共查询到19条相似文献,搜索用时 62 毫秒
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由于信道情况差的中继对协作贡献小,且消耗额外的能量,基于某种标准选择出一个或者多个好的中继参加协作,可以提高协同通信系统性能,所以中继选择是协同通信系统的研究热点。针对一个发送端、接收端及每个中继都配置单根天线的无线中继网络,在假设发送方不知道信道信息而接收方已知全部信道信息前提下,本文提出了中继未知任何信道信息时的中继选择方案。首先提出基于信噪比最大的单中继选择方案,推导了单中继选择的成对错误概率表达式;其次提出基于中继排序方法的多中继选择方案,推导了选择2个中继的成对错误概率的下界;最后给出了仿真结果。理论与仿真结果都表明,中继未知任何信道信息的情况下,选择2个中继参加协作的系统错误概率却高于单中继选择。 相似文献
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将中继协作技术用于认知无线电网络可有效对抗信道衰落,提高频谱利用率,然而如何选择中继协助源节点传输信息是一个亟待解决的问题。该文根据多中继协作时目的节点信噪比的一阶偏导数特征,定义了中继协作效率,设计了基于协作效率的迭代中继选择方案。考虑到认知中继网络的非集中式结构,该文将虚拟计时器引入中继节点,提出了基于迭代中继选择方案的分布式算法,通过各中继基于协作效率的虚拟倒计时及信息交互实现了分布式迭代中继选择。复杂度分析和数值仿真结果表明,该算法复杂度较低,且性能接近最优解。 相似文献
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针对多源多中继协作网络模型,提出一种公平的节点选择与用户调度方案。出于优化平均信道质量的思想,每个传输时隙,选择信道条件差异最大的两个用户同时进行传输信息。中继节点选择基于PF比例公平调度算法,能保证中继节点处的负载均衡。然后在中继端采用一种网络编码传输方案。最后,与其他2种调度方案相比较仿真系统的误码率性能。 相似文献
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为了优化译码转发(DF)协同通信系统的网络生存时间,提出一种基于信道状态信息(CSI)和剩余能量信息(REI)的动态多中继选择算法,该算法根据信道-能量函数和信道容量增益门限选择协同中继节点。仿真结果表明,对中继功率进行动态分配时,该算法选择四个中继可使系统性能达到最优。当中继节点数为4时,与仅基于CSI的中继选择算法相比,该算法能延长网络生存时间最高达75%。 相似文献
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提出了一种中继蜂窝网络的基于负载均衡的中继节点选择策略(Load Balancing Relay Selection,LB-Rs).根据每个用户的具体信道状况以及中继节点服务的用户数目,LB-RS以分布式的方式为每个用户选择最优的中继节点.仿真结果表明,与基于单一物理层参数的中继节点选择算法相比,所提出的中继选择算法综... 相似文献
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提出了一种放大转发网络中的中继选择方案,假设目的节点配置多个天线,源节点和所有中继节点都配置单个天线,方案选择一组中继同时在相同的频带上放大转发接收到的源节点信息以最大化接收信噪比。与只择一个最优中继的方案相比,方案在保持满分集阶数的情况下获得了更高的中断容量和更优的误符号率性能。与只选择一个最优中继的方案相比,在0.000 01的误符号率水平上,少需要发射功率1.6 dB。 相似文献
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提出了一种协作中继网络的交互式中继节点选择(IRS)策略。用户首先分布式构造基于信道状况及中继节点负载情况的中继选择函数,选择最优的中继节点;中继节点再根据资源分配情况、业务优先级以及加权信道调度算法进行反向用户选择。仿真结果表明,相比于已研究的算法,所提出的IRS算法结合了信道状况、MAC层资源与用户业务状况等因素,利用用户和中继之间的两步式交互中继选择来调节小区内的用户负载分布,获得了小区吞吐量与用户公平性之间的折衷。 相似文献
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Bin Han Wenbo Wang Zhongyuan Zhao Mugen Peng 《International Journal of Communication Systems》2014,27(5):763-775
In this paper, we propose an Nth best relay selection (Nth‐RS) scheme for analog network coding in two‐way relay systems. In traditional two‐way single‐relay selection schemes, only the best one is selected to forward network‐coded signals. However, in practical applications, the best relay may be unavailable because of the scheduling or overload constraints. In this case, we investigate a more general scheme, where the Nth best but available relay is selected. To evaluate the transmission of reliability, the expression of outage probability in exponential–integral form and its asymptotic expression in closed form are presented. Moreover, the upper bound and lower bound of outage probability are also derived. The analysis reveals that the diversity order of Nth‐RS equals to (M ? N + 1), where M is the number of relay nodes, and the results are verified by simulations. In order to improve system performance, transmit power between sources and relay is optimally allocated to minimize the upper bound of outage probability under total power constraint. Simulation results show that Nth‐RS scheme with proposed power allocation can achieve substantial improvement over equal power allocation scheme. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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研究了Nakagami信道中联合网络编码和双向协作中继选择的中断与平均误码率的性能,基于3个时隙的网络编码方案提出了一种最小化较差用户误码率的协作中继选择策略。在Nakagami信道下,从双向通信的角度,通过理论分析得出其中断概率和平均误码率的解析式和渐近式,同时推导了无协作中继选择时网络编码的中断概率和平均误码率解析式。通过理论分析发现,当Nakagami信道衰落参数降低时,联合网络编码的协作中继选择方案相对于无协作中继选择时的性能增益将逐渐升高。数值仿真实验结果表明,所提策略的平均误码率性能要显著高于无协作中继选择时的网络编码性能。 相似文献
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MIKKO Valkama 《中国邮电高校学报(英文版)》2011,18(6):51-58
