低轨卫星网络的航点分段路由及业务性能分析

提出一种基于卫星航点的分段路由（waypoint-segmentrouting,WSR）算法，WSR算法以可预测的卫星网络拓扑运动周期为基础，根据卫星节点链路状态确定卫星航点的位置；利用分段路由灵活规划分组传输路径的机制，提前响应网络拓扑变化，计算得到一条不受网络拓扑快照切换影响的传输路径。基于NS-3仿真平台进行仿真实验，设置源节点与目标节点在反向缝同侧与不同侧两种场景，选取优化链路状态路由（optimized link state routing,OLSR）算法和最短路径算法与WSR进行时延抖动与分组丢失率的对比分析。实验证明WSR与OLSR相比，两种场景下最大时延抖动分别降低46 ms与126 ms，分组丢失率分别降低30%和21%，并且能够解决拓扑快照切换导致分组传输路径中断的问题。     

一种低时延的短波自组网优化链路状态路由协议

优化链路状态路由(Optimized Link State Routing,OLSR)协议是一种先验式路由协议,网络中的所有节点通过周期性地发送控制消息来计算全网路由信息。在短波自组织网络中,节点周期性地发送控制消息会占据大量的信道资源,大幅增加网络的控制开销,浪费短波有限的带宽资源,导致网络通信性能急剧下降。其次,受到地形地貌、天线方向和接收性能的个体差异等影响,造成无线链路不稳定,导致网络中存在非对称链路,增加了通信端到端时延。为此,提出了一种低时延的短波自组网OLSR协议。该协议在执行MPR(Multipoint Relay)选择算法时综合考虑了节点的连接度和链路可靠性,在优化MPR节点个数的同时选择链路可靠性较大的节点作为MPR节点,在进行路由选择时能够利用网络中的非对称链路。仿真结果表明,该协议能优化数据包投递成功率、吞吐量、端到端时延和网络控制开销等性能指标。     

Directed information dissemination in vehicular ad-hoc networks

In this article, we utilize the idea of multipoint relays (MPRs) found in literature (Jacquet et al. in Proceedings of IEEE INMIC, 2001), to propagate accident information in a restricted way (e.g., only backwards). We devise an algorithm to identify MPRs that are geographically situated behind a particular node using only its neighbor table, and speed information of the neighboring vehicles. With the identification of the backward MPRs, it is possible to restrict the information dissemination to vehicles behind a particular vehicular ad-hoc network (VANET) node only. This might benefit the approaching vehicles so that the driver could take preventive measures in real-time since he/she will have an indication of the severity of road conditions ahead. We assume that there exists an inter vehicular network using optimized link state routing (OLSR) where accident information can be propagated to all nodes using on-going OLSR control packets. We envision our application will run on top of existing routing protocols (e.g., OLSR), thereby resulting in very little integration effort, and retaining OLSR’s reduced network traffic advantage through the use of MPRs. We analyze our back MPR identification algorithm in a detailed manner. We also show that by using our approach the location of the accident alert instigator node could be pinpointed if a subset of the nodes in the same VANET know their geographical positions. We use VANET mobility models generated by SUMO into NS-3 for our simulations, and also perform preliminary experiments to verify the algorithm’s effectiveness. Our analysis and experiments show favorable results.     

Unified routing protocol based on passive bandwidth measurement in heterogeneous WMNs

