• 한국정보통신학회논문지
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• 제24권6호
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• pp.744-750
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• 2020

본 논문에서는 무선통신 시스템의 주파수 효율과 에너지 효율을 개선하기 위하여 딥러닝 기반의 송신 전력 제어 기법을 제안한다. 무선통신 시스템에서 다수의 송수신기의 위치는 균일 분포를 따르고 송수신기 간 채널은 나카가미 페이딩 채널을 가정하여 제안하는 송신 전력 제어 기법에 대한 주파수 효율과 에너지 효율의 성능을 분석한다. 제안하는 송신 전력 제어 기법은 딥러닝 기반의 학습에서 주파수 효율과 에너지 효율을 개선하기 위하여 배치 정규화 기법을 이용한다. 시뮬레이션을 통해 송수신기의 위치 범위를 제한하는 지형적 크기와 나카가미 페이딩 지수에 대하여 제안하는 송신 전력 제어 기법과 기존의 송신 전력 제어 기법의 주파수 효율과 에너지 효율의 성능 결과를 비교한다. 성능 결과의 비교를 통해 제안하는 기법이 기존의 기법보다 우수한 성능을 제공함을 입증한다.

• 한국통신학회논문지
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• 제25권3A호
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• pp.391-398
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• 2000

In this paper, MRC(Maximum Ratio Combine) diversity, (23, 12) Golay code, (7, 5) Reed-Solomon code, and (3, 1) majority selection code are employed to improve the performance of DS/CDMA BRSK in Nakagami fading channel. and MRC diversity combined with other coding techniques is suggested, with which, the performance of DS/CDMA BRSK is compared and analyzed. Also, system required Eb/N0 to meet BER=10-5 for multi user data communication is obtained according to each techniques. From the results, when each techniques is employed to DS/CDMA BRSK system. coding employed system shows better performance than diversity employed system. Especially, Golay code shows better performance than oter codes. also MRC diversity is employed, the number of multiple access user to meet data communication requirement of BER=10-5 can accomodate up to 8 users. and when each code is employed, Golay code, majority selection code, and Reed-Solomon code shows the capacity of 14, 12, and 10 user respectively. But MRC diversity combined with coding techniques can reduce restriction of multiple access user. However, it is desirable these combined technique are employed according to service types and requirements provided.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.653-657
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• 2004

The average bit error rate (HER) performance of a Gray coded arbitrary rectangular quadrature amplitude modulation (AR-QAM) signal with maximal ratio combining (MRC) diversity in an arbitrarily correlated Nakagami-m fading channel is derived and analyzed. The derived two types of general solutions are a simple closed-form and an integral form, depending on the types of the values (integer and non-integer) of the fading parameter. Using the derived equations in this paper, we analyzed the HER performances numerically based on the practical base station antenna configuration. The results show that MRC reception is a very effective scheme so far even though the combined signals are not independent each other because of the correlation values. The antenna height and separation of the MRC system relate to the correlation coefficient value between antennas, and go a long way with the diversity advantage. In particular, it is needed to be determined the antenna height that is carefully do for the diversity advantage because the correlation coefficient and the antenna height gain are contrary to each other from the aspect of the system performance. The expressions presented here can offer a convenient way to evaluate the exact HER performance of an arbitrary rectangular QAM signal with MRC diversity reception for various cases of practical interest on a correlated Nakagami fading channel.

• ETRI Journal
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• 제36권1호
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• pp.22-30
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• 2014

Recently, efficient partial relay selection (e-PRS) was proposed as an enhanced version of PRS. In comparing e-PRS, PRS, and the best relay selection (BRS), there is a tradeoff between complexity and performance; that is, the complexity for PRS, e-PRS, and BRS is low to high, respectively, but vice versa for performance. In this paper, we study the outage probability for e-PRS in decode-and-forward (DF) relaying systems over non-identical Nakagami-m fading channels, where the fading parameter m is an integer. In particular, we provide closed-form expressions of the exact outage probability and asymptotic outage probability for e-PRS in DF relaying systems. Numerical results show that e-PRS achieves similar outage performance to that of BRS for a low or medium signal-to-noise ratio, a high fading parameter, a small number of relays, and a large difference between the average channel powers for the first and the second hops.

• Journal of Communications and Networks
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• 제1권2호
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• pp.111-117
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• 1999

Using a method recently reported in the literature for analyzing the bit error probability (BEP) performance of noncoherent Mary orthogonal signals with square-law combining in the presence of independent and identically distributed Nakagami-m faded paths, we are able to reformulate this method so as to apply to a generalized fading channel in which the fading in each path need not be identically distributed nor even distributed ac-cording to the same family of distribution. The method leads to exact expressions for the BEP in the form of a finite-range integral whose integrand involves the moment generating function of the combined signal-to-noise ratio and which can therefore be readily evaluated numerically. The mathematical formalism is illustrated by applying the method to some selected numerical examples of interest showing the impact of the multipath intensity profile (MIP) as well as the fading correlation profile (FCP) on the BEP performance of M-ary orthogonal signal over Nakagami-m fading channels. Thses numerical results show that both MIP and FCP induce a non-negligible degradition in the BEP and have therefore to be taken into account for the accurate prediction of the performance of such systems.

