共查询到17条相似文献,搜索用时 218 毫秒
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基于非正交多址接入(NOMA,Non-Orthogonal Multiple Access)的认知无线电(CR,Cognitive Radio)网络物理层传输面临主用户干扰和第三方窃听双重干扰威胁.本文提出利用空时编码(STBC,Space Time Block Coding)技术提高认知用户物理层安全性能,推导了任意认知用户的安全中断概率闭合表达式.通过蒙特卡洛仿真进行验证,结果表明,所提STBC-CR-NOMA相比未采用STBC编码方案的CR-NOMA可以明显提高用户的安全中断概率,且随着认知发射功率的增大,近端用户安全中断性能提高越大,而远端用户安全中断性能提升受认知基站发射功率的影响较小.仿真结果还表明,通过调整功率分配系数对远端用户和近端用户的安全中断性能影响不同. 相似文献
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针对未来海量用户设备接入的物理层安全(physical layer security,PLS)应用需求,提出了一种组合非正交多址接入(non-orthogonal multiple access,NOMA)、终端直通(device-to-device,D2D)与中继协作的NOMA-D2D协作无线系统PLS模型。该模型由采用发射天线选择(transmit antenna selection,TAS)的基站、分别作为基站和D2D发射端的NOMA远端蜂窝用户、D2D接收端以及被动窃听者组成,其中的D2D发射端承担基站的 NOMA 近端用户和解码转发中继两种角色。利用高斯—切比雪夫正交定理推导两种 TAS 方案下NOMA-D2D协作无线系统的安全中断概率、非零安全容量概率以及渐近安全中断概率的近似表达式。数值计算和仿真实验验证了NOMA-D2D协作无线系统PLS性能分析的准确性;在基站总功率恒定时增大分配给远端蜂窝用户的功率能有效提升NOMA-D2D协作无线系统的PLS性能。 相似文献
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针对合谋窃听场景下单天线多中继修改转发(MF)协作无线系统的安全性能较差问题,提出一种合谋窃听场景下联合源节点发送天线选择(TAS)和多中继选择的MF协作物理层安全系统,考虑最优的最大化主信道信噪比(SNR)和次优的最大化源节点-中继节点链路 SNR 两种中继选择方案,推导其安全中断概率(SOP)和遍历安全容量(ESC)的解析表达式。最优或次优中继选择的MF安全中继系统的SOP和ESC的数值计算结果与仿真结果相吻合,验证了上述理论分析的正确性;同时也表明源节点发射天线数和中继节点数越多、窃听节点数越少,最优或次优中继选择的MF安全中继系统的物理层安全性能越好。 相似文献
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非正交多址接入(non-orthogonalmultipleaccess,NOMA)与无线携能通信(simultaneouswireless information and power transfer,SWIPT)技术的组合可提高无线系统的频谱效率,并能够解决用户节点的电能供应问题。然而,当能量收集器要恶意窃听基站发送的机密信息时,SWIPT-NOMA系统的信息安全传输会受到威胁,为增强其物理层安全(physical layer security,PLS)性能,提出了一种采用发射天线选择和功率分割策略的SWIPT-NOMA系统PLS模型。如果各能量收集器的空间位置随机分布服从泊松点过程,利用空间泊松分布生成函数推导SWIPT-NOMA系统的安全中断概率和非零安全容量概率近似表达式。数值计算与仿真结果表明,所推导的表达式具有很高的准确性,且可用于研究窃听者密度、基站与远近端信息接收者之间的距离、基站发射天线数以及功率分割因子等参数对SWIPT-NOMA系统PLS性能的影响。 相似文献
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由于非正交多址接入(Non-orthogonal Multiple Access,NOMA)能够显著提升系统的频谱资源利用率,在下一代移动通信中得到广泛应用。对NOMA环境下多中继协作网络的最优中继选择方案和系统安全性能进行了分析和讨论,其中包含窃听者仅窃听中继和窃听者同时窃听中继及源节点这2种情况下的系统安全性能表现,并与相同场景下正交多址接入(Orthogonal Multiple Access,OMA)网络进行了对比。最终的理论分析和仿真结果表明,在所提出系统模型中,当信道条件相同时,NOMA网络总能取得相较于OMA网络更好的安全性能,同时随着系统中继节点数目的增多,NOMA网络在物理层安全性能上获得更大的优势。 相似文献
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分析了智能反射面(IRS)辅助的星地融合认知网络系统的中断性能。首先,针对卫星采用点波束技术服务地球站,而基站通过智能反射面扩大通信范围,并采用非正交多址接入(NOMA)技术服务多用户场景,在系统采用认知无线电技术来实现卫星主网络与地面次级网络之间频谱共享的情况下,建立以地面用户平均信干噪比最大化为目标的优化问题;其次,基于角度域的信道状态信息提出了一种低复杂度的IRS相移设计方案,从而得到智能反射面相移矩阵;接着,分别推导出地面用户在固定和移动2种情况下的中断概率闭合表达式。为了进一步分析系统性能,推导了高信噪比条件下系统的中断概率近似表达式。最后,计算机仿真验证了中断概率表达式的正确性,并分析了主要参数对系统性能的影响。 相似文献
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Md Fazlul Kader 《International Journal of Electronics》2013,100(6):1050-1062
Non-orthogonal multiple access (NOMA) has attracted a significant attention to the research community as a potential candidate for 5G or future radio access. This article presents a NOMA-based cooperative network where a transmitter considered as a base station communicates simultaneously with two users treating as a far user and a near user via the help of a half-duplex decode-and-forward relay. We investigate the outage probability and the outage capacity of the proposed network over independent Rayleigh slow fading channels. Closed-form expressions of the outage probabilities are derived for both users. Approximate outage capacity of the users are also investigated at high signal to noise ratio regime. It has been shown that the proposed cooperative NOMA can achieve superior performance compared to the non-cooperative NOMA in terms of outage probability. The tightness between the simulation and theoretical results confirms the efficiency of the proposed protocol. 相似文献
