• Title/Summary/Keyword: 증폭-후-전달

Search Result 32, Processing Time 0.017 seconds

Performance Comparison of Relay Selection-Based Amplify-and-Forward Relaying Systems using Full or Partial Channel Information (전체 채널 정보와 부분 채널 정보를 이용하는 중계 노드 선택 기반 증폭 후 전달 중계 시스템의 성능 비교)

  • Lee, In-Ho
    • The Journal of The Korea Institute of Intelligent Transport Systems
    • /
    • v.11 no.6
    • /
    • pp.70-80
    • /
    • 2012
  • In this paper, we consider the amplify-and-forward relaying systems with the relay selection (AF-RS) using full channel information (FCI) and using partial channel information (PCI), respectively, in which the direct communication link between a source and a destination is available. And, the outage probabilities for the AF-RS using FCI and using PCI are investigated in Rayleigh fading channels, respectively. We provide exact outage probabilities, tight outage probability lower bounds, and asymptotic outage probabilities, respectively. And also, we present coding gains achievable by the AF-RS using FCI and using PCI. Through numerical investigation, all the analytic expressions are verified, and the coding gains are respectively evaluated with different average channel powers for the first and the second hop as well as different numbers of relays.

New Analytical Approach for Dual-hop AF Relay systems over Rayleigh Fading Channels (레일리 페이딩 채널에 대한 이중 홉 증폭 후 전달 릴레이 시스템의 새로운 분석 기법)

  • Ko, Kyun-Byoung;Seo, Jeong-Tae
    • Journal of the Institute of Electronics Engineers of Korea TC
    • /
    • v.48 no.8
    • /
    • pp.1-6
    • /
    • 2011
  • In this paper, another analytical approach for dual-hop amplify-and-forward(AF) relay systems is proposed over Rayleigh fading channels. Previous approaches derived the moment generating function(MGF) by using the cumulative distribution function(CDF) or probability density function(PDF) of the received signal-to-noise ratio(SNR) for source-relay-destination(S-R-D) link. Then, the average symbol error rate is expressed based on derived MGFs. In this paper, another new approach is proposed. It means that the MGF is directly derived by utilizing PDFs of both source-relay(S-R) and relay-destination(R-D) links. Additionary, the newly derived MGF is compared and analyzed with previous ones. Furthermore, simulation results are presented to validate the accuracy of proposed analytical expression. Based on this, it is confirmed that the proposed analytical approach can be a another solution for dual-hop AF relay systems.

A Low Complexity Subcarrier Pairing Scheme for OFDM Based Multiple AF Relay Systems (OFDM 기반 다중 증폭 후 전달 릴레이 시스템에서 낮은 복잡도를 가지는 부반송파 페어링 기법)

  • Jeon, Eun-Sung;Yang, Jang-Hoon;Kim, Dong-Ku
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.34 no.1A
    • /
    • pp.12-17
    • /
    • 2009
  • We consider an OFDM based multiple AF relaying systems. Since the channel between first hop (source station-relay station) and second hop (relay station -destination station) varies independently, the subcarrier in the first hop can be paired to another subcarrier in the second hop for the increase of the system capacity. The conventional pairing which uses the brute force searching requires large complexity while giving optimal pairing for maximum system capacity. In this paper, we present sub-optimal subcarrier pairing scheme with low complexity. Every RS firstly pairs the subcarrier with the highest channel gain in the first hop to the subcarrier with highest channel gain in the second hop. The pair with the highest SNR among all the pairs is determined as final selected pair and the corresponding subcarriers are not selected at other RSs in the next paring iteration. This process is repeated until all the subcarriers are paired. Simulation results show the proposed pairing scheme achieves near optimal performance with low complexity.

MMSE-Based Relaying Method for Multiuser Bidirectional Communications (여러 사용자 양방향 통신을 위한 MMSE-기반 중계 기법)

  • Joung, Jin-Gon
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.34 no.5A
    • /
    • pp.408-413
    • /
    • 2009
  • In this paper, minimum mean-square-error (MMSE)-based transceiver processing of a bidirectional amplify-and-forward (AF) relay having multiple antennas is proposed. Besides, the optimal beamforming vectors of users are designed in the sense of the sum rate maximization. Simulation results show that the proposed relay processing can effectively reduce both co-channel interferences and self-interferences and that the proposed beamforming method is proper to the bidirectional communication employing the AF relay.

Optimal Power Splitting for Wireless Energy and Information Transfer in Amplify-and-Forward Two-Way Relaying (증폭-후-전달 양방향 릴레이에서 무선 에너지 정보 전송을 위한 최적 전력 분할)

  • Do, Thinh Phu;Kim, Yun Hee
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.41 no.2
    • /
    • pp.175-177
    • /
    • 2016
  • This letter considers wireless energy and information transfer for an amplify-and-forward two-way relay network. When the relay harvests the energy and transfers the information signal through power splitting, the optimal power splitting minimizing the outage probability is derived explicitly and its gain is confirmed by simulations.

