移动Ad Hoc网络中基于移动代理的路由协议

分析了移动Ad Hoc网络现有两类路由协议的优缺点,提出基于移动代理的AODV路由协议。仿真结果表明,该方案通过移动代理的漫游来更新途经节点路由表,大大减少路由请求报文发起数,降低了平均端到端的数据传输时延,网络负载增加不大。     

移动IPv6移动性能的改进

主要问题是移动IPv6协议中移动主机移动性能的改进。通过对现有方案的研究和分析，提出了一种新的多层次移动IPv6方案。新方案中采用了新的方法计算主机的移动速度以便移动主机选择合适的MAP，同时还提出了新的缓存机制来减少转交过程中数据包的丢失。还利用了NS2对新方案进行了模拟仿真。新方案可以适应移动主机的快速移动，并能够减少绑定更新报文和数据包的丢失。     

移动IP多播及其实现方法

分析了移动IP和多播实现的原理,在此基础上,讨论了使移动IP支持多播的方案,包括多播组管理和报文路由的实现并对它们进行了分析比较。     

移动支持协议移动管理代价研究

针对移动支持协议的移动管理代价进行了研究,提出了一种合适的网络模型.在此网络模型的基础上,采用理论分析的方法分析了使用各移动支持协议时,为支持MH(mobile host)移动给网络带来的信令开销,并采用数值仿真的方法,对只使用移动IP协议和引入层次移动时的信令开销以及采用MIP-RR,CIP和HAWAII等不同微移动协议时的信令开销进行了比较.结果表明:引入层次移动与只使用移动IP相比,显著减少了网络的信令开销;在不同的微移动协议中,使用显式删除旧路径的路径维护策略与频繁发送周期性的刷新报文相比,给网络带来的信令开销较小;使用路径更新报文发送到交叉MRA(mobile routing Agent)的路径更新方法与路径更新报文发送到GW(gateway)相比,具有较小的网络信令开销.     

移动IP技术及其路由优化

随着网络通信技术的发展，移动计算机用户对Internet移动接入的需求急剧增长，IETF设计了移动IP协议，使Internet上的移动接入成为可能，该文介绍了移动IP的工作原理、目前移动IP路由方面的问题及其改进方案。     

移动IPv6通信协议研究

对IETF提出的移动IPv6进行了研究，首先介绍了移动IPv6的基本原理，分析了移动IPv6的不足，然后提出了一种新的、为移动节点分配一个专用地址空间的思想，并且为移动IPv6扩展了一个新的扩展头、两个新的ICMP报文，在这些协议扩展的基础上提出了对移动IPv6的一种优化策略。     

自组网中基于移动代理的具有移动和能量感知的AODV路由协议

自组网是由一组带有无线收发装置的移动节点组成的一个能够支持多跳的临时性的计算机通信网络．通过引入移动代理，结合本地移动和能量感知策略，该文提出了一种基于移动代理的AODV节能路由协议．仿真结果表明，该方案通过移动代理的漫游来更新途径节点路由表，大大减少路由请求报文发起数，降低了端到端的平均数据传输时延，并延长了网络的生存时间．     

移动家乡代理接入死锁的解决方法

针对网络移动由于家乡代理位于移动网络或本身就是移动路由器而可能出现的接入死锁问题,提出基于接入路由器树状模型和基于树根节点配置移动路由器转交地址的死锁解决方案。分析结果表明,该方案在保障移动网络节点和Internet上任意节点会话连续性的同时,实现了浮动嵌套移动网络节点之间的相互可访问性,而且通信延时、数据包包头损耗率以及网络切换延时与网络移动基本支持协议和返回路由头路由优化方案相比大大减小,嵌套层次越深,端到端通信节省的时间和空间开销越大。     

MIPv6家乡代理功能在高性能路由器中的设计与实现

提出了一种移动IPv6(MIPv6)协议中家乡代理功能在高性能路由器上的实现方案。将MIPv6协议规范中家乡代理的协议处理功能和报文转发功能加以分解,并将它们分布于高性能路由器主控单元和线路接口板上。测试结果表明,该方案无需改变路由器原有结构即能可靠地实现移动IPv6功能。     

一种基于移动预测的分层移动组播协议

组播通信有效地节约了网络资源,在无线移动网络环境中引入组播有着非常重要的意义。论文简要分析了现有移动组播协议,提出了一种新的基于移动预测的分层移动组播方案。仿真与分析表明,该协议组播树重构频率低,子网切换延迟小,可减少组播包的丢失,减少协议开销,优化组播包的传输路径。     

