共查询到16条相似文献,搜索用时 78 毫秒
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非对称信道下协作通信系统中断概率的研究 总被引:1,自引:0,他引:1
首先建立了非对称信道下协作系统的数学模型,考虑了源节点到目的节点的直通链路,利用特征函数法推导出协作系统的平均中断概率公式,通过仿真验证了该中断概率公式的精确性,理论和仿真都表明协作系统的中断概率和中继节点的个数、位置分布以及协作系统的功率分配因子有着密切关系,并且考虑源到目的节点的直通链路相对于不考虑直通链路的情况具有更高的性能增益;然后又在此公式基础卜就协作系统中继节点的位置分布对最优功率分配因子的影响进行了仿真分析,并指出协作系统的最优功率分配因子受制于中继节点的位置分布情况. 相似文献
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自由空间光通信(FSOC)具有通信容量大、信息传输快等优点,在未来大数据时代中有着巨大的应用价值。激光作为携带信息的载波,在大气中传输时受到大气湍流的严重影响,会使光通信系统的稳定性和可靠性得不到保证。文中研究了在斜路径信道上,自由空间光通信系统的中断概率受大气湍流的影响,数值模拟分析了平面波、球面波和高斯波为信息载波时,大气湍流强度、内尺度和外尺度、传输距离、天顶角、波长等参数对FSOC系统中断概率的影响机理。研究结果可以为将来实现全光网络设计自由空间光通信系统提供有益的理论参考。 相似文献
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针对分布式MIMO系统中断概率和信道容量这2大性能指标,在复合衰落信道模型下,当上行链路采用最大比发送—选择合并,下行链路采用选择发送—最大比合并时,利用Lognormal分布对复杂Gamma-Lognormal分布的近似,推导得到当移动台位置给定时,系统中断概率和信道容量的闭合表达式,证明了系统性能指标与移动台分布之间存在密切的联系;随后依照实际通信环境,提出一种考虑存在小区热点的移动台非均匀分布模型,然后推导得到考虑该分布模型后的系统平均中断概率和平均信道容量闭合表达式;最后通过计算机仿真,证明了所提近似处理的精确性以及各项理论分析的合理性。 相似文献
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为充分提高通信网络的频谱效率,异构网络采用多个微小基站同时在相同频段上支持用户数据传输的方式;为保障系统通信效能,需要有效控制不同数据接口上信号之间存在的相互干扰。提出了采用资源分配方法利用通信中断概率作为衡量不同微小基站数据分支通信性能的准则,通过将中断概率约束条件有效近似,从而使原复杂矩阵优化问题转换为基于标量的几何规划问题,进而极大地降低计算复杂度。数值仿真结果验证了所提方法的有效性。 相似文献
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针对复合衰落信道模型下分布式MIMO系统下行中断概率问题,首先建立了一个综合考虑Nakagami-m衰落、路径损耗和阴影衰落的复合衰落信道模型;然后针对存在中心基站的分布式MIMO系统,提出了一种更符合实际应用环境的准均匀小区移动台分布模型;接着利用矩生成函数、Gauss-Hermite积分公式和Simpson积分公式等数学手段推导了任意移动台分布下、单小区内系统平均下行中断概率闭合表达式;最后将准均匀移动台分布模型应用到该中断概率闭合表达式,并通过MATLAB仿真证明了所推导得到的闭合表达式及小区分布模型的合理性。 相似文献
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在LTE系统中引入设备直传(D2D)通信技术,会因为D2D用户复用蜂窝用户资源进行通信而产生同频干扰.在现有的干扰协调与资源分配研究中,都需要基站获取各个通信链路的信道状态信息(CSI),但这样无疑会增加基站的信令负担.为减小干扰与基站的信令负担,提出了一种基于用户中断概率的干扰协调与资源分配算法,首先在保证蜂窝用户正常通信的情况下,通过限制D2D用户到基站间的距离来降低干扰;其次通过遍历所有蜂窝用户的频谱资源,选择能使D2D用户的总中断概率最低的频谱资源进行复用.仿真结果表明,所提算法能够在保证蜂窝用户正常通信的情况下,明显降低D2D用户的平均中断概率,同时还能够降低基站信令负担. 相似文献
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针对存在有信道估计误差的正交频分多址( OFDMA)中继系统,在考虑用户传输中断概率的同时,提出了满足不同用户最小服务质量( QoS)需求和比例公平性约束条件下的中继选择、子载波分配和功率分配的联合优化问题,建立了以最大化系统总容量为目标的优化模型。在此基础上以速率最大化为目标进行最佳中继选择,并通过动态子载波分配来满足用户的最小QoS需求和比例公平性,最后采用拉格朗日乘子法来得到最优功率分配方案。仿真结果表明,此算法在降低用户中断概率的同时,提高了系统吞吐量并保证了用户速率的比例公平性。 相似文献
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An amplify-and-forward (AF) based multi-relay network is studied. In order to minimize the system outage probability with a required transmission rate, a joint power allocation (PA) and multi-relay selection scheme is proposed under both total and individual power constraints (TIPC). In the proposed scheme, the idea of ordering is adopted to avoid exhaustive search without losing much system performance. Besides the channel quantity, the ordering algorithm proposed in this article also takes relays' maximal output ability into consideration, which is usually ignored in traditional relay ordering algorithms. In addition, simple power reallocation method is provided to avoid repetitive PA operation during the process of searching all possible relay subsets. By Adopting the idea of ordering and using the proposed power reallocation method lead to remarkable decrease of the computation complexity, making the scheme easier and more feasible to implement in practical communication scenarios. Simulations show that the proposed multi-relay selection scheme provides similar performance compared to the optimal scheme with optimal PA and exhaustive search (OPAES) but with much lower complexity. 相似文献
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In this article, an exact closed-form expression is derived for outage probability of decode-and-forward (DF) cooperative communications over independent identically distributed Nakagami-m fading channels. Simulation results verify that the theoretical expressions for the outage probability are correct. The optimal power allocation based on the derived outage probability is also studied. 相似文献
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This paper investigates the performance of an underlay cognitive relay system where secondary users(SUs) suffer from a primary outage probability constraint and spectrum-sharing interference imposed by a primary user(PU). In particular, we consider a secondary multi-relay network operating in the selection decode-and-forward(SDF) mode and propose a best-relay selection criterion which takes into account the spectrum-sharing constraint and interference. Based on these assumptions, the closed-form expression of the outage probability of secondary transmissions is derived. We find that a floor of the outage probability occurs in high signal-to-noise ratio(SNR) regions due to the joint effect of the constraint and the interference from the PU. In addition, we propose a generalized definition of the diversity gain for such systems and show that a full diversity order is achieved. Simulation results verify our theoretical solutions. 相似文献
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Herein, we consider an underlay cognitive radio network (CRN) where mobile secondary user wishes to transmit a confidential information to the secondary destination in the presence of an illegitimate eavesdropper which is trying to steal the classified message signal. The proposed scenario can be viable for a secondary safety task force working with a primary regiment, which wishes to transmit the confidential information to the commander while an eavesdropper is trying to intercept the classified information. In the analysis, two novel power allocation methods are considered by assuming perfect and limited feedback channels of the primary network, and for both methods, exact and asymptotic expressions of secrecy outage probability (SOP) are derived for N*Nakagami‐m fading channels which are used to model fading channels such as mobile‐to‐mobile/vehicle‐to‐vehicle communication systems where the nodes are moving into a rich scattering environment. We further verified our analytic results through Monte‐Carlo simulations. It is shown from the numerical results that the cascading degree of the channels has a worsening effect on the secrecy outage performance of the CRN systems. 相似文献