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CSCW协作多用户接口的设计与实现 被引量:25
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作者 郑庆华 李人厚 《小型微型计算机系统》 EI CSCD 北大核心 1998年第1期40-46,共7页
协作多用户接口是CSCW的关键技术之一。本文在分析协作多用户接口特性的基础上,提出了其组成部件,分析并评价了它的两种支撑结构—集中式结构和重复式结构。最后提出了一种基于显示代理的混合型结构及其实现模型。该模型在“分布... 协作多用户接口是CSCW的关键技术之一。本文在分析协作多用户接口特性的基础上,提出了其组成部件,分析并评价了它的两种支撑结构—集中式结构和重复式结构。最后提出了一种基于显示代理的混合型结构及其实现模型。该模型在“分布式多媒体协同工作系统DMCS”中得到实现。 展开更多
关键词 CSCW 多用户接口 设计 人机系统
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LabVIEW在远程虚拟实验平台中的应用 被引量:6
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作者 李莉玲 方康玲 周波 《武汉科技大学学报》 CAS 2004年第4期403-405,共3页
详细介绍虚拟实验室的功能、组成及特点,并以Siemens6RA70直流控制系统驱动的直流电机为控制对象,搭建了一个远程多用户虚拟实验平台。
关键词 LABVIEW 虚拟实验室 远程控制 多用户
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多用户分段移位差分混沌键控通信方案 被引量:12
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作者 张刚 孟维 张天骐 《电子与信息学报》 EI CSCD 北大核心 2017年第5期1219-1225,共7页
为了满足现代通信的需求,多用户接入技术是近年来混沌通信的一个重要发展趋势。为了进一步改善现有多用户混沌通信方案的误码性能,该文提出一种多用户分段移位差分混沌键控(Multi User Segment Shift Differential Chaos Shift Keying,M... 为了满足现代通信的需求,多用户接入技术是近年来混沌通信的一个重要发展趋势。为了进一步改善现有多用户混沌通信方案的误码性能,该文提出一种多用户分段移位差分混沌键控(Multi User Segment Shift Differential Chaos Shift Keying,MU-SSDCSK)通信方案。该方案根据传输的用户数,将MU-SSDCSK中的参考信号等分成m个信号段,再将这m个信号段进行移位,并配以不同的Walsh码,形成相互正交的信息携带信号。文中推导了该系统在加性高斯白噪声信道中的理论误码率公式并进行了仿真。仿真结果表明,该文提出的MU-SSDCSK方案能有效改善系统误码性能,在混沌通信领域具有一定的应用前景。 展开更多
关键词 多用户 WALSH码 分段移位 传输速率 比特误码率
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Two Schemes of Blind MMSE Multiuser Receiver for Space-Time Coded CDMA Systems 被引量:8
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作者 LUMin XUChang-jiang FENGGuang-zeng 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2004年第1期45-51,共7页
Minimum Mean Square Error (MMSE) multiuser detection yields the highest output SINR among all linear detectors. The blind MMSE linear detector can be implemented with batch processes or sequential processes. In this p... Minimum Mean Square Error (MMSE) multiuser detection yields the highest output SINR among all linear detectors. The blind MMSE linear detector can be implemented with batch processes or sequential processes. In this paper, according to the different implementations of blind detectors, the authors analyze two schemes of the blind MMSE multiuser receiver for space-time coded CDMA Systems and make a comparison between both schemes by the theoretical analysis and numerical simulations. 展开更多
关键词 channel estimation CDMA MMSE multiuser receiver space-time block coding transmit diversity.
