MANET中基于AODV的跨层多度量路由协议

针对无线自组网按需平面距离向量路由协议(AODV)路由度量的单一化而引起的节点能耗枯竭,形成的网络区域化以及路径拥塞问题,提出一种多度量路径选择机制的路由协议――M-AODV。以AODV路由协议为基础,在路由发现阶段,根据设定的能量阈值和接收信号强度阈值选择能量较高和信号强度较强的节点作为路由节点;在路径选择阶段,首先根据物理层的接收信号强度、拥塞度和跳数计算每段链路稳定值,其次将每段路径稳定值进行累加得到整条路径的稳定值,最后选择稳定值最大的路径作为最优路径。使用NS2.35仿真软件仿真,结果表明：改进后的协议与AODV相比在端到端延时缩短了近30%,在数据包传输率、吞吐量和节点存活率方面优于AODV和I-AODV-SE路由算法。     

基于时间序列分析的链路质量预测和稳定路由算法研究

针对现有链路质量预测算法不适用于实际通信场景的问题,该文提出一个不依赖于任何特定信号传输模型和节点移动模型、低复杂度的实时链路质量预测算法,并将其应用于稳定路由协议设计。通信节点存储并更新其邻节点的接收信号强度集合以构成时间序列,将时间序列分析中的局部线性核平滑方法和滑动窗口局部多项式预测方法引入链路质量判断及预测。在此基础上,结合跨层协作思想,提出了节点移动自适应的提前路由修复机制。仿真结果表明,该预测算法具有较高的预测准确度,并能显著增强路由稳定性,提高网络性能。     

一种基于信号强度的OLSR路由协议改进算法

借助接收分组时测得的信号强度,提出OLSR-PSSA(Pre-rerouting and Signal Strength A-ware OLSR)改进协议。为了建立和维护生存时间更长、链路更加健壮的路由,并加入预切换路由机制,来适应节点的移动和网络拓扑结构的频繁变化。OPNET仿真结果显示,与传统OLSR协议相比,OLSR-PSSA改进协议提升了传输成功率,增加了网络吞吐量。     

适用于分段运动模式的基于链路维持概率的跨层路由协议

MANET中节点移动造成路由中断带来端到端传输性能下降,为解决这一问题提出了一种适用于分段运动模式的链路稳定概率计算方法,并在此算法的基础上设计了一种适用于分段运动模式的基于链路维持概率的跨层路由协议(LPCP).LPCP跨层结合路由层和传输层,能够兼顾端到端连接的稳定性和最小跳数.制定了"路由切换"、"数据存储转发"、"ACK再确认"等机制尽可能减少路由中断的发生及其带来的端到端传输性能下降.仿真结果表明LPCP能够有效减小路由中断带来的丢包,提高端到端传输吞吐量.     

基于中断概率的多跳混合协作地理路由算法

为了减小无线传感器网络中路由的路径长度,该文提出基于中断概率的多跳混合协作地理路由(MHCGR)算法。首先对不同协作机制的链路进行分析,理论分析表明,在一定中断概率要求下,采用译码放大转发混合协作机制可以进一步扩大传输距离,并推导了每跳协作链路的理想最大协作传输距离和理想中继的位置。在无信标地理路由(BLGR)算法的基础上,MHCGR算法结合节点位置信息为每跳选择最佳的中继节点和转发节点,建立从源节点到目的节点的多跳协作路由。仿真表明,与ENBGCR算法和基于DF协作机制的MPCR算法两种协作地理路由算法相比,MHCGR算法可明显减少路由的跳数,改善路由的整体发射功率。     

基于第一跳节点累积的AODV协议改进

利用DSR协议的源路由策略,对AODV协议进行修改——在其路由发现过程中,将第一跳节点的地址信息添加到路由消息中。中间节点接收路由消息后,建立或者更新到达第一跳节点的路由。将修改后的协议称为AODV-FA协议,并在ns2中模拟仿真其路由性能。结果表明:相较于AODV协议,AODV-FA在分组传输率、平均端到端时延和归一化路由负载3个路由性能上均有提升。     

基于IPv6无线传感网络的最佳转发路由协议

提出一种基于IPv6无线传感网络的最佳路由转发协议,在性能上其吞吐量比RIP(路由信息协议)和贪婪算法路由协议要分别提高11%和43%。该转发是基于对从该节点到邻居节点的链路估值、代价估值和接收信号强度估值计算得出的转发值进行的。如果该链路数据传输不成功,该协议将会选择其他具有次最佳转发权值的节点进行转发。     

