, is under active research and we expect the maximization of application to the vehicle as well as smart-phone. In this paper, we improve the BER performance of Visual-MIMO system by using the brightness information of a received image. We also suggest the error correction method to minimize the error due to Inter-Symbol-Interference. The performance analysis according to the noise and distance variation will verify the validity of our proposed method including results through simulation and hardware experiment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.773-781
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• 2000

The average bit error rate of wideband CDMA in forward link is evaluated for frequency and timing errors in multipath Rayleigh fading channel. The channel BER is evaluated analytically and information BER is investigated with simulation. The performance degradation due to the code/frequency synchronization errors was obtained through simulation for particular two coding schemes - convolutional codes and turbo codes. The results show 1dB degradation due to Tc/4 timing error and 0.5dB degradation due to 50Hz frequency error, for both coding schemes.

• The Journal of the Acoustical Society of Korea
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• v.29 no.5
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• pp.303-313
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• 2010

This paper describes an acoustic communication receiver structure, which is designed for QPSK (Quadrature Phase Shift Keying) signal with 25 kHz carrier frequency and 5 kHz symbol rate, and takes samples from received signal at 100 kHz sampling rate. Based on the described receiver structure, optimum design parameters, such as number of taps of FF (Feed-Forward) and FB (Feed-Back) filters and forgetting factor of RLS (Recursive Least-Square) algorithm, of joint equalizer are determined to minimize the BER (Bit Error Rate) performance of the joint equalizer output symbols when the acquisition data in shallow water using implemented acoustic transducers is decimated at a rate of 2:1 and then enforced to the input of receiver. The transmission distances are 1.4 km, 2.9 km, and 4.7 km. Analysis results show that the optimum number of taps of FF and FB filters are different according to the distance between source and destination, but the optimum or near optimum value of forgetting factor is 0.997. Therefore, we can reach a conclusion that the proper receiver structure could change the number of taps of FF and FB filters with the fixed forgetting factor 0.997 according to the transmission distance. Another analysis result is that there are an acceptable performance degradation when the 16-tap-length simple filter is used as a low-pass filter of receiver instead of 161-tap-length matched filter.

• Journal of Broadcast Engineering
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• v.20 no.2
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• pp.248-256
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• 2015

In this paper, we model the interference plus noise signal for terrestrial cloud transmission systems and present bit error rate (BER) performances. Since terrestrial cloud transmission systems experience co-channel interference from one or more transmitters, they have to operate under a negative signal-to-interference plus noise ratio (SINR) region. The interference plus noise signal can be modeled as Gaussian random variable under the required SINR region and we observe the BER performance of the cloud transmission system using the derived model. Also, we propose an improved channel estimation scheme by averaging the channel estimates based on least square based interpolation scheme. Simulation results show that the cloud transmission system can operate under negative SINR region using the proposed channel estimation scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.517-529
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• 2011

In this paper, the parameters of the RTT (Radio Transmission Techniques) for SANET (Ship Ad-hoc NETwork), which is considered for the next generation maritime communication systems, are set up. A channel model has been analyzed based on the practical measured maritime wireless channel in VHF (Very-High Frequency) for SANET system. Also, by considering the frame structure including preamble, guard time and pilots for both single and multi-carrier systems, the BER (Bit Error Rate) performances are evaluated and analyzed in the aspects of channel compensation and channel coding techniques. Based on the simulation results, optimal modulation & coding schemes are suggested for SANET. That is, in single-carrier system by using differential modulation schemes, channel compensation is not necessary. However, channel coding is helpful to achieve additional gain. On the other hand, when 16-QAM modulation is employed in multi-carrier system, the implementation of both channel compensation and channel coding techniques show huge performance gain for various of K values, which are related to different maritime environments, and the rolling effects of wave.

• Journal of Broadcast Engineering
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• v.8 no.3
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• pp.228-237
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• 2003

Eureka-147 DAB(Digital Audio Broadcasting) system on which DMB(Digital Multimedia Broadcasting) system is based, was designed for the requirements of CD qualify audio with ${10}^{-4}$ bit error rate. Audio program may be primary service in DAB system, but multimedia program can be primary service in DMB system. Therefore, the bit error rate required must be below ${10}^{-7}$∼${10}^{-8}$ to transmit multimedia data via DMB channel. In order to meet the requirements and keep backward compatibility of DAB system we propose an outer channel coding scheme using Reed-Solomon coding and convolutional interleaving. This paper shows the simulation results for DMB channel performance based on mobile channel model. Also, it describes the needs and the effects of the outer channel coding.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.67-72
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• 2014

In this paper, an energy harvesting scheme is applied in the cooperative communication. The proposed scheme uses an energy harvesting relay in which the relay harvests the energy from the source node and transfers to the power form in forwarding the received data to the destination node. The well-known maximal ratio combining (MRC) technique is applied to increase the diversity gain at the destination. Therefore, with applying the proposed energy harvesting scheme, the limited power at the relay is solved, and the operation efficiency of the network and the mobile devices is improved. Finally, performance of the proposed protocol is analyzed in terms of bit error rate, outage probability, power collection efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.8
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• pp.629-637
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• 2013

Chaos communication systems have the characteristics such as non-periodic, wide-band, non-predictability of signals and easy implementation. There have been many studies about chaos communication systems because of these advantages. But, chaos communication systems have low BER(Bit Error Rate) compare to general digital communication system. Existing researches on chaos communication systems only analyze BER performance according to various chaos maps. There are no studies on analysis of BER performance according to PDF(Probability Density Function) of chaos maps. In this paper, we analyze the BER performance according to changing parameter, equation, and initial values of chaos map's PDF. In addition, we propose new chaos map to improve BER performance. Simulation results show that BER performance of CDSK(Correlation Delay Shift Keying) is changed when PDF of chaos map changed. And the proposed chaos map has a better BER performance compare to previous chaos maps such as Tent map, Logistic map, and Henon map.