Experimental results from a MANET testbed in outdoor bridge environment considering BATMAN routing protocol

A set of wireless mobile terminals, which cooperate by routing packets to each other creates a Mobile Ad-hoc Network (MANET). MANETs are continuing to grow their interest in research environment and they are attracting attention for their potential use in several fields such as collaborative computing and disaster recovery environments. Considering mobility of the terminals, the topology changes rapidly and routing becomes a key process for operation of MANETs. In this paper, we analyze the performance of Better Approach To MANET (BATMAN) routing protocol in an outdoor bridge environment considering mobility and vertical communication. We implement two scenarios on our testbed and evaluate the performance in terms of throughput and packetloss.     

无线移动网关配置协议研究

向移动领域扩展是下一代互联网的主要发展方向,移动互联网不仅能支持单个移动终端,而且需要支持中小规模的移动子网,其中移动网关的配置及服务策略是关键技术之一。为此提出了一个层次化的配置协议,利用移动自组网（MANET）分簇管理的思想,将移动终端进行适当分簇并选举簇首管理内部节点,集成移动网关将不同移动簇群的无线网络进行连接。在此基础上提出了三种移动网关的服务策略,对该配置协议进行了仿真试验,分析比较了在不同服务策略下移动网关的关键性能指标,验证了该协议能够较好地满足移动网络的需求。     

无线移动自组织网路由协议性能研究

路由是无线移动自组织网的关键技术之一。目前已经提出的MANET路由协议有很多种,因此如何针对一定应用场景选择一个最佳的路由协议,是人们十分关心的一个问题。该文对已经通过IETF认可的三种MANET路由协议：DSR、AODV和OLSR进行了仿真对比分析。设计了大量的场景,通过对路由协议的分组传送率、端到端时延和所选路径长度等指标的比较,得出了在不同的网络环境下MANET最佳路由协议选择方案。仿真中发现同是采用按需的路由发现策略的DSR和AODV在高移动、高负荷的网络环境下的性能存在较大差异,对此原因进行了深入分析,并根据分析对DSR提出了改进方案。     

High level MANET protocol: Enhancing the communication support for mobile collaborative work

Mobile collaborative activities involve on-demand interactions among nomad users. Unavailability of communication support in the physical scenario where users are located cannot be a limitation to carry out such collaboration instances. Mobile workers can take advantage of the communication capability embedded in their mobile devices in order to create communication channels between them. The Mobile Ad-hoc Networks (MANET) are infrastructures that can be used to support the nomad users' activities. However, these networks have a short communication threshold; therefore, they need to include a routing protocol as part of its infrastructure to allow mobile workers to collaborate when they are not physically close. This paper presents an application level routing protocol that was designed to support nomad workers performing mobile collaborative activities. The protocol, named High Level MANET Protocol (HLMP), provides several automatic services that are required by mobile collaborative systems. Some of these services are the automatic MANET formation, peer detection and messages routing. HLMP has been implemented in a mobile communication infrastructure and used in several mobile groupware systems.     

基于克隆选择的移动Ad hoc网络簇化的优化方法

在权值簇化算法WCA的基础上,利用人工免疫系统中的克隆选择原理来提高移动Ad-hoc网络的簇化性能,从而实现用尽可能少的簇头来管理尽可能多的簇成员,以保证网络拓扑结构的相对稳定。仿真结果表明,利用克隆选择原理优化的方法在簇头的数量、更新次数等多方面均优于WCA算法。     

New quantum-genetic based OLSR protocol (QG-OLSR) for Mobile Ad hoc Network

Due to the mobility, self-organization and distributed control of Mobile Ad hoc Network (MANET), the routing protocol of MANET must adapt to the rapid changes of the network structure, and ensure the maximum savings of network resources. This paper proposes a kind of new quantum-genetic based OLSR protocol (QG-OLSR) for MANET. The protocol adopts the MPR (multi-point relay) technology in OLSR (Optimal Link State Routing). By embedding new augmented Q-Learning algorithm and combining the OLSR algorithm to optimize the selection of MPR sets, it can effectively reduce the consumption of network topology control, improve the delivery rate of data packets, and reduce the time delay of the end-to-end packet transmission between nodes. The results of the experimental testings show that the new protocol is reliable and highly efficient, which is suitable for many applications of MANET.     