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The mutual interference between cellular links and D2D links can bring the secrecy gain to cellular users in D2D-enable cellular networks.To make full use of them,a cooperative secrecy transmission scheme was proposed based on wireless channels.The channel direction information and gains depict the interference from D2D links to cellular links and other D2D links in the proposed scheme.Firstly,only the D2D users which meet the limited interference conditions were accessed to cellular networks to ensure their reliable communications.It was assumed that legitimate users and eavesdroppers were independent two-dimensional homogeneous Poisson point processes (PPP) distribution.Then the security outage probability (SOP) was derived for cellular users and the connection outage probability (COP) for D2D users,and the impacts of interference thresholds were discussed on their performances.Next,an optimization model was given to minimize D2D users’ COP while ensuring the secrecy performance requirements of cellular users,thus achieving the optimal performance.Finally,simulation results verify the validity of the proposed scheme. 相似文献
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提出一种多中继协同无线网络的机会编码协同策略,该策略基于Turbo编码,利用信道条件信息机会选择最优协同节点。通过数学分析,给出了系统中断性能和瑞利衰落下的中断概率表达式,计算机仿真结果进一步揭示了机会编码协同相对于传统编码协同的优势。 相似文献
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Cognitive radio allows Secondary Users (SUs) to dynamically use the spectrum resource li-censed to Primary Users (PUs ), and significantly improves the efficiency of spectrum utilization and is viewed as a promising technology. In cognitive radio networks, the problem of power control is an important issue. In this paper, we mainly focus on the problem of power control for fading channels in cognitive radio networks. The spectrum sharing un-derlay scenario is considered, where SUs are al-lowed to coexist with PUs on the condition that the outage probability of PUs is below the maximum outage probability threshold limitation due to the interference caused by SUs. Moreover, besides the outage probability threshold which is defined to protect the performance of PUs, we also consider the maximum transmit power constraints for each SU. With such a setup, we emphasize the problem of power control to minimize the outage probability of each SU in fading channels. Then, based on the statistical information of the fading channel, the closed expression for outage probability is given in fading channels. The Dual-Iteration Power Control (DIPC) algorithm is also proposed to minimize the outage probability based on Perron-Frobenius theo-ry and gradient descent method under the constraint condition. Finally, simulation results are illustrated to demonstrate the performance of the proposed scheme. 相似文献
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Physical-layer security could be used to effectively combat eavesdroppers and the transmission reliability of the main link could be improved.A wireless relay network with multiple both decode and forward eavesdroppers and relays were considered,in the presence of the link from source to destination.A best relay selection scheme based on multieavesdropper’s cooperation was proposed,and the outage probability and the intercept probability was deduced under both schemes without relay and with best relay.Then,the security and reliability influenced by different relay selection schemes were analyzed.The simulation results show that the achievable channel capacity at the destination node and the system outage probability are directly affected by different relay selection scheme.Lower system outage probability can be achieved by the proposed scheme,and the system outage probability and intercept probability are both decreased with the increase of the number of relays.The intercept probability increases with the increase of the number of eavesdroppers,which,however,can be reduced by increasing the number of relays to ensure the main link’s reliable transmission. 相似文献