• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.128-131
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• 2003

본 논문에서는 채널의 진폭 특성만을 고려한 실내 무선 페이딩 환경에서 PPM 변조된 UWB 통신 시스템의 채널 성능을 분석하였다. 페이딩 채널은 기존에 발표되었던 UWB 전파 실험을 통한 데이터를 바탕으로 Nakagami-m분포 모델을 이용하여 페이딩 지수 m에 따른 다양한 채널 환경을 고려하였다. 또한, 채널 성능을 평가하기 위해 신호대 잡음비, 페이딩 지수 m, 그리고 시스템 성능 파라미터인 펄스반복개수(Ns)를 이용하여 다양한 페이딩 환경에서의 UWB 시스템 성능을 분석하였다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.638-644
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• 2018

Relay systems have recently gained attentions because of its capability of cell coverage extension and the power gain as the one of key technologies for 5G. Relays can be exploited for small-cell base stations and the autonomous network, where communication devices communicate with each other cooperatively. Therefore, the relay technology is expected to enable the low power and large capacity communication. In order to maximize the benefits of using a limited number of relays, the efficient relay selection method is required. Especially, when two nodes exchange their data with each other via relay, the relay selection can maximize the average data rate by the spatial location of the relay. For this purpose, the average data rate is analyzed first according to the relay selection. In this paper, we analyzed the average data rate when two nodes exchange their data via dual-hop decode and forward relaying considering the interference by the concurrent transmission under Nakagami-m fading channel. The correctness of the analysis is verified by the Monte Carlo simulation. The results show that the concurrent transmission is superior to the non-concurrent transmission in the high required data rate region rather than in the low required data rate region.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.567-574
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• 2003

It is important to design and evaluate the chip waveform with the minimum MAI under the bandwidth constraint in the interference-limited DS-CDMA system. In this paper, by approximation we present the analytical chip waveforms that are proposed and optimized in the reference. Their performances are compared with performances of three conventional chip waveforms: rectangular, half-sine and raised-cosine. Waveform 1 of the proposed chip waveform outperforms the conventional ones. BER and throughput performance are evaluated in the Rayleigh and Nakagami-m fading channels when DPSK modulation is used. When the required BER is 10$\^$-3/ in two fading channels, the capacity of the waveform 1 is improved about 20 % rather than raised-cosine one. When the offered traffic is 30 and the number of packet per bit(N$\sub$d/) is 14, maximum throughput of the waveform 1 is better than raised-cosine chip waveform about 18 % in two fading channels.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3412-3431
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• 2015

This paper considers the effect of co-channel interference on hybrid satellite-terrestrial relay network. In particular, we investigate the problem of amplify-and-forward (AF) relaying in hybrid satellite-terrestrial link, where the relay is interfered by multiple co-channel interferers. The direct link between satellite and terrestrial destination is not available due to masking by surroundings. The destination node can only receive signals from satellite with the assistance of a relay node situated at ground. The satellite-relay link is assumed to follow the shadowed Rice fading, while the channels of interferer-relay and relay-destination links experience Nakagami-m fading. For the considered AF relaying scheme, we first derive the analytical expression for the moment generating function (MGF) of the output signal-to-interference-plus-noise ratio (SINR). Then, we use the obtained MGF to derive the average symbol error rate (SER) of the considered scenario for M-ary phase shift keying (M-PSK) constellation under these generalized fading channels.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.311-315
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• 2000

본 논문에서는 임펄스 잡음과 나카가미 페이딩 채널에서 블록 에러 NFSK 시스템을 제안하고, 이의 성능을 구하였다. 블록 에러 확률을 구하는데 있어서 나카가미 채널 페이딩 속도(즉, slow fading, fast fading)를 고려하여 임펄스 잡음지수의 변화에 따른 성능을 구하였다. 블록 에러의 성능을 개선시키는 방안으로 다이버시티 기법과 에러정정 부호화 기법을 적용하여 다이버시티 수(L), 에러정정능력(M), 임펄스 잡음지수(A)를 함수로 하여 성능 개선이 커지고, 저속 페이딩 (임펄스 잡음지수 A=0.1, 1에서 3dB 개선)보다 고속 페이딩에서 (임펄스 잡음지수 A=0.1, 1에서 2～4dB 개선)의 성능개선 정도가 우수하였다. MRC 다이버시티 기법은 저속 페이딩에서 부호화 기법을 적용했을 때 보다 우수한 성능을 보이고 페이딩의 영향이 클 때 성능개선이 크게 이루어짐을 알 수 있었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.1005-1015
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• 2000