基于OPNET的MAODV协议仿真实现及分析

移动Ad Hoc网络(MANET)的路由协议对网络的性能有较大影响,尤其在多播的场景下,好的多播路由协议可以节省大量无线传输带宽。MAODV路由协议是在AODV路由协议的基础上进行的多播扩展,也是目前MANET网络多播路由协议的研究热点。通过使用OPNET网络仿真软件,对MAODV协议进行仿真建模,使OPNET在MANET场景下支持多播路由协议的仿真,为其它需要MANET网络多播路由协议的场景提供支持。对仿真建模的结果进行了多方面的验证,以保证建模的正确性和有效性。     

基于克隆选择算法的MANET簇化

以权值簇化算法——WCA为基础,利用人工免疫系统中的克隆选择算法来提高移动Ad-hoc网络的簇化性能,从而实现用尽可能少的全局优化簇头来管理尽可能多的簇成员,以保证MANET拓扑结构的相对稳定和合理。仿真结果表明,利用克隆选择算法优化后的WCA在簇的数量等许多方面均优于WCA算法。     

Reaching Agreement among Virtual Subnets in Hybrid Failure Mode

Fault-tolerance is an important research topic in the study of distributed systems. To cope with the influence of faulty components, reaching a common agreement in the presence of faults before performing certain tasks is essential. However, the Byzantine Agreement (BA) problem is a fundamental problem in fault-tolerant distributed systems. In previous studies, protocols dealing with the BA problem focused on static networks; however, these do not perform well in dynamically changing mobile networks. The most well known mobile network is the Mobile Ad-hoc Network (MANET). To enhance fault-tolerance and MANET reliability, the BA problem in virtual subnets of MANET is revisited in this paper. The proposed protocol is called the Hybrid Agreement Protocol (HAP). It achieves agreement on a common value among all functional mobile processors in a minimal number of message exchange rounds, and can tolerate a maximal number of allowable faulty components in the virtual subnet of MANET.     

Moving routing protocols to the user space in MANET middleware

Mobile Ad Hoc Network (MANET) middleware must be aware of the underlying multi-hop topology to self-adapt and to improve its communication efficiency. For this reason, many approaches rely on specific cross-layer communications to interact with the network protocols in the kernel space. But these solutions break the strict layering of the network stack and hinder the portability of middleware and applications.The main argument of this paper is to move the routing protocols to the user space to simplify the development, testing, deployment and portability of middleware and applications. If routing is just another software component in the user space, cross-layering can be elegantly solved using advanced software engineering techniques like component frameworks and explicit APIs. As a consequence, a slight performance cost must be paid to achieve portability and easy deployment. But we will demonstrate that the performance obtained by a user-space routing protocol is satisfactory for a wide range of applications.We have implemented the unicast MANET OLSR protocol in Java (jOLSR) and, on top of it, we have created a novel overlay multicast protocol (OMOLSR). We have then integrated both routing protocols (jOLSR, OMOLSR) as software components in a well-known group communication toolkit (JGroups). Modifying the JGroups toolkit, we have devised a topology-aware group communication middleware for MANETs (MChannel). In our MChannel middleware, group membership is obtained directly from OMOLSR multicast trees and failure detection is obtained from jOLSR active probing. We have validated our approach in several real testbeds to demonstrate the feasibility and efficiency of our middleware.     

城市场景下VANET路由协议大规模仿真研究

车载自组网(VANET)是移动Ad Hoe网络(MANET)技术在交通领域的应用,由于VANET独特的场景特点,需要重新评估MANET中路由协议在VANET场景下的适用程度.为了提高仿真实验结果的准确性,实现了车辆运动模型并结合西安城区卫星地图构造了逼真的城市道路场景.在场景下利用QualNet仿真平台进行了大规模的路由协议仿真实验,评估了四种典型的MANET路由协议在城市场景VANET中的适用性.结果表明,这些协议难以满足通信需求,不适合用于城市环境下车载自组网研究.     