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Multiuser-to-multiuser entanglement distribution based on 1550 nm polarization-entangled photons 被引量:10
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作者 Dong-Yang Cao 《Science Bulletin》 SCIE EI CAS CSCD 2015年第12期1128-1132,I0003,共6页
Telecom-band polarization-entangled photon- pair source has been widely used in quantum communi- cation due to its acceptable transmission loss. It is also used in cooperation with wavelength-division multiplexing (... Telecom-band polarization-entangled photon- pair source has been widely used in quantum communi- cation due to its acceptable transmission loss. It is also used in cooperation with wavelength-division multiplexing (WDM) to construct entanglement distributor. However, previous schemes generally are not suitable for multinode scenario. In this paper, we construct a telecom-band po- larization-entangled photon-pair source, and it shows ul- trahigh fidelity and concurrence which are both greater than 90 % (raw data). Moreover, we set up a four-by-four entanglement distributor based on WDM. We check the 16 Clauser-Horne-Shimony-Holt inequalities, which show nonlocality. Lastly, as an example of practical application of this source, we estimate the quantum bit error rates and quantum secret key rates when it is used in quantum key distribution. Furthermore, the transmission of entanglement in long optical fibers is also demonstrated. 展开更多
关键词 Entanglement distribution multiuser Telecom-band
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学分制网络化选课系统及其应用 被引量:5
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作者 车战斌 贾晓辉 《郑州纺织工学院学报》 1995年第4期41-46,共6页
本文首先对选课的方案进行了论证,从而提出了选课系统的软件方案,并介绍了该方案的硬件环境及软件构成。最后还介绍了利用该方案所编制的选课系统软件在NOVELL系统的NETWARE386操作系统下运行的情况。
关键词 学分制 局域网 校园网 选课系统
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云环境下支持多用户模糊检索加密算法研究 被引量:9
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作者 李陶深 王翼 黄汝维 《小型微型计算机系统》 CSCD 北大核心 2016年第10期2244-2248,共5页
为了提供云计算环境中多个授权用户共享加密文件并支持模糊检索,提出一种支持多用户共享的模糊检索加密算法(WPER).算法通过运用Elgamal代理加密机制及基于通配符技术的模糊集构造方法,对数据所有者的文件进行多次加密,并且针对文件中... 为了提供云计算环境中多个授权用户共享加密文件并支持模糊检索,提出一种支持多用户共享的模糊检索加密算法(WPER).算法通过运用Elgamal代理加密机制及基于通配符技术的模糊集构造方法,对数据所有者的文件进行多次加密,并且针对文件中的关键词进行模糊词集的构造后存储至云服务器端,云服务器根据授权用户的搜索请求进行关键词的模糊检索并返回相关加密文件,最后授权用户利用自己的私钥解密文件,实现了多个授权用户利用自己的私钥对数据进行加解密,并支持对加密字符串的模糊检索.安全性分析和性能评估证明算法是IND-CPA安全的,并能有效的实现数据共享和模糊检索. 展开更多
关键词 云计算 加密检索 多用户 模糊检索
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The Least Square Constant Modulus Algorithm for Blind Adaptive Multiuser Detection 被引量:5
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作者 LIU Sheng mei, XU Chang jiang, FENG Guang zeng (Nanjing University of Posts and Telecommunications, Nanjing 210003, P.R. China) 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2001年第4期63-67,共5页
In this paper, we apply the Least Square Constant Modulus Algorithm( LSCMA ) to the blind Multiuser Detection( MUD ). The algorithm is shown to be globally stable and convergent for any linearly independent set of... In this paper, we apply the Least Square Constant Modulus Algorithm( LSCMA ) to the blind Multiuser Detection( MUD ). The algorithm is shown to be globally stable and convergent for any linearly independent set of input data and converge faster than the conventional Steepest Descent CMA(SDCMA ) and Linearly Constrained CMA(LCCMA ),but more complex. 展开更多
关键词 LSCM CDMA LCCM blind multiuser detection
