• Title/Summary/Keyword: Decode-and-forward relaying system

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Outage Analysis of OFDM-Based Dual-hop Multi-Relay Systems with Best Relay Selection (최선 릴레이 선택을 적용한 OFDM 기반 이중-홉 다중 릴레이 시스템의 아웃티지 성능 분석)

  • Park, Jae-Cheol;Wang, Jin-Soo;Lee, Ji-Hye;Kim, Yun-Hee
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.5C
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    • pp.487-494
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    • 2010
  • This paper presents an OFDM-based dual-hop multi-relay system with best relay selection maximizing the mutual information. For the system either with decode-and-forward (DF) relays or with amplify-and-forward (AF) relays, we derive a lower-bound on the outage probability and the diversity order achievable in frequency selective fading channels and provide the outage capacity from simulation. Performance evaluation shows that both DF and AF provide the same diversity order as in the lower-bound but DF of which the outage probability is much closer to the lower-bound provides a better outage capacity than AF. It is also observed that the SNR gain of DF over AF gets larger as either the number of resolvable multipaths or the number of relay candidates increases, which makes DF relaying more favorable to the OFDM-based multi-relay system.

Achievable Rate Analysis for Opportunistic Non-orthogonal Multiple Access-Based Cooperative Relaying Systems

  • Lee, In-Ho;Lee, Howon
    • Journal of Information Processing Systems
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    • v.13 no.3
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    • pp.630-642
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    • 2017
  • In this paper, we propose the opportunistic non-orthogonal multiple access (NOMA)-based cooperative relaying system (CRS) with channel state information (CSI) available at the source, where CSI for the source-to-destination and source-to-relay links is used for opportunistic transmission. Using the CSI, for opportunistic transmission, the source instantaneously chooses between the direct transmission and the cooperative NOMA transmission. We provide an asymptotic expression for the average achievable rate of the opportunistic NOMA-based CRS under Rayleigh fading channels. We verify the asymptotic analysis through Monte Carlo simulations, and compare the average achievable rates of the opportunistic NOMA-based CRS and the conventional one for various channel powers and power allocation coefficients used for NOMA.

Cooperation Method for Cellular Communication Systems

  • Kim, Eung-Sun;Kim, Young-Doo;Park, Sang-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.12A
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    • pp.1251-1259
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    • 2007
  • A scheme for selecting the mode with the maximum system capacity is proposed for cooperative relaying. Three possible modes are presented based on decode-and-forward relaying, and the time required by each mode is evaluated. Based on these results, a method is then developed for selecting the optimal mode with the minimum time duration (or maximum channel capacity). Computer simulations confirm that the optimal mode outperforms the other modes.

Optimization Algorithm for Spectrum Sensing Delay Time in Cognitive Radio Networks Using Decoding Forward Relay

  • Xia, Kaili;Jiang, Xianyang;Yao, Yingbiao;Tang, Xianghong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.3
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    • pp.1301-1312
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    • 2020
  • Using decode-and-forward relaying in the cognitive radio networks, the spectrum efficiency can improve furthermore. The optimization algorithm of the spectrum sensing estimation time is presented for the cognitive relay networks in this paper. The longer sensing time will bring two aspects of the consequences. On the one hand, the channel parameters are estimated more accurate so as to reduce the interferences to the authorized users and to improve the throughput of the cognitive users. On the other hand, it shortens the transmission time so as to decease the system throughput. In this time, it exists an optimal sensing time to maximize the throughput. The channel state information of the sub-bands is considered as the exponentially distributed, so a stochastic programming method is proposed to optimize the sensing time for the cognitive relay networks. The computer simulation results using the Matlab software show that the algorithm is effective, which has a certain engineering application value.

Performance Analysis of an Opportunistic Cooperative Diversity System with Impulsive Noise in Rayleigh Fading (레일레이 페이딩하에서 임펄시브 잡음을 갖는 기회전송 협동 다이버시티 시스템의 성능해석)

  • Kim, Nam-Soo
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.6
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    • pp.99-105
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    • 2010
  • The most frequently used noise model for the performance analysis of a communication system is additive white Gaussian noise. However impulsive noise model is more practical for the real communication environments, currently the performance analysis of a communication system in impulsive noise is increasing. In this paper, therefore, the performance of a cooperative system, which is recently one of the most intensive research topics, is derived in impulsive noise. We analytically derive and compare the performance of two opportunistic cooperative diversity systems which have an amplify-and-forward (AF) relaying or a decode-and-forward (DF) relaying. It is noticed that the impulsive noise component is increases with decreasing the average number of impulses in impulsive noise, consequently the performance of two systems is degraded in high SNR region. Also it is shown that the performance of the opportunistic cooperative system with DF relaying is superior to that with AF relaying.

