Pull-based P2P live streaming is a promising solution for the large scale streaming systems, like PPStream, PPlive, due to its high scalability, low cost and high resilience. However, they usually suffer from bad dela...Pull-based P2P live streaming is a promising solution for the large scale streaming systems, like PPStream, PPlive, due to its high scalability, low cost and high resilience. However, they usually suffer from bad delay performance. In this paper, we seek to improve the delay performance under ensuring video display quality stemming from chunk scheduling. And so we model Pull-based chunk scheduling problem as a multi-objective optimization problem to minimize the video delay and maximize video display quality in the environment of heterogeneous upload bandwidths, heterogeneous and dynamic propagation delays. Finally we put up with a greedy Pull-based scheduling approach(GPSA) to solve the optimization problem. The evaluation shows GPSA can outperform two classical chunk scheduling approaches and adapt to dynamic variance of propagation delays.展开更多
In order to solve the problem that the existing data scheduling algorithm cannot make full use of neighbors' bandwidth resources when allocating data request among several senders in the multisender based P2P stre...In order to solve the problem that the existing data scheduling algorithm cannot make full use of neighbors' bandwidth resources when allocating data request among several senders in the multisender based P2P streaming system,a peer priority based scheduling algorithm is proposed.The algorithm calculates neighbors' priority based on peers' historical service evaluation as well as how many wanted data that the neighbor has.The data request allocated to each neighbor is adjusted dynamically according to the priority when scheduling.Peers with high priority are preferred to allocate more data request.Experiment shows the algorithm can make full use of neighbors' bandwidth resources to transmit data to reduce server pressure effectively and improve system scalability.展开更多
Mobile Edge Computing(MEC)is a promising solution to tackle the upcoming computing tsunami in 5G/6G era by effectively utilizing the idle resource at the mobile edge.In this work,a multi⁃hop D2D⁃enabled MEC scenario w...Mobile Edge Computing(MEC)is a promising solution to tackle the upcoming computing tsunami in 5G/6G era by effectively utilizing the idle resource at the mobile edge.In this work,a multi⁃hop D2D⁃enabled MEC scenario was studied,where mobile devices at network edge connect and share resources with each other via multi⁃hop D2D.The research focus was on the micro⁃task scheduling problem in the multi⁃hop D2D⁃enabled MEC system,where each task was divided into multiple sequential micro⁃tasks,such as data downloading micro⁃task,data processing micro⁃task,and data uploading micro⁃task,according to their functionalities as well as resource requirements.A joint Task Failure Probability and Energy Consumption Minimization(TFP⁃ECM)problem was proposed,aiming at minimizing the task failure probability and the energy consumption jointly.To solve the problem,several linearization methods were proposed to relax the constraints and convert the original problem into an integer linear programming(ILP).Simulation results show that the proposed solution outperformed the existing solutions(with indivisible tasks or without resource sharing)in terms of both total cost and task failure probability.展开更多
目的:评价中文版神经精神病学评定表2.1(Schedules for Clinical Assessment in Neuropsychiatry Version 2.1,SCAN2.1)在精神科应用的信度和效度。方法:选取门诊及住院的各类精神障碍患者100例,选取与精神障碍组在性别、年龄及教育程...目的:评价中文版神经精神病学评定表2.1(Schedules for Clinical Assessment in Neuropsychiatry Version 2.1,SCAN2.1)在精神科应用的信度和效度。方法:选取门诊及住院的各类精神障碍患者100例,选取与精神障碍组在性别、年龄及教育程度相匹配的正常对照100例作为对照。由6名研究人员对8例病例同时进行评定以检验研究者信度;选取另外10例病例由1名研究人员1周后进行重测,以检验重测信度。精神科医生对200例入组者根据国际疾病和相关健康问题统计分类第十版(ICD-10)做出的临床诊断作为"金标准",6名研究者对200例被试用SCAN2.1中的精神现状检查第十版(PSE-10)部分进行访谈,得出诊断结果与"金标准"进行比较,评估中文版SCAN2.1的效度;结果:SCAN2.1中文版研究人员之间信度和重测信度kappa值分别为0.76和0.74。校标效度中,灵敏度95.0%,特异度100%,阳性预测值100%,阴性预测值95.2%,kappa值0.95。对精神分裂症病诊断的灵敏度88.5%、特异度100%、阳性预测值100%、阴性预测值98.9%、kappa值0.89;对心境障碍病的灵敏度100%、特异度100%、阳性预测值100%、阴性预测值100%、Kappa值1.0,对神经症、应激相关及躯体形式障碍病种的灵敏度92.3%、特异度100%、阳性预测值100%、阴性预测值98.9%、kappa值0.95。结论:神经精神病学评定表2.1中文版有较高的信度和效度,可在国内临床中应用。展开更多
