• Title/Summary/Keyword: mRelay

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Analysis on the Interference Effects of Radio-Relay Stations into HAPS System (무선중계국이 HAPS 시스템에 미치는 간섭 영향 분석)

  • Kim, Bong-Seok;Park, Sang-Jun;Ham, Hyung-Il;Kang, Young-Heung
    • Journal of Advanced Navigation Technology
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    • v.6 no.1
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    • pp.10-16
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    • 2002
  • High altitude platform station(HAPS) is being developed actively in some countries as well as Korea. At the same time Resolution 734 was adopted in WRC-2000 to study the sharing of HAPS into the existing fixed services in the bands above 3GHz. As one of the sharing studies, interferences between HAPS and radio-relay stations should be analyzed by dividing into two cases, the one is the interference effects of HAPS system into radio-relay stations and on the contrary, the other that of radio-relay stations into HAPS system. Since the former case had been already studied, only the latter case will be focused on this paper. Analysis result shows that the coordination distance must be needed above 100 km when the trendline of radio-relay is located vertical to HAPS service area and the transmitting power is -50 dBW/MHz.

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Reactive CDF-based Relay Selection for Wireless Relay Networks over Nakakami-m Fading Channels (나카가미-m 페이딩 채널 환경을 가진 무선 중계 네트워크에서 reactive 누적분포함수 기반 중계기 선택 기법)

  • Nam, Eungkuk;Park, Jinhyun;Lee, Jae Hong
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2015.07a
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    • pp.303-305
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    • 2015
  • 본 논문에서는 나카가미-m 페이딩 채널 환경을 가진 무선 중계 네트워크에서 reactive 누적분포함수(cumulative distribution function) 기반 중계기 선택 기법을 제안한다. 제안된 기법은 수신 신호대잡음비(signal-to-noise ratio)의 누적분포함수 값에 따라 중계기를 선택한다. 본 논문에서는 제안한 기법의 불능 확률(outage probability)과 다이버시티 차수(diversity order)를 분석한다. 제안된 기법이 얻을 수 있는 다이버시티 차수는 중계기의 개수와 페이딩 파라미터에 의해 결정되며 최대 다이버시티(full diversity)를 얻음을 볼 수 있다. 그리고 모의 실험에서는 분석된 불능 확률 및 다이버시티 차수가 정확하게 일치하는 것을 확인한다.

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Outage Analysis of CRNs with SC Diversity Over Nakagami-m Fading Environment

  • Zhang, Zongsheng;Wu, Qihui;Zheng, Xueqiang;Wang, Jinlong;Li, Lianbao
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.7 no.12
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    • pp.3003-3017
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    • 2013
  • In this paper, we investigate the outage performance of a cognitive relay network. We consider mutual interference in an independent, non-identically distributed Nakagmai-m fading environment. We first derive the close-form outage probability expression, which provides an efficient means to evaluate the effects of several parameters. This allows us to study the impact of several parameters on the network's performance. We then derive the asymptotic expression and reveal that the diversity order is strictly determined by the fading severity of the cognitive system. It is not affected by the primary network. Moreover, the primary network only affects the coding gain of the cognitive system. Finally, Monte Carlo simulations are provided, which corroborate the analytical results.

PER Analysis for Cooperative Multi-Hop Transmission Protocol over Nakagami-m Fading Channels

  • Duy, Tran Trung;Kong, Hyung-Yun
    • Journal of electromagnetic engineering and science
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    • v.12 no.3
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    • pp.189-195
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    • 2012
  • In this paper, we propose a novel protocol called a Multi-hop Diversity Transmission protocol in which the retransmission is realized by a relay that is Nearest to a current Source (MDTNS). We derive the mathematical expressions of the packet error rate (PER) and the average number of transmissions over Nakagami-m fading channels, and verify them by Monte Carlo simulations. The simulation results show that the MDTNS protocol improves the performance of the network in terms of PER when compared to the Multi-hop Diversity Transmission protocol in which the retransmission is done by a relay that is Nearest to Destination (MDTND) and to the conventional multi-hop transmission (CMT) protocol.

Frequency Control of Demand Users with Power Plants by Under-frequency Relay (저주파수 계전기에 의한 수용가 발전설비 계통 주파수 제어)

  • Kim, H.M.;Kim, D.H.;Chun, Y.H.;Kim, J.W.;Kook, K.S.;Jeon, J.H.
    • Proceedings of the KIEE Conference
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    • 2001.05a
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    • pp.233-235
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    • 2001
  • This paper deals with frequency control of demand users that have power plants by under-frequency relay. The demand users supply electrical power to a part of their loads by their power plants and to other rest of their loads by utility. While electrical power supply is stopped by faults of utility network, the system of demand users network is separated from total power system and their system frequency goes below normal limits. In this paper, this situation and the effect of under-frequency relay application are simulated by EMTDC.

