面向无人机自组网编队控制的通信组网技术

随着技术的发展,多无人机系统协同作业的研究得到越来越多的关注。编队控制是无人机协同作业的关键技术,对具有动态信道与拓扑特征的无人机自组网的通信组网技术提出了极高的要求。首先介绍了无人机自组网编队控制的相关模型;基于此,从编队保持和重组、任务更新、编队可靠性等方面综述并分析了5种编队控制策略以及它们对无人机自组网通信组网技术的不同需求;最后展望了面向无人机自组网编队控制的通信组网技术的发展前景和方向。     

固定翼无人机集群分布式固定时间编队跟踪控制

为实现固定翼无人机集群对理想编队构型的跟踪,研究了执行器存在未建模动态和不确定性的无人机集群系统的固定时间编队跟踪控制问题。首先,建立了无人机集群的三自由度运动学模型。其次,基于一种收敛时间独立于初始条件的固定时间终端滑模,设计了分布式固定时间编队协同跟踪控制器,利用控制器中的鲁棒项补偿外部扰动,通过Lyapunov稳定性理论证明了闭环系统的固定时间稳定性。最后,对所设计的控制器进行了数值仿真验证,仿真结果表明：所设计的控制器能够使无人机集群在固定时间内组成理想编队构型,同时系统具有鲁棒性。     

针对固定翼无人机集群的快速任务规划算法

为解决固定翼无人机集群的快速任务规划问题，提出一种基于聚类算法和改进化学反应优化模型的快速集群任务规划算法，满足固定翼无人机集群对规划时间的限制和实际飞行中机载计算机工作场景。利用聚类的方式降低算法的计算负担，通过改进化学反应优化算法保证规划问题的可靠快速收敛，实现无人机集群的快速任务规划。数值仿真结果表明。在与同类算法的比较中该算法有更好的计算效率和收敛效果，通过硬件在环仿真实验模拟了算法在机载计算机环境下运行的效率和结果，验证了在真实场景下算法的可靠性。     

一种高效快速的无人机自组网网关切换算法

针对无人机自组网网关节点突然失效给网络性能和网络可靠性带来的不利影响,提出一种高效快速的无人机自组网网关切换算法。首先,设计了备份网关的选择机制,通过考虑网关节点和邻居节点之间的距离因素从而选出备份网关节点;其次,改进了网关失效识别机制,备份网关可以更快地检测出网关节点是否失效;最后,提出了高效快速的无人机自组网网关切换机制,减少了网关功能失效的时间。仿真结果表明,所提算法可以降低无人机自组网网关的失效时间,提高无人机网络的可靠性并使时延、吞吐量等性能得到了提升。     

基于网络编码的无人机数据链技术研究

为了提高无人机数据链网络的传输性能,针对其具有的高动态、多中继和大容量等显著特点,提出了对流链路网络编码策略;通过分析多无人机协同执行任务时形成的网络拓扑结构,利用网络仿真平台NS2建立了高动态多跳移动自组网模型,分别改变模型中节点的移动速度、跳数和数据包大小,观察其对网络吞吐率的影响;仿真结果表明,对流链路网络编码策略能够有效地改善仿真模型的传输性能,很好地应用在无人机数据链网络中。     

无人机自组网路由协议研究综述

随着无人机软硬件技术的发展,多无人机集群自组织形成的无人机自组网（Flying Ad-Hoc networks, FANETs）受到了越来越多的来自学术界和工业界的关注,其灵活的部署和快速的反应能力使其能高效地完成多种多样的任务。而无人机自组网路由协议是提高服务质量（Quality of service, QoS）最重要的方法之一,但无人机自组网的移动性和动态性给路由协议的设计带来了严峻的挑战。传统的移动路由协议不能很好地满足无人机自组网的路由需求,因此研究者们从基于拓扑、地理和分层的角度提出了各式各样的无人机自组网路由协议,旨在克服移动性和提高网络的服务质量,并指出未来无人机自组网的路由协议可以考虑机会路由、软件定义网络（Software defined network,SDN）决策和预测驱动决策等综合提高QoS。本文主要针对无人机自组网网络特征,从不同的路由方法出发,SDN对路由协议进行总结和归纳,并对未来的研究方向进行了展望。     

一种基于状态一致性模型的固定翼无人机编队控制机制

在固定翼无人机编队飞行的过程中,通常需要根据任务需求或环境的变化构建并保持一种队形,或者变换为另一种队形.目前,无人机编队构建、保持和变换采用了不同的定义与关键技术,产生了无人机编队控制技术的发展瓶颈.本文提出了一种基于状态一致性模型的编队控制机制来解决这一问题.首先,建立固定翼无人机编队的六元状态一致性模型,并基于该模型统一了编队构建、保持和变换的定义.其次,提出了一种基于六元状态一致性模型的集中式与分布式相结合的混合式编队控制机制,主节点集中式地确定无人机在编队中的位置的分配方案,从节点分布式地计算自身的Dubins路径并调整偏航角,然后自主调整节点的航速以实现编队的状态一致性.第三,基于OMNeT++设计了相应的仿真试验,试验结果表明六元状态一致性模型能够将无人机编队飞行的各个阶段有机关联起来,同时验证了混合式编队控制机制的可行性和有效性.     