The performance of the graph-based scheduling for device-to-device communications overlaying cellular networks is studied. The graph-based scheduling consists of two stages, the frequency assignment stage and the time...The performance of the graph-based scheduling for device-to-device communications overlaying cellular networks is studied. The graph-based scheduling consists of two stages, the frequency assignment stage and the time slot scheduling stage. For such scheduling, a theoretical method to analyze the average spectrum efficiency of the D2D subsystem is proposed. The method consists of three steps. First, the frequency assignment stage is analyzed and the approximate formula of the average number of the D2D links which are assigned the same frequency is derived. Secondly, the time slot scheduling stage is analyzed and the approximate formula of the average probability of a D2D link being scheduled in a time slot is derived. Thirdly, the average spectrum efficiency of the D2D subsystem is analyzed and the corresponding approximate formula is derived. Analysis results show that the average spectrum efficiency of the D2D subsystem is approximately inversely linearly proportional to the second- order origin moment of the normalized broadcast radius of D2D links. Simulation results show that the proposed method can correctly predict the average spectrum efficiency of the D2D subsystem.展开更多
基金supported by National Key Basic Research Program of China(973 Program)(2009CB320504)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 60821001)+1 种基金Beijing Municipal Commission of Education to build the project special,Research Fund for the Doctoral Program of Higher Education of China (20090005120012)National Natural Science Foundation (60672121)
文摘Pull-based P2P live streaming is a promising solution for the large scale streaming systems, like PPStream, PPlive, due to its high scalability, low cost and high resilience. However, they usually suffer from bad delay performance. In this paper, we seek to improve the delay performance under ensuring video display quality stemming from chunk scheduling. And so we model Pull-based chunk scheduling problem as a multi-objective optimization problem to minimize the video delay and maximize video display quality in the environment of heterogeneous upload bandwidths, heterogeneous and dynamic propagation delays. Finally we put up with a greedy Pull-based scheduling approach(GPSA) to solve the optimization problem. The evaluation shows GPSA can outperform two classical chunk scheduling approaches and adapt to dynamic variance of propagation delays.
基金Supported by the National High Technology Research and Development Program of China(No.2009AA01A339,2008AA01A317)the National Natural Science Foundation of China for Distinguished Young Scholars(No.60903218F0208)the Science and Technology Support Plan of China(No.2008BAH28B04)
文摘In order to solve the problem that the existing data scheduling algorithm cannot make full use of neighbors' bandwidth resources when allocating data request among several senders in the multisender based P2P streaming system,a peer priority based scheduling algorithm is proposed.The algorithm calculates neighbors' priority based on peers' historical service evaluation as well as how many wanted data that the neighbor has.The data request allocated to each neighbor is adjusted dynamically according to the priority when scheduling.Peers with high priority are preferred to allocate more data request.Experiment shows the algorithm can make full use of neighbors' bandwidth resources to transmit data to reduce server pressure effectively and improve system scalability.
基金National Natural Science Foundation of China(Grant Nos.61831008,61525103 and 61972113)the Guangdong Science and Tech⁃nology Planning Project(Grant No.2018B030322004)the Basic Research Project of Shenzhen Science and Technology Program(Grant No.JCYJ20190806112215116).