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Cross-layer packet scheduling for downlink multiuser OFDM systems 被引量:6
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作者 WANG JunBo CHEN HuaMin +1 位作者 CHEN Ming WANG JiangZhou 《Science in China(Series F)》 2009年第12期2369-2377,共9页
This paper proposes a channel and queue aware fair (CQAF) packet scheduling scheme for the downlink packet transmission in multiuser orthogonal frequency division multiplexing (OFDM) systems. By making use of the ... This paper proposes a channel and queue aware fair (CQAF) packet scheduling scheme for the downlink packet transmission in multiuser orthogonal frequency division multiplexing (OFDM) systems. By making use of the information on the channel conditions and the queue lengths, the proposed CQAF packet scheduling scheme efficiently allocates the subcarriers, transmission power and modulation level to users under the constraints of total transmission power, the number of subcarriers, bit-error-rate (BER) requirement and generalized processor sharing (GPS)-based fairness requirement. The numerical results show that the proposed CQAF packet scheduling scheme can reduce the transmission delay and queue length significantly while maximizing system throughput and maintaining fairness among users. 展开更多
关键词 OFDM multiuser fair packet scheduling power allocation
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比例速率约束下基于遗传策略的多用户OFDM系统资源自适应分配算法 被引量:8
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作者 李鹤 赵晓晖 刘熠 《吉林大学学报(工学版)》 EI CAS CSCD 北大核心 2008年第3期709-714,共6页
基于遗传策略提出了载波和功率自适应分配算法,它在最大化多用户OFDM系统下行链路总容量的同时维持用户之间的比例公平性,是一种将子载波分配和功率分配独立开的低复杂度次优算法。当总功率在载波间均等分布时,首先进行子载波的分配。... 基于遗传策略提出了载波和功率自适应分配算法,它在最大化多用户OFDM系统下行链路总容量的同时维持用户之间的比例公平性,是一种将子载波分配和功率分配独立开的低复杂度次优算法。当总功率在载波间均等分布时,首先进行子载波的分配。随后引入遗传算法通过全局搜索实现用户间的功率分配,以满足比例公平性要求。功率分配结束后,针对每一个用户使用等功率分配方式实现容量分配并实现总功率的最大化。仿真结果表明,所提出的资源分配算法平衡了总容量和公平性之间的折中问题。与最小容量最大化算法相比,满足了用户之间不同的速率要求。相对于总容量最大化算法,容量在用户之间分布更公平。 展开更多
关键词 信息处理技术 自适应资源分配 正交频分复用 多用户 遗传策略 比例速率约束
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基于希尔伯特变换的多用户DCSK通信系统性能分析 被引量:7
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作者 张刚 许嘉平 张天骐 《电子与信息学报》 EI CSCD 北大核心 2018年第11期2744-2751,共8页
针对差分混沌移位键控(DCSK)传输速率低的问题,该文提出一种基于希尔伯特变换的多用户DCSK(HMU-DCSK)通信系统。在固定阶数的Walsh码条件下,通过希尔伯特变换将正交基信号集合提高1倍,并确保分配给每个用户的载波信号正交。推导了在Rayl... 针对差分混沌移位键控(DCSK)传输速率低的问题,该文提出一种基于希尔伯特变换的多用户DCSK(HMU-DCSK)通信系统。在固定阶数的Walsh码条件下,通过希尔伯特变换将正交基信号集合提高1倍,并确保分配给每个用户的载波信号正交。推导了在Rayleigh衰落信道下的误码率公式并进行仿真。结果表明,相同N值下HMU-DCSK系统的传输速率是传统多用户DCSK系统的2倍;相同传输速率下HMU-DCSK系统的误码性能明显优于传统多用户DCSK系统。 展开更多
关键词 混沌通信 多用户 WALSH码 希尔伯特变换 传输速率
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多用户降噪差分混沌键控通信方案 被引量:7
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作者 张刚 陈和祥 张天骐 《电子与信息学报》 EI CSCD 北大核心 2019年第2期362-368,共7页
传统多用户差分混沌键控主要缺点是误码率差,该文提出一种多用户降噪差分混沌键控(MU-NRDCSK)通信方案。在发射端,发送M/P长度混沌序列,复制P次后作为参考信号,所有用户共用同一参考信号,信息信号延迟不同的时间来区分用户。在接收端,... 传统多用户差分混沌键控主要缺点是误码率差,该文提出一种多用户降噪差分混沌键控(MU-NRDCSK)通信方案。在发射端,发送M/P长度混沌序列,复制P次后作为参考信号,所有用户共用同一参考信号,信息信号延迟不同的时间来区分用户。在接收端,将接收到的信号通过滑动平均滤波器平均,再与其不同时间延迟后的信号进行相关。该方案通过降低噪声项的方差来提高系统误码性能。文中推导了该方案在加性高斯白噪声(AWGN)信道和Rayleigh信道下的理论误码率公式并进行了蒙特卡洛仿真。理论分析和仿真结果表明,理论公式与仿真结果能较好地吻合,MU-NRDCSK方案能较好地提高系统误码性能,在混沌通信领域具有很好的发展前景与研究价值。 展开更多
关键词 混沌通信 多用户 滑动平均滤波器 降噪 比特误码率
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多输入多输出系统下行链路发射与接收的联合线性预编码 被引量:6
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作者 孟银阔 殷勤业 +1 位作者 田红波 邓科 《西安交通大学学报》 EI CAS CSCD 北大核心 2007年第4期475-478,492,共5页