Systems are always designed and optimized based on full traffic load in the current literatures.However,practical systems are seldom operating at full load,even at peak traffic hours.Instead of maximizing system rate to achieve the full load,an optimal energy-efficient scheme to minimize the transmit power with required rates is investigated in this article.The considered scenario is a two-way relay channel using amplify-and-forward protocol of physical layer network coding,where two end nodes exchange mess... 相似文献
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DING Yi LIU Yuan-an XIE Gang DENG Pan-liang LI Xing-zheng .School of Electronic Engineering Beijing University of Posts Telecommunications Beijing China .School of Information Communication Engineering China .Key Laboratory of Universal Wireless Communication Ministry of Education China .China Mobile Group Design Institute Co. Ltd Beijing ... 《中国邮电高校学报(英文版)》2011,(4):45-51
In this paper,we consider the joint relay selection and power allocation problem for two-way relay systems with multiple relay nodes.Traditionally,relay selection schemes are primarily focused on selecting one relay node to maximize the transmission sum rate or minimize the outage probability.If so,it is possible to cause certain relay nodes overloaded.In addition,the joint relay selection and power allocation problem is a mixed integer program problem and prohibitive in terms of complexity.Therefore,we pro... 相似文献
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针对负载失衡或热点覆盖无线中继网络,提出一种基于负载均衡的自适应中继选择和频谱转移联合优化策略。定义了一种衡量一个站点对周围同频站点干扰程度的干扰容量,为某站点对其他站点的干扰提供了量化分析指标。当用户申请接入时,首先根据各条链路的信道状况选择首选接入站点和备选接入站点,当首选接入站点负载过重而无足够资源使其接入时,对接入备选站点和从与首选站点同扇区的其他站点向首选站点进行频谱转移的性能进行比较,选择一种维持系统性能较好的方式接入。仿真结果表明,所提算法在中心小区的频谱效率和阻塞率都优于单一的基于负载均衡的中继选择策略和单一的基于负载均衡的频谱转移策略,并且平均干扰容量也最低,对周围小区的系统性能影响较小。 相似文献
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This article addresses the design problem of selecting an appropriate relay in amplify-and-forward(AF) cooperative diversity systems.In this regard,this article focuses on relay selection based on partial channel knowledge only across the source and relay links.In particular,the two fundamental questions will be answered,that is,whether to cooperate and whom to cooperate with.Through answering these two questions,an improved relay selection strategy based on partial relay link,which emphasizes that cooperat... 相似文献
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Haiquan Wang Baofeng Zhao Lei Hong 《International Journal of Communication Systems》2016,29(5):977-991
For a relay network system with amplify and forward protocol, in this paper, analysis of performance is conducted, and an upper bound of pairwise error probability is obtained. Moreover, a scheme of relay selection is analyzed under assumptions that (i) the relays amplify and forward received signals without any signal processing; (ii) the receiver only knows channel state information from the relays to the receiver; and (iii) the transmitter and the relays do not have any channel state information. Based on the upper bound, a criterion of designing codebook is proposed. Surprisingly, this bound shows that increasing the number of relays can hardly improve performance. Furthermore, the error probability is decreasing with a speed of P?1, no matter how large the relay number is, where P is the total energy. Also, for the relay selection, the optimal selecting way is to select only one relay with the largest channel gain, which is very different from existing schemes. These results are all confirmed by simulations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献