文摘Mobile Edge Computing(MEC)is a promising solution to tackle the upcoming computing tsunami in 5G/6G era by effectively utilizing the idle resource at the mobile edge.In this work,a multi⁃hop D2D⁃enabled MEC scenario was studied,where mobile devices at network edge connect and share resources with each other via multi⁃hop D2D.The research focus was on the micro⁃task scheduling problem in the multi⁃hop D2D⁃enabled MEC system,where each task was divided into multiple sequential micro⁃tasks,such as data downloading micro⁃task,data processing micro⁃task,and data uploading micro⁃task,according to their functionalities as well as resource requirements.A joint Task Failure Probability and Energy Consumption Minimization(TFP⁃ECM)problem was proposed,aiming at minimizing the task failure probability and the energy consumption jointly.To solve the problem,several linearization methods were proposed to relax the constraints and convert the original problem into an integer linear programming(ILP).Simulation results show that the proposed solution outperformed the existing solutions(with indivisible tasks or without resource sharing)in terms of both total cost and task failure probability.
文摘目的:评价中文版神经精神病学评定表2.1(Schedules for Clinical Assessment in Neuropsychiatry Version 2.1,SCAN2.1)在精神科应用的信度和效度。方法:选取门诊及住院的各类精神障碍患者100例,选取与精神障碍组在性别、年龄及教育程度相匹配的正常对照100例作为对照。由6名研究人员对8例病例同时进行评定以检验研究者信度;选取另外10例病例由1名研究人员1周后进行重测,以检验重测信度。精神科医生对200例入组者根据国际疾病和相关健康问题统计分类第十版(ICD-10)做出的临床诊断作为"金标准",6名研究者对200例被试用SCAN2.1中的精神现状检查第十版(PSE-10)部分进行访谈,得出诊断结果与"金标准"进行比较,评估中文版SCAN2.1的效度;结果:SCAN2.1中文版研究人员之间信度和重测信度kappa值分别为0.76和0.74。校标效度中,灵敏度95.0%,特异度100%,阳性预测值100%,阴性预测值95.2%,kappa值0.95。对精神分裂症病诊断的灵敏度88.5%、特异度100%、阳性预测值100%、阴性预测值98.9%、kappa值0.89;对心境障碍病的灵敏度100%、特异度100%、阳性预测值100%、阴性预测值100%、Kappa值1.0,对神经症、应激相关及躯体形式障碍病种的灵敏度92.3%、特异度100%、阳性预测值100%、阴性预测值98.9%、kappa值0.95。结论:神经精神病学评定表2.1中文版有较高的信度和效度,可在国内临床中应用。
基金The National Natural Science Foundation of China(No.61571111)the National High Technology Research and Development Program of China(863 Program)(No.2014AA01A703,2015AA01A706)the Fundamental Research Funds for the Central Universities of China(No.2242016K40098)
文摘The performance of the graph-based scheduling for device-to-device communications overlaying cellular networks is studied. The graph-based scheduling consists of two stages, the frequency assignment stage and the time slot scheduling stage. For such scheduling, a theoretical method to analyze the average spectrum efficiency of the D2D subsystem is proposed. The method consists of three steps. First, the frequency assignment stage is analyzed and the approximate formula of the average number of the D2D links which are assigned the same frequency is derived. Secondly, the time slot scheduling stage is analyzed and the approximate formula of the average probability of a D2D link being scheduled in a time slot is derived. Thirdly, the average spectrum efficiency of the D2D subsystem is analyzed and the corresponding approximate formula is derived. Analysis results show that the average spectrum efficiency of the D2D subsystem is approximately inversely linearly proportional to the second- order origin moment of the normalized broadcast radius of D2D links. Simulation results show that the proposed method can correctly predict the average spectrum efficiency of the D2D subsystem.
