• ETRI Journal
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• v.43 no.2
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• pp.184-196
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• 2021

The research domain of underwater communication has garnered much interest among researchers exploring underwater activities. The underwater environment differs from the terrestrial setting. Some of the main challenges in underwater communication are limited bandwidth, low data rate, propagation delay, and high bit error rate (BER). As such, this study assessed the underwater acoustic (UWA) aspect and explored the expression of error performance based on t-distribution noise. Filter orthogonal frequency-division multiplexing refers to a new waveform candidate that has been adopted in UWA, along with turbo and polar codes. The empirical outcomes demonstrated that the noise did not adhere to Gaussian distribution, whereas the simulation results revealed that the filter applied in orthogonal frequency-division multiplexing could significantly suppress out-of-band emission. Additionally, the performance of the turbo code was superior to that of the polar code by 2 dB at BER 10-3.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.65-68
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• 2001

In this paper a CI(carrier interferometry) chip waveform shaping scheme which Is made up of orthogonal carriers equally spaced in frequency, and used to introduce frequency diversity benefits into DS-CDMA, is considered. A new communication scheme referred to as CI/DS-CDMA using CI chip shaping, is introduced. Through the performance evaluation of CI/DS-CDMA systems in a typical frequency selective fading channel environment, it is shown that the frequency diversity benefits of this system results in significant performance enhancements relative to traditional DS-COMA with RAKE receivers using the path diversity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1051-1060
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• 2014

In this paper, performance of an orthogonal frequency division multiplexing (OFDM) system in an impulsive noise environment is analyzed. Here, it is verified that performance of the OFDM system with window nonlinearity, which is one of the impulsive noise mitigation algorithms, is dependent on the over-sampling rate and the size of window. With respect to the variation of those parameters, we also provide an appropriate region of threshold values that control amplitudes of the sampled waveform of received signals. As a result, a new combination of parameters which improves error performance of OFDM system in an impulsive noise environment as compared to the previously reported parameters is presented.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.314-316
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• 2005

본 논문에서는 UWB 통신을 위한 직교 변형 Hermite 파형형성함수와 정현파를 이용한 변조 Hermite펄스함수의 시간과 주파수 영역에서의 특성을 검토하였다. 그리고 이를 이용한 직교 펄스 다원접속 시스템의 송신기와 수신기를 구성하고 그 성능을 분석하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.142-155
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• 2016

In order to satisfy 5th generation mobile system's requirements, recently many works have been done in various layers. Especially in physical layer, new waveforms like Filter bank Multi-Carrier(FBMC), Universal Filtered Multi-Carrier(UFMC), Generalized Frequency Division Multiplexing(GFDM) have been proposed and their performance have been evaluated. But most previous researches have provided limited information by comparing couple new waveforms each other with different assumptions and simulation parameters. In this paper, we investigate the key technique of each 5G new waveform, and compare them in various aspects and the same simulation environment, and finally provide what waveform is appropriate in different application scenarios.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.725-734
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• 2016

Recently, novel candidate waveform techniques for spectral efficiency improvement was proposed in order to satisfy key performance indicators(KPIs) of 5th generation(5G) mobile communication. Multi-carrier based universal filtered multi-carrier(UFMC) and filter bank multi-carrier(FBMC) are very famous as 5G candidate waveform techniques. Also, weighted orthogonal frequency division multiplexing (W-OFDM) that has low-complexity is receiving the spotlight slowly. In this paper, firstly, we describe a basic OFDM system. And then, we also describe UFMC, FBMC, and W-OFDM system. Next, we evaluate and analyze spectrum and BER performance of these systems under the nonlinear high power amplifier(HPA) environment. As simulation results, spectrum characteristic and BER performance of UFMC, FBMC, and W-OFDM are similar to each other. Therefore, under the nonlinear HPA environment, W-OFDM system is more advantageous because W-OFDM system uses a simple time-domain windowing technique and has similar characteristics to the others.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.1
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• pp.60-65
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• 2009

In this paper, we propose a new exponential pulse shaping function based on Chebychev identity equation and Bessel coefficients. The proposed pulse shaping function can produce various pulses with the different characteristics in the time and frequency domain by changing its two parameters. By differentiating the exponential pulse shaping function, we obtain new different pulse functions, in which the even order derivatives of the exponential pulse shaping function are orthogonal to its odd order derivatives. To find the efficiency of the proposed exponential pulse shaping function we analyze its essential characteristics and compare them with those of the conventional Gaussian pulses. We can choose the most suitable exponential pulse waveform according to the design criteria of communication systems.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.427-430
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• 2005

A multi-code biorthogonal code keying (MBCK) system consists of multiple waveform coding blocks, and the sum of output codewords is transmitted. Drawback of MBCK is that it requires amplifier with high linearity because its output symbol is multi-level. MBCK with constant amplitude precoding block (CA-MBCK) has been proposed, which guarantees sum of orthogonal codes to have constant amplitude. The precoding block in CA-MBCK is a redundant waveform coder whose input bits are generated by processing the information bits. Redundant bits of constant amplitude coded CA-MBCK are not only used to make constant amplitude signal but also used to improve the BER performance at the receiver. In this paper, we proposed a transmission scheme which combines CA-MBCK with $Q^2PSK$ modulation to improve bandwidth efficiency of CA-MBCK and also uses chip interleaving to maintain a constant amplitude feature of CA-MBCK. bandwidth efficiency of a proposed transmission scheme is increased fourfold. And the BER performance of the scheme is same as that of CA-MBCK.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.2
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• pp.109-116
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• 2014

In this paper, we propose a frequency reuse method for efficient frequency use of multi-site weather radar. Our method uses a set of orthogonal pulse compression codes and CLEAN algorithm for sidelobe interference cancellation. Computer simulation results show that performance of proposed method meet performance requirements of [1], The current S-band weather radars in South Korea use the 8 different frequency channels to avoid interference. Using proposed method, number of occupied channels can reduce from 8 to 1, the 7 frequency channels may be use for other services.

• Journal of the Korean Magnetics Society
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• v.12 no.6
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• pp.206-211
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• 2002

We have constructed a new kind of magnetic motion capture sensor based on the pulse magnetic field method. 3-orthogonal magnetic pulse fields were generated in turns only one period of sinusoidal waveform using 3-orthogonal magnetic dipole coils, ring counter and analog multiplier. These pulse magnetic fields were measured with 3-orthogonal search coils, of which induced voltages by the x-, y-, and l-dipole sources using S/H amplifier at the time position of maximum induced voltage. Using the developed motion capture sensor, we can measure position of sensor with uncertainty of ${\pm}$0.5％ in the measuring range from ${\pm}$0.5 m to ${\pm}$1.5 m.