Complexity of minimum length scheduling for precedence constrained messages in distributed systems

Switching networks are the core of many communication and multiprocessor systems. In these systems, a set of entities (communication equipment or processors) communicate through the switching network by exchanging messages. Simultaneous transmission or reception of two 01 more different messages through an input or output port results in the corruption of the messages (also called collision), which are useless and must be retransmitted later. This causes a performance degradation. Collisions can be avoided only by a proper scheduling of the messages. The same problem also arises in single-hop purely optical WDM systems, where simultaneous reception or transmission over the same wavelength channel results in a collision. In this paper, we study the problem of minimum length scheduling of a set of messages subject to precedence constraints. We show that the decision version of the problem is NP-complete even in very restricted cases. This means that the optimization problem cannot be solved in polynomial time, unless P=NP. Since the problem cannot be optimally solved by fast algorithms, we then investigate the existence of polynomial time approximation algorithms, by first proving that approximation algorithms cannot exist with performance ratio bounded by 4/3 or smaller and successively presenting an /spl epsiv/-approximation algorithm with /spl epsiv/<2 for the case of two precedence classes of messages. Finally, we assess the existence of an asymptotically optimal schedule in the general case of an unrestricted number of precedence classes.     

A protocol to achieve independence in constant rounds

Independence is a fundamental property needed to achieve security in fault-tolerant distributed computing. In practice, distributed communication networks are neither fully synchronous or fully asynchronous, but rather loosely synchronized. By this, we mean that in a communication protocol, messages at a given round may depend on messages from other players at the same round. These possible dependencies among messages create problems if we need n players to announce independently chosen values. This task is called simultaneous broadcast. In this paper, we present the first constant round protocol for simultaneous broadcast in a reasonable computation model (which includes a common shared random string among the players). The protocol is provably secure under general cryptographic assumptions. In the process, we develop a new and stronger formal definition for this problem. Previously known protocols for this task required either O(log n) or expected constant rounds to complete (depending on the computation model considered)     

基于本地安全关联的移动网络接入认证机制

为减少网络移动中身份认证对性能的影响,提出了一种基于本地安全关联的接入认证机制。该机制通过认证消息携带地址注册信息,整合认证和绑定更新过程,采用本地移动性管理策略,通过建立本地安全关联,实现了域内切换流程本地化,保护了地址注册信息,避免了隧道嵌套。性能分析表明,该机制在实现双向认证的同时能够抵抗重放等多种攻击,相比其他方案,该机制减小了计算开销,缩短了切换时延。     

A social-aware routing protocol for opportunistic networks

Understanding nodes mobility is of fundamental importance for data delivery in opportunistic and intermittently connected networks referred to as Delay Tolerant Networks (DTNs). The analysis of such mobility patterns and the understanding of how mobile nodes interact play a critical role when designing new routing protocols for DTNs. The Cultural Greedy Ant (CGrAnt) protocol is a hybrid Swarm Intelligence-based approach designed to address the routing problem in such dynamic and complex environment. CGrAnt is based on: (1) Cultural Algorithms (CA) and Ant Colony Optimization (ACO) and (2) operational metrics that characterize the opportunistic social connectivity between wireless users. The most promising message forwarders are selected via a greedy transition rule based mainly on local information captured from the DTN environment. Whenever global information is available, it can also be used to support decisions. We compare the performance of CGrAnt with Epidemic, PROPHET, and dLife protocols in two different mobility scenarios under varying networking parameters. Results obtained by the ONE simulator show that CGrAnt achieves a higher message delivery and lower message redundancy than the three protocols in both scenarios. The only exception is in one of the scenarios, when messages have a time to live lower than 900 min, where CGrAnt delivers a bit less messages than dLife, although with a lower message redundancy.     

