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D2D Multicast Retransmission Algorithm in Mobile Cloud Based on SINR Constraint

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China Communications 2016年第8期13卷 41-52页

作者： zufan zhang Lisha Luo Lisha Wang Chongqing Key Labs of Mobile Communications Technology Chongqing University of Posts and Telecommunications

In cellular network, users with same demand and in proximity to each other form the mobile cloud, in which the short-range D2 D technology is employed by users to improve the data dissemination efficiency. In view of the fact that the D2 D links with the poor channel conditions are likely to be the bottleneck of resource utilization improvement, aiming at the differentiation of link quality, this paper proposes a intra-cloud D2 D multicast retransmission algorithm based on SINR constraint to meet the minimum requirement of D2 D retransmission for Qo S. In the proposed algorithm, the model of system link cost is built, the number of multicast retransmission times is restricted and each link quality matrix is traversed to reasonably select the multicast transmitter as well as its routing, which further reduces the link cost consumption, and in turn improves the bandwidth efficiency. Simulation results show that the proposed algorithm is more efficient to improve the bandwidth utilization when the ratio between normal user and non-normal user is small in mobile cloud.

关键词： mobile cloud D2D multicast SINR bandwidth efficiency

A low-complexity AMP detection algorithm with deep neural network for massive mimo systems

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Digital Communications and Networks 2024年第5期10卷 1375-1386页

作者： zufan zhang Yang Li Xiaoqin Yan Zonghua Ouyang School of Communication and Information Engineering Chongqing University of Posts and Telecommunications International College Chongqing University of Posts and Telecommunications College of Engineering Informatics and Applied Sciences Northern Arizona University

Signal detection plays an essential role in massive Multiple-Input Multiple-Output(MIMO) ***,existing detection methods have not yet made a good tradeoff between Bit Error Rate(BER) and computational complexity,resulting in slow convergence or high *** address this issue,a low-complexity Approximate Message Passing(AMP) detection algorithm with Deep Neural Network(DNN)(denoted as AMP-DNN) is investigated in this ***,an efficient AMP detection algorithm is derived by scalarizing the simplification of Belief Propagation(BP) ***,by unfolding the obtained AMP detection algorithm,a DNN is specifically designed for the optimal performance *** the proposed AMP-DNN,the number of trainable parameters is only related to that of layers,regardless of modulation scheme,antenna number and matrix calculation,thus facilitating fast and stable training of the *** addition,the AMP-DNN can detect different channels under the same distribution with only one *** superior performance of the AMP-DNN is also verified by theoretical analysis and *** is found that the proposed algorithm enables the reduction of BER without signal prior information,especially in the spatially correlated channel,and has a lower computational complexity compared with existing state-of-the-art methods.

关键词： Massive MIMO system Approximate message passing (AMP) detection algorithm Deep neural network (DNN) Bit error rate (BER) Low-complexity

The deep spatiotemporal network with dual-flow fusion for video-oriented facial expression recognition

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Digital Communications and Networks 2023年第6期9卷 1441-1447页

作者： Chenquan Gan Jinhui Yao Shuaiying Ma zufan zhang Lianxiang Zhu School of Cyber Security and Information Law Chongqing University of Posts and TelecommunicationsChongqing400065China School of Communications and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing400065China Engineering Research Center of Mobile Communications Ministry of EducationChongqing400065China School of Computer Science Xi'an Shiyou UniversityXi'an710065China

The video-oriented facial expression recognition has always been an important issue in emotion *** present,the key challenge in most existing methods is how to effectively extract robust features to characterize facial appearance and geometry changes caused by facial *** this basis,the video in this paper is divided into multiple segments,each of which is simultaneously described by optical flow and facial landmark *** deeply delve the emotional information of these two representations,we propose a Deep Spatiotemporal Network with Dual-flow Fusion(defined as DSN-DF),which highlights the region and strength of expressions by spatiotemporal appearance features and the speed of change by spatiotemporal geometry ***,experiments are implemented on CKþand MMI datasets to demonstrate the superiority of the proposed method.

