无线传感器网络中基于链路质量的路径延时分析

基于链路质量给出了路径满足实时性概率的上界,并证明了计算其上界的时间复杂度为指数级。另外在考虑链路质量的基础上,提出了一种在给定的延迟阈值下最大化端到端数据分组发送成功概率的贪心算法(RROP)。根据给定的延迟阈值和链路质量,RROP算法通过设置每跳链路的最大重传次数来优化端到端数据分组发送成功的概率。证明该算法能够在多项式时间内找到最优解并且通过该最优解获得路径满足实时性概率的一个近似最优的下界。实验结果表明给出的路径延迟分析上界和下界是准确的,并且提出的RROP算法在节省能量和满足实时性上比传统的方法能够获得高出10%以上的性能。     

具有传输成功率保证的概率路由算法的TTL预测模型

概率路由算法是机会网络中一种常用的路由算法,其TTL的设置将直接影响路由的性能.本文首先利用马尔可夫链对概率路由的转发过程进行建模,并从消息的传输成功率和传输延时方面进行性能评估,不仅可以计算出一个消息从源节点到目的节点所需的传输延时,还可以预测出在给定传输成功率下所需要的最短消息生存周期TTL,这对于TTL的设置具有理论上的指导作用.其次,本文建立的预测模型还可以使一些无法到达目的节点的消息及时被删除,从而减少不必要的转发,达到节约网络资源的目的.最后,在两个真实数据集中的实验结果表明,本文提出的模型能够为概率路由中TTL值的准确设置提供有效参考.     

车联网中基于动态传输距离的多跳稳定路由

数据传输是车联网(VANETs)实现交通安全的基础。然而,车辆的移动、信号传输的衰减以及彼此间的干扰对链路的可靠性均有影响。为此,提出基于动态传输距离的多跳稳定(DTMS)路由。DTMS路由在选择下一跳转发节点时,考虑到因衰减而导致的传输距离的变小,先估计车辆动态传输距离,再依据动态传输距离估计链路的连通时间以及距离因素,然后,计算邻居节点的权重,最后,基于节点权重值设置定时器,进而竞争产生下一跳转发节点。仿真结果表明,提出的DTMS路由有效地提高了数据包传输成功率。     

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。     

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。     

水下传感网络中基于链路质量和位置的协作路由

水下传感网络是开发水域环境的有效技术手段。但在水下环境传输数据,信号衰减快,通信链路质量差,降低了数据包传递率。提出基于链路质量和位置的协作(LQLC)路由。LQLC路由引用协作路由思想,利用链路质量和节点能量信息,构建候选转发节点集;再从候选转发节点集中选择具有最优链路质量的节点作为转发节点;最后在候选转发节点集中选择离转发节点最近的节点作为协作节点。仿真结果表明,提出的LQLC路由提高了数据包传递率。     

移动自组织网络环境中负载均衡策略研究

针对移动自组织网络中负载分布不均所导致的网络性能恶化问题,提出了一种基于分组转发行为不确定度量的网络负载计算方法,并以此为基础提出了负载均衡按需路由协议,通过监测分组转发过程中的行为变化特征,采用信息熵的形式对其进行量化和度量,并在路由发现过程中利用节点负载监测信息合理规避网络热点区域,以达到网络负载均衡分布的目的。仿真结果表明,基于负载均衡策略的路由协议能够有效提高分组递交成功率,降低分组传输延迟。     

支持多速率传输的动态Ad hoc路由协议

该文提出了一种支持动态多速率传输的无线Ad hoc网络路由方案,它能够增加网络的吞吐量和减少分组的传输时延。该方案把路由功能分为两个部分:广域路由功能和本地路由功能。本地路由功能是一个独立的子层,负责在广域路由功能选择的中继节点之间适当地增加新转发节点,使最终路由中的每段链路都能使用高速率进行传输,从而减小数据发送过程中总的信道占用时间。该文设计了一种LDSR协议来执行本地路由功能。仿真结果显示了新的路由方案能够有效地利用网络节点的多速率传输能力,获得更好的网络性能。     

一种新的基于部分网络编码的机会路由机制

网络编码能够提升无线网络传输性能,网络中的节点若采用传统的全网络编码,必须等待所有的数据包到达后才能进行解码,而这将造成网络的延迟。通过将部分网络编码和机会路由相结合,提出了一种新的路由协议(ORoPNC),该协议可以降低网络编码延迟,提高网络的稳定性。同时,设计了一种新的转发策略——ETXoEC。在这一策略下,转发节点的选取决定于当前链路状态和节点的剩余能量。仿真结果表明,网络的延迟降低了25%左右,能量消耗也得到了较好的平衡,整个网络的稳定性得到进一步提高。     

基于链路可用性预测的AODV路由协议研究

传统的AODV路由协议无法适应Ad hoc网络拓扑的高度动态变化.对AODV路由算法进行链路可用性预测扩展,节点通过接收分组的能量值和链路连续可用时间选择最可靠的路径进行路由,并在链路真正失效之前启动预先修复过程.仿真结果表明,改进后的AODV协议提高了分组的投递率,降低了分组端到端平均传输延时,路由协议的可靠性得到改进.     

