Q-Learning Driven Routing for Aeronautical Ad-Hoc Networks

The aeronautical ad-hoc network (AANET) is one of the critical methodologies to satisfy the Internet connectivity requirement of airplanes during their flights. However, the ultra-dynamic topology and unstable air-to-air link characteristics increase the need for AANETs to a particular routing algorithm compared to the terrestrial networks. This need is mainly because these AANET-specific characteristics increase the delays, packet losses, and network load with accuracy reduction by continuously changing topology and breaking air-to-air links during routing. The works in the literature do not satisfy the ultra-dynamic topology and unstable air-to-air link characteristics of AANETs during routing. On the other hand, the routing algorithm can adapt to the dynamic conditions of AANETs by utilizing Artificial Intelligence (AI) based methodologies. For adaptation to this dynamic environment, we aim to let the airplanes find their routing path through exploration and exploitation by mapping the AANET environment to QLR. Clearly, this article proposes an updated Layered Hidden Markov Model (updated-LHMM) estimation-based Q-learning (QLR) routing for AANETs to solve the delay, packet loss, network load, and accuracy problems. For this aim, the Bellman Equation is adapted to the AANET environment by proposing different methodologies for its related QLR components. Results reveal that the proposed strategy mainly reduces the routing delay and packet losses by 30% and 33% compared to the methods in the literature.     

基于链路稳定度的车载网路由协议研究

针对车载网中节点移动速度快,拓扑结构变化速度快的特点,以及AODV协议广播式路由链路存活时间短、平均端到端时延大等问题,提出了一种通过计算链路稳定度的方式来改进AODV协议.在节点进行广播时,首先计算转发角度,然后,再将投影最长和链路生存时间最长作为综合选择条件,以此高效地选择路径相对较短以及链路相对稳定的路由.通过这种方式,改进后的AODV协议很好地解决了网络中链路易断裂的问题,提高了数据包的投递率,降低了平均端到端的时延.利用NS2仿真软件进行性能仿真,结果表明:改进后的AODV协议在包递率、平均时延和吞吐量方面优于传统模型.     

面向航空自组网的节点失效波及影响分析模型

为有效分析航空自组网(AANET)中节点失效对整个网络造成的影响,并提高网络在发生安全事件之后的稳定性,提出一种面向AANET的节点失效波及影响分析模型.首先,根据AANET的主要业务建立有向加权业务网络,基于实时AANET建立以各类航空器为节点的无向加权物理网络,并通过业务?物理网络映射关系建立相依网络模型;其次,提...     

IGR:面向车载网的基于地理信息的数据传输协议

由于车辆的高速移动和拓扑的动态变化,基于地理信息的数据传输协议被广泛应用于车载网.然而,现存的多数协议在路由决定时并没有考虑链路的质量,导致数据包丢失率升高,增加了传输时延.为此,提出了新的基于地理信息的数据包传输协议(IGR).IGR协议在路由决策时充分考虑车辆的移动方向、位置和链路质量3项信息.其中,利用beacon接收率体现链路质量.将这3项信息融合成节点权值.源节点择优选择权值高的节点作为下一跳转发节点.与同类协议相比,提出的IGR协议具有低的传输时延和高的传输率.     

AODV路由协议的本地修复算法

针对传统按需平面距离矢量(AODV)路由修复算法路由开销大和端到端时延长的问题,提出一种改进的AODV本地路由修复算法。通过路由修复阶段2hop_RREQ和NOTICE报文的传递,将修复限制在断链的2跳范围内。在NS2平台下的仿真结果表明,与传统算法相比,改进算法的路由开销减少约50%,包投递率增加约5%。     

无人机自组网按需寻路的可靠OLSR协议

无人机自组网应用场景中,针对OLSR(Optimized Link State Routing)协议在数据通信阶段,无人机快速移动可能引起通信链路中断,并且OLSR协议没有链路维护机制,导致发包成功率降低和时延增加.在节点入网阶段,无人机无法及时获取全网拓扑信息,导致通信失败.本文借鉴AODV(Ad Hoc On Demand Distance Vector)路由协议中按需寻路思想,提出一种按需寻路的可靠OLSR协议.该算法提出了两个优化思路:基于TC全网寻路机制和基于HELLO邻居寻路机制,通过增加路由获取途径,维护多跳链路的稳定性.通过仿真实验将该协议与现有协议进行比较,实验结果表明,该协议在不增加控制开销的前提下,提高网络的发包成功率,端到端时延和吞吐量.     

