下一代高速铁路异构网络切换安全认证

近年来,随着高速铁路无线通信技术的快速发展, GSM-R无线通信系统将逐步向LTE-R系统演进。在此演进过程中存在GSM-R和LTE-R长期共存的局面,如何实现高速铁路无线通信异构网络之间的快速切换和安全认证成为铁路无线通信研究的热点问题。针对高速铁路无线通信异构网络切换认证过程中,存在安全性低和认证开销高等问题,提出了一种适用于下一代高速铁路异构网络的轻量级切换安全认证方案。首先,采用哈希函数等操作生成切换请求Token和异构网络切换认证码PASS,实现了用户身份匿名性和可追溯性等安全要求,并且高速列车无需多次注册就可实现异构网络间的无缝切换。其次,设计了基于椭圆曲线密钥交换的轻量级切换算法,完成了高速列车与目标基站的相互认证和密钥协商,降低了计算开销和通信开销,实现了会话协商密钥的前后向安全性。最后,采用形式化方式BAN逻辑进行了安全性验证,并使用朔黄铁路LTE-R线路实测数据进一步对本文所提方案的有效性进行了验证,分析得出所提方案能够满足可追溯性、匿名性、抗伪装用户攻击、抗中间人攻击和抗重放攻击等安全特性。性能分析表明,本文方案在通信开销和计算开销方面较比较方法性能更优,能够满足...     

网络与终端协同选择及切换机制的研究

提出了一种智能切换机制,用于实现在异构网络中网络与终端的协同选择及切换功能。随着各种业务和应用的发展,异构网络融合是信息和通信技术的必然趋势。根据多接入、多终端等应用环境的要求,采用AHP与URA等多属性决策理论,为用户选择最佳的目标网络和目标终端,并提出相应的智能切换信令流程,包括网络切换、终端切换、网络与终端联合切换方式,最终构建以用户为中心的多终端智能空间,实现个人移动性管理。仿真表明,该智能切换机制可以有效地实现网络和终端的协同选择,并可以保证在异构网络切换QoS性能,为现代服务业的业务及应用的发展提供可靠的理论依据。     

融合Ad-hoc和蜂窝网络的中继设备设计

为了改善现有移动蜂窝网络在人口密集区域时常出现拥塞的现象,对Ad-hoc和蜂窝网络融合技术进行了研究,提出了一种融合Ad-hoc和蜂窝网络的中继设备实现方案.该方案采用S3C2440控制芯片、无线通信模块和GPRS通讯模块作为硬件开发平台,分析了硬件接口设计和配置,设计了软件系统,实现了Ad-hoc和GSM网络的互联.提出了一种改进的基于信号强度的切换算法,实现了异构网络无缝切换.通过搭建平台对设备进行了测试,结果表明了该设计的可行性.     

基于预判决和改进灰关联的异构网络切换算法

传统异构网络切换算法容易引起乒乓效应和切换准确度不高等问题; 同时,现有异构网络切换算法存在网络属性权重确定不合理问题,容易增加不必要的切换次数。因此,针对异构网络切换算法判决不准确带来的乒乓效应问题进行了研究,提出了一种基于差值门限比率和改进灰色关联分析相结合的异构网络切换算法。首先采用差值门限比率进行预判决,初步确定网络是否切换;再利用改进灰色关联分析算法选取目标切换网络,从而决定是否切换网络。搭建了WLAN和UMTS融合的异构网络环境,采用了MATLAB、OPNET等仿真工具。仿真结果表明：该算法有效提高了网络切换判决的准确性,减少了网络切换次数,降低了网络切换失败率。     

基于Mobile IP的异构网络系统切换方法的研究

针对当前3G网络的发展和无线局域网（Wlan）的兴起,研究了Wlan和3G网络的集成架构和混合异构网络的垂直切换管理。引入Mobile IP技术来达到无缝漫游,同时提出了多接入网络环境下检测Wlan信号强度的异构网间切换方法,并根据延时和中断时间来分析切换方法的性能。试验结果表明该切换方法能够及时有效地改进异构网络的切换效率。     

异构网络垂直切换决策算法仿真

在异构网络无缝切换的研究中,切换判决是实现异构网络无缝切换中最为关键的一步。在不同接入网之间,为保证业务连续性,需要考虑终端及网络的多方因素,进行综合判决,选择最合适的网络进行接入。以往的垂直切换决策算法普遍存在一些未解决的问题,如考虑的判决因素不全面,决策权值太过主观,对不确定性因素难以描述,算法复杂度和性能无法很好的权衡等。为进一步提高算法性能,针对WLAN/UMTS的异构无线网络环境,提出一种更客观科学的垂直切换决策算法。并用Matlab/Simulink平台进行仿真建模,通过和传统的决策算法的对比分析,验证改进算法的有效性。仿真结果表明,新算法能及时准确地切换至最优网络,各网络负载均衡,且减少了不必要的切换。     