关键词： Facial expression recognition Deep spatiotemporal network Optical flow Facial landmark trajectory Dual-flow fusion

Consensus of multi-agent systems with dynamic join characteristics under impulsive control

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Frontiers of Information Technology & Electronic Engineering 2021年第1期22卷 120-133页

作者： Xiang HU zufan zhang Chuandong LI School of Communication and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing 400065China Chongqing Key Laboratory of Nonlinear Circuits and Intelligent Information Processing College of Electronic and Information EngineeringSouthwest UniversityChongqing 400715China

We study how to achieve the state consensus of a whole multi-agent system after adding some new agent groups dynamically in the original multi-agent *** analyze the feasibility of dynamically adding agent groups under differen t forms of net work topologies that are currently common,and obtain four feasible schemes in theory,including one scheme that is the best in actual industrial ***,we carry out dynamic modeling of multi-agent systems for the best *** control theory and Lyapunov stability theory are used to analyze the conditions so that the whole multi-agent system with dynamic join characteristics can achieve state ***,we provide a numerical example to verify the practicality and validity of the theory.

关键词： Multi-agent system Network topology Impulsive input Dynamic join charac teristics State consensus

智能反射表面辅助无线能量传输的保密率最大化算法

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电子与信息学报 2022年第7期44卷 2366-2373页

作者：张祖凡张迪重庆邮电大学通信与信息工程学院重庆400065

为了减少窃听者对合法接收者的信息接收影响和窃听者的有用信息接收量,该文研究利用智能反射表面(IRS)来实现无线供电通信网络(WPCN)中窃听端处的波束抵消。首先在传输能量的同时进行窃听检测,IRS根据合法用户的能量状态选择是否采取防... 详细信息

为了减少窃听者对合法接收者的信息接收影响和窃听者的有用信息接收量,该文研究利用智能反射表面(IRS)来实现无线供电通信网络(WPCN)中窃听端处的波束抵消。首先在传输能量的同时进行窃听检测,IRS根据合法用户的能量状态选择是否采取防窃听模式,然后在存在窃听的情况下,研究了窃听信道完美和不完美状态下系统的保密率最大化问题。分析表明,这一最大化问题是相移、功率分配、时间分配的多变量耦合非凸问题,可以采用分步优化、变量替换和S-Lemma等方法进行求解。仿真结果表明,与基准算法相比,所提算法提升了保密率,当智能反射表面元件数为80时保密率提升了44%,发射功率为40 dBm时保密率提升了34%。

关键词：无线供电通信网络智能反射表面保密率

IRS多分区辅助太赫兹多子阵列波束成形设计

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通信学报 2023年第8期44卷 78-88页

作者：张祖凡唐睿重庆邮电大学通信与信息工程学院重庆400065 重庆移通学院通信与信息工程学院重庆401520

在智能反射表面(IRS)辅助太赫兹(THz)通信系统中,为突破信道稀疏性对系统空间多路复用增益的限制,提出收发端采用宽间隔多子阵列混合波束成形架构,设计IRS多分区辅助THz多子阵列的传输方案。首先,基于频谱效率最大化原则,构建一个含有... 详细信息

在智能反射表面(IRS)辅助太赫兹(THz)通信系统中,为突破信道稀疏性对系统空间多路复用增益的限制,提出收发端采用宽间隔多子阵列混合波束成形架构,设计IRS多分区辅助THz多子阵列的传输方案。首先,基于频谱效率最大化原则,构建一个含有多变量耦合和非凸约束的非凸目标函数;然后,将优化问题解耦成2个易于求解的子问题,即IRS反射系数矩阵设计问题和收发端混合波束成形矩阵设计问题;最后,采用黎曼流形优化算法计算IRS反射系数矩阵,并通过数理推导得到混合波束成形矩阵的闭式解。仿真结果表明,与基准方案相比,所提方案可以获得更好的频谱效率。

关键词：智能反射表面两级空间多路复用混合波束成形黎曼流形优化

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城市街道下场景IRS辅助D2D通信系统波束成形设计

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电子与信息学报 2024年第9期46卷 3571-3582页