移动自组网基于动态簇的MAC协议与QoS路由

论文针对移动自组网提出了一种基于动态簇的MAC协议和QoS路由算法,使用全分布式动态簇生成算法实现了对网络拓扑的分簇与维护;利用正交编码原理和蜂窝小区技术实现了基于动态簇的MAC协议;融合资源预留、移动预测和后备路径技术实现了具有QoS保障的路由算法。仿真结果对比表明:在满足QoS条件下,它提高了路由效率。     

Efficient energy conservation in MANET using Energy Conserving Advanced Optimised Link State Routing model

Mobile Ad-hoc Network (MANET) is formed dynamically by the independent organisation of the mobile nodes connected through wireless links without using any centralised administration. Energy consumption is the most significant issue in the MANETs, since most of the mobile hosts operate on limited battery resources. Reduction in the energy consumption results in the increase in the lifetime and throughput of the network. The performance of existing techniques was less in terms of energy conservation issues. To overcome these limitations, this paper proposes an energy conservation mechanism integrated with a proactive MANET routing scheme. The routing schema is based on the energy level and the mobility of the nodes. Calculation of energy cost is performed based on the prediction of the energy consumption level of the node, using Energy Conserving Advanced Optimised Link State Routing (ECAO) model. The performance of the proposed ECAO model is compared with the existing Optimised Link State Routing and Advanced Optimised Link State Routing models. From the comparison result, it is clearly observed that the proposed model achieves better performance in terms of number of TC messages, Packet Delivery Ratio, average time, end-to-end delay, and link delay and energy consumption.     

一种安全的移动自组网链路状态路由协议：SOLSR

移动自组网是一种新型的无线移动网络，具有无中心、自组织、拓扑结构变化频繁以及开放式通讯信道等特性，因此移动自组网下的路由协议所面临的安全问题比有线网环境下更为严重。OLSR（Optimized Link State Routing）协议于2003年成为RFE3626草案，该协议首先假设网络中所有节点都是友好的，无恶意行为，同时认为安全问题可以利用IPSec来解决，但是，OLSR协议的通讯通常是“一对多”的广播形式，IPSec是针对端到端通讯的安全方案，故而单单依靠IPSec并不能完全解决OLSR的安全问题。由于OLSR自身还存在着机制上的漏洞，恶意节点针对这些漏洞进行攻击，可以导致路由协议无法正常工作，继而影响到整个网络的运行。本文在对OLSR的安全性分析的基础上，对协议进行了改进，加强了协议中对“邻居关系”的定义，同时引入了虫洞检测和身份认证机制，以及通讯报文的安全附加项，从而提出了安全链路状态路由协议——SOLSR来保证移动自组网中路由协议的正常运行。     

基于机器学习的移动自组织网络入侵检测方法

移动自组织网络是由无线移动节点组成的复杂分布式通信系统。研究了移动自组织网络的入侵检测问题,采用了一种新型的基于机器学习算法的异常入侵检测方法。该方法获取正常事件的内部特征的相互关系模式,并将该模式作为轮廓检测异常事件。在Ad hoc 按需距离向量协议上实现了该方法,并在网络仿真软件QualNet中对其进行了评估。     

Managing concurrent execution of transactions in mobile ad-hoc network database systems: an energy-efficient approach