MANETs中基于节点移动度的虚连接的路由

由于移动自组织网络MANETs中节点的快速移动,使得维持源节点与目的节点间的通信路径成为一项挑战性工作。节点的高速移动导致通信链路频繁断裂。为此,提出基于节点移动度的虚连接的路由(MDVRP)。虚路由为一条动态的逻辑路由,其由一系列的特定地理区域构成。每个区域内的节点依据自己的移动度设置转发数据包的定时器,移动度越小,具有优先转发数据包权。MDVRP通过虚路由策略,在源节点与目的节点间建立了多条传输路通,每个节点能独立选取下一跳转发节点,并利用节点移动度,择优选取转发数据包下一跳节点,从而提高链路的稳定性。仿真结果表明,提出的路由协议在端到端传输时延、路由开销以及数据包传输率性能均得到提高。     

一种基于AODV的链路质量与能效优先的跨层路由协议

无线ad-hoc网络部署在非人为控制的外部环境中,采用电池供电.在这种应用环境中,如何通过合理的路由协议设计降低能量开销、提高网络的生存时间是近年来研究的热点.文章提出一种结合链路质量与能效的跨层路由协议.在路由建立阶段综合考虑链路质量、发送数据包的能耗和节点剩余能量来建立路由.通过在路由维护阶段对链路质量和节点剩余能量进行检测,预测路由中断的发生,并进行本地修复.通过在IEEE 802.15.4 Matlab模拟器下进行仿真,验证了该协议能够有效地提高网络的生存时间、数据投递率及AODV协议的性能和稳定性.     

移动Ad hoc网络基于链路质量和拓扑质量的路由协议

移动Ad hoc网络中节点的移动性使得频繁的路由失效与路由发现,路由发现中的控制开销是影响路由性能的一个重要的因素。传统的按需路由协议多采用洪泛的方式进行路由发现,并选取最小跳数路由。每个中间节点盲目的转发收到的路由请求包,不仅没有考虑链路质量,而且会引起广播风暴问题。本文提出一种基于链路质量和拓扑质量的路由协议,该协议根据相邻节点之间剩余链路生存期作为链路质量指标,同时根据中间节点与"源-目的"节点连线的距离关系作为拓扑质量指标。结合两个指标设置转发概率,不仅能避免频繁的路径断开,而且限制了路由请求包的传播范围。模拟结果显示,本文提出的方法在显著地降低路由控制开销的同时,还能够提高分组投递率并降低端到端延迟,从而提高了路由性能。     

Reliable routing mechanism based on neighbor stability for MANET

One critical issue for routing in mobile Ad-hoc networks (MANETs) is how to select a reliable path that can last longer because mobility may cause frequent breakdown in radio links. A novel routing mechanism based on link lifetime estimation is proposed in this article. In this mechanism, the node's received signal strength is obtained continuously by using Newton interpolation polynomial, and by method of middle value and interception, the reference points are selected to estimate the link lifetime. With the constraint of link lifetime and hop counts, the source nodes set up the route hop by hop. The simulations show that link lifetime can be predicted regardless of mobility pattern. Moreover, the route discovery times and packet drop ratio can be reduced by the proposed mechanism, and thus improving the performance of MANETs.     

移动Ad hoc网络中基于链路稳定性预测的按需路由协议

移动Ad hoc网络拓扑的高度动态变化是造成传统按需路由协议的路由频繁通断的主要原因,因此在传统按需路由协议的基础上进行链路稳定性预测扩展,增强路由稳定性具有十分重要的意义。该文利用分组的接收功率把节点间的相对运动划分为靠近和远离两种类型,然后在不同相对运动类型下根据节点间距离得到了的链路平均维持时间。在路由过程中,中间节点利用得到的链路平均维持时间设置请求报文的转发延迟,通过一定转发规则选择稳定性较强的链路构成路径。仿真结果表明进行链路稳定性预测扩展后的按需路由协议能够有效增强路由的稳定性,并提高网络性能。     

Ant-based routing and QoS-effective data collection for mobile wireless sensor network

Mobility management in mobile wireless sensor networks (MWSNs) is a complex problem that must be taken into account. In MWSN, nodes move in and out of the network randomly. Hence, a path formed between two distant nodes is highly susceptible to changes due to unpredictable node movement. Also, due to the limited resources in WSN, the paths used for data transmission must be tested for the link quality and time consumed for data forwarding. In order to solve these issues, in this paper, an ant-based routing protocol with QoS-effective data collection mechanism is proposed. In this protocol, the link quality and link delay are estimated for each pair of nodes. Link quality is estimated in terms of packet reception rate, received signal strength indicator, and link quality index. A reliable path is chosen from the source to the destination based on the paths traversed by forward ants and backward ants. Then, if the link is found to be defective during data transmission, a link reinforcement technique is used to deliver the data packet at the destination successfully. The mobile robots collect the information with high data utility. In addition, each mobile robot is equipped with multiple antennas, and space division multiple access technique is then applied for effective data collection from multiple mobile robots. Simulation results show that the proposed routing protocol provides reliability by reducing the packet drop and end-to-end delay when compared to the existing protocols.     

