异构无线Mesh网络层次化平滑切换方案

针对现有异构无线Mesh网络缺乏对域间移动切换支持的问题,提出支持域间切换的异构无线Mesh网络层次化切换方案,区分域内切换和域间切换,降低切换时延。采用缓存策略,有效降低丢包率,支持终端的快速移动。仿真结果表明,该方案可支持速度达23 m/s的终端移动,在域间切换时,平均丢包数减少66.7%~95.5%。     

快速层次移动IPv6的域间移动管理

为了提升移动IPv6域间切换的性能,在FHMIPv6的机制上提出了一种基于边缘接入路由器的域间移动管理方案。在这种方式下,移动主机在移动到边缘接入路由器上时,进行域内切换并把链路转交地址在前移动锚点和新移动锚点上同时进行重复地址检测;完成切换后,在边缘接入路由器域内对新区域转交地址进行配置并在新MAP中与链路转交地址绑定。通过NS-2实验仿真验证能够有效减少域间切换带来的延迟,同时也降低了分组的丢失率。     

基于快速组播切换的分层移动组播体系结构

移动通信在人们的日常生活中发挥着越来越重要的作用,受到了越来越多的重视.人们希望能够在移动的时候获得与静态联网者相同的网络服务,这里最主要的就是要解决移动切换和无线网络带宽受限的问题.由于组播技术不仅能够提供很多新型的网络应用,而且能够高效地实现多点传送,并有效节省网络带宽,因此移动和组播的相互融合对两者的应用和发展都会带来较大的促进.提出了在移动环境中部署IP组播的框架体系,即基于快速组播切换的分层移动组播体系结构(fast multicast handoff based hierarchical mobile multicastarchitecture,简称FHMM).FHMM通过分层移动组播管理将节点在域内的移动对外屏蔽,提高了域间组播转发树主干的稳定性.FHMM还提出了快速组播切换机制,从而减少了切换延迟以及由此引发的分组丢失.另外,当节点移动到不支持组播的子网时,FHMM仍然可以为节点提供组播服务.模拟结果显示,FHMM具有分组丢失率低、组播分组传送效率高以及组播维护开销少等优点,是一种高效的移动组播解决方案.     

一种基于无线局域网的移动IP快速切换方案

为了使移动节点在无线局域网环境中进行快速有效的切换，我们提出了一种基于管理域的快速切换方案。该方案将多个相邻的无线局域网组成一个单独的域，采用层次管理方式，使域内各个子网通过专用的Mac桥连接，减少了移动节点域内切换过程中产生的注册时延和数据包的丢失。     

Intra domain route optimization for ubiquitous network

The main advantage of a wireless network is user mobility, which calls for efficient routing support at the network layer. An architecture combines hierarchical mobile IPv6 and network mobility for a network mobile and mobile nodes move in tandem and make a hierarchy in the wireless network to management of micro-mobility and seamless handoff. But the capability of the architecture for intra domain route optimization is impaired. So we propose functionality in domain nodes to enable intra domain path optimization for ubiquitous network. It is shown that intra domain cost effect is beneficial in every hierarchical domain that spans mesh network topology. We address the key function for our proposed scheme and analyze the usefulness of our proposed method using mathematically. We show that our proposed scheme performs much better than Network Mobility protocol, especially when the number of mobile nodes or mobile routers or correspondent nodes increases in hierarchically nested in ubiquitous networks.     

