共查询到18条相似文献,搜索用时 140 毫秒
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多输入多输出(MIMO)技术应用于移动通信系统中可以提高频谱利用率,增加通信系统的容量.提高用户传输速率,因此,该技术已经成为后3G的关键技术之一。其信道容量不仅和通信环境有关。而且和阵元间信道响应的相关系数有很大的关系。为了对设计的MIMO系统进行评估,则需对其性能进行测试。提出了根据测试相关系数,间接得出信道传输矩阵H的方法。并在实验室环境下,以多天线系统为例。通过采集试验数据。对相关系数做了分析计算。 相似文献
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一种多用户多中继MIMO通信系统迭代预编码方案 总被引:1,自引:0,他引:1
该文针对多中继MIMO通信系统多用户传输时的用户间干扰问题,提出了一种可以有效抑制多用户干扰的发射端与中继端迭代预编码的方案。该方案首先在中继端进行多中继联合的迫零预编码,然后将基站与多用户之间等效为一个点到多点的MIMO信道,采用最大化信漏噪比的预编码方法,在发射端进一步消除用户间的干扰,同时避免了噪声放大的影响,进而通过中继端预编码与发射端预编码的多次迭代,更好地保持了多中继并行传输引入空间分集所带来的性能优势,有效地抑制了用户间干扰,获得了更高的系统和容量。 相似文献
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干扰对齐技术是解决无线通信系统中同频干扰的重要手段,与传统干扰管理方法相比可获得更大的信道复用增益,提高系统容量。基于工程应用实现的考虑,重点研究了多小区MIMO系统中干扰对齐技术的实现,对求闭式解的经典算法和分布式迭代典型算法在系统容量、收敛性等方面的性能进行了分析比较。针对未来Massive MIMO技术的应用,同时仿真分析了算法在空间相关信道下性能,并分析总结了算法的适用情况。仿真结果表明,基于矩阵投影距离的分布式迭代干扰对齐算法综合性能最优,且具有更好的工程适用性。 相似文献
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本文针对由一条授权通信链路和多条次用户干扰信道组成的认知多输入多输出(Multiple Input Multiple Output,MIMO)系统,首先提出了基于信号子空间的认知干扰对齐迭代优化算法,并且利用单调有界理论证明了该算法可以收敛到稳定点。为了进一步提升系统的和速率性能,提出了一种联合信号子空间和功率分配的增强认知干扰对齐算法。该算法通过在每个次用户的多个数据流之间进行自适应功率分配,解决了次用户的有用信号空间中总是有残余的干扰信号的问题。数值仿真结果表明,相对于传统的认知干扰对齐算法,所提的算法能够获得较为明显的性能提升。 相似文献
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考虑到无线电频谱资源日益紧缺,提出了一种基于组间组内协作传输的多播组新机制,涉及多个多播组并使用同一频谱资源以协作方式传输信息。基于认知无线网络中该机制,研究了系统的资源优化配置,理论分析得出了功率分配方案,进而讨论了系统加权总传输速率的优化,同时考虑了主用户和认知用户之间信号干扰及功率限制对传输速率的影响,最优化用户性能。仿真结果表明,优化方案下多播组传输速率随用户人数的增加而上升,达到最优化用户服务质量;当功率限制时,通过设置加权因子,能够保证主用户拥有良好的通信性能。 相似文献
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为实现认知多输入多输出(MIMO)系统中主次用户的高效频谱共享,提出一种基于部分投影的干扰抑制算法,该算法将主用户的空间传输特性引入次用户的设计中。分析了干扰的结构化特征,指出泄漏到主用户空闲维度上的次用户信号并非有害干扰。通过将次用户发射信号投影到干扰信道低维子空间的零空间上即可消除干扰。理论分析和仿真表明,算法在有效消除对主用户干扰的同时,次用户传输速率和算法适用性相比传统算法都有显著提升。 相似文献
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针对多个主用户和多个次用户的MIMO认知网络,本文给出了一种不依赖信道互惠性和不需要前后向链路交替式迭代的干扰对齐方法。对于次用户,首先,通过对其进行编码,建立了消除主次用户间相互干扰后的等效模型。然后,在等效模型的基础上,以最大化总容量为目标函数设计预编码矩阵,并采用基于Grassmann流形上的梯度法对目标函数进行求解得到预编码。最后,在接收端以最大信干噪比准则来设计接收滤波器矩阵。仿真结果显示,在低信噪比时,本文算法与现有典型算法性能相同,而在高信噪比时本文算法性能更优。 相似文献
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This article investigates a multiuser cognitive environment where secondary users compete to communicate over a channel licensed to a primary user using spectrum sharing. In this environment, both the primary and secondary users transmit to the same receiver unit, and the transmission power of the scheduled secondary user should satisfy the outage probability requirement of the primary user. Secondary users are ranked according to their channel strength, and performance measures are derived as a function of a generic channel rank. Bit error rate, channel capacity, and generated interference are investigated as performance measures. In addition, the performance of the proportional fair, random selection, and round-robin scheduling algorithms are investigated. Numerical results are presented to verify the theoretical analysis and investigate the effects the parameters of the communication environment have on the performance measures and the transmission power of the cognitive users. 相似文献
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Lun Tang Qianbin Chen Guangyu Wang Xiaoping Zeng Huan Wang 《Telecommunication Systems》2013,52(4):2071-2082
In this paper we have studied the subcarrier and optimal power allocation strategy for OFDM-based cognitive radio (CR) networks. Firstly, in order to protect the primary user communication from the interference of the cognitive user transmissions in fading wireless channels, we design an opportunistic power control scheme to maximize the cognitive user capacity without degrading primary user’s QoS. The mathematical optimization problem is formulated as maximizing the capacity of the secondary users under the interference constraint at the primary receiver and the Lagrange method is applied to obtain the optimal solution. Secondly, in order to limit the outage probability within primary user’s tolerable range we analyze the outage probability of the primary user with respect to the interference power of the secondary user for imperfect CSI. Finally, in order to get the better tradeoff between fairness and system capacity in cognitive radio networks, we proposed an optimal algorithm of jointing subcarrier and power allocation scheme among multiple secondary users in OFDM-based cognitive radio networks. Simulation results demonstrate that our scheme can improve the capacity performance and efficiently guarantee the fairness of secondary users. 相似文献
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In this paper, we consider a cognitive cooperative wireless system consisting of two primary users, a cognitive base station (CBS) and a secondary user. A cognitive two-way relaying (CTWR) scheme is proposed, where the secondary user tries to assist the primary users to meet their target quality of service (QoS) by acting as a cognitive two-way relay, when the direct link of the two primary users cannot meet the target QoS. As a return, the primary network shares its transmission time-slot with the secondary user. First, the system outage probabilities of traditional direct transmission and CTWR scheme are analyzed, giving both the exact and approximated expressions. Second, a transmission time-slot splitting algorithm between the primary and secondary users is proposed. Third, the ergodic capacity of the secondary user under the CTWR scheme is examined. Finally, simulation results show that the proposed scheme cannot only help the primary users to meet their target QoS, but also improve the communication opportunities of the secondary user. 相似文献