The past few years have witnessed a surge of wireless mesh networks (WMNs)‐based applications and heterogeneous WMNs are taking advantage of multiple radio interfaces to improve network performance. Although many routing protocols have been proposed for heterogeneous WMNs, most of them mainly relied on hierarchical or cluster techniques, which result in high routing overhead and performance degradation due to low utilization of wireless links. This is because only gateway nodes are aware of all the network resources. In contrast, a unified routing protocol (e.g., optimal link state routing (OLSR)), which treats the nodes and links equally, can avoid the performance bottleneck incurred by gateway nodes. However, OLSR has to pay the price for unification, that is, OLSR introduces a great amount of routing overhead for broadcasting routing message on every interface. In this paper, we propose unified routing protocol (URP), which is based on passive bandwidth measurement for heterogeneous WMNs. Firstly, we use the available bandwidth as a metric of the unification and propose a low‐cost passive available bandwidth estimation method to calculate expected transmission time that can capture the dynamics of wireless link more accurately. Secondly, based on the estimated available bandwidth, we propose a multipoint relays selection algorithm to achieve higher transmission ability and to help accelerate the routing message diffusion. Finally, instead of broadcasting routing message on all channels, nodes running URP transmit routing message on a set of selected high bandwidth channels. Results from extensive simulations show that URP helps improve the network throughput and to reduce the routing overhead compared with OLSR and hierarchical routing. Copyright © 2016 John Wiley & Sons, Ltd.     

The Impact of Deployment Pattern and Routing Scheme on the Lifetime in Multi-Sink Wireless Sensor Network

Extensive use of sensor and actuator networks in many real-life applications introduced several new performance metrics at the node and network level. Since wireless sensor nodes have significant battery constraints, therefore, energy efficiency, as well as network lifetime, are among the most significant performance metrics to measure the effectiveness of given network architecture. This work investigates the performance of an event-based data delivery model using a multipath routing scheme for a wireless sensor network with multiple sink nodes. This routing algorithm follows a sink initiated route discovery process with the location information of the source nodes already known to the sink nodes. It also considers communication link costs before making decisions for packet forwarding. Carried out simulation compares the network performance of a wireless sensor network with a single sink, dual sink, and multi sink networking approaches. Based on a series of simulation experiments, the lifetime aware multipath routing approach is found appropriate for increasing the lifetime of sensor nodes significantly when compared to other similar routing schemes. However, energy-efficient packet forwarding is a major concern of this work; other network performance metrics like delay, average packet latency, and packet delivery ratio are also taken into the account.

     

一种适用于无线移动Mesh网的路由算法

针对无线移动Mesh网络的特点,以先应式最优链路状态路由协议为基础,整合有限分发路由信息机制与高效分发路由信息机制。结合自适应的检测模块,提出了一种自适应视觉朦胧的链路状态路由协议———自适应视觉的朦胧的链路状态(Adaptive Fuzzy Sighted Link State,AFSLS)路由协议。NS2仿真结果表明,AFSLS路由协议在平均时延、网络吞吐量以及丢包率方面有良好的性能,能够满足无线移动Mesh网络对路由协议的要求。     

Proficient link state routing in mobile ad hoc network-based deep Q-learning network optimized with chaotic bat swarm optimization algorithm

Mobile ad-hoc network (MANET) is a category of ad-hoc network that can be reconfigurable its network. MANETS are self-organized networks, that can use the wireless links to connect various networks via mobile nodes: but it consumes more energy and it also has routing problems. This is the major drawback of being connected with the MANET technology. Therefore, this study proposes a new protocol as deep Q-learning network optimized with chaotic bat swarm optimization algorithm (CBS)-based optimized link state routing (OLSR) (CBS-OLSR) for MANET. This protocol reduces MANET energy usage and adopts OLSR multi-point relay (MPR) technology. MANET's OLSR and the CBS algorithm utilize a similar method to locate the best optimum path from source to destination node. By embedding the new improved deep Q-learning and OLSR algorithms, both are used for optimizing the MPR sets selection, it can efficiently diminish the energy consumption in the network topology, but automatically increase the lifespan of the network. It also enhances the package delivery ratio and decreases end-to-end delay. The experimental outcomes prove that the proposed protocol is reliable and proficient that is appropriate for numerous MANET applications.     