基于MIH的异构无线网络切换优化研究

近年来,随着科技的发展,人们逐渐进入信息化时代,无线通信、计算机网络、微电子技术在生活中的应用也随处可见,而这些技术实行的基础是无线网络通信,随着时代的进步,无线网络通信也不断的在进行着变革,逐渐朝着高宽带、高智能、个人化的方面发展。MIH(媒体独立切换)的异构无线网络切换优化方式在网络通信之中得到了广泛的应用,本文就基于MIH的异构无线网络切换优化管理和方式等方面进行了详细的研究与分析。     

一种融合网络语音业务系统的实现方法的研究

目前,基于信息与通信技术以及现代管理理念的现代服务行业迅速发展。现代服务业中用户通信需求的差异性以及通信接入方式的多样性,决定了支撑现代服务业发展的通信网络呈现为包含固定、移动多种接入方式在内的异构形态。用户对通信业务的连续性以及服务体验的一致性要求,对复杂的异构通信网络中的切换机制提出了挑战。文中研究并提出了一种适用于异构网络的,以用户为中心的语音业务系统的实现方法。该系统可根据终端及网络信息选择合理的终端进行最好的网络接入,并以智能切换保持语音业务的连续性和一致性。     

提高硬件多线程处理器性能的方法

在当今的网络处理器中，为了提高吞吐率、实现高性能，部分处理器采用了流水线技术和硬件多线程技术。支持硬件多线程不仅有效地隐藏了访存延迟，而且略去了线程切换时线程相关信息的保存与恢复，减少了线程切换的开销，从而提高了性能。然而硬件多线程并未能彻底消除线程切换的开销，线程切换时仍需要清除与重载流水线，这将浪费一定的时钟周期，不能充分利用多线程带来的好处。该文在IXP2400网络处理器的基础上，提出了一种新的设计方法，使得线程切换时略去了清除与重载流水线的环节，减少了这部分的开销，从而提高了处理器性能。     

异构网络的垂直切换仿真建模及其性能评估

针对无线网络的异构化趋势,对WLAN和UMTS形成的异构网络进行扩展,使其包含WLAN, WiMAX和UMTS 3种网络。基于介质独立切换对扩展后异构网络中的垂直切换进行仿真建模。评估切换时延、切换期间的丢包数目和网络使用效率,结果表明,链路即将断开(LGD)方式的切换时延小于链路断开(LD)方式,且丢包数较少,网络使用效率随着功率强度门限系数的增大而降低。     

一种基于标地分离的卫星网络移动切换管理技术

移动卫星网络因具有覆盖区域广、通信延时低等优势受到广泛关注,当前有大量研究旨在开发IP协议的组网技术,并将其与地面IP网络融合。融合网络的挑战之一,即为卫星移动性,用户在卫星网络中的接入点频繁切换导致移动管理问题,而现有的移动IP技术不能高效支持卫星网络移动切换。为了高效支持移动切换,在卫星网络中应用标地分离思想,在标地分离的架构下研究切换管理问题;用映射服务系统对终端进行位置管理,在移动切换中由新接入卫星网关和终端的标志为主要信息在原卫星中形成通告转发表。仿真结果表明,相对移动IP技术,该方法有明显优势。将其应用于卫星网络时可以降低切换延时,减少大量的绑定更新开销或是次优路由,提升系统的性能和可扩展性。     

Mobility management for m-commerce requests in wireless cellular networks

Increasing number of sophisticated services provided by the current wireless communication systems have caused a significant transition from E-commerce to M-commerce. Enterprises have provided considerable new opportunities to promote their businesses accessible from small mobile devices such as personal digital assistant (PDA) or mobiles phones. These facilities are envisioned as the most convenient way of using M-commerce. Using such services from mobile phones or PDAs equipped with GSM/GPRS involve effective mobility management mechanisms in cellular networks—a popular architecture for wireless networks. Success of such systems will largely depend on the reliable connection for the roaming users. Consequently, Quality of Service (QoS) provision is one of the most challenging issues in the heterogeneous wireless network-based m-commerce systems. Such m-commerce systems enable users to roam between different wireless networks operators and geographical areas while providing interactive broadband services and seamless connectivity. This paper presents an analytical framework to model scarce channels in any cell for maximizing channel utilization and efficient handling of handover requests. Typical numerical experiments are presented to validate the analytical solution against simulation to study the effect of bursty traffic upon the performance of the cell in any cellular networks.     

基于蜂窝无线网络的移动IP（IPv6）研究

Introduce method and technology of combination of the TCP/IP protocol based on IPv6 and the cellular wireless communication network. Analyze the cut-in point and key technology of the combination from the view of frame, system structure and the realization of protocols. The 3G cellular wireless communication is a hotspot today and the mobile IP technology is one of the developing directions for the Internet's future. We put forward a new idea and method for the mobile communication technology from the practical view.     

A robust method for soft IP handover

Multimedia streaming over wireless networks - often called mobile multimedia streaming lets users access music, movie, and news services at any time, regardless of location. Given that multimedia streaming is a key goal of third-generation and future wireless networks, vendors will soon deploy streaming clients in advanced mobile terminals. Current mobile terminals, however, fail to adequately support mobile multimedia communication because wireless networks have high packet-loss rates. To eliminate packet loss during handover, we use a packet path diversity scheme and an end-to-end bicasting mechanism that enables soft IP handover. To offset wireless errors, we use a forward error correction (FEC) scheme and embed it in the bicasting mechanism. Our bicasting method encodes the data stream and then splits it, providing more effective diversity than general bicasting, which sends the same data down both paths.' To support our method, we propose the mobile multimedia streaming protocol (MMSP), a new transport-layer protocol that supports multihoming and bicasting in combination with FEC.     

