基于WiFi的战术互联网路由协议性能分析

以分层分布式战术互联网实际应用环境为背景,在WiFi组成的战术互联网中,利用仿真平台QualNet对AODV、DSR、LAR、OLSR路由协议的性能进行了仿真比较．实验结果表明,AODV协议在高传输速率和大负荷的战场环境下,能更好地发挥其性能．     

An altruistic cross‐layer recovering mechanism for ad hoc wireless networks

Video streaming services have restrictive delay and bandwidth constraints. Ad hoc networks represent a hostile environment for this kind of real‐time data transmission. Emerging mesh networks, where a backbone provides more topological stability, do not even assure a high quality of experience. In such scenario, mobility of terminal nodes causes link breakages until a new route is calculated. In the meanwhile, lost packets cause annoying video interruptions to the receiver. This paper proposes a new mechanism of recovering lost packets by means of caching overheard packets in neighbor nodes and retransmit them to destination. Moreover, an optimization is shown, which involves a video‐aware cache in order to recover full frames and prioritize more significant frames. Results show the improvement in reception, increasing the throughput as well as video quality, whereas larger video interruptions are considerably reduced. Copyright © 2014 John Wiley & Sons, Ltd.     

基于OLSR协议的最小MPR集选择算法

针对传统优化链路状态路由(OLSR)协议中利用贪婪算法求解最小多点中继(MPR)集时存在冗余的问题,提出了一种基于全局改进的Global_OP_MPR算法。首先引入了一种基于贪婪算法改进的OP_MPR算法,该算法通过逐步优化MPR集的方法去除冗余,可以简单高效地得到最小MPR集;然后在OP_MPR算法的基础上,将全局因素加入MPR选择判据中,引入"全局优化"代替"局部优化",最终利用该算法可以得到整个网络的最小MPR集。在OPNET上采用Random Waypoint运动模型进行仿真,与传统OLSR协议相比,采用OP_MPR和Global_OP_MPR算法的OLSR协议在整个网络上有效地减少了MPR节点的数量,并且具有更少的网络负担拓扑控制(TC)分组数和更低的网络延时。仿真结果表明,所提出的算法均能优化MPR集的大小,提高协议的网络性能;同时,Global_OP_MPR算法由于考虑了全局因素,达到了更好的网络性能效果。     

Trust-based security for the OLSR routing protocol

The trust is always present implicitly in the protocols based on cooperation, in particular, between the entities involved in routing operations in Ad hoc networks. Indeed, as the wireless range of such nodes is limited, the nodes mutually cooperate with their neighbors in order to extend the remote nodes and the entire network. In our work, we are interested by trust as security solution for OLSR protocol. This approach fits particularly with characteristics of ad hoc networks. Moreover, the explicit trust management allows entities to reason with and about trust, and to take decisions regarding other entities.In this paper, we detail the techniques and the contributions in trust-based security in OLSR. We present trust-based analysis of the OLSR protocol using trust specification language, and we show how trust-based reasoning can allow each node to evaluate the behavior of the other nodes. After the detection of misbehaving nodes, we propose solutions of prevention and countermeasures to resolve the situations of inconsistency, and counter the malicious nodes. We demonstrate the effectiveness of our solution taking different simulated attacks scenarios. Our approach brings few modifications and is still compatible with the bare OLSR.     

Development and Verification of Simulation Model Based on Real MANET Experiments for Transport Layer Protocols （UDP and TCP）

There is a lack of appropriate guidelines for realistic user traces, mobility models, routing protocols, considerations of real-life challenges, etc. for general-purpose mobile ad hoc networks (MANET). In this paper, four laptops are used in an open field environment in four scenarios to evaluate the performances of Internet control message protocol (ICMP) based ping and transmission control protocol (TCP) based streaming video applications using optimised link state routing (OLSR) implementation in an IEEE 802.11g wireless network. Corresponding simulations are developed in Network Simulator ns-2 by setting simulation parameters according to the real experiments. Difficulties faced to regenerate real-life scenarios have been discussed and the gaps between reality and simulation are identified. A setup guideline to produce realistic simulation results has been established.     

Betweenness estimation in OLSR-based multi-hop networks for distributed filtering

In traditional networks special efforts are put to secure the perimeter with firewalls: particular routers that analyze and filter the traffic to separate zones with different levels of trust. In wireless multi-hop networks the perimeter is a concept extremely hard to identify, thus, it is much more effective to enforce control on the nodes that will route more traffic. But traffic filtering and traffic analysis are costly activities for the limited resources of mesh nodes, so a trade-off must be reached limiting the number of nodes that enforce them. This work shows how, using the OLSR protocol, the centrality of groups of nodes with reference to traffic can be estimated with high accuracy independently of the network topology or size. We also show how this approach greatly limits the impact of an attack to the network using a number of firewalls that is only a fraction of the available nodes.     

一种基于OLSR路由协议中MPR节点的攻击方案及实现

文中在研究hdHoc无线自组网中OLSR（Optimized Link State Routing Protocol）路由协议的基础上,针对其中关键结构-MPR（multipoint relays）节点的特性,提出了一种通过改变乐意度对其进行攻击的方案。最后,用NS仿真工具对论文中介绍的攻击进行了仿真,论证了攻击方案的可行性。     

基于OLSR的QoS路由新方案

基于OLSR协议及扩展的最短路径算法,提出了综合折中跳数与带宽的一种路由计算新量度。组合MPR选择算法及路由计算新量度,设计了三种新的QoS路由方案。基于在NS-2环境中对新路由方案及OLSR原始协议进行的仿真,着重分析比较了它们的时延及分组递交率性能,探讨了带宽量度用于路由计算时对这两项性能产生的影响及主要原因,结果表明新量度能有效实现跳数少与带宽大之间的折中。     

基于OLSR的MANET地址自动配置机制

为了解决现有无线自组织网络地址自动配置协议过于复杂、开销大、可实现性不强的问题,利用OLSR在全网拓扑信息维护、低开销消息洪泛等方面的优势,提出一种以OLSR为基础的地址自动配置方案。实现IP地址的快速分配,并只需对OLSR协议消息作简单修改即可在网络运行过程中维护地址的唯一性。所提出的方案具有开销低、实现简单的特点,适合大型网络地址分配需要。     

基于复杂网络理论的移动自组网路由算法研究

移动自组网中节点通信时路由开销较大,从而引起整个自组网的能耗过高;为了解决这一问题,针对移动自组网的现实组网特征进行了研究,提出了基于复杂网络理论的移动自组网路由算法;在该路由算法中,路由发现基于源节点到目的节点的梯度方向,源节点选取下一级跳数据转发对象时,在其邻域范围内以选取路径是否符合最速下降法作为判断依据;当源节点和目的节点之间存在的节点个数超过复杂网络理论中的达到条件时,源节点在路由方向上选取其邻域内最接近的节点进行转发后,按照最速下降法继续寻找最优路径;实验表明,该路由算法具有较少的跳级数,可以减轻整个自组网的数据存储压力,路由开销在节点疏密度不同时,介于OLSR协议和AODV协议之间.