针对多用户多输入多输出系统下行链路线性预编码中的迫零法及正交化法对接收端的噪声有较强放大作用的问题,提出了一种发射与接收联合预编码的波束成形迭代法.该方法把联合预编码直接转变为波束成形问题,以惟一确定的最小范数解作为预... 针对多用户多输入多输出系统下行链路线性预编码中的迫零法及正交化法对接收端的噪声有较强放大作用的问题,提出了一种发射与接收联合预编码的波束成形迭代法.该方法把联合预编码直接转变为波束成形问题,以惟一确定的最小范数解作为预编码矩阵,通过迭代得到各用户的预编解码矩阵.由于所得到的解码矩阵具有最小范数的特性,在解码时产生的噪声能量最小,从而有效地减少了对噪声的放大作用.同时,在基站总发射功率一定的条件下,根据用户的信道质量动态地分配功率可以使信道质量较差的用户得到较多的发射功率.仿真实验表明,所提出的方法与迫零法相比,在相同的仿真条件下,在平均误比特率为10-4时可以获得约9 dB的性能增益. 展开更多
关键词 波束成形 多输入多输出 下行链路 多用户 线性预编码
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多用户OFDM系统中的快速自适应分配策略 被引量:5
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作者 柯峰 叶梧 +1 位作者 冯穗力 龚汉东 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2005年第3期40-43,共4页
将自适应技术应用于多用户正交频分复用(OFDM)系统,能够提高频谱利用率,降低系统发射功率,从而使系统的整体性能达到最优.文中给出了多径频率选择性衰落信道下多用户OFDM系统中自适应比特和功率分配的数学模型,提出了一种次优快速自适... 将自适应技术应用于多用户正交频分复用(OFDM)系统,能够提高频谱利用率,降低系统发射功率,从而使系统的整体性能达到最优.文中给出了多径频率选择性衰落信道下多用户OFDM系统中自适应比特和功率分配的数学模型,提出了一种次优快速自适应分配算法,根据信道特性的瞬时估计值,自适应地为各用户分配子信道和比特,在给定误码率的条件下使总的发送功率最小.仿真结果表明,该算法计算简单,优化效率高,可以达到接近理论上的最优水平. 展开更多
关键词 分配策略 正交频分复用 多用户 自适应比特分配
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Evaluation of Linear Precoding Schemes for Cooperative Multi-Cell MU MIMO in Future Mobile Communication Systems
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作者 Juma Said Ally 《Journal of Computer and Communications》 2023年第6期28-42,共15页
In Mobile Communication Systems, inter-cell interference becomes one of the challenges that degrade the system’s performance, especially in the region with massive mobile users. The linear precoding schemes were prop... In Mobile Communication Systems, inter-cell interference becomes one of the challenges that degrade the system’s performance, especially in the region with massive mobile users. The linear precoding schemes were proposed to mitigate interferences between the base stations (inter-cell). These schemes are categorized into linear and non-linear;this study focused on linear precoding schemes, which are grounded into three types, namely Zero Forcing (ZF), Block Diagonalization (BD), and Signal Leakage Noise Ratio (SLNR). The study included the Cooperative Multi-cell Multi Input Multi Output (MIMO) System, whereby each Base Station serves more than one mobile station and all Base Stations on the system are assisted by each other by shared the Channel State Information (CSI). Based on the Multi-Cell Multiuser MIMO system, each Base Station on the cell is intended to maximize the data transmission rate by its mobile users by increasing the Signal Interference to Noise Ratio after the interference has been mitigated due to the usefully of linear precoding schemes on the transmitter. Moreover, these schemes used different approaches to mitigate interference. This study mainly concentrates on evaluating the performance of these schemes through the channel distribution models such as Ray-leigh and Rician included in the presence of noise errors. The results show that the SLNR scheme outperforms ZF and BD schemes overall scenario. This implied that when the value of SNR increased the performance of SLNR increased by 21.4% and 45.7% for ZF and BD respectively. 展开更多
关键词 Precoding Schemes Cooperative Networks Interference Multi-Input Multi-Output (MIMO) Multi-Cell and multiuser
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Novel scheduling strategy for downlink multiuser MIMO system: Particle swarm optimization 被引量:4
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作者 HEI YongQiang LI XiaoHui YI KeChu YANG Hong 《Science in China(Series F)》 2009年第12期2279-2289,共11页