车载网中一种基于链路稳定度的路由方法

车载自组织网络VANET(vehicular ad hoc network)由于车辆高速移动性、分布不均匀、运动行为受交通环境限制等因素的影响,使得VANET具有网络拓扑结构变化频繁、传输信号受干扰大、网络易于断裂等固有特性。路由选择是VANET的重要组成部分。如何选择下一跳节点是实现路由方法的关键,链路稳定度是衡量VANET性能的重要因素。本文通过计算预期路径的链路稳定度来选择下一跳节点,提出一种基于链路稳定度的路由方法。实验结果表明与传统的AODV相比,本文提出的方法在端到端延时,数据包的传递率等方面有较大的提高。     

基于模糊神经网络的稳定AODV协议改进方案

车载自组网的重要特征之一是节点的高移动性。针对节点的自由移动导致链路频繁断裂这一问题,在路由协议中选择稳定链路进行数据传输尤为重要。提出了一种具有链路稳定性的按需距离矢量路由协议（AODV）改进方案,即GF-AODV（AODV with GASA FNN）。该方案在路由发起和选择阶段,使用模糊神经网络对节点信息进行计算,得到节点稳定度以评估链路质量,并均衡考虑链路稳定性与跳数,选出稳定且跳数较小的路径。在路由维护阶段,针对实际环境使用遗传模拟退火算法对模糊神经网络的参数进行实时优化,以确保计算出的节点稳定度符合实际情况。实验表明,GF-AODV相对于AODV在平均时延、包投递率、路由开销等方面均有所改善。     

Ad Hoc网络链路质量QoS多路径按需路由协议

传统的MANET路由协议是基于最小跳数的路由,没有考虑链路质量,不能适应网络拓扑的动态变化。针对这一问题,提出了一种Ad Hoc网络链路质量QoS多路径按需路由协议（QMORP）。QMORP采用移动预测来计算链路的生存时间,应用能量模型获得链路的剩余能量,综合链路生存时间和剩余能量两种因素来计算链路质量。选择链路质量大的路径转发分组。仿真实验表明,相比AOMDV协议,QMORP协议提高了网络的生命周期,降低了网络的平均端对端延迟、提高了网络的发包率和吞吐率。     

能量捕获无线传感器网络中速率自适应路由算法

能量捕获无线传感器网络是无源感知技术中非常重要的一类,它能够有效解决节点能量受限的问题,保持网络运行的持续性.现有的路由方法并未充分利用节点的能量捕获特性,也没有考虑到链路的成功收包率和节点的传输速率.为进一步提高网络的性能,提出了一种结合链路成功收包率的速率自适应路由算法.通过对节点的剩余能量和链路的成功收包率进行建模,给出了一个节点可作为路由中继节点所需要满足的两个条件;基于优化方程,为传输路径上的每一跳节点自适应配置时延最小化的传输速率;提出路由发现步骤来找出端到端传输时延最小的传输路径.实验结果表明,相比于固定传输速率的路由算法,所提算法所得到的传输路径具有较低的端到端传输时延和较高的吞吐率.     

移动Ad Hoc网络的可靠多播路由协议

在移动Ad Hoc网络环境中，分组的重传和路由的重构比有线网络更频繁。在网络多播树变化的情况下提供高的分组传输率是移动Ad Hoc网络多播路由的主要难题。文中提出了一种基于协议转接概念的移动Ad Hoc网络的可靠多播路由协议(RMRP)，该协议较好地减少了移动Ad Hoc网络中大量的路由重构和数据分组的重传。仿真实验显示RMRP具有较高的传输率和较低的端到端分组延迟。     

A versatile model for predicting the performance of deflection-routing networks

Deflection routing can be used in networks whose stations have the same number of input and output links. Fixed-length packets arrive synchronously on the station's input links at the beginning output link that offers the shortest path to its destination. Since the number of packet buffers at each output link is finite, the simultaneous contention of two packets for the last buffer of the common output link must be resolved by “deflecting” one of the packets according to a specified criterion (e.g. at random, by destination proximity, or by packet age). Deflection routing can therefore be used with as few as one packet buffer per output link.