SafeMesh: A wireless mesh network routing protocol for incident area communications

Reliable broadband communication is becoming increasingly important during disaster recovery and emergency response operations. In situations where infrastructure-based communication is not available or has been disrupted, an Incident Area Network needs to be dynamically deployed, i.e. a temporary network that provides communication services for efficient crisis management at an incident site. Wireless Mesh Networks (WMNs) are multi-hop wireless networks with self-healing and self-configuring capabilities. These features, combined with the ability to provide wireless broadband connectivity at a comparably low cost, make WMNs a promising technology for incident management communications. This paper specifically focuses on hybrid WMNs, which allow both mobile client devices as well as dedicated infrastructure nodes to form the network and provide routing and forwarding functionality. Hybrid WMNs are the most generic and most flexible type of mesh networks and are ideally suited to meet the requirements of incident area communications. However, current wireless mesh and ad-hoc routing protocols do not perform well in hybrid WMN, and are not able to establish stable and high throughput communication paths. One of the key reasons for this is their inability to exploit the typical high degree of heterogeneity in hybrid WMNs. SafeMesh, the routing protocol presented in this paper, addresses the limitations of current mesh and ad-hoc routing protocols in the context of hybrid WMNs. SafeMesh is based on the well-known AODV routing protocol, and implements a number of modifications and extensions that significantly improve its performance in hybrid WMNs. This is demonstrated via an extensive set of simulation results. We further show the practicality of the protocol through a prototype implementation and provide performance results obtained from a small-scale testbed deployment.     

TEASE: A novel Tunnel-based sEcure Authentication SchemE to support smooth handoff in IEEE 802.11 wireless networks

With the growing popularity of WiFi-based devices, WiFi-based wireless networks have received a great deal of interest in the wireless networks community. However, due to the limited transmission range of WiFi-based networks, mobile users have to switch their associated access points constantly to maintain continuing communications during their movement. The process of switching access points is called handoff. Handoff management is a key service in mobile networks, because providing seamless roaming in wireless networks is mandatory for supporting real-time applications in a mobile environment, such as VoIP, online games, and eConference. Security is another important issue in network communications, and to prevent possible attacks, authentication is required during the handoff process to guarantee the reliability of mobile clients and access points. In this paper, we propose a novel authentication scheme to achieve a smooth handoff in WiFi-based networks, which we refer to as TEASE. A tunnel is introduced to forward data packets between the new access point and the original reliable access point. The processing of a complete secure authentication and the transmitting of data between mobile terminals and their correspondence nodes can go on simultaneously. The security of handoff is achieved without increasing overhead to authentication servers, and handoff latency can be minimized to support seamless roaming. Simulation results show that our proposed scheme reduces significantly the communication interruption time and generates low packet loss ratio, and our method is suitable to be used for secure handoff in real-time applications.     

Design and evaluation of a novel MAC layer handoff protocol for IEEE 802.11 wireless networks

In recent years, the IEEE 802.11 wireless network family has become one of the most important set of standards in the wireless communications industry. IEEE 802.11 compliant devices are inexpensive and easier to configure and deploy than other wireless technologies. In an IEEE 802.11 wireless network, wireless terminals can move freely. As a result, when the wireless terminal moves away from its current access point, it must switch to another access point to maintain the active connection. This is known as the MAC layer handoff process. MAC layer handoff latency should be minimized to support real-time applications and to provide mobile devices with seamless roaming in IEEE 802.11 wireless networks. This paper proposes a novel MAC layer handoff protocol over IEEE 802.11 wireless networks by introducing advertisement messages sent from other mobile nodes and from which wireless terminals are able to receive the information of access points in their neighborhood. A mobile node can try to associate with access points based on the prediction before starting the probe process. The experimental results demonstrate that our solution can reduce MAC layer handoff latency to meet the requirements of real-time applications.     

层次型移动IPv6域间无缝切换方案

针对层次型移动IPv6协议中存在的域间切换问题,提出一种交互式实时应用的层次型移动IPv6域间快速无缝切换方案,该方案能够优化移动IPv6的切换延迟以及分组发送延迟。仿真实验结果表明,该方案是有效可行的。     

无线网状网跨层路由的研究

目前,无线网状网跨层路由设计方兴未艾,以往无线路由设计是基于最小跳数的,缺少对无线网状网特性的综合考虑,并不能充分发挥出无线网状网的优势。该文提出了基于"队列负载率"和"链路传输效率"的跨层路由协议算法,通过将MAC层的网络状态信息传递给网络层的路由代理,以便选择负载较小的最佳路由。通过仿真可以发现,改文提出的路由不仅显著提高了吞吐量,而且使包的投递更加可靠,提高了QoS。     