In this paper the scheduling problem in downlink multiuser MIMO system is described as an optimization problem and particle swarm optimization (PSO) algorithm is introduced to address such problem. Two PSO schedulin... In this paper the scheduling problem in downlink multiuser MIMO system is described as an optimization problem and particle swarm optimization (PSO) algorithm is introduced to address such problem. Two PSO scheduling methods with different objective functions applicable to different requirements on capacity and complexity are investigated. One is the capacity based PSO(C-PSO) scheduling method aiming at achieving the near optimal capacity; and the other is the lower bound of eigenvalue based PSO (LBE-PSO) scheduling method with the purpose of reducing computational complexity and at the same time achieving as large as possible capacity gain. Furthermore, convergence analysis of PSO from both the particle and the velocity aspects is also presented to derive the convergent condition, which is validated by several examples of different parameter values. Simulation results reveal that the C-PSO can obtain nearly the same capacity as the exhaustive search method with lower complexity, while the LBE-PSO provides a viable approach by striking a better tradeoff between capacity and computational complexity. 展开更多
关键词 multiuser MIMO SCHEDULING downlink transmission particle swarm optimization
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Joint beamforming and scheduling in the downlink of cognitive radio networks 被引量:4
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作者 XI Wei YIN ChangChuan YUE GuangXin 《Science in China(Series F)》 2009年第12期2324-2331,共8页
Cognitive radio has been recently proposed as a promising technology to improve the spectrum utilization. In this paper, we consider a system where a licensed radio spectrum is shared by a primary network and a second... Cognitive radio has been recently proposed as a promising technology to improve the spectrum utilization. In this paper, we consider a system where a licensed radio spectrum is shared by a primary network and a secondary network. Based on the subspace theory, a novel low-complexity algorithm for secondary user selection has been proposed. On the basis of the scheduling scheme, we jointly consider transmit beamforming, scheduling and power allocation, and subsequently present a complete set of solution for secondary network downlink. Simulation results has shown that our proposed scheme not only can limit the introduced interference at primary users within the tolerable range, but also can achieve high sum-rate throughput of secondary network, simultaneously. Furthermore, as is proved by simulation results, our scheme is very robust due to the fact that only a little tolerable performance drop is introduced when simple but nonoptimal equal power allocation is adopted. 展开更多
关键词 cognitive radio multiple-input multiple-output (MIMO) BEAMFORMING multiuser diversity power allocation water filling
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Cross-Layer Framework for Capacity Analysis in Multiuser Ultra-Dense Networks with Cell DTx 被引量:4
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作者 Qing Li Yu Chen +2 位作者 Qimei Cui Yu Gu Guoqiang Mao 《China Communications》 SCIE CSCD 2019年第9期106-121,共16页