Cooperative Communication Transmission Scheme using Partially Differential Modulation (부분차등변조 방식을 이용한 협력통신 전송기법)

  • Cho, Woong
    • The Journal of the Korea institute of electronic communication sciences
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    • v.9 no.7
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    • pp.805-810
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    • 2014
  • Cooperative communication, which transmit signal via arbitrary number of relays, enhances the overall communication performance by providing virtual Multi-Input Multi-Output (MIMO) gain without imposing multiple antennal limitation in physical system. There are two representative relaying protocols, i.e., Amplify-and-Forward (AF) and Decode-and-Forward (DF), where we analyze the performance of cooperative communication by adopting DF relaying protocol applying partially differential modulation. The performance is based on symbol error rate (SER), and the effect of relay location on the performance is analyzed. We also compare the performance of the proposed scheme with the system which uses differential modulation scheme.

Determination of Effective Relay Candidates for the Best Relay Selection in Wireless Systems in the Presence of Interference (간섭이 존재하는 무선 시스템에서 최적의 중계 노드 선택을 위한 효과적인 중계 노드 후보 결정 방법 연구)

  • Lee, In-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.12
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    • pp.2812-2817
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    • 2013
  • In this paper, an outage probability for the best relay selection in decode-and-forward relaying systems in the presence of interference is analyzed over Rayleigh fading channels. Based on the outage performance results, we propose a method to determine effective relay candidates for the best relay selection, where the effective relay candidates represent the relays except for relays that make no contribution to improving the performance. in all possible relays given in the system. By determining the effective relay candidates, the feedback overhead of channel state information and the energy consumption of relays can be significantly reduced while minimizing the performance degradation. In this paper, we provide important parameters that affect the determination of the effective relay candidates.

Sum Transmission Rate Maximization Based Cooperative Spectrum Sharing with Both Primary and Secondary QoS-Guarantee

  • Lu, Weidang;Zhu, Yufei;Wang, Mengyun;Peng, Hong;Liu, Xin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.5
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    • pp.2015-2028
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    • 2016
  • In this paper, we propose a sum transmission rate maximization based cooperative spectrum sharing protocol with quality-of-service (QoS) support for both of the primary and secondary systems, which exploits the situation when the primary system experiences a weak channel. The secondary transmitter STb which provides the best performance for the primary and secondary systems is selected to forward the primary signal. Specifically, STb helps the primary system achieve the target rate by using a fraction of its power to forward the primary signal. As a reward, it can gain spectrum access by using the remaining power to transmit its own signal. We study the secondary user selection and optimal power allocation such that the sum transmission rate of primary and secondary systems is maximized, while the QoS of both primary and secondary systems can be guaranteed. Simulation results demonstrate the efficiency of the proposed spectrum sharing protocol and its benefit to both primary and secondary systems.

Impact of Power Control Optimization on the System Performance of Relay Based LTE-Advanced Heterogeneous Networks

  • Bulakci, Omer;Redana, Simone;Raaf, Bernhard;Hamalainen, Jyri
    • Journal of Communications and Networks
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    • v.13 no.4
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    • pp.345-359
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    • 2011
  • Decode-and-forward relaying is a promising enhancement to existing radio access networks and is already standardized in 3rd generation partnership project (3GPP) as a part of long term evolution (LTE)-Advanced Release 10. Two inband operation modes of relay nodes are supported, namely type 1 and type lb. Relay nodes promise to offer considerable gain for system capacity or coverage, depending on the deployment prioritization, in a cost-efficient way. Yet, in order to fully exploit the benefits of relaying, the inter-cell interference which is increased due to the presence of relay nodes should be limited. Moreover, large differences in the received power levels from different users should be avoided. The goal is to keep the receiver dynamic range low in order to retain the orthogonality of the single carrier-frequency division multiple access system. In this paper, an evaluation of the relay based heterogeneous deployment within the LTE-Advanced uplink framework is carried out by applying the standardized LTE Release 8 power control scheme both at evolved node B and relay nodes. In order to enhance the overall system performance, different power control optimization strategies are proposed for 3GPP urban and suburban scenarios. A comparison between type 1 and type 1b relay nodes is as well presented to study the effect of the relaying overhead on the system performance in inband relay deployments. Comprehensive system level simulations show that the power control is a crucial means to increase the cell edge and system capacities, to mitigate inter-cell interference and to adjust the receiver dynamic range for both relay node types.

Outage Analysis of Cooperative Transmission in Two-Dimensional Random Networks over Rayleigh Fading Channels

  • Tran, Trung Duy;Kong, Hyung-Yun
    • Journal of electromagnetic engineering and science
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    • v.11 no.4
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    • pp.262-268
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    • 2011
  • In this paper, we evaluate the outage performance of cooperative transmission in two-dimensional random networks. Firstly, we derive the joint distributions of the source-relay and the relay-destination links. Secondly, the outage probability for the decode-and-forward relaying system is derived when selection combining (SC) is employed at the destination. Finally, we calculate the average outage probability of the system and then attempt to express it by a simple approximate expression. The simulation results are presented to verify the accuracy of the derivations. Similar to deterministic networks, the cooperative transmission in random networks outperforms direct transmission at a high signal-to-noise ratio (SNR).