一种无人机自组网DSR协议优化方法

针对DSR协议的路由优化问题,结合无人机网络的特点,提出一种基于萤火虫算法的无人机自组网DSR协议优化方法。该方法综合利用节点的能量消耗、缓冲拥塞、移动速率和传输损耗构建萤火虫的适应度函数,根据适应度函数来衡量萤火虫的荧光亮度,通过萤火虫初始化、萤火虫移动和更新荧光值等阶段的路由搜索过程,对DSR协议的路由算法进行综合优化,解决无人机自组网传输链路稳定性不佳的问题。使用OPNET仿真工具评估了优化前后DSR协议的各项指标,仿真结果表明,相比传统方法,优化方法在无人机场景下,业务接收速率提高了33.8%,平均端到端时延降低了73.91%,路由负荷发送速率减少了44.99%,路由负荷接收速率减少了37.55%,丢包率减少了68.01%。所提方法均衡优化了无人机自组网的网络性能和路由开销,可以为无人机自组网提供稳定高效的路由服务。     

一种基于OLSR的无人机网络适用路由算法

无人机自组网的高动态特性以及节点能量高度受限的特点,使得传统路由协议难以适用于无人机网络。针对该问题,在OLSR协议的基础上提出一种无人机网络适用路由（UAV-OLSR）算法。依据链路变化情况实现无人机集群状态感知,综合考虑节点能量、节点位置等因素进行节点质量评估。采用多径思想并通过特定的路径度量准则选择较优路径进行数据转发。仿真结果表明,与OLSR和AODV协议相比,UAV-OLSR具有更低的数据包平均传输延迟、更高的数据包投递率以及更好的能量均衡效果,可以延长无人机网络的生存时间。     

无人机多跳自组网实时视频传输性能评估

基于当前无人机广泛采用的M-JPEG与MPEG-2视频编解码器,构建了实时半实物仿真环境,并基于此对无人机多跳自组网实时视频传输进行了性能评估。结果表明,实时条件下的M-JPEG编解码器无法支持多跳实时视频传输,而MPEG-2能够支持2跳至3跳的实时视频传输;在1~10跳的实时传输条件下,MPEG-2较之M-JPEG在分组投送成功率和解码率意义下的视频质量平均分别提高了55.69%和205.64%。相对于传统的单飞单控方式,无人机多跳自组网在将无人机系统的作用范围扩大4~9倍的同时能够支持实时视频传输。     

LLACA: An adaptive localized clustering algorithm for wireless ad hoc networks

Performance of ad hoc networks dramatically declines as network grows. Cluster formation in which the network hosts are hierarchically partitioned into several autonomous non-overlapping groups, based on proximity, is a promising approach to alleviate the scalability problem of ad hoc networks. In this paper, we propose a localized learning automata-based clustering algorithm for wireless ad hoc networks. The proposed clustering method is a fully distributed algorithm in which each host chooses its cluster-head based solely on local information received from neighboring hosts. The proposed algorithm can be independently localized at each host. This results in a significantly reduction in message overhead of algorithm, and allows cluster maintenance can be locally performed only where it is required. To show the performance of proposed algorithm, obtained results are compared with those of several existing clustering methods in terms of the number of clusters, control message overhead, clustering time, and load standard deviation.     

基于改进萤火虫群优化的无线自组网路由算法

针对无线自组网络拓扑结构多变、网络生存时间受限及数据包分组传输效率低下等问题,借鉴萤火虫群优化算法,提出了一种改进萤火虫群优化的无线自组网络路由算法.路由算法将萤火虫优化算法中的荧光素强度更新与无线自组网络中的节点移动速度、拥塞程度、节点剩余能量、节点间距离等因素进行相互映射,同时改进萤火虫群优化算法中的搜索萤火虫、驻留萤火虫及回溯萤火虫用于完成无线自组网络中路由协议的路由发现、路由选择及路由维护等过程,整个协议无须传送大量的控制分组,即可实现无线自组网络的稳定传输.仿真实验结果表明,与AODV及基于蚁群优化的路由算法AntRouting协议相比,本文所提出的路由算法在端到端延时、分组数据传输率及网络生存时间上均有良好的性能.     

Backup path set selection in ad hoc wireless network using link expiration time

Topological changes in mobile ad hoc networks frequently render routing paths unusable. Such recurrent path failures have detrimental effects on quality of service. A suitable technique for eliminating this problem is to use multiple backup paths between the source and the destination in the network. Most of the proposed on-demand routing protocols however, build and rely on single route for each data session. Whenever there is a link disconnection on the active route, the routing protocol must perform a path recovery process. This paper proposes an effective and efficient protocol for backup and disjoint path set in an ad hoc wireless network. This protocol converges into a highly reliable path set very fast with no message exchange overhead. The paths selection according to this algorithm is beneficial for mobile ad hoc networks, since it produces a set of backup paths with much higher reliability. Simulations are conducted to evaluate the performance of our algorithm in terms of route numbers in the path set and its reliability. In order to acquire link reliability estimates, we use link expiration time (LET) between each two nodes.In another experiment, we save the LET of entire links in the ad hoc network during a specific time period, then use them as a data base for predicting the probability of proper operation of links.Links reliability obtains from LET. Prediction is done by using a multi-layer perceptron (MLP) network which is trained with error back-propagation error algorithm. Experimental results show that the MLP net can be a good choice to predict the reliability of the links between the mobile nodes with more accuracy.     