The potentially unbounded number of routes that a given packet can take makes analyzing the performance of such networks difficult. Using independence assumptions, we develop an efficient, high-fidelity performance model of deflection routing that allows us to estimated the mean end-to-end packet delay in a network that has any given two-connected topology, a single packet buffer at each output port, and an arbitrary traffic matrix.     

大规模互联网端到端行为评价指标研究

目前,Internet端到端行为的研究仅仅局限在包延迟、包丢失等测量指标的研究上,但如何根据测量指标对链路的性能进行评价却没有做深入研究。文章针对链路特性提出了两个评价指标:稳定系数和总体评价系数,对链路的稳定性和总体性能进行了评价。其中,稳定系数是评价网络链路稳定性的一个系数,总体评价系数是体现链路稳定性和链路速率的综合特性的一个系数,它反映了目前链路给用户的总体使用效果。接着文章介绍了在实际测量中用到的笔者自己编写的测量工具Posip。该工具采用指数间隔进行测量采样,并解决了一般ping工具中的“应答包丢失”问题。最后,文章使用工具posip对我国Internet教育网和科技网中的43条链路进行了测量和分析,并使用两种评价指标对所测链路进行了评价,取得了较好的效果。     

一种车载自组织网络连通性维护方法

车载自组织网络（VANET）中的高速移动性节点和动态的网络拓扑结构使得车辆间通信链路存在传输时延长、连接时间短的问题。通过引入双簇头选择算法,提出一种改进的AODV路由协议（AODV-CMIRP）,用于VANET的连通性维护。利用分簇技术降低全局网络拓扑的动态性,通过引入节点的相对移动度和相对速度作为簇头选择指标,并选取辅助簇头节点以延长车载自组织网络整体生存时间。仿真结果表明,在保证网络连通性和稳定性的前提下,相比CBDRP和AODV协议,AODV-CMIRP协议具有较低的平均端到端时延和较高的分组投递率,能够有效延长簇头生存时间并提高网络的稳定性。     

Energy Aware Routing Algorithm in Manet Using Linear Programming

Mobile ad hoc networks (MANET) are wireless network without infrastructure and suffering from low power battery. Therefore the main objective in finding a route for traffic transfer from a given source to a given destination is to minimize the node energy consumption. This paper solves the problem of finding a route satisfying the main objective of minimum energy consumption and other QoS requirements such as minimum delay and maximum packet delivery ratio by using linear programming technique. Two cases are considered: 1. The traffic amount of a given request is transmitted into single path, and 2. The traffic amount of a request can be distributed into parallel paths. A preprocessing step is done first for network topology design. This step leads to formulate the first case as integer linear programming problem and the second case as linear programming and not mixed integer linear programming. The two obtained solutions are evaluated in terms of three criteria: energy consumption, execution time, and packet delivery ratio using an experimental study. The results show that the solution of second case is much better than the first case in terms of energy consumption and execution time. Packet delivery ratio in the second case is 100% while in the first case is only 76%.     

