随着网络技术的发展,无线网络接入认证技术的应用越来越广泛。通过远程认证拨入用户服务(Remote Authentication Dial In User Service,RADIUS)和数字证书配合使用,可以实现较为安全完善的无线网络接入认证。介绍RADIUS和数字证书的相...随着网络技术的发展,无线网络接入认证技术的应用越来越广泛。通过远程认证拨入用户服务(Remote Authentication Dial In User Service,RADIUS)和数字证书配合使用,可以实现较为安全完善的无线网络接入认证。介绍RADIUS和数字证书的相关概念,概述使用RADIUS和数字证书进行无线网络接入时的网络拓扑与接入认证过程,给出RADIUS代理服务器、认证服务器以及数字证书的配置方法同时,给出验证该无线网络接入认证技术的方法,也是Linux客户端进行网络接入认证的方法。通过搭建RADIUS网络接入环境,使用数字证书作为认证凭证,实现客户端对无线网络的接入认证。展开更多
Purpose:The purpose of the research is to investigate public needs for digital information service in the Chinese libraries and museums and seek ways to help these public service institutions improve their service to ...Purpose:The purpose of the research is to investigate public needs for digital information service in the Chinese libraries and museums and seek ways to help these public service institutions improve their service to meet user needs.Design/methodology/approach:An online questionnaire survey was used to study the publicneeds for digital information service provided by libraries and museums.A total of 474 valid questionnaires were retrieved for analysis.Findings:The primary purpose of using the digital library and museum service was for knowledge acquisition,followed by work or class assignment and leisure and entertainment.Users need one-stop information service that provides information and service in a more integrated form and allows cross-database searching as well.Research limitations:A majority of the respondents were young and middle-aged people who often use the Internet.We would need to increase our sample size and include different groups of users such as children and retirees to make the sample more representative.Practical implications:Libraries and museums should collaborate to provide the users with one-stop digital information service.Meanwhile,the research can serve as a reference source for the future studies of digital library and museum service.Originality/value:Few studies were published on the public needs for digital library and museum service in China.This study bridges the gap and contributes to our understanding of the Chinese users’ needs for digital information service in libraries and museums.展开更多
星地融合网络通过实现卫星网络与地面蜂窝网络的有机融合,可为用户提供灵活的网络接入服务,满足多场景用户应用需求.然而,卫星网络拓扑结构的动态变化、星地链路的复杂特性、多网和多用户资源调度粒度的显著差异性,以及资源共享模式的...星地融合网络通过实现卫星网络与地面蜂窝网络的有机融合,可为用户提供灵活的网络接入服务,满足多场景用户应用需求.然而,卫星网络拓扑结构的动态变化、星地链路的复杂特性、多网和多用户资源调度粒度的显著差异性,以及资源共享模式的多样性,均对星地融合网络用户关联及资源调度问题带来困难及挑战.本文针对星地融合网络下行链路增强型移动宽带用户(Enhanced mobile broadband User,EU)及高可靠低延迟通信用户(ultra-Reliable and low latency communications User,RU)数据传输场景,研究用户关联及资源调度问题.在满足用户传输需求、网络可用资源、资源共享模式等约束条件下,将联合用户关联及资源块调度问题建模为系统效用函数最大化问题.由于该优化问题为强耦合问题,不易直接求解,本文将原优化问题分解功率分配子问题、用户关联及资源调度子问题.针对功率分配子问题,利用拉格朗日部分松弛法对离散变量进行连续化,进而将功率分配子问题转换为凸优化问题,采用拉格朗日对偶算法进行求解.基于得到的功率分配策略,本文提出一种启发式算法确定用户关联模式及资源块分配策略,在对蜂窝网络可用时频资源状态进行评估的基础上,分别针对时频资源充足及时频资源不充足的情况设计用户关联及资源块调度策略.针对时频资源充足情况,根据用户资源调度模式,分别定义RU及EU的时空资源调度粒度,进而针对采用正交频分多址接入(Orthogonal Frequency Division Multiple Access,OFDMA)模式的RU及EU,基于KM匹配算法优化确定时频资源块调度策略;进而,针对采用穿孔模式的RU与EU,提出一种基于贪婪算法的EU资源块重调度策略,以满足用户最小传输速率;针对占用相邻子信道的EU优化确定OFDMA模式及非正交多址接入(Non-Orthogonal Multiple Access,NOMA)模式,以实现效用函数的提升.针对蜂窝网络时频资源不充足的情况,为无法接入蜂窝网络的用户分配卫星关联模式,并设计基于Kuhn-Munkres匹配算法的资源块调度策略.最后,通过仿真验证本文所提算法的有效性.展开更多