A survey of secure wireless ad hoc routing

Ad hoc networks use mobile nodes to enable communication outside wireless transmission range. Attacks on ad hoc network routing protocols disrupt network performance and reliability. The article reviews attacks on ad hoc networks and discusses current approaches for establishing cryptographic keys in ad hoc networks. We describe the state of research in secure ad hoc routing protocols and its research challenges.     

An efficient hop count routing protocol for wireless ad hoc networks

An efcient hop count route fnding approach for mobile ad hoc network is presented in this paper.It is an adaptive routing protocol that has a tradeof between transmission power and hop count for wireless ad hoc networks.During the route fnding process,the node can dynamically assign transmission power to nodes along the route.The node who has received route request message compares its power with the threshold power value,and then selects a reasonable route according to discriminating algorithms.This algorithm is an efective solution scheme to wireless ad hoc networks through reasonably selected path to reduce network consumption.Simulation results indicate that the proposed protocol can deliver better performances with respect to energy consumption and end-to-end delay.     

AODV路由算法的多播通信

ah—hoc网络具有网络拓扑结构易变的特性，苒加上移动网络本身具有的通信带宽有限，电池能源有限等特性。使得设计适合ad-hoc的路由协议具有一定的难度。AODV（Ad Hoc On—demand Distance Vector）是现在被广泛应用于adhoc网络中的一种按需路由算法，并且还设计了多播功能。多播是指一次给一个有明确定义的组发送消息。AODV的多播功能是路由器通过建立多播书树的方法实现的。本文主要介绍AODV路由协议算法的多播通信，其中详细介绍了多播树的建立过程和维护过程。并且选取传输半径和发包率为参     

An Efcient Hop Count Routing Protocol for Wireless Ad Hoc Networks

An efcient hop count route fnding approach for mobile ad hoc network is presented in this paper.It is an adaptive routing protocol that has a tradeof between transmission power and hop count for wireless ad hoc networks.During the route fnding process,the node can dynamically assign transmission power to nodes along the route.The node who has received route request message compares its power with the threshold power value,and then selects a reasonable route according to discriminating algorithms.This algorithm is an efective solution scheme to wireless ad hoc networks through reasonably selected path to reduce network consumption.Simulation results indicate that the proposed protocol can deliver better performances with respect to energy consumption and end-to-end delay.     

Distributed initialization algorithms for single-hop ad hoc networks with minislotted carrier sensing

An ad hoc network is a self-organized and distributed entity, consisting of n mobile stations (MSs) without the coordination of any centralized access point. Initialization is one of the fundamental tasks to set up an ad hoc network, which involves assigning each of the n MSs a distinct ID number from 1 to n, distributedly. In Nakano et al. (2000), randomized initialization protocols are developed for single-hop ad hoc networks under different conditions. However, carrier sensing has not been utilized and suitable acknowledgment schemes for the algorithms are not developed. Moreover, the assumption taken by Nakano et al. about MSs being able to listen while transmitting is not valid for ad hoc networks. In this context, we describe two algorithms for initializing an ad hoc network with carrier sensing capability. First, a novel acknowledgment scheme is proposed for notifying a transmitting MS whether its transmission is successful during the initialization. Then, two distributed and randomized initialization algorithms are developed and analyzed, under the assumptions of a known and unknown number of users in the network, respectively. Both algorithms are obtained based on optimizing some key parameters to minimize the total time required to complete the initialization. Both theoretical analysis and simulations indicate that the proposed initialization algorithms outperform the existing methods, in the sense that they take much less time to complete the initialization and the average number of transmission attempts before success is much smaller.     

基于元胞自动机的蜂群无人机故障影响模型

基于固定翼无人机飞行特性以及蜂群无人机控制策略,针对无人机控制器遭受恶意攻击的情形,采用时序网络与元胞自动机理论分析蜂群无人机故障影响机理.首先,通过时序网络分析蜂群无人机拓扑网络的变化情况,提出基于跳数的故障传播路径的确定方法;其次,考虑蜂群无人机状态信息,建立符合蜂群无人机特征的元胞对象,同时基于局部信息交互原则,确定元胞自动机的状态演变规则,并依据近邻信息对无人机控制律的影响,提出矢量投影法来确定故障影响权值,辨识出各无人机故障影响程度的动态变化情况;最后,建立仿真模型,利用预测与实际故障影响程度结果,基于DCG算法与模式距离验证所建故障影响模型的有效性.