Layer Selective Cooperation Using Superposition Coding for Reduction of Expected Distortion (평균 왜곡 감소를 위한 중첩 부호화 기반 레이어 선택적 협력 전송)

  • Wang, Jin-Soo;Park, Jin-Bae;Kim, Yun-Hee
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.37 no.7B
    • /
    • pp.517-527
    • /
    • 2012
  • This paper considers a cooperative communication system with a single relay node, where two-layer superposition coding and successive decoding is employed to reduce the expected distortion of a Gaussian source delivered. For the system, we propose a relay scheme which forwards an appropriate relay signal at the relay node, based on the local decoding result of layers and the decoding result of layers at the destination node fed back to the relay node. In the scheme, the relay signal is designed not only by applying decode-and-forward but also by applying amplify-and-forward to reduce the outage probability in final decoding of each layer. The performance of the proposed scheme is evaluated numerically in terms of the expected distortion at various relay locations using outage probabilities derived. The results show that the proposed scheme outperforms the conventional schemes in most cases of the relay location and the gain gets larger when the relay node is closer to the source node in particular.

Trend of IEEE 802.16 Mobile Multi-hop Relay (IEEE 802.16 MMR 동향)

  • Kim, Y.I.;Shin, J.C.;Cho, H.S.;Ahn, J.H.;Hwang, S.K.
    • Electronics and Telecommunications Trends
    • /
    • v.21 no.3 s.99
    • /
    • pp.91-99
    • /
    • 2006
  • 중계기(relay station)는 기존의 이동통신 시스템에서 음영 지역 해소를 위해 도입되어 현재 사용중인 기술이다. 중계기 기술은 단순히 증폭 후 전달(amplify-and-forward)방식에서 디코딩 후 전달(decode-and-forward), 재구성/재조합 후 전달(reconfiguration/reallocation-and-forward) 등 지능화된 형태로 진화하고 있다. 특히, 차세대이동통신 시스템에서 지능화된 다수의 중계기 도입은 기지국 증설 비용과 백홀(backhaul) 통신망의 유지 비용을 줄이는 동시에 커버리지 확대와 데이터 처리율 향상을 위해 불가피할 것으로 예상된다. 이에 본 고에서는 중계기 방식과 종류 등 일반적인 사항에 대해 살펴보고, 최근 표준화 활동이 시작되어 이슈화되고 있는 IEEE 802.16MMR의 동향에 관해 기술한다.

Performance Bounds of an Amplify-and-Forward Relay System with Multiple Rayleigh-faded Co-channel Interferers (레일리 페이딩을 겪는 다중 간섭 채널 환경에서 증폭-후-전달 릴레이 시스템의 성능 한계)

  • Ryu, Hyun-Seok;Kang, Chung-G.
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.37 no.2B
    • /
    • pp.87-96
    • /
    • 2012
  • In this paper, we consider a 2-hop relay system where both the relay and destination nodes suffer from the arbitrary number of co-channel interferers. More specifically, assuming that the relay and access channels as well as interference channels are all subject to Rayleigh fading, we derive an exact closed-form expression for outage probability of the amplify-and-forward (AF) relay system, and furthermore compute its upper and lower bounds. Based on these bounds, we derive the upper and lower bounds on the average bit error rate (BER) of the AF relay system. We also confirm the accuracy of our derivation by investigating the performance gap between the performance bounds under consideration and simulation results.

Joint Channel estimation in Asynchronous Amplify-And-Forward Relay Networks based on OFDM signaling (OFDM 신호를 이용한 비동기식 증폭 후 전달 중계망에서의 결합 채널 추정)

  • Yan, Yier;Jo, Gye-Mun;Balakannan, S.P.;Lee, Moon-Ho
    • Journal of the Institute of Electronics Engineers of Korea SC
    • /
    • v.46 no.1
    • /
    • pp.55-62
    • /
    • 2009
  • In this paper, we propose a method on the training sequence based on channel estimation issues for relay networks that employ amplify-and-forward(AF) transmission scheme. In $^{[1]}$ and $^{[2]}$, we have to point out that jointly estimating the channel from source to relay and from relay to destination suffers from many drawbacks in fast fading case because the estimation of previous pilots is not suitable for current channel. In this paper, we consider a new joint estimation of overall channel impulse response(CIR) using one OFDM signal without pilots. Using the maximum likelihood(ML) function, we derive a channel estimator by taking the frequency domain of transmitted signal as Gaussian and averaging the ML function over the resulting Gaussian distribution. Simulation results show that our proposed channel estimator performs a fraction of 1dB compared with $^{[1]}$ in high SNR region.

Design of Amplify-and-Forward Helper Stations for Cellular Networks with Device-to-Device Links (단말 간 직접 통신을 포함하는 셀룰러 망을 위한 증폭 후 전달 방식 조력국의 설계 방법)

  • Chung, Jihoon;Kim, Donggun;Sung, Youngchul
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.41 no.5
    • /
    • pp.539-545
    • /
    • 2016
  • In this paper, the use of an amplify-and-forward (AF) helper station in a cellular network with device-to-device (D2D) communication links is considered to enhance D2D rates and control the interference caused by D2D users to the cellular network. Two design criteria for the AF helper station are considered to improve the overall system quality-of-service (QoS). One is maximization of the worst D2D user rate under a constraint on interference caused by D2D users to the cellular network and the other is its dual, i.e., minimization of interference caused by D2D users to the cellular network with minimum rate guarantee for each D2D user. It is shown that the considered problems reduce to semi-definite programming (SDP) problems. Numerical results show that the proposed AF helper station significantly improves the system performance.