文摘随着网络技术的发展,无线网络接入认证技术的应用越来越广泛。通过远程认证拨入用户服务(Remote Authentication Dial In User Service,RADIUS)和数字证书配合使用,可以实现较为安全完善的无线网络接入认证。介绍RADIUS和数字证书的相关概念,概述使用RADIUS和数字证书进行无线网络接入时的网络拓扑与接入认证过程,给出RADIUS代理服务器、认证服务器以及数字证书的配置方法同时,给出验证该无线网络接入认证技术的方法,也是Linux客户端进行网络接入认证的方法。通过搭建RADIUS网络接入环境,使用数字证书作为认证凭证,实现客户端对无线网络的接入认证。
基金supported by the National Social Science Foundation of China(Grant No.:13ATQ001)
文摘Purpose:The purpose of the research is to investigate public needs for digital information service in the Chinese libraries and museums and seek ways to help these public service institutions improve their service to meet user needs.Design/methodology/approach:An online questionnaire survey was used to study the publicneeds for digital information service provided by libraries and museums.A total of 474 valid questionnaires were retrieved for analysis.Findings:The primary purpose of using the digital library and museum service was for knowledge acquisition,followed by work or class assignment and leisure and entertainment.Users need one-stop information service that provides information and service in a more integrated form and allows cross-database searching as well.Research limitations:A majority of the respondents were young and middle-aged people who often use the Internet.We would need to increase our sample size and include different groups of users such as children and retirees to make the sample more representative.Practical implications:Libraries and museums should collaborate to provide the users with one-stop digital information service.Meanwhile,the research can serve as a reference source for the future studies of digital library and museum service.Originality/value:Few studies were published on the public needs for digital library and museum service in China.This study bridges the gap and contributes to our understanding of the Chinese users’ needs for digital information service in libraries and museums.
文摘星地融合网络通过实现卫星网络与地面蜂窝网络的有机融合,可为用户提供灵活的网络接入服务,满足多场景用户应用需求.然而,卫星网络拓扑结构的动态变化、星地链路的复杂特性、多网和多用户资源调度粒度的显著差异性,以及资源共享模式的多样性,均对星地融合网络用户关联及资源调度问题带来困难及挑战.本文针对星地融合网络下行链路增强型移动宽带用户(Enhanced mobile broadband User,EU)及高可靠低延迟通信用户(ultra-Reliable and low latency communications User,RU)数据传输场景,研究用户关联及资源调度问题.在满足用户传输需求、网络可用资源、资源共享模式等约束条件下,将联合用户关联及资源块调度问题建模为系统效用函数最大化问题.由于该优化问题为强耦合问题,不易直接求解,本文将原优化问题分解功率分配子问题、用户关联及资源调度子问题.针对功率分配子问题,利用拉格朗日部分松弛法对离散变量进行连续化,进而将功率分配子问题转换为凸优化问题,采用拉格朗日对偶算法进行求解.基于得到的功率分配策略,本文提出一种启发式算法确定用户关联模式及资源块分配策略,在对蜂窝网络可用时频资源状态进行评估的基础上,分别针对时频资源充足及时频资源不充足的情况设计用户关联及资源块调度策略.针对时频资源充足情况,根据用户资源调度模式,分别定义RU及EU的时空资源调度粒度,进而针对采用正交频分多址接入(Orthogonal Frequency Division Multiple Access,OFDMA)模式的RU及EU,基于KM匹配算法优化确定时频资源块调度策略;进而,针对采用穿孔模式的RU与EU,提出一种基于贪婪算法的EU资源块重调度策略,以满足用户最小传输速率;针对占用相邻子信道的EU优化确定OFDMA模式及非正交多址接入(Non-Orthogonal Multiple Access,NOMA)模式,以实现效用函数的提升.针对蜂窝网络时频资源不充足的情况,为无法接入蜂窝网络的用户分配卫星关联模式,并设计基于Kuhn-Munkres匹配算法的资源块调度策略.最后,通过仿真验证本文所提算法的有效性.
