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针对认知异构网络中的干扰抑制问题,文中研究了如何降低其对宏用户(MU)的干扰并提高系统吞吐量。通过全面分析干扰来源,建立不完全频谱感知下的干扰模型;结合用户拓扑信息,综合考虑总功率约束和干扰约束,以最大化下行链路的吞吐量为准则构建优化问题;然后分析KKT条件,简化优化问题,进而设计出基于不完全频谱感知的分步式资源分配算法。仿真结果及性能分析表明,相比于基于完全频谱感知的资源分配算法,所提算法对MU造成的干扰更小,并且获得了更优的吞吐量性能。 相似文献
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为在不完美频谱检测环境下对资源进行优化分配,提出一种分布式认知无线电网络资源分配算法。根据贝叶斯理论给出子载波状态信任指数与统计平均干扰功率的概念,利用拉格朗日对偶分解理论,将原分配问题分解为独立的子问题并进行求解,以实现多用户资源的有效分配。仿真结果表明,相对基于回避准则的优化算法,该算法能有效提高系统容量,且能更快地达到循环结束条件。 相似文献
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超密集网络中,严重的小区间干扰制约了终端用户的数据速率,针对该问题,该文提出一种基于干扰协调的资源分配方案。该方案分为两个模块:第一模块基于毫微微接入点(Femtocell Access Points, FAPs)间的干扰程度,将干扰强的FAPs分到同一簇内,同簇内的FAPs共享频带资源,通过FAPs间的协作使不同簇之间实现频谱的复用;第二模块基于最大功率和最低速率的公平性准则进行最优功率分配,动态分配资源。仿真结果表明,该算法在超密集网络场景下能够有效控制FAPs间的干扰,最大化系统吞吐量。 相似文献
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针对下行的异构认知超密集异构网络(UDN)的多维资源配置问题,提出一种以毫微微小区用户最大吞吐量为目标的联合优化用户关联和资源分配的改进遗传算法。首先,在算法开始之前进行预处理,初始化用户可达基站和可用信道矩阵;其次,采用符号编码,将用户与基站以及用户与信道的匹配关系编码为一个二维的染色体;然后,将动态择优复制+轮盘赌作为选择算法,以加快种群的收敛;最后,为避免算法陷入局部最优,在变异阶段加入早熟判决的变异算子,从而在有限次迭代下求得基站、用户、信道的连接策略。实验结果表明,在基站与信道数量一定时,所提算法与三维匹配的遗传算法相比在用户总吞吐量方面提高了7.2%,在认知用户吞吐量方面提高了1.2%,且计算复杂度更低。所提算法缩小了可行解的搜索空间,能在较低复杂度下有效提高认知UDN的总吞吐量。 相似文献
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针对无线认知网次用户快速寻找可用信道与检测主用户出现的问题,提出一种新的高效频谱感知机制。该机制通过感知与传输并发以减少感知的时间开销,利用干扰消除技术消除自身传输对感知的干扰;通过结合不同采样速率下信道状态的观察,实现宽频谱的信道感知;在传输中,利用特征匹配技术检测主用户的出现。实验结果表明,新机制可减少感知时间50%,提高吞吐量100%以上。因此,新机制有效降低了频谱感知的资源消耗,提高了认知通信的效率。 相似文献
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Cognitive radio has emerged as a promising technology for maximizing the utilization efficiency of the limited spectrum resources
while accommodating the increasing amount of services and applications in wireless networks. One of the most important and
critical components of the cognitive radio is spectrum sensing and accordingly, detection of primary users. Considering the
hardware constraints existing in cognitive devices, based on the coarse estimation of channel occupancy, partial cooperative
spectrum sensing with adaptive spectrum schedule scheme is proposed to increase the possibility to discover more spectrum
opportunities promptly. Simulation results show the gain of sensing performance and the energy-saving feature of partial spectrum
sensing. Special security scheme is designed to protect the reliability of sensing result from the false message attack. For
the scenarios tested, the proposed scheme is shown to increase opportunities by up to 15 percent. 相似文献
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The concept of cognitive radio networks (CRNs) is a promising candidate for enhancing the utilization of existing radio spectrum. In CRNs, secondary users (SUs) are allowed to use the spectrum unused by primary users (PUs). In order to mathematically estimate the system performance of dynamic spectrum allocation strategy with multi-channel and imperfect sensing, we propose a novel preemptive priority queueing model. We establish a discrete-time Markov chain in line with the stochastic behaviour of SU and PU packets. Then, we derive some performance measures, such as the interference rate of PU packets, the normal throughput and the average delay of SU packets. Moreover, we provide theoretical and simulation experiments to investigate the system performance. Numerical experiments show that there is a tradeoff between different performance measures when imperfect sensing is considered. Finally, we present an optimal design for setting the number of the channels in a spectrum. 相似文献
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为优化非完美信道状态信息下的解码转发全双工中继网络的能效和谱效,提出了一种基于该网络模型的能效谱效均衡策略。通过构建能量效率和频谱效率的折中优化函数,将一个非凸的多目标优化问题转换为一个凸的单目标优化问题,利用求导法和拉格朗日乘子法求解在不同折中因子下的最优中继发射功率。仿真结果表明,可以通过改变折中因子来优化系统的能效和谱效值,获得最优能效和谱效的性能折中。 相似文献
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基于可信度的认知无线电协同频谱检测 总被引:1,自引:1,他引:0
认知无线电中随着参与协同检测的认知用户数目的增大,频谱检测性能逐渐增强。但是过多的认知用户参与协同检测,会使整个认知无线电网络的灵敏度降低,同时也会造成巨大的系统开销。针对上述问题,提出了一种新的基于可信度的协同频谱检测方法。在满足目标错误概率的条件下,该算法只选择可信度较高的一些认知用户参与协同频谱检测。仿真结果表明当认知用户中存在恶意节点或者故障节点时,该算法同传统算法相比较,频谱检测性能更好,具有更强的健壮性。 相似文献
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This paper is concerned with the resource allocation for multiple input multiple output and orthogo- nal frequency division multiplexing access (MIMO-OFDMA) downlink cognitive radio systems where a cognitive radio MIMO-OFDMA system is under spectrum sharing with an existing primary radio (PR) network. We use the channel learning scheme to estimate the channel information from cognitive radio transmitter (CR-TX) to PR and then make beamforming to transmit signal. Considering the interference from CR-TX to PR caused by the imperfect channel learning, we intend to maximize CR throughput under the interference power constraint at PR and CR transmit power constraint. A nearly optimal subcarrier and power allocation algorithm with linear complexity is proposed. The proposed algorithm is global optimal when the maximum transmit power is beyond certain threshold. Simulation results show that the proposed algorithm has a good performance very close to the global optimal algorithm. 相似文献
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