一种自适应的ICN移动性机制

信息中心网络（information-centric networking,ICN）内在地支持兴趣请求者移动而不支持内容提供者移动,然而在实际的场景中往往发生的是内容提供者移动。当前的移动性解决方案存在一些缺憾,如没有真正地考虑移动设备的加入/离开、机制过于单一不能应对各种移动场景、网络切换时延过长等。为解决上述问题,面向区域划分设计一种自适应的移动性机制,包括基于汇聚点的域内移动解决方案、基于兴趣转发的域间移动解决方案和基于回溯的基站间移动解决方案。仿真在GTS网络拓扑上进行,实验结果表明所提的移动性机制较基准机制有高的分发率、低的切换时延和少的路由跳数,说明所提的移动性机制具有广泛的应用价值,为推动诸如5G应用的全面落地具有现实的意义。     

Performance analysis of Virtual Mobility Domain scheme vs. IPv6 mobility protocols

The population of mobile users seeking connectivity to the Internet has been growing over the years, spurred by the capabilities of handsets and the increasing rich Internet content and services. Mobility management to enable efficient Internet access for users on the move is thus gaining significance. IETF has standardized several protocols such as Mobile IPv6, Hierarchical Mobile IPv6, and Proxy Mobile IPv6 to provide mobility management on the IP network. With future Internet design initiatives gaining momentum, it is important that these initiatives consider mobility management as an integral part of the design. In this article, we introduce the concept of Virtual Mobility Domain and describe the main features and key strengths of Virtual Mobility Domain that are designed to provide mobility management in a newly proposed tiered Internet architecture. Instead of IP addressing, the proposed Virtual Mobility Domain uses a tiered-addressing scheme to identify a mobile node with a single address regardless of its location. The tiered addressing provides a dynamic address length which brings less signaling overhead and scalable management. We also propose a collaborative network-based mobility management mechanism to provide low-latency handoffs and less processing-overhead on the mobile node compared to the IPv6-based protocols. The proposed mobility scheme unifies inter and intra-domain mobility management by introducing common anchor cloud concept which provides a distributed management and seamless mobility experience. We present comparative qualitative and quantitative performance analysis of Virtual Mobility Domain and aforementioned IPv6-based mobility protocols for Intra-AS roaming support. We examine handoff latency and signaling overhead performance of each protocol based on numerical results retrieved from analytical models and OPNET modeler based simulations. The results from a comparative performance study show the potential for more efficient mobility management under the proposed Internet architecture.     

Performance evaluation for on-demand routing protocols based on OPNET modules in wireless mesh networks

In wireless networks, users expect to get access to the network securely and seamlessly to share the data flow of access points anytime and anywhere. However, either point-to-point or point-to-multipoint methods in traditional wireless networks make the network bandwidth decrease rapidly, which cannot meet the requirements of users. Recently, a new wireless broadband access network, wireless mesh networks (WMNs), has emerged. As one of the key technologies in WMNs, wireless routing protocols plays an important role in performance optimization of WMNs. Therefore, in this paper, we address the on-demand routing protocols by focusing on dynamic source routing (DSR) protocol and ad hoc on-demand distance vector (AODV) routing protocol in WMNs. Then, we use the OPNET modules to establish the simulation models of DSR and AODV protocols in WMNs. Simulation and results show that, DSR protocol that is based on the dynamic source routing is not suitable for wireless transmission, while AODV routing protocol that is based on the purpose-driven routing is suitable for wireless transmission with rapid change of network topology.     