• 한국정보통신학회논문지
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• 제6권8호
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• pp.1234-1240
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• 2002

본 논문에서는 Nakagami 페이딩 채널 특성의 이동 통신 환경에서 정보 데이터를 PN 시퀀스로 대역 확산시켜 BPSK 변조를 취한 CDMA 시스템에 MRC 다이버시티와 반복 전송(다수결 선택)이나 부호화 기법을 다양하게 결합하였을 때의 블록 오율 성능 향상에 대하여 분석한다. 분석 결과로써, 부호화는 다이버시티 기법보다 더 효과적인 성능 향상을 보였다. 그러나 부호화는 더 넓은 주파수 대역을 필요로 하게 된다. 또한 MRC 다이버시티와 부호화 기법을 결합하였을 때 성능 개선이 크게 향상되었다.

• 한국전자파학회논문지
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• 제15권12호
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• pp.1199-1206
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• 2004

본 논문에서는 나카가미-m 페이딩 채널에서 정규화된 부반송파의 간격에 따라 구분되는 직교 MC DS- CDMA 시스템과 오브래핑 되지 않는 MC DS-CDMA시스템을 분석하였다. 다중 반송파 시스템에서 발생하는 선택 경로수를 줄이기 위하여 Hybrid SC/MRC 방식이 적용되어 MRC 방식을 사용한 경우와 비교 분석하였다. 분석 결과, Hybrid SC/MRC 방식을 MRC 방식으로 대체할 수 있으며, 주어진 대역폭이 고정되어 있는 경우 부반송파의 수를 증가시키면 부반송파 간격이 증가하고 필요한 대역폭이 더 많이 필요함으로 부반송파의 수는 주어진 대역폭을 고려하여 선택하여야함을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권1호
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• pp.81-108
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• 2018

In this paper, we derive the theoretical Symbol Error Probability (SEP) of cooperative systems with best relay selection for Nakagami-m fading channels. For Amplify and Forward (AF) relaying, the selected relay offers the best instantaneous Signal to Noise Ratio (SNR) of the relaying link (source-relay-destination). In cooperative networks using Decode and Forward (DF), the selected relay offers the best instantaneous SNR of the link between the relay and the destination among the relays that have correctly decoded the transmitted information by the source. In the second part of the paper, we derive the SEP when all participating AF and DF relaying is performed. In the last part of the paper, we extend our results to cognitive radio networks where there is interference constraints : only relays that generate interference to primary receiver lower than a predefined threshold T can transmit. Both AF and DF relaying with and without relay selection are considered.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권5호
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• pp.2416-2432
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• 2017

In this paper, we investigate the security performance for cooperative networks over Nakagami-m fading channels. Based on whether the channel state information (CSI) of wiretap link is available or not, optimal relay selection (ORS) and suboptimal relay selection (SRS) schemes are considered. Also, multiple relays combining (MRC) scheme is considered for comparison purpose. The exact and asymptotic closed-form expressions for secrecy outage probability (SOP) are derived and simulations are presented to validate the accuracy of our proposed analytical results. The numerical results illustrate that the ORS is the best scheme and SRS scheme is better than MRC scheme in some special scenarios such as when the destination is far away from the relays. Furthermore, through asymptotic analysis, we obtain the closed-form expressions for the secrecy diversity order and secrecy array gain for the three different selection schemes. The secrecy diversity order is closely related to the number of relays and fading parameter between relay and destination.

• 한국통신학회논문지
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• 제25권1A호
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• pp.34-42
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• 2000

본 논문에서는 나카가미 페이딩 채널에서 동일한 페이딩 인자와 상이한 페이딩 인자를 갖는 L-가지 최대비 합성 다이버시티 시스템 그리고 동일한 평균 전력을 가지며 나카가미 m-분포를 가지는 수신 신호들에 대한 다수의 다이버시티 가지를 크기 순서대로 선택하고 합성하는 순서 통계량(order statistics)의 개념을 이용하여 일반화된 선택성 합성 기법에서 DPSK의 비트 오류 확률식을 유도한다. 특히 선택성 합성 다이버시티에서 L=1일 경우 나카가미 페이딩에서 DPSK 신호의 오류 확률식이 됨을 확인하며 다이버시티 가짓수 L과 페이딩 지수 m을 변화시켜 가면서 최대비 합성 기법과 선택성 합성 기법에 대한 성능을 비교 분석한다.