Optimized link state routing for quality‐of‐service provisioning: implementation,measurement, and performance evaluation

This paper provides a measurement‐based performance evaluation of the Optimized Link State Routing (OLSR) protocol. Two versions of OLSR, OLSR‐ETX and OLSR‐ETT, are implemented and evaluated on a mesh network that we built from off‐the‐shelf commercial components and deployed within our department building. OLSR‐ETX uses the Expected Transmission Count (ETX) metric, whereas OLSR‐ETT uses the Expected Transmission Time (ETT) metric as a means of assessing link quality. The paper describes our implementation process of the ETT metric using the plug‐in feature of OLSRd, and our calculation method of link bandwidth using the packet‐pair technique. A series of measurements are conducted in our testbed to analyze and compare the performance of ETX and ETT metrics deemed useful for quality of service. Our measurements show that OLSR‐ETT outperforms OLSR‐ETX significantly in terms of packet loss, end‐to‐end delay, jitter, route changes, bandwidth, and overall stability, yielding much more robust, reliable, and efficient routing. Copyright © 2012 John Wiley & Sons, Ltd.     

SD-FANET下基于节点合作的低开销且可靠有效路由解决方案

针对分布式无人机网络初始建网时间过长、周期性组网开销过大、链路稳定性与可靠性低的问题,提出了软件定义飞行自组网下基于节点合作的低开销且可靠有效路由解决方案（Low-overhead,Reliable and Efficient Routing Solution Based on Node Cooperation,NC-SDN）。首先,通过普通节点局部感知和软件定义网络（Software Defined Network,SDN）控制器全局感知配合,缩短了初始建网时间并减少了周期性组网开销;其次,通过普通节点主动感知链路状态与周期性传递告警信息,减少了未过期无效路由带来的不可靠传输风险;最后,通过SDN控制器的预测与切换,降低了用户业务传输中断的风险。仿真表明,NC-SDN在初始建网时间、周期性组网开销和丢包率等方面性能优于现有的SDN、优化链路状态路由和无线自组网按需平面距离向量路由。     

WRE‐OLSR,a new scheme for enhancing the lifetime within ad hoc and wireless sensor networks

Within ad hoc and wireless sensor networks, communications are accomplished in dynamic environments with a random movement of mobile devices. Thus, routing protocols over these networks are an important concern to offer efficient network scalability, manage topology information, and prolong the network lifetime. Optimized link state routing (OLSR) is one of those routing protocols implemented in ad hoc and wireless sensor networks. Because of its proactive technique, routes between two nodes are established in a very short time, but it can spend a lot of resources for selecting the multipoint relays (MPRs: nodes responsible for routing data) and exchanging topology control information. Thus, nodes playing for a long time a role of MPR within networks implementing such protocol can rapidly exhaust their batteries, which create route failures and affect the network lifetime. Our main approach relies on analyzing this concern by introducing a new criterion that implements a combination between the residual energy of a node and its reachability in order to determine the optimal number of MPRs and sustain the network lifetime. Simulations performed illustrate obviously that our approach is more significant compared with the basic heuristic used by original OLSR to compute the MPR set of a node.     

基于OLSR协议的无线MESH网络系统设计

本文针对传统单跳无线网络(WLAN)可伸缩性低、鲁棒性差等缺点,提出了一种基于OLSR协议的无线MESH网络系统设计方法,该方法在提高对网络拓扑变化动态适应性的同时, 达到减少控制开销的目的。每个子网选择部分节点作为网络控制分组的多点中继节点(MPR), 其它邻居节点收到该节点发送的控制分组时,只进行处理而不转发,通过这种方式显著地减少了传统先应式路由协议网络拓扑信息广播的控制分组数量。每一个 MPR 节点只报告自己与其 MPR 节点之间的链路,进一步地减少了网络控制开销。该方法在城市数字化、城市无线监控等领域具有较高应用前景。     

Improving mobile ad hoc network routing with satellite out‐of‐band signaling

Routing in mobile ad hoc networks is a complex task due to the mobility of the nodes and the constraints linked to a wireless multihop network (e.g., limited bandwidth, collisions, and bit errors). These adverse conditions impair not only data traffic but also routing signaling traffic, which feeds route computation. In this contribution, we propose to use satellite communications to help in the distribution of mobile ad hoc network routing signaling. The optimized link‐state routing (OLSR) is chosen among several routing protocols to be extended with satellite‐based signaling, yielding a version we call OLSR hybrid signaling (OLSR‐H). This new scheme is evaluated through simulations and yields improvements of approximately 10% in the data delivery ratio compared with a regular OLSR. This evaluation is conducted using two different network topology models, one being fit for representing forest firefighting operations. Copyright © 2013 John Wiley & Sons, Ltd.     

