• International Journal of Computer Science & Network Security
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• v.23 no.5
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• pp.121-127
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• 2023

A 500 km/h linear motor high speed terrestrial transportation service is planned to launch 2027 in Japan. In order to support 5G service in the train, the Sub-carrier spacing frequency of 30 kHz is planned to be used instead of common 15 kHz sub-carrier spacing to mitigate Doppler effect in such high-speed transportation. In addition, to increase the cell size of 5G mobile system, plural Base Station antenna will transmit the identical Down Link (DL) signal to form the expanded cell size along the train rail. In this situation, forward and backward antenna signals will be Doppler shifted by reverse direction respectively and the receiver in the train might suffer to estimate accurate Channel Transfer Function (CTF) for its demodulation. In this paper, Delay and Doppler Profiler (DDP) based Channel Estimator is proposed and it is successfully implemented in signal processing simulation system. Then the simulated performances are compared with the conventional Time domain linear interpolated estimator. According to the simulation results, QPSK modulation can be used even under severe channel condition such as 500 km/h, 2 path reverse Doppler Shift condition, although QPSK modulation can be used less than 200 km/h with conventional Channel estimator.

• 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.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.659-662
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• 2005

A parameterized FFT/IFFT core generator (PFFT_CoreGen) is designed, which can be used as an essential IP (Intellectual Property) in various OFDM modem designs. The PFFT_CoreGen generates Verilog-HDL models of FFT cores in the range of 64 ${\sim}$ 2048-point. To optimize the performance of the generated FFT cores, the PFFT_CoreGen can select the word-length of input data, internal data and twiddle factors in the range of 8-b ${\sim}$ 24-b. Some design techniques for low-power design are considered from algorithm level to circuit level.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.318-321
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• 2003

In case, sensor system performs where it is difficult to access physically and it is in the poor environment, it is limited to communicate by using wire and installing power module in sensor system. In this paper, it suggests how information is obtained from telemetry sensor by means of inductive coupling without battery. Comparing with the telemetry sensor system of inductive coupling by the power supply, this system estimates the capacitance of sensor with high precision in using RLSE, not the process of modulation and demodulation. In order to activate this system, inductive model is used and in case of time variant parameter, telemetry sensor system which has got high rate in accuracy is implemented by using the forgetting factor.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.15 no.1
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• pp.20-26
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• 2015

It is very difficult to design an underwater communication system because of multipath, Doppler effects, noise, and attenuation. These factors lead to errors in the communication performance and maximum propagation distance. In this study, we calculate the distance that can be realized using the direct-sequence code division multiple access (DS-CDMA) technique with direct-sequence spread spectrum (DSSS) in an underwater communication system considering only the attenuation and noise. We also compare the estimated and calculated propagation distances obtained for several different scenarios.

• Journal of electromagnetic engineering and science
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• v.4 no.4
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• pp.175-182
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• 2004

When the M-ary signal experiences the Rayleigh fading, the diversity schemes can reduce the effect of fading since the probability that all the signals components will fade simultaneously is reduced considerably. The symbol error probabilities for various M-ary signals, such as MDPSK(M-ary DPSK) and MPSK(M-ary PSK), are mathematically derived for the Selection Combining 2(SC-2) and Selection Combining 3(SC-3) demodulation system which requires a less complex receiver than Maximum Ratio Combining(MRC). The propagation model used in this paper is the frequency-nonselective slow Rayleigh fading channel corrupted by the Additive White Gaussian Noise(AWGN). The numerical results presented in this paper are expected to provide information for the design of radio system using M-ary modulation method for above mentioned channel environment.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.45-50
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• 2005

This paper make an analysis of UWB Communication System. In case endoscope, medical equipment, is applied to UWB, We could study through body-channel that frequency transmitted of received signal is differ from wireless in the existing air. It suggested TR-UWB form, non-coherent received method in dispersion-medium like humans bodies by accomplishing ability analysis of BPM, TR, BER of Differential, UWB Communication modulation and demodulation form.

• Journal of electromagnetic engineering and science
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• v.7 no.1
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• pp.1-6
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• 2007

Recently, Mc(Multi-code) modulation/demodulation(modem) technique has been explored for high speed data transmission in wireless environment. The conventional Mc modem generates some side effects such as allocating Walsh codes, which motivates to propose a novel Mc modem method with sub-code. Our proposed system should expanded the size of sub-code to provide high-rate data transmission, which also affect adversely to the performance of the system with high PAPR(Peak to Average Power Ratio). Thus, in this paper, we propose a novel pre-coded Multi-Dimensional HCOC(High Capacity Orthogonal Code) Mc modem technique to reduce the high PAPR, which enables the performance improvement. This proposed system can be easily designed by concatenating HCOC Mc modem with the generic Mc modem. The pre-coding technique that is used in this paper is CAC(Constant Amplitude Coding), that helps the system maintain the constant transmission power and reduce the maximum transmission power.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.207-211
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• 2004

The performance of an inductive position sensor has approved by previous research papers. In this paper, magnetic circuit model of a ring-type multi-pole insuctive position sensor is described. The magnetic circuit model is required to design in ductive position sensor as well as draw a fault tolerance algorithm. Using the magnetic circuit theory, we derived the relationship between voltage applied and flux density in the normal air-gap. By idealizing the modulation/demodulation processes of signal processing circuit, sensor gain with respect to change of displacement is theoretically calculation using the magnetic circuit model, which validate the theoretical derivation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.485-489
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• 2000

본 논문에서는 단일 PLL을 사용하여 400MHz 대역의 트랜시버를 구현하였다. 일반적인 트랜시버의 경우, 송수신부에 각각 한 개의 PLL과 수신부에 2단의 믹서를 사용하여 구현되어진다. 이러한 구성은 트랜시버의 가격과, 부피에 상당히 큰 영향을 미친다. 본 논문에서는 기존의 방식을 탈피하여 단일 PLL방식의 데이터 전송용 특정 소출력 무선기기의 송, 수신단의 회로설계, 제작 및 특성측정을 하였다. 설계된 트랜시버의 주파수 대역은 424.7-424.95MHz이고, Low Side Injection방식을 사용하여 450KHz의 If 주파수로 변환(Conversion)하였고, 반이중(Semi duplex Communication) 통신방식, PLL Synthesized, 21 Channel, 12.5KHz Channel BandwidttL FSK Modulation / Demodulation 방식을 사용하였다.