Moralism: mobility prediction with link stability based multicast routing protocol in MANETs

In recent research, link stability is getting tremendous attention in mobile adhoc networks (MANETs), because of several impediments that occur in a reliable and robust network. Link stability metric is used to improve network performance in terms of end-to-end delay, data success delivery ratio (DSDR) and available route time (ART). Energy consumption, bandwidth and communication delay of major concern in ad hoc networks. A high mobility of MANET nodes reduces the reliability of network communication. In a dynamic networks, high mobility of the nodes makes it very difficult to predict the dynamic routing topology and hence cause route/link failures. Multicast in MANETs is an emerging trend that effectively improves the performance while lowering the energy consumption and bandwidth usage. Multicast routing protocol transmits a packet to multicast a group at a given time instant to achieve a better utilization of resources. In this paper, node mobility is considered to map better their movement in the network. So, the links with long active duration time can be identified as a stable link for route construction. Variation in signal strength is used to identify whether the direction of the node is towards or away from estimating node. We consider signal strength as QoS metric to calculate link stability for route construction. Efforts are made to identify the link with highly probable longer lifetime as the best suitable link between two consecutive nodes. We predict the movement time of nodes that define the route path to the node destination. Exata/cyber simulator is used for network simulation. The simulation results of the proposed routing protocol are compared with on-demand multicast routing protocol and E-ODMRP, which works on minimum hop count path. Analysis of our simulation results has shown improvement of various routing performance metrics such as DSDR, ART, routing overhead and packet drop ratio.     

Signal strength based link sensing for mobile ad-hoc networks

Mobility causes frequent link failures in ad-hoc networks. This results in a severe degradation of performance specially in case of high mobility of nodes. This is because the routing protocols for ad-hoc networks are not equipped to handle high mobility. In this paper, we have presented a new link management algorithm to locally manage links. This new mechanism is based on signal strength measurements. Researchers over the years have presented approaches which use signal strength measurements but their focus has been on re-active protocols while our algorithm is aimed at pro-active protocols. Pro-active protocols are used since they provide greater flexibility to take advantage of the mesh configuration. We develop the hysteresis mechanism provided by OLSR, based on hello packets, to include signal strength measurements. The mechanism in OLSR uses Hello packets received/lost to decide to establish link or not. The problem with this approach arises when there is high mobility in which case the time to break the link and use a new path becomes significant. To overcome this, we propose to use signal strength to determine if the link-quality is improving or deteriorating. This combination of the two mechanisms, makes the link management more robust and also helps in anticipating link breakages thereby greatly improving performance.     

Link Stability-Based Clustering and Routing in Ad-Hoc Wireless Networks Using Fuzzy Set Theory

An ad-hoc wireless network has multihop architecture and is more mobile than single-hop network architecture in the real world. But the ad-hoc wireless network has some challenge with respect to mobility, real-time communication, routing path, maintenance, spatial reuse, bandwidth management, and packets broadcast overhead. This paper investigates two important issues to ensure more stable path routing and less re-clustering to improve the system performance. Novel Linked Stability-Based Clustering (LSC) and Linked Stability-Based Routing (LSR) algorithms, using fuzzy set theory, are proposed. The LSC algorithm guarantees the stability of the cluster to reduce the probability of re-clustering because the cluster-head is not easily replaced. The LSC algorithm proposed in this paper reduces the easy re-clustering problem of the HCC algorithm by considering not only connectivity but also the link's signal strength between the mobile nodes obtained from a fuzzy set in cluster-head determination. The membership function of the LSC algorithm, based on the link's signal strength, predicts a more stable link routing path using fuzzy set theory. Simulation results show that the proposed algorithm ensures the stability of the cluster and avoids unnecessary re-clustering; for example, the LSC algorithm occurs less frequently than LID and HC algorithms. Similarly, the LSR routing algorithm that uses fuzzy sets and membership functions is based on the mean signal strength and the relative movement between nodes, to obtain the lifetime of each connection and the path lifetime, from fuzzy inferences and fuzzy rules for reference. The LSR algorithm provides more reliable path lifetime and more stable transmission than the table-driven or on-demand approaches. Simulation results reveal that the path lifetime of the LSR algorithm is longer than that of DSR, with a lower probability of path drop and avoiding rerouting. The LSR algorithm has a higher mean number of hoppings, because it always finds the most suitable path and is more stable than DSR, without searching again for a new path when the paths drop.     