一种基于链路质量的移动Ad-hoc网络地理路由算法

如何实现简单的路由机制,使节点能够快速、高效地完成分组传递,是移动aa-ho}网络研究的一个基本问题。针对无线链路在高误码率和杭干扰技术方面的不足,提出了将链路质量作为路由选择的度量,设计并实现了基于链路质量的地理路由算法LQPR,解决了在非理想无线链路上采用传统贪婪算法引起数据分组传送率下降的问题。该算法综合了链路质量选择模式和边界选择模式,并利用目标定位技术获取的地理位置信息指导分组的转发,以减少控制开销,优化路径选择,实现数据分组快速有效的传输。在NS-2中完整实现了LQPR协议的仿真,并通过对网络节点发送数据包的端到端时延、吞吐量以及包传送率进行比较、评估和检侧,验证了LQPR路由协议的有效性。     

移动自组网路由局部修复算法的研究

移动自组织网(mobile ad hoc networks,MANET)的多跳的无线连接、动态拓扑和有限的带宽等特征,给其路由协议带来了很多挑战.当多跳路径失效时,路由协议需要对其进行修复.已有的修复机制需要很多的开销和很长的端到端时延.在此修复机制的基础上,提出了一种新的路由局部修复算法,将修复尽量限制在断链的局部范围内,以减少对链路断裂的反应时间和降低路由维护的开销,而且不用考虑失效链路在整个路由上的相对位置,都可以对其进行修复,提高了处理失效链路的能力,有利于提高MANET的可扩展性.仿真表明,这种新的路由局部修复算法明显地提高了网络多方面的性能.     

Link stability based multicast routing scheme in MANET

The group-oriented services are one of the primary application classes that are addressed by Mobile Ad hoc Networks (MANETs) in recent years. To support such services, multicast routing is used. Thus, there is a need to design stable and reliable multicast routing protocols for MANETs to ensure better packet delivery ratio, lower delays and reduced overheads. In this paper, we propose a mesh based multicast routing scheme that finds stable multicast path from source to receivers. The multicast mesh is constructed by using route request and route reply packets with the help of multicast routing information cache and link stability database maintained at every node. The stable paths are found based on selection of stable forwarding nodes that have high stability of link connectivity. The link stability is computed by using the parameters such as received power, distance between neighboring nodes and the link quality that is assessed using bit errors in a packet. The proposed scheme is simulated over a large number of MANET nodes with wide range of mobility and the performance is evaluated. Performance of the proposed scheme is compared with two well known mesh-based multicast routing protocols, i.e., on-demand multicast routing protocol (ODMRP) and enhanced on-demand multicast routing protocol (EODMRP). It is observed that the proposed scheme produces better packet delivery ratio, reduced packet delay and reduced overheads (such as control, memory, computation, and message overheads).     

分布式星群网络中基于蚁群算法的通信量分类路由

给出了一种分布式星群网络(Distributed Satellite Cluster Network,DSCN)体系架构,阐明了DSCN拓扑变化的特点。在分析网络状态获取方式和路由计算方法的基础上,提出了一种适用于DSCN的基于蚁群算法的通信量分类路由(Ant Colony Optimization Based Traffic Classified Routing,ATCR)算法。ATCR算法将通信量分为时延敏感型通信量A、带宽敏感型通信量B以及提供尽力而为服务的通信量C,并对蚁群算法(Ant Colony Optimization,ACO)收敛慢的缺点进行了改进。仿真实验表明,ATCR算法提高了收敛速度,可以有效平衡网络流量。通信量A和C的端到端时延要小于未采用通信量分类的改进ACO算法。由于减少了重负载链路的数量及拥塞引起的丢包,ATCR算法在分组递交率上的表现优于改进的ACO算法。     

基于虚拟信道多路径融合认知无线网络路由算法

针对认知无线网络中频谱的动态性、时变性、多样性以及节点移动性, 提出了一种基于虚拟信道的多路径融合认知无线网络路由算法. 在路由建立过程中, 为解决源节点与目的节点信道同步问题, 源节点在公共控制信道上广播添加虚拟信道的路由请求, 在当前所处信道为虚拟信道的节点中转发. 目的节点对多条路径通过信道切换进行融合, 以规避主用户的活动区域, 减少路径跳数, 提高链路的稳定性. 在路由维护阶段, 通过卡尔曼滤波对节点移动速度进行预测, 在链路断裂之前启动路由修复. 最后通过NS2中CRCN Simulator仿真结果表明, 该算法在链路通信的稳定性、分组投递率、吞吐量、端到端时延等方面有明显的改善, 提高了网络的整体性能.