基于拓扑快速变化的OLSR改进路由协议研究

针对优化链路状态路由协议（OLSR）在网络拓扑结构快速变化时性能下降的问题,提出了一种新的结合鱼眼状态路由和能量感知的自适应改进路由协议,命名为AFE-OLSR。该改进协议通过监听节点链路集和多点中继选择集的变化情况,自动调整HELLO和拓扑控制消息的发送频率,实现移动感知。同时,它借鉴鱼眼状态路由的思想,节点自动调整拓扑控制消息的转发次数。通过这些机制,该协议能够记录接收消息的能量大小实现能量感知,以及根据能量感知和移动感知的结果来帮助节点选择更稳定和更可靠的路由。仿真结果表明,AFE-OLSR在网络拓扑变化时端到端时延减少8%,分组到达率提高11%,建立全网路由时间减少12%;在网络拓扑静止时HELLO发送量减少19%,TC转发量减少15%。     

Restricted usage of anonymous credentials in vehicular ad hoc networks for misbehavior detection

The automobile industry is entering a new era of digitalization with major impact on human mobility and transportation infrastructures. A result of such a convergence between the automobile and information technologies is vehicular ad hoc network (VANET), a type of mobile ad hoc networks that has recently enjoyed a lot of attention from the industry, the research community, lawmakers and privacy activists. In VANET, vehicles frequently broadcast various types of messages, including location data. This enables innovative applications and improvements in safety and driving experience. As messages broadcasted in the VANET are digitally signed and the receiver must be able to verify the sender’s authentication and message integrity, there is a need to ensure broadcast authentication and protect driver’s anonymity. However, communication in VANETs takes place with high frequency, and malicious vehicles can hide behind anonymity in order to duplicate packets and get advantage over other vehicles in the network. Indeed, state-of-the-art approaches to privacy-preserving messages broadcast in the VANET typically ensure that each vehicle has a number of pseudonymous certificates that are changed regularly in order to thwart an automated tracing of its activities. However, the possibility of uncontrolled simultaneous use of pseudonyms by misbehaving vehicles remain unaddressed. This paper proposes a set of anonymous credential system based protocols for VANET that enables the detection and limitation of pseudonym/credential overspending. The revocation of the misbehaving vehicle can be also achieved through the proposed solutions. With the prototypical implementation of the proposed protocols, it has been shown that the successful detection of fraud, i.e., pseudonyms overspending and the subsequent revocation of credentials are possible in VANET.     

移动数据库系统乐观事务处理策略

在移动数据库系统中，计算平台的移动性，频繁的断接性以及长事务等特性使得传统的事务处理模式不再适用，为了解决移动数据中的事处处理问题，提出了一种新的移动事务处理模型－乐观两阶段提交移动事务模型（O2PC－MT），该模型采用乐观并发控制与两阶段提交协议相结合的方法，对移动事务的长事务特性提供了灵活与有效的支持，此外，该模型允许移动计算机分多发送中务操作，且在事务执行过程中可以任意移动，从而提供了对交互式事务及随意移动性的支持，实验结果表明，与基于两段锁协议及其变形的其它移动事务处理模型相比，O2PC－MT提高了系统的事务吞吐率并改善了系统的总体性能。     

基于簇中心预测的Ad Hoc网络位置更新算法

本文根据许多实际应用场合下网络节点所表现出来的群组性移动特征,提出了一种基于簇中心预测的位置更新算法.它通过计算和估计簇中心的移动特性,并在此基础上预测各个节点的位置.只有当预测位置与实际位置的偏差超过一定范围时,才产生新的位置更新消息,由此可以极大地减少所需传送的位置更新消息.仿真结果表明,该算法下的位置消息大大少于常规的基于距离的算法.     

基于定向广播的AODV控制报文抑制研究

AODV路由协议是通过全向广播请求报文和定时广播Hello报文来建立Ad Hoc网络的路由,但在路由发现阶段需要广播发送大量的请求控制报文,导致了协议性能的下降。针对此问题,提出了一种新的基于定向广播的路由协议,该协议通过定向广播发送请求报文,并根据节点的移动性动态调整Hello报文的发送时间间隔来减少报文的发送。理论分析和仿真结果表明,该方法能有效地减少控制报文的数量,减少路由负载,也显著提高了端到端时延、平均投递率等性能参数。     

Computing Associative Functions Distributively in Spite of Link Failures

Repeated computation of associative functions is central to many asynchronous distributed algorithms reported in the literature. We present efficient distributed algorithms for computing associative functions in spite of undetectable link failures in non-partitioned distributed systems. Two distributed; algorithms are presented for function computation assuming that the distributed system is preprocessed by a one-time preprocessing step that uses O(|E| |V|) messages (where |E| and |V| are the number of links and the number of nodes of the system, respectively). The first algorithm tolerates single link failures using O(|V| log |V|) messages and the second algorithm, which is an extension of the first algorithm, copes with the simultaneous failure of k links using O(k|E| log |V|) messages. Efficient computation of associative functions in the presence of multiple link failures has been an open problem, and our work solves this open problem.