作者：张祖凡刘建张晨璐重庆邮电大学通信与信息工程学院重庆400065 维沃移动通信有限公司深圳518049

针对城市街道场景下蜂窝用户和D2D通信用户共享频谱以及城市街道下无线信道特性,该文提出一种IRS辅助的联合波束成形设计方法。在D2D链路信号与干扰加噪声比的约束下,以最大化蜂窝用户容量为目标,设计了最优的波束形成向量、相移矩阵和... 详细信息

针对城市街道场景下蜂窝用户和D2D通信用户共享频谱以及城市街道下无线信道特性,该文提出一种IRS辅助的联合波束成形设计方法。在D2D链路信号与干扰加噪声比的约束下,以最大化蜂窝用户容量为目标,设计了最优的波束形成向量、相移矩阵和D2D链路发射功率。引入松弛变量将非凸且变量耦合的优化问题转换为解耦后的凸优化问题和二分法搜索功率分配,采用黎曼共轭梯度算法对反射相移矩阵进行优化。仿真结果表明,所提算法收敛性较好,且与基准方案相比能有效地提升用户信道容量。

关键词：智能反射面 D2D 波束成形交替优化

基于3D-Markov链的异构网络用户QoE分析方法

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中国科学：信息科学 2016年第1期46卷 85-99页

作者：张祖凡张宇重庆邮电大学通信与信息工程学院重庆400065 重庆邮电大学移动通信技术重庆市重点实验室重庆400065

针对融合IEEE802.11ad的LTE-A异构网络中的用户接入体验质量(quality of experience,QoE)问题,本文通过引入接入竞争时间窗口函数,构造一种适用于异构网络用户接入退避行为的3DMarkov链模型,考虑不同业务类型用户体验质量,分析系统服务... 详细信息

针对融合IEEE802.11ad的LTE-A异构网络中的用户接入体验质量(quality of experience,QoE)问题,本文通过引入接入竞争时间窗口函数,构造一种适用于异构网络用户接入退避行为的3DMarkov链模型,考虑不同业务类型用户体验质量,分析系统服务质量(quality of service,QoS),采用典型的平均意见得分(mean opinion score,MOS)评价方法映射得到用户Qo E性能指标.计算机仿真结果表明,在系统带宽一定情形下,融合IEEE802.11ad的LTE-A异构网络可以提高包括吞吐量、时延、丢包率等指标的系统QoS和包括MOS的用户QoE.

关键词：异构网络接入控制服务质量体验质量 3D-Markov链

智能反射表面辅助太赫兹信道估计的低复杂度算法

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电子与信息学报 2023年第10期45卷 3640-3647页

作者：张祖凡杨作为王国仲重庆邮电大学通信与信息工程学院重庆400065 重庆电子工程职业学院重庆401331

信道估计是智能反射表面(IRS)辅助太赫兹(THz)通信中的一大挑战。为了减少由收发端天线和IRS反射元件数增加引起的信道估计导频开销过大的问题,该文提出一种基于正则平行因子(CP)分解的信道估计算法。首先在分析信道特点的基础上对IRS... 详细信息

信道估计是智能反射表面(IRS)辅助太赫兹(THz)通信中的一大挑战。为了减少由收发端天线和IRS反射元件数增加引起的信道估计导频开销过大的问题,该文提出一种基于正则平行因子(CP)分解的信道估计算法。首先在分析信道特点的基础上对IRS阵元进行分组设计,然后将IRS辅助的无线通信信道表示为统一数学表达式,接着利用多天线THz信道固有的低秩结构将信号接收矩阵构建成一个3维张量,并且利用基于正则平行因子分解算法对张量进行分解,最后利用相关性对信道参数进行估计。通过蒙特卡罗仿真表明,该算法在信道传输条件相同的情况下相对于基准算法有4.28 dB和7.12 dB左右的性能提升,并且具有更低的计算复杂度。

关键词：太赫兹通信智能反射表面信道估计正则平行因子分解