Cell discontinuous transmission(Cell DTx)is a key technology to mitigate inter-cell interference(ICI)in ultra-dense networks(UDNs).The aim of this work is to understand the impact of Cell DTx on physical-layer sum rat... Cell discontinuous transmission(Cell DTx)is a key technology to mitigate inter-cell interference(ICI)in ultra-dense networks(UDNs).The aim of this work is to understand the impact of Cell DTx on physical-layer sum rates of SBSs and link-layer quality-of-service(QoS)performance in multiuser UDNs.In this work,we develop a cross-layer framework for capacity analysis in multiuser UDNs with Cell DTx.In particular,we first extend the traditional one-dimensional effective capacity model to a new multidimensional effective capacity model to derive the sum rate and the effective capacity.Moreover,we propose a new iterative bisection search algorithm that is capable of approximating QoS performance.The convergence of this new algorithm to a unique QoS exponent vector is later proved.Finally,we apply this framework to the round-robin and the max-C/I scheduling policies.Simulation results show that our framework is accurate in approximating 1)queue length distribution,2)delay distribution and 3)sum rates under the above two scheduling policies,and further show that with the Cell DTx,systems have approximately 30% higher sum rate and 35% smaller average delay than those in full-buffer scenarios. 展开更多
关键词 effective capacity QoS performance SUM rates multiuser scheduling ultra-dense network (UDN)
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基于椭圆曲线加密的多用户可搜索对称加密方案
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作者 陈珊 潘文伦 《信息安全研究》 CSCD 北大核心 2024年第7期624-633,共10页
可搜索加密(searchable encryption,SE)是数据安全检索环节的关键技术之一,它允许服务器在不解密的情况下直接搜索加密数据.为解决云存储环境下数据安全共享时面临的密文检索问题,对现有单用户场景下的动态可搜索对称加密(searchable sy... 可搜索加密(searchable encryption,SE)是数据安全检索环节的关键技术之一,它允许服务器在不解密的情况下直接搜索加密数据.为解决云存储环境下数据安全共享时面临的密文检索问题,对现有单用户场景下的动态可搜索对称加密(searchable symmetric encryption,SSE)方案进行多用户拓展,提出一种高效、安全且客户端无存储的多用户动态可搜索对称加密方案.该方案创新性地采用椭圆曲线加密系统实现多用户间的密钥管理和访问密钥的分发,有效避免了传统多用户解决方案中的密钥共享问题和双线性对操作,且同时满足查询隐私、搜索不可伪造性和用户可撤销性.此外,经过多用户拓展后的可搜索对称加密方案依然保持了原单用户方案泄露信息少、文档搜索高效、文档删除高效且客户端无存储等优点. 展开更多
关键词 数据共享 隐私保护 可搜索对称加密 动态可搜索加密 多用户 椭圆曲线加密
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Cluster-Based Massive Access for Massive MIMO Systems
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作者 Shiyu Liang Wei Chen +2 位作者 Zhongwen Sun Ao Chen Bo Ai 《China Communications》 SCIE CSCD 2024年第1期24-33,共10页
Massive machine type communication aims to support the connection of massive devices,which is still an important scenario in 6G.In this paper,a novel cluster-based massive access method is proposed for massive multipl... Massive machine type communication aims to support the connection of massive devices,which is still an important scenario in 6G.In this paper,a novel cluster-based massive access method is proposed for massive multiple input multiple output systems.By exploiting the angular domain characteristics,devices are separated into multiple clusters with a learned cluster-specific dictionary,which enhances the identification of active devices.For detected active devices whose data recovery fails,power domain nonorthogonal multiple access with successive interference cancellation is employed to recover their data via re-transmission.Simulation results show that the proposed scheme and algorithm achieve improved performance on active user detection and data recovery. 展开更多
关键词 compressive sensing dictionary learning multiuser detection random access
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