Neighborhood discovery and link management mechanism using hysteresis with an exponentially weighted moving average

The neighborhood discovery and link management (NDLM) mechanism is an important component of routing protocols for self-organizing multihop wireless networks. High network performance is ensured when this mechanism quickly responds to topology changes and establishes stable links with an acceptable packet delivery ratio. The NDLM mechanism of optimized link state routing (OLSR) protocol is considered. This mechanism uses hysteresis with an exponentially weighted moving average. The efficiency of the mechanism is analytically estimated, and the mechanism is adjusted for various scenarios.     

Link failure and congestion-aware reliable data delivery mechanism for mobile ad hoc networks

Link failures and packet drops due to congestion are two frequently occurring problems in mobile ad hoc networks, degrading the network performance significantly. In this paper, we propose a link failure and congestion-aware reliable data delivery (LCRDD) mechanism that jointly exploits local packet buffering and multilevel congestion detection and control approaches for increasing the data delivery performance. On the detection of link failure or congestive state, an LCRDD intermediate node buffers the incoming data packets at the transport layer queue and resumes transmission when the route is repaired locally. In addition, LCRDD’s multilevel congestion detection helps it to take the most appropriate action proactively. Thus, it offers increased reliability and throughput and decreased end-to-end packet delivery delay and routing overhead compared to state-of-the-art protocols, as shown in results of performance evaluations carried out in network simulator v-2.34.     

基于功率损耗均衡化控制机制的移动无线传感网数据传输算法

为了解决当前移动无线传感网数据传输中存在的同步寻址困难以及节点间功率交互难以均衡化的问题,提出了一种新的移动无线传感网数据传输算法。首先,采取广播机制实现同步控制分组传输,降低同步流量对寻址过程造成的压力;随后使用区域节点流量阀控制机制,且通过侦听方式记录并获取sink节点—区域节点链路间的数据流量,进一步采取流量—链路均衡方式促进流量均衡化;最后,通过基于轮数—sink 链路周期抖动筛选方式确认受限带宽,减少带宽受限导致的传输故障。仿真实验表明,与BLT-NB2R算法、NLSC算法和HT2C算法相比,所提出的算法可改善数据传输带宽,降低数据分组丢失频率,能够较好地满足实践需求。     

一种环境感知的无线Mesh网络自适应QoS路径选择算法

本文针对如何改善无线多跳Mesh网络的服务质量,满足无线多媒体业务对数据传输的带宽、时延、抖动的要求等问题,研究了一种基于无线信道状态和链路质量统计的MAC层最大重传次数的自适应调整算法。该算法通过对无线Mesh网络的无线信道环境的动态感知,利用分层判断法区分无线分组丢失的主要原因是无线差错还是网络拥塞导致,实时调整MAC层的最佳重传次数,降低无线网络中的分组冲突概率。基于链路状态信息的统计和最大重传策略,提出了一种启发式的基于环境感知的QoS路由优化机制HEAOR。该算法通过动态感知底层链路状态信息,利用灰色关联分析法自适应选择最优路径,在不增加系统复杂度的基础上,减少链路误判概率,提高传输效率。NS2仿真结果表明,HEAOR算法能有效减少重路由次数,降低链路失效概率,提高网络的平均吞吐率。本文提出的方法不仅能够优化MAC层的重传,而且通过发现跨层设计的优化参数实现对路径的优化选择。      

