• Title, Summary, Keyword: Radio Relay System

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Opportunistic Transmit Cognitive Radio Relay Systems with CSI Delay (CSI 지연을 갖는 기회전송 상황 인지 릴레이 시스템)

  • Kim, Nam-Soo
    • The Journal of The Institute of Internet, Broadcasting and Communication
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    • v.10 no.5
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    • pp.39-44
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    • 2010
  • In this paper, we analyze the performance of the cooperative cognitive radio relay system which is adapted the recently highly focused cognitive radio system. The performance comparison is made between the system with and that without the opportunistic transmission relay. Especially the selection combining is considered at the destination for simple implementation. In this case, the effect of the channel state information (CSI) delay, which is caused essentially by the process during the CSI delivery, to the system performance is considered. It is noticed that the performance of the system with the opportunistic relay degrades up to 0.6 dB at a given condition compared to the system without the opportunistic relay. And it is shown that the system performance is more sensitive to the CSI delay compared to the frequency acquisition probability of the cognitive radio relay.

A Simple If In-Phase Combiner and Its Performance for Point-to-Point Radio Relay System with Space Diversity

  • Suh Kyoung-Whoan
    • Journal of electromagnetic engineering and science
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    • v.5 no.1
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    • pp.1-7
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    • 2005
  • The implementation of a simple analog in-phase combiner is presented for a high capacity radio relay system with space diversity. It provides good performance in terms of simple hardware and easy control, and measured results are in good agreement with simulated ones. To suggest practical applications, signatures with/without diversity are measured for STM-1 signal of 64-QAM radio relay system combined with a 13-tap equalizer, and they provided more than 25 dB fade depth at 10$^{-3}$ BER under the frequency selective fading condition.

Throughput Capacity of a Wireless Multi-hop Relay Network using Cognitive Radio (Cognitive Radio 무선 다중홉 릴레이 네트워크의 Throughput 용량)

  • Hassan, Md. Imrul;Song, Ju-Bin;Kim, Young-Il
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.5
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    • pp.33-39
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    • 2007
  • In this paper, we investigate the throughput capacity of a multi-hop relay with cognitive radio (CR) enabled relay stations (RS). We suggest a TDMA/FDMA based frame structure where RSs dynamically select unused channels to communicate with the base station (BS) using CR techniques to analyze the throughput capacity. We develop the throughput capacity model for the proposed system based on utilization factor. The analytical results based on those equations show significant improvement in throughput capacity for CR enabled multi-hop relay system.

Efficient Radio Resource Allocation for Cognitive Radio Based Multi-hop Systems (다중 홉 무선 인지 시스템에서 효과적인 무선 자원 할당)

  • Shin, Jung-Chae;Min, Seung-Hwa;Cho, Ho-Shin;Jang, Youn-Seon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.5A
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    • pp.325-338
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    • 2012
  • In this paper, a radio resource allocation scheme for a multi-hop relay transmission in cognitive radio (CR) system is proposed to support the employment of relay nodes in IEEE 802.22 standard for wireless regional area network (WRAN). An optimization problem is formulated to maximize the number of serving secondary users (SUs) under system constraints such as time-divided frame structure for multiplexing and a single resource-unit to every relay-hop. However, due to mathematical complexity, the optimization problem is solved with a sub-optimal manner instead, which takes three steps in the order of user selection, relay/path selection, and frequency selection. In the numerical analysis, this proposed solution is evaluated in terms of service rate denoting as the ratio of the number of serving SUs to the number of service-requesting SUs. Simulation results show the condition of adopting multi-hop relay and the optimum number of relaying hops by comparing with the performance of 1-hop system.