无线传感器网络中基于最优转发集的协作式编码传输协议

针对当前大多数据传输协议没有充分利用无线信道的广播特性这一问题,本文提出了基于网络编码的机会路由协议NCOR（Network Coding based Opportunistic Routing protocol）.首先,通过分析网络端到端传输代价,本文提出了最优转发集构造机制以最小化传输代价.此后,NCOR在转发集内执行节点协作式编码传输以保证传输可靠性.最后,理论分析了NCOR的传输可靠性结论.仿真实验表明NCOR可适用于不同的链路环境,且在保证可靠传输的同时,大幅降低了网络能耗.     

A novel real-time scheme for (m,k)-firm streams in wireless sensor networks

The multimedia transmission based real-time applications have posed a big challenge to wireless sensor networks (WSNs) where both reliability and timeliness need to be guaranteed at the same time, to support an acceptable Quality of Service (QoS). The existing real-time routing protocols, however, are not able to meet the QoS requirements of realtime applications because of the inherent resource constraint of sensor nodes and instability of wireless communication. Therefore, we propose a real-time scheme in this paper, including a QoS-aware routing protocol and a set of fault recovery mechanisms, for (m,k)-firm based real-time applications over WSNs. A local status indicator which is specially devised for (m,k)-firm stream, is used for intermediate nodes to monitor and evaluate their local conditions. The proposed routing protocol takes into account of packet deadline, node condition and remaining energy of next hop, to make optimal forwarding decision. Additionally, according to the stream QoS and node condition, the proposed fault recovery mechanisms are utilized for nodes to handle the congestion, link failure and void problems occurred during transmission and remain the desired reliability and timeliness requirements. The proposed scheme has been well studied and verified through simulations. The results have proved the efficiency of the proposed scheme in terms of high successful transmission ratio, small end-to-end delay and long lifetime of network.     

DFR: an efficient directional flooding‐based routing protocol in underwater sensor networks

Unlike terrestrial sensor networks, underwater sensor networks (UWSNs) have salient features such as a long propagation delay, narrow bandwidth, and high packet loss over links. Hence, path setup‐based routing protocols proposed for terrestrial sensor networks are not applicable because a large latency of the path establishment is observed, and packet delivery is not reliable in UWSNs. Even though routing protocols such as VBF (vector based forwarding) and HHVBF (hop‐by‐hop VBF) were introduced for UWSNs, their performance in terms of reliability deteriorates at high packet loss. In this paper, we therefore propose a directional flooding‐based routing protocol, called DFR, in order to achieve reliable packet delivery. DFR performs a so‐called controlled flooding, where DFR changes the number of nodes which participate in forwarding a packet according to their link quality. When a forwarding node has poor link quality to its neighbor nodes geographically advancing toward the sink, DFR allows more nodes to participate in forwarding the packet. Otherwise, a few nodes are enough to forward the packet reliably. In addition, we identify two types of void problems which can occur during the controlled flooding and introduce their corresponding solutions. Our simulation study using ns‐2 simulator proves that DFR is more suitable for UWSNs, especially when links are prone to packet loss. Copyright © 2011 John Wiley & Sons, Ltd.     

基于eNSP的LACP聚合仿真设计与实现

在企业网络中,数据在转发的过程中,容易发生阻塞,链路聚合可以降低阻塞发生的可能性,提高链路带宽,提高数据传输的可靠性,使用三层链路连接设备,还可以节省IP地址,因此,文章设计了三个实验使学习者全方位掌握LACP聚合协议,理解其工作原理。     

水声传感器网络数据可靠传输协议IPool-ADELIN的研究

ADELIN(ADaptive rELIable transport protocol)协议利用冗余传输节点来增强了水声传感器网络数据传输的可靠性,下游节点实际上已经接到冗余节点转发的绝大多数数据包.本文提出了基于IPool(Improved Pool)节点的IPool-ADELIN协议.通过监听节点的数据传输,IPo...     

An efficient MAC protocol with cooperative retransmission in mobile ad hoc networks

In emerging wireless networks, cooperative retransmission is employed to replace packet retransmission between a pair of sender and receiver with poor channel condition. A cooperative MAC protocol which utilizes such benefit is proposed in this paper to improve the network performance in mobile ad hoc networks. In the proposed protocol, relay nodes between sender and receiver are used if the sender cannot communicate with the receiver reliably. Furthermore, the receiver may also stop forwarding the received data frame if the frame is received by the next‐hop receiver on the route to the final destination node. Simulation results show that the proposed protocol outperforms previous works in terms of increased transmission reliability and reduced delay time. Copyright © 2010 John Wiley & Sons, Ltd.     

车载自组织网中基于车辆密度的可靠性路由协议

为了降低转发节点在转发范围内直接寻找一个最优或次优节点的复杂度、减少平均跳数和提高链路的可靠性,提出一种车载自组织网络中基于车辆密度的可靠性路由协议,转发节点首先根据道路车辆密度设置最优块的大小,并将转发范围分割成若干大小相等的块,然后选择其中一个距离转发节点最远的块,最后在被选中的块里根据可靠性原则选择连接时间最长的邻居节点作为中继节点进行转发。仿真结果表明,与EG-RAODV 相比,所提路由协议的平均跳数较少,平均每跳前进距离较大,能够使数据分组快速到达目的节点。     

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.