高动态Ad Hoc路由协议性能分析

Ad Hoc网络是一种没有固定设施的无线移动自组织网络,动态变化的拓扑结构对路由协议的性能有着重要影响。研究了动态源路由(DSR)协议、Ad Hoc按需距离矢量(AODV)路由协议和最优链路状态路由(OLSR)协议3种传统路由协议,利用OPNET软件作为仿真工具,设计了2种不同网络规模条件下空中飞行平台网络拓扑结构背景的高动态仿真方案,通过比较网络时延、归一化网络吞吐量、路由负载和数据传送成功率,分析了它们的性能。仿真结果表明,OLSR协议的综合性能优于其它协议,更适合于节点高速移动且网络拓扑结构频繁变化的Ad hoc网络,并为下一步研究打下基础。     

基于NS-3的声电协同网络实现及路由性能分析

水下无线通信主要依靠水声通信的方式进行信息传输。但水声链路本身具有高时延和高误码率等不足,为水下应用提供低时延的通信服务是一项具有挑战性的工作。声电协同网(CRAN)旨在充分利用水面无线电链路弥补水声网络(UAN)的性能局限,提升网络的整体性能。其中,CRAN中的路由协议需要构建声、电混合路径,是声电协同网络研究中的关键问题。该文首先在网络模拟器3(NS-3)中设计并实现了声电浮标节点与CRAN协议栈,搭建了CRAN的仿真平台。随后探讨了以无线自组网按需平面距离向量路由协议(AODV)为代表的被动式路由在CRAN中的应用。该文发现,AODV协议使用的距离向量准则在CRAN中能够更多地选择高速的无线电链路进行数据转发,有效地降低了网络传输时延。最后,通过仿真对AODV与其他协议的性能进行了对比、分析。结果表明,CRAN在投递率、传输时延、网络吞吐量、能效和路由响应速度方面对比水声通信网有较大提升。同时,以AODV为代表的被动路由协议,相比于以优化链路状态路由协议(OLSR)为代表的主动路由协议更适用于CRAN。     

An energy aware algorithm for OLSR clustering

One of the important aspects of a mobile ad hoc network (MANET) is the limitation of the amount of available energy and the network lifetime. The tremendous amount of using mobile nodes in wireless communication medium makes energy efficiency a fundamental requirement for MANETs. In this paper, we propose a novel energy aware clustering algorithm for the optimized link state routing (OLSR) routing protocol. This algorithm takes into account the node density and mobility and gives major improvements regarding the number of elected cluster heads. Our objective is to elect a reasonable number of cluster heads that will serve for hierarchical routing based on OLSR. The proposed algorithm aims to increase the network lifetime by considering the ad hoc residual energy while taking routing decisions. It also optimizes the delay of carried flows by adopting a selective forwarding approach based on a hierarchical routing model.     

R-Code: Network coding-based reliable broadcast in wireless mesh networks

Broadcast is an important communication primitive in wireless mesh networks (WMNs). Applications like network-wide software updates require reliable broadcast to ensure that every node in the network receives the information completely and correctly. With underlying unreliable wireless links, a key challenge in implementing reliable broadcast in WMNs is to achieve 100% information reception rate at every node with high communication efficiency and low latency. Recently, network coding has emerged as a promising coding scheme in terms of communication efficiency especially for one to many communication patterns. In this paper, we put forward R-Code, a network coding-based reliable broadcast protocol. We introduce a guardian–ward relationship between neighboring nodes that effectively distributes the responsibility of reliable information delivery – from the global responsibility of the source to the localized responsibilities of guardians to their corresponding wards. We use a link quality-based minimum spanning tree as a backbone to guide the selection of guardians adaptively and the transmission of coded packets accordingly. Opportunistic overhearing is also utilized to improve the performance of the protocol. Extensive simulation results show that R-Code achieves 100% packet delivery ratio (PDR), while enjoying significantly less transmission overhead and shorter broadcast latency, compared with a state-of-the-art reliable broadcast protocol, AdapCode.