In this paper, the performance of Hybrid CDU MFSK system has been analyzed in the environment that narrowband Class-A impulsive noise include Gaussian noise in wireless communication channel and Nakagami fading. The performance of system improved to adopting both of technique MRC diversity and BCH channel coding. The results show that there is substantial degraded in Hybrid CDMA system performance by impulse index is stronger and the fading index is smaller. But also improvement can be obtained when BCH coding techniques are adopted. Additional MRC diversity techniques is more improvement than BCH coding techniques when degraded environment with the low fading index. But BCH coding techniques is more improvement than MRC diversity techniques when fading index has been increased. The Hybrid CDMA MFSK system is incomplete to voice communication standard BER$(10^{-3})$ in Rayleigh fading by independent each adopting techniques BCH coding and MRC diversity. But it's satisfy(improvement can be obtained) to voice communication standard BER in strong impulse noise(24dB over) by adopting techniques BCH coding and MRC diversity at a time. Additional it's a substantial enhancement $(10^{-3})$satisfaction) in fading index (m=3, 22dB) in addition to strong impulse noise and 24dB over with data service standard $(10^{-5})$ BER satisfaction. This result show that there is error performance improved by diversity branch and coding advantage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.6
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• pp.489-497
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• 1991

The error rate pquations of digital radio signals transmitted throught the Nakagami's m-distribution fading channel have been both for nondiversity reception and for diversity reception cases in the environmment of Gaussin noise. Using the derived equation. erro rate performance has been evaluated and represented in figures as a function of carrier to noise ratio, fading figure, and the power correlation coefficient between two diversity branches. By comparing the diversity reception case with nondiversity reception case. We could measure the amount of error rate performance improvenment of digital radiosignals in fanding enviroment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.4
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• pp.527-534
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• 2002

In this paper, efficiency in the acquisition of the PN code of the DS/CDMA system was analyzed by using the Nakagami-m probability density function that can model diverse fading channels. The system considers the fading environment that inevitably exists in the mobile communications channel environment. To analyze the efficiency of the system, the equations related to detection probability PD and false alarm probability PFA required for the acquisition of the PN code were induced by using the Nakagami-m probability density function. They were verified through simulation. For the DS/CDMA system an adaptive serial search technique was applied to acquire the PN code. To correct phase error, the equations related to detection probability PD and false alarm probability PFA that influence the time to acquire codes were induced after adding the PLL to each branch of the Rake Receiver. By using an induced equation, detection probability PD and false alarm probability PFA were verified through simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1968-1976
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• 2007

This paper proposes a hybrid pseudo-noise (PN) code acquisition scheme for Multicarrier Direct Sequence - Code Division Multiple Access (MC DS-CDMA) mobile communication systems on the code acquisition performance for Nakagami-m fading channel. The hybrid acquisition scheme combines parallel search with serial search to cover the whole uncertainty region of the input code phase. It has a much simpler acquisition hardware structure than the total parallel acquisition and can achieve the mean acquisition time (MAT) slightly inferior to that of the total parallel acquisition. The closed-form expressions of the detection and false-alarm probabilities are derived.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.3
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• pp.53-59
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• 2000

A received signal in mobile communication environments exhibits variation in both amplitude and phase due to the multipath fading. Therefore we analyzed the performance of DS/CDMA(Direct Sequence/code Division Multiple Access) DPSK(Differential Phase Shift Keying) system for the variations of PLL(Phase Locked Loop) gain with Tikhonov probability density function, assuming that the phase difference between transmitter and receiver signals is phase error. As a result, it is discovered that the performance of system could be improved by the control of PLL gain in compared with the DPSK system which does not consider the phase error. If the PLL gain is 1dB, the difference of two systems is 4.8dB and 0.4dB at 7dB. and if 30dB, it coincides. From above, it