【作者】 王杉；

【导师】 庄钊文；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2006， 博士

【摘要】 战场通信环境是移动Ad hoc网络的一种很重要的应用背景,在此环境中,要求网络具有更高的整体顽存性、更低的开销和时延、更强的抗干扰能力以及更可靠的安全性能。围绕此背景,论文研究了战场环境下Ad hoc网络路由的能量均衡、拥塞控制、抗干扰性能以及路由安全等问题,提出了相应的改进算法和策略,并通过详细的仿真评测,分析与验证了这些算法的有效性。战场环境下移动自组网的上述背景需求在网络性能上主要体现在分组递交率、路由开销、传输时延以及吞吐量等方面,影响这些性能的因素涉及到网络中从应用层到物理层的多方面内容,其中路由是非常关键的影响因素之一。因此论文首先在典型的战术网络场景下,对移动自组织网络通用的路由协议进行了研究与评估,提出了战场环境下移动Ad hoc网络较优的系统设计方案。此外,考虑到战场环境中存在的通信干扰和网络攻击会对系统性能产生进一步的恶化,因此有效提升网络性能的根本解决方法应该是采用更优的路由协议以及完善与改进协议自身的相关机制,指出了论文研究的方向和侧重点。区域路由协议(ZRP)综合了先验式与反应式两种路由的优点,扩展性很强,是移动Ad hoc网络在战场环境中的一种非常具有应用潜力的路由机制。论文在该协议基础上,分别从拥塞控制和能量均衡的角度,提出了两种新的改进路由算法:基于节点位置与网络密度修正的区域路由(MZRP)以及基于功耗考虑的多径区域路由(EAZRP)。前者利用GPS等定位设备提供的节点位置信息,调整了邻节点发现机制中相关中断的产生频度,并且根据网络密度合理的缩短路由表查询长度,有效的降低了网络的路由开销和平均传输时延。EAZRP算法则是在路由选择过程中引入了多径方式,将数据流随机的分配于可用的多条最优路径上,在业务总量不变的情况下,使得更多的节点分担了数据转发任务。该算法可以有效的降低网络节点能量消耗值的差别(即功耗方差),同时其它的性能指标并没有受到任何损伤。功耗方差的减小使得节点的工作寿命趋于平均,Ad hoc网络的整体生存能力得到了很大的改善。另一方面,通用的移动Adhoc网络很多采用全向天线进行传输,由于符号间串扰以及多址接入等干扰,造成网络性能非常低劣。如果采用波束宽度有限的定向天线,可以有效减少传播信号间的相互干扰,提高系统的空间复用度,而且在相同的发射功率条件下,可以获得更远的传输距离,因此定向天线可以有效的提升网络容量和抗干扰性能。区别于传统的波达方向(DOA)计算方法,论文中利用节点的位置信息对定向天线的波束方向进行调整,有效的减少了计算复杂度。在此基础上,提出了一种抗干扰自组网定向波束调度策略(SDBA),该算法以中间件的形式,对单播的数据报文或选定的控制报文进行定向传输,可以有效提升移动Ad hoc网络在战场环境下的路由性能以及链路稳定性,很大程度上改善了系统的抗干扰能力。对于路由安全性的考虑,已有的算法大多是基于信息加密的方式,实现较为复杂和困难。论文对移动Ad hoc网络中四种典型路由协议的安全攻击进行了分析和仿真评测,得出先验式和反应式路由分别对虚假路由表和Rushing攻击非常敏感的结论,并且针对前者,提出了一种基于位置信息的先验式安全路由策略。该策略利用节点的位置信息判断所接收路由表的可信度,避免了虚假路由信息在网络中的扩散,从而有效的降低了攻击节点对网络性能的影响。更多还原

【Abstract】 Field communication is one of the most primary application backgrounds for mobile ad hoc networks, which need stronger survivability, less overhead, lower delay, anti-jamming and robust security. So, under this circumstance, the thsis has researched on energy balance, congestion control, anti-jamming and secure routing for ad hoc networking, also some novel improved algorithms and schemes have been brought forward. Finally, detailed simulations and analyses have been done to verify the validity of these algorithms.The application requests for the performance of ad hoc networking in field communication mainly represent as packet delivery ratio, overhead, end-to-end delay and throughput, etc. But there are so many factors influencing its performance that the considerations should be from the application layer to the physical one, and the routing is more significant. So, firstly the thesis has analyzed and evaluated many current routing protocols that are applied to the field ad hoc networks, and then proposed some better choices and designments. In addition, the performance maybe further deteriorated due to the interference and intended attacks in battlefield, so the basic solution to promote the networking performance is to use more advanced routings and improve corresponding strategies simultaneously, which is the orientation and the emphasis of my research.Zone routing protocol (ZRP), as the hybrid of proactive and reactive routing, is targeted for scalable networks, so it is greatly fit for military ad hoc networking. Based on this protocol, the thesis has promoted two novel algorithms for the congestion control and energy equilibriums separately. One is modified zone routing (MZRP) based on nodes position and networking density, and the other is energy-awareness zone routing (EAZRP). The former utilizes the information of locations provided by GPS to reduce the frenquency of corresponding interrupts during neighbor maintenance. Also, the depth of the search when traversalling the routing records is shortened according to the density. These two adjustments can reduce the overhead and propagation delay effectively. The latter, EAZRP, introduces multi-paths into zone routing and distributes the traffic over many available optimum paths during packets routing. So in a situation that the total amount of the business does not change, more nodes participate in the delivering, which can obviously decrease the variance of energy consumption among all terminals while other performance indexes have not got any damage. The decrease of consumption variance makes the nodal working life become more average, so the life-time of entire ad hoc networking is improved greatly.The current mobile ad hoc networks adopt the omnidirectional antenna to transmit signals, and the performance is very poor because of ISI and the multi-access interference. Directional beams have limited bandwidth, which can not only reduce the mutual interference among the propagated signals, but also increase the spatial-reuse of the system. Moreover, under the same transmission power condition, directional antennas can get a further propagation distance than omnidirectional ones. These characters can promote the network capacity and anti-jamming performance effectively. Different from the typical DOA algorithms, we adjust the directivity of beams with the aid of position information provided by localizers, which can simplify the realizable complexity. Based on this, SDBA, a novel scheme for anti-jamming ad hoc networks using directional beams has been put forward. It was designed as a middle-ware that could transceive unicast data packets and/or selected control ones with directional antennas. This could greatly improve the ad hoc routing performance and link stabilities, thus the anti-jamming capability of battlefield networking was promoted.Considering the routing securities, current algorithms are mostly ways based on that information is encrypted, which is quite complicated and difficult to realize. By means of detailed evaluations of the attacks on four typical ad hoc routing protocols, we have found that the proactive and reactive routing are very sensitive to the illusive route-table and rushing attack respectively. Accordingly, a position beased secure routing schedule for the proactive has been proposed in the thesis. It estimated the reliability of received route-table making use of positions information, so the diffuseness of hostile packets was confined to a limited area, thus the influence of malicious nodes was severely restrained.更多还原