A Mobile Ad-hoc Network (MANET) is a collection of mobile, wireless and battery-powered nodes without any fixed infrastructure. Therefore, it fits well in mission-critical applications such as disaster rescue and military operations. However, when a node runs out of energy, communication may fail and transactions may be aborted if they are time-critical and miss their deadlines. In order to provide timely and correct results for multiple concurrent transactions, energy-efficient database concurrency control (CC) techniques become critical for database systems built for MANET. Due to the characteristics of MANET databases, existing CC algorithms cannot work effectively. In this paper, an energy-efficient CC algorithm is developed for mission-critical MANET databases in a clustered network architecture where nodes are divided into clusters, each of which has a cluster head, responsible for the processing of all nodes in the cluster. The cluster structure is constructed using a novel weighted clustering algorithm, which uses node mobility, remaining energy and workload to group nodes into clusters and select cluster heads. In our CC algorithm, we elect cluster heads to work as coordinating servers to conserve energy and balance energy consumption among servers, and propose an optimistic CC algorithm to offer high concurrency and avoid wasting limited system resources. Besides correctness proof and theoretical analysis, comprehensive simulation experiments were conducted, and simulation results show the superiority of our CC algorithm over existing techniques in terms of transaction abort rate, total energy consumption by all servers, and degree of balancing energy consumption among servers.     

基于OPNET的通信网络半实物仿真方法研究

OPNET作为网络仿真软件具有仿真功能,但基于OPNET的半实物仿真方法的研究较少.对几种基于OPNET的通信网络半实物仿真方法进行了系统的介绍和分析,比较了方法的优缺点,并探讨了半实物仿真需要注意的问题;最后对一个基于OPNET的通用的通信网络半实物仿真环境进行了介绍,并实现了一个具体的移动自组织网络的半实物仿真,取得了良好的效果.仿真方法的研究成果能够广泛应用于OPNET网络环境与其它HLA仿真系统、各类真实网络节点、电台等信道传输设备的互连及其综合仿真验证分析.     

移动自组网中路由协议的分析与研究

移动自组网是一种由具有自配置功能的移动设备通过无线连接方式组成的网络。近几年来,对无线自组网各方面的研究十分突出,尤其是在灾难救援和执法等领域。一个自然而然的想法就是,将基于位置的操作引进到无线自组网中。在各种应用中,节点的身份认证事实上往往不如节点的位置有用。在可疑的无线自组网中,节点之间甚至不能信任彼此,因此它们的身份必须隐藏。本文将对移动自组网中的路由协议进行研究和对比。     

Video transmission enhancement in presence of misbehaving nodes in MANETs

Mobile Ad-hoc NETworks (MANET) are infrastructureless networks where self-configuring mobile nodes are connected by wireless links. Because of its decentralized operation, these nodes rely on each other to store and forward packets. Video transmission over MANETs is more challenging than over conventional wireless networks due to rapid topology changes and lack of central administration. Most of the proposed MANET protocols assume that all nodes are working within a cooperative and friendly network context. However, misbehaving nodes that exhibit abnormal behaviors can disrupt the network operation and affect the network availability by refusing to cooperate to route packets due to their selfish or malicious behavior. In this paper, we examine the effect of packet dropping attacks on video transmission over MANETs. We also study the effects of mitigation using intrusion detection systems to MANET in presence of video traffic. To the best of our knowledge, this is the first attempt to study multimedia over such environments. We propose a novel intrusion detection system, which is an adaptive acknowledgment scheme (AACK) with the ability to detect misbehaved nodes and avoid them in other transmissions. The aim of AACK scheme is to overcome watchdog weaknesses due to collisions and limited transmission power and also to improve TWOACK scheme. To demonstrate the performance of our proposed scheme, simulation experiments are performed. The results of our experiments show that MPEG4 is more suitable for our simulation environment than H264 video traffic. The simulation results show that AACK scheme provides better network performance with less overhead than other schemes; it also shows that AACK outperforms both TWOACK and watchdog in video transmission applications in the presence of misbehaving nodes.     

移动自组网软件平台的研究与设计

终端设备的独有特性包括它们的移动性、个性化和位置感知,形成了新型的无线应用,能满足普遍存在的移动计算需求。展示一种在移动自组网环境下的无线终端设备。终端设备选择在Linux嵌入式平台进行开发。在该设备上,实现了AODV、MAODV路由算法并在NS-2上进行了路由协议性能的比较和分析。最后给出了终端设备原型的实现,并且提出了未来的改进方向和应用场景。