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Simulator by use of DSP TMS320C32 for Digital Relay Test (DSP TMS320C32를 이용한 디지털 계전기 시험을 위한 시뮬레이터)

  • Park, C.W.;An, T.P.;Ko, I.S.;Shin, M.C.
    • Proceedings of the KIEE Conference
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    • 2004.07e
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    • pp.120-122
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    • 2004
  • This paper describes the digital relay simulator by use of DSP for digital relay test. The simulator software has EMTP simulation data file conversion. user define simulation data generation. data analysis engine. etc. The simulator hardware design uses 32bit floating point DSP architecture to achivev flexibility and high speed operation.

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A universal logic graphical simulator for power system protection (송전계통 보호계전기 가변 로직 그래픽 동작 시뮬레이터)

  • Kim, K.H.;Min, B.W.;Cho, P.S.;Lee, S.J.;Kang, S.H.;Choi, M.S.
    • Proceedings of the KIEE Conference
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    • 2001.07a
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    • pp.25-27
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    • 2001
  • To verify operation of relay is a difficult job for relay engineers. This paper reports the development of logic simulator. Fault data is generated from EMTP and system information generator. The developed system has a universal characteristics that can deal with any relay logic.

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Developed Ability of Zero-phase Overcurrent Relay by Changed setting point value (설정치 변경에 의한 영상과전류계전기의 성능개선)

  • Kim, N.H.;Yoon, D.S.;Chang, S.I.;Choi, J.H.
    • Proceedings of the KIEE Conference
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    • 1998.11a
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    • pp.220-222
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    • 1998
  • This paper presents a method, which develops an ability of Zero-phase Overcurrent Relay. Zero-phase current is very useful factor of Fault decision in Protect Relaying system. Actually, the setting-point value of Designed Relay, using Zero-phase current, is fixed. So in the case of deciding fault, Fixed setting-point value is not suitable for changing Load. and cause errors in Distributions system. For solving this problem, This paper proposes the Changed setting point value Algorithm, which can be adaptive for changing Distributions system using Zero-phase current r.m.s. indexes. The results of simulation under Load changing and High impedance fault show that proposed algorithm is useful for changing Distributions system and decreasing errors.

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Adaptive Power Control Strategy based on Spectrum Sensing for Cognitive Relay Networks (CR 넷워크를 위한 주파수 감지에 기번한 적응적인 전력 제어 전략)

  • HU, SIYUAN;Joe, Inwhee
    • Proceedings of the Korea Information Processing Society Conference
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    • 2019.05a
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    • pp.82-85
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    • 2019
  • An adaptive power control scheme is proposed for the cognitive relay networks with joint overlay and underlay spectrum sharing model. The transmit power of the secondary user is adjusted adaptively according to the spectrum sensing results and the interference channel condition. The outage probability of the secondary user is compared by Monte - Carlo simulations between the fixed power control scheme and pure overlay or underlay spectrum sharing schemes. The results show that, by employing the adaptive power control strategy, the interference probability of the secondary user to the primary user is decreased by 70 % ~ 80 % under the same outage probability. Also, the outage probability of the secondary user is reduced by 1 ~ 2 orders of magnitude under the same interference probability. Thus, the performance of the spectrum sharing is improved effectively.

Optimal Power Allocation and Outage Analysis for Cognitive MIMO Full Duplex Relay Network Based on Orthogonal Space-Time Block Codes

  • Liu, Jia;Kang, GuiXia;Zhu, Ying
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.3
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    • pp.924-944
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    • 2014
  • This paper investigates the power allocation and outage performance of MIMO full-duplex relaying (MFDR), based on orthogonal space-time block codes (OSTBC), in cognitive radio systems. OSTBC transmission is used as a simple means to achieve multi-antenna diversity gain. Cognitive MFDR systems not only have the advantage of increasing spectral efficiency through spectrum sharing, but they can also extend coverage through the use of relays. In cognitive MFDR systems, the primary user experiences interference from the secondary source and relay simultaneously, owing to full duplexing. It is therefore necessary to optimize the transmission powers at the secondary source and relay. In this paper, we propose an optimal power allocation (OPA) scheme based on minimizing the outage probability in cognitive MFDR systems. We also analyse the outage probability of the secondary user in noise-limited and interference-limited environments in Nakagami-m fading channels. Simulation results show that the proposed schemes achieve performance improvements in terms of reducing outage probability.