Research on routing protocol facing to signal conflicting in link quality guaranteed WSN

Wireless sensor networks (WSN), as a new type of environment monitoring system, has became a hot research topic in recent years. This paper mainly focuses on the problem of signal conflicting in WSN. The link quality (quality between two neighboring nodes) can be guaranteed by the layout of network, but, the end-to-end routing quality can not be guaranteed in the same way because of random signal conflicting (even if CSMA/CA is used in WSN). The end-to-end routing will have higher performance if the routing has lower signal conflicting probability. So, the main work of this paper is designing a routing protocol to find out the routing with the lowest signal conflicting probability. This paper proposed a Minimum conflicting probability routing protocol (MCR) in link quality guaranteed WSN. Firstly, MCR combines the degree value with workload of nodes, forming a new degree and cache based routing metric (DBM). Secondly, MCR finds out the best routing by the Random Walk theory on basis of DBM. The simulation results show that, MCR protocol is more effective to avoid the signal conflicting, it has a higher end-to-end reliability and a more stable network throughput than other routing protocols in the same link quality guaranteed WSN.

     

Variable Bit Rate Flow Routing in Wireless Sensor Networks

Since energy constraint is a fundamental issue for wireless sensor networks, network lifetime performance has become a key performance metric for such networks. In this paper, we consider a two-tier wireless sensor network and focus on the flow routing problem for the upper tier aggregation and forwarding nodes (AFNs). Specifically, we are interested in how to perform flow routing among the nodes when the bit rate from each source node is time-varying. We present an algorithm that can be used to construct a flow routing solution with the following properties: (1) If the average rate from each source node is known a priori, then flow routing solution obtained via such algorithm is optimal and offers provably maximum network lifetime performance; (2) If the average rate of each source node is unknown but is within a fraction (epsiv) of an estimated rate value, then network lifetime by the proposed flow routing solution is within 2epsiv/1-epsiv from the optimum. These results fill in an important gap in theoretical foundation for flow routing in energy-constrained sensor networks.     

Probabilistic routing protocol for a hybrid wireless underground sensor networks

A wireless underground sensor network (WUSN) is defined as a network of wireless sensor devices in which all sensor devices are deployed completely underground (network sinks or any devices specifically for relay between sensors and a sink may be aboveground). In hybrid wireless underground sensor network (HWUSN), communication between nodes is implemented from underground‐to‐air or air‐to‐underground, not underground‐to‐underground. This paper proposes a novel hybrid underground probabilistic routing protocol that provides an efficient means of communication for sensor nodes in HWUSN. In addition, signal propagation based on the shadowing model for underground medium is developed. The proposed routing protocol ensures high packet throughput, prolongs the lifetime of HWUSN and the random selection of the next hop with multi‐path forwarding contributes to built‐in security. Moreover, the proposed mechanism utilizes an optimal forwarding (OF) decision that takes into account of the link quality, and the remaining power of next hop sensor nodes. The performance of proposed routing protocol has been successfully studied and verified through the simulation and real test bed. Copyright © 2011 John Wiley & Sons, Ltd.     

基于交叉流网络编码的节能路由

节能路由是无线自组织网络的一个重要研究课题,对延长网络生存时间极为重要。在传统路由下,多对节点之间通信使用的多条数据传递路径会出现交叉存在公共节点,这些公共节点因需要转发来自多条交叉路径的数据包而比其它节点消耗更多的能量,从而过早因能量耗竭而失效。为了克服这一能耗不均衡问题,该文提出基于网络编码的节能路由NCBEER (Network Coding Based Energy Efficient Routing),它可捕捉多条路径交叉的机会,让公共节点对所转发的数据包进行编码,然后把编码数据包多播(Multicast)邻居节点,以减少公共节点转发数据包次数从而降低能耗;推导了编码节点使全部接收节点接收到编码数据包所需要的平均多播次数,定义了无线链路的传输代价,并将之作为信源将流量分配给不同路径的依据。仿真试验表明,NCBEER可降低和均衡节点的能耗,且能够延长网络生存时间。