双链路移动IP系统的实现与性能分析

为了解决移动IP中的切换时延和丢包问题,提出了一个基于链路层触发的双链路移动IP系统的实现方案,即利用链路层触发提前发起切换缩短切换延时,利用链路冗余防止丢包达到无缝切换的效果。详细介绍了该系统的设计和结构,以及链路层触发的发现、无线连接控制、移动路由和隧道的实现方法。最后对系统的性能进行了测试与分析,通过与基本的移动IP系统进行比较,验证该系统达到了无缝切换的效果。     

新型多层联合组通信模型的设计与性能分析

针对流媒体业务需要网络提供大规模组通信支持的应用需求,将网络层组通信模型和应用层组通信模型,按域内和域间的网络划分进行巧妙地联合部署,提出了"域间单播 域内组播"或"域间组播 域内单播"的新型多层联合组通信模型,为下一代网络的组通信模型发展提供了一种全新的技术途径.性能分析表明,多层联合组通信模型继承了单层组通信模型的技术优势,改善了其存在的技术缺陷,在时延、抖动和丢包率等关键性能指标上均要明显优于目前的单播通信模型.     

An enhanced real-time routing protocol with load distribution for mobile wireless sensor networks

Mobile wireless sensor network (MWSN) is a wireless ad hoc network that consists of a very large number of tiny sensor nodes communicating with each other in which sensor nodes are either equipped with motors for active mobility or attached to mobile objects for passive mobility. A real-time routing protocol for MWSN is an exciting area of research because messages in the network are delivered according to their end-to-end deadlines (packet lifetime) while sensor nodes are mobile. This paper proposes an enhanced real-time with load distribution (ERTLD) routing protocol for MWSN which is based on our previous routing protocol RTLD. ERTLD utilized corona mechanism and optimal forwarding metrics to forward the data packet in MWSN. It computes the optimal forwarding node based on RSSI, remaining battery level of sensor nodes and packet delay over one-hop. ERTLD ensures high packet delivery ratio and experiences minimum end-to-end delay in WSN and MWSN compared to baseline routing protocol. In this paper we consider a highly dynamic wireless sensor network system in which the sensor nodes and the base station (sink) are mobile. ERTLD has been successfully studied and verified through simulation experiment.     

Proactive Highly Ambulatory Sensor Routing (PHASeR) protocol for mobile wireless sensor networks

This paper presents a novel multihop routing protocol for mobile wireless sensor networks called PHASeR (Proactive Highly Ambulatory Sensor Routing). The proposed protocol uses a simple hop-count metric to enable the dynamic and robust routing of data towards the sink in mobile environments. It is motivated by the application of radiation mapping by unmanned vehicles, which requires the reliable and timely delivery of regular measurements to the sink. PHASeR maintains a gradient metric in mobile environments by using a global TDMA MAC layer. It also uses the technique of blind forwarding to pass messages through the network in a multipath manner. PHASeR is analysed mathematically based on packet delivery ratio, average packet delay, throughput and overhead. It is then simulated with varying mobility, scalability and traffic loads. The protocol gives good results over all measures, which suggests that it may also be suitable for a wider array of emerging applications.     

车辆网络中一种有效的信息查询方案

研究车辆网络中的信息查询问题,提出一种有效的信息查询方案。首先,分别设计查询路由和回复路由;接着,设计数据包转发策略;最后,提出一些异常情况的处理方法和优化方案。基于真实车辆行驶数据的仿真实验表明,相比较其它方法,本文提出的方法实现了更低的延迟和更高的成功率。     

无线传感器网络的安全地理位置跨层协议

许多无线传感器网络(WSN)协议设计过程中,没有考虑到安全问题。提出一种安全地理位置跨层协议(Secure Geo-graphic Integrated Protocol,SGIP)。在安全协议的设计过程中,同时考虑了安全引导过程。首先改进了基于位置的密钥引导方案,使其不但充分利用地理信息,而且可以同时为广播包和单播包加密,并且转发区域内所有节点都与源节点有共享密钥。在此基础上,采用基于MAC层竞争的地理路由选择算法,并对不同数据包采用不同的加密方式,设计了安全的路由/MAC跨层协议。分析表明协议具有很好的安全性能,并且开销较小。