CDMA和WLAN之间的移动IPv6切换

随着IP技术和无线通信技术的发展和融合,移动IPv6成为了全球移动解决方案。针对移动IPv6的大规模应用,该文通过建立Silkroad隧道,实现CDMA和WLAN之间的移动IPv6垂直切换。针对CDMA网络进行切换优化的情况,提供了一种在蜂窝网和WLAN之间运用的移动IPv6切换方案。实验证明了该方案的有效性。     

A MIH-based approach for best network selection in heterogeneous wireless networks

In the next generation wireless networks, different technologies belonging to one or more operators should be integrated to form a heterogeneous environment based on an IP core network infrastructure. This ensures user mobility and service continuity by maintaining connections when switching between various technologies and it introduces new resources and possibilities for applications. In this context, an automatic interface selection based on instantaneous and practical constraints and user preferences (Quality of Service (QoS) parameters, available resources, security, power consumption, etc.) is therefore required. The different network selection and handover schemes proposed in the literature can be classified into three approaches according to who is responsible for making the handover decision: the terminal, the network or by a cooperation between both of them. However, these approaches keep presenting some drawbacks; namely the problem of resources management and network load balancing whenever the selection is controlled by the mobile terminal (MT) and the problem of scalability and unknown operator's management policy whenever the selection is rather controlled by the network.In this article, first we propose a MIH based approach for handover initiation and preparation for heterogeneous wireless network. The proposed framework is based on the principals of IEEE 802.21 for context information gathering and optimized handover decision making. Second, we propose a new architecture and new network selection scheme that explicitly take into account the current resource usage and the user preferences. Furthermore, our solution ensures the selection of the most suitable network for each flow while taking into consideration its expectations in terms of QoS. A feasibility study of implementing a new architecture on a single MT is evaluated by using typical scenarios and using various algorithms. Thanks to the introduced function entities and modules in the proposed architecture, network utilization balancing and user and application expectations, which are successfully assured without operator intervention. Performance analysis shows that the proposed algorithm best meets the common quality requirements.     

基于模糊逻辑技术的切换策略

下一代宽带无线通信网在为用户提供高速率语音服务以及图像、视频信息的传输和高速接入Internet服务等丰富的业务类型的同时,也给系统的切换策略带来新的挑战。以往仅考虑单一因素对系统影响的切换策略已不适用于具有丰富业务类型的下一代宽带无线通信网络。该文利用模糊逻辑技术进行切换过程中的目标小区选取。相比传统方案,模糊逻辑技术可以兼顾多种因素,使得选取结果更加合理,并且可以均衡系统负载、减少切换的拒绝率。     

Handoff performance analysis of PMIPv6-based distributed mobility management protocol-urban scenario

Mobility management allows the networks to track down a mobile user's location for sending datagrams and to retain the connection when the user changes its location points repeatedly. Whenever a node switches between one base station and another, the connectivity is maintained through a process called handoff management. For real-time traffic implementations in wireless network communications, handover performance is essential. A mobile node is blocked from transmitting and receiving a datagram for a longer time as the handover delay increases. Unacceptable handover delays are common in real-time communication services. To guarantee smooth connectivity and continuous provision of services, effective handoff methods are required. The handoff efficiency of network-based distributed mobility management (DMM) is studied extensively in this article, along with a comparison to PMIPv6. We specifically investigate how handover delay, session recovery, and packet loss are influenced by cell radius. From the analytical and simulation findings this paper concludes that network-based DMM performs better than PMIPv6.     

一种基于时间阈值和协作分集的切换优化机制

针对基于协作节点的分层移动IPV6协议(PHMIPv6)在域间切换时,因未充分考虑非合作节点而可能导致的预切换操作失败问题,该文通过计算移动节点与协作节点的链路终止时间(LET)并引入时间阈值,保证所选择的协作节点能够及时执行预切换过程并返回新的转交地址,有效缩短切换准备时长;另外,在切换完成后,以协作节点为中继,移动节点与新的接入点在上下行建立包括蜂窝网络和Ad hoc网络的异构协作信道,充分利用协作分集技术来提高小区边缘的通信质量.应用NS2搭建了仿真环境,并分别从预切换成率、丢包数、切换时延等三个方面验证了该切换机制在性能上的优越性.     

基于蜂窝无线网络的移动IP(IPV6)研究

介绍了基于IPv6技术的TCP／IP协议与蜂窝无线通信网络结合的方法和技术。从框架、体系结构、协议实现各个角度分析了这两种技术结合的切入点和技术关键。3G蜂窝无线通信技术是当今一大研究热点，移动IP技术是今后网络的发展方向，从实用的角度为移动通信技术提出了新的观点和方法。