A Cognitive Radio based Multi-hop Relay Cellular Network

  • Hassan, Md. Imrul;Song, Ju-Bin;Kim, Young-Il
    • Proceedings of the IEEK Conference
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    • pp.97-98
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    • 2007
  • In this paper, we investigate the throughput capacity of a multi-hop relay network with cognitive radio (CR) enabled relay stations (RS). We suggested a TDMA/FDMA based frame structure where RSs dynamically select unused channels to communicate with the base station (BS) using CR techniques to analyze the throughput capacity. We developed the throughput capacity model for the proposed system based on utilization factor. The analytical results based on those equations show significant improvement in throughput capacity for CR enabled multi-hop relay system.

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Network Coding and Relay Selection for a Bidirectional Ship-to-Ship Relay Communication System (양방향 선박-대-선박 릴레이 통신 시스템을 위한 네트워크 부호화와 릴레이 선택)

  • Do, Thinh Phu;Jeong, Hyun Woo;Jung, Min-A;Kim, Yun Hee
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.7
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    • pp.1420-1423
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    • 2015
  • This letter considers a ship-to-ship communication system in which two ships exchange their information with the help of multiple relay ships. For the system, we propose a novel relay scheme that allows relay ships to select a method between analog network coding (ANC) and digital network coding (DNC) adaptively based on channel state information. We also provide a relay selection criterion in supporting the proposed adaptive network coding. The simulation results show that the proposed scheme outperforms the conventional scheme employing only the ANC or only the DNC.

Performance of Spectrum Sensing Using AF Cooperative Relay for Cognitive Radio System (인지 무선 통신에서 AF 협력 릴레이를 이용한 스펙트럼 센싱 성능)

  • Lee, Mi-Sun;Kim, Yoon-Hyun;Kim, Jin-Young
    • The Journal of The Institute of Internet, Broadcasting and Communication
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    • v.12 no.4
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    • pp.31-36
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    • 2012
  • In this paper, we proposed spectrum sensing using cooperative relay to solve problem of sensing performance degradation due to CPE (Customer-Premises equipments) which causes low SNR (signal-to-noise ratio) problem. In cooperative communication system, AF (amplify-and-forward) and DF (decoded-and-forward) is widely used for relay mechanism. Also, it is expected that cooperative relay scheme guarantees the high sensing performance by its diversity gain. Based on these backgrounds, in this paper, we apply to cooperative relay scheme to the CR (Cognitive Radio) system, and simulation results show comparison of the sensing performance.

Performance of Spectrum Sensing Using Cooperative Relay for Cognitive Radio System (인지 무선 통신을 위한 협력 릴레이 센싱 성능)

  • Lee, Mi-Sun;Kim, Yoon-Hyun;Kim, Jin-Young
    • Journal of Satellite, Information and Communications
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    • v.7 no.1
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    • pp.7-12
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    • 2012
  • In this paper, we proposed spectrum sensing using cooperative relay to solve problem of sensing performance degradation due to CPE (Customer-Primise equipments) which causes low SNR (signal-to-noise ratio) problem. In cooperative communication system, AF (amplify-and-forward) and DF (decoded-and-forward) is widely used for relay mechanism. Also, it is expected that cooperative relay scheme guarantees the high sensing performance by its diversity gain. Based on these backgrounds, in this paper, we apply to cooperative relay scheme to the CR (cognitive radio) system, and simulation results show comparison of the sensing performance between AF and DF.

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
    • The 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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Performance Evaluation of Co-channel Digital Radio-relay Systems (동일 채널방식을 이용한 디지털 무선 중계시스템의 성능평가)

  • 이형수;이일근
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.7 no.4
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    • pp.288-299
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    • 1996
  • The co-channel digital radio-relay system improves effectively the use of radio frequency allocations by transmitting signals separately on both orthogonal allocations, and thereby not only the total transmission capacity of frequency band but also its bandwidth effciency are almost doubled, compared tothe interleaved digital radio-relay system. Therefore, the study on the development and application of the con-channel scheme is of importance, for the efficient use of limited frequency bnad. In this paper, we derived the eqations for calculating fade margin as a function of path length as well as error performance in terms of the outage probability for co-channel digital radio-relay system below 10GHz. And, simulation was given to demonstrate how to apply those equations to the real situation.

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