共查询到20条相似文献,搜索用时 15 毫秒
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针对以太网存在节点时钟漂移、网络链路延迟、同步能力差等问题,文中基于RTEthernet协议的通信原理,构建了时钟同步系统的模型。文中研究了RTEthernet的组成、工作原理,考虑了影响实时以太网时钟同步精密度的三大因素:漂移率、网络传输延迟和时钟拜占庭故障,并基于此分析了原始的FTA时钟同步算法,发现它在拜占庭故障增多的情况下容错性能明显降低,进而引入“容错中值”的思想进行改进并提出了RTE-FTM算法。通过CANoe仿真平台,对系统(7个节点)中存在2个拜占庭故障与不存在拜占庭故障进行对比分析。结果表明系统的精密度损失率降低了3.1%,并由此验证了该算法的收敛性和有效性。 相似文献
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Aiming at the problem that the location distribution of cluster head nodes filtered by wireless sensor network clustering routing protocol was unbalanced and the data transmission path of forwarding nodes was unreasonable,which would increase the energy consumption of nodes and shorten the network life cycle,a clustering routing protocol based on improved particle swarm optimization algorithm was proposed.In the process of cluster head election,a new fitness function was established by defining the energy factor and position equalization factor of the node,the better candidate cluster head node was evaluated and selected,the position update speed of the candidate cluster head nodes was adjusted by the optimized update learning factor,the local search and speeded up the convergence of the global search was expanded.According to the distance between the forwarding node and the base station,the single-hop or multi-hop transmission mode was adopted,and a multi-hop method was designed based on the minimum spanning tree to select an optimal multi-hop path for the data transmission of the forwarding node.Simulation results show that the clustering routing protocol based on improved particle swarm optimization algorithm can elect cluster head nodes and forwarding nodes with more balanced energy and location,which shortened the communication distance of the network.The energy consumption of nodes is lower and more balanced,effectively extending the network life cycle. 相似文献
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Geetha D. Devanagavi N. Nalini Rajashekhar C. Biradar 《International Journal of Communication Systems》2016,29(1):170-193
Wireless sensor network (WSN) should be designed such that it is able to identify the faulty nodes, rectify the faults, identify compromised nodes from various security threats, and transmit the sensed data securely to the sink node under faulty conditions. In this paper, we propose an idea of integrating fault tolerance and secured routing mechanism in WSN named as fault tolerant secured routing: an integrated approach (FASRI) that establishes secured routes from source to sink node even under faulty node conditions. Faulty nodes are identified using battery power and interference models. Trustworthy nodes (non‐compromised) among fault‐free nodes are identified by using agent‐based trust model. Finally, the data are securely routed through fault‐free non‐compromised nodes to sink. Performance evaluation through simulation is carried out for packet delivery ratio, hit rate, computation overhead, communication overhead, compromised node detection ratio, end‐to‐end delay, memory overhead, and agent overhead. We compared simulation results of FASRI with three schemes, namely multi‐version multi‐path (MVMP), intrusion/fault tolerant routing protocol (IFRP) in WSN, and active node‐based fault tolerance using battery power and interference model (AFTBI) for various measures and found that there is a performance improvement in FASRI compared with MVMP, IFRP, and AFTBI. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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一种基于状态机的串口通信协议的设计与实现 总被引:2,自引:0,他引:2
为解决串口通信中的数据传输容易出错、可靠性差、安全性不高且容错能力低等问题,设计并实现了一种基于状态机的串口通信协议,并将此协议应用到称重仪表的上位机通信中。本文介绍了串口通信协议的数据包格式以及其通信状态机,并给出了协议实现的部分示例代码及算法流程图。在数据包格式定义中通过设置起始标志、数据长度、校验、结束标志等字段,保证数据传输的正确性;并在数据包接收过程中引入状态机方法,简化编程模型的同时,提高了通信过程的可靠性、安全性以及数据传输的容错能力。 相似文献
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加入无线中继节点构成多跳传输链路,可以实现较长距离的无线通信。本文在已有文献的基础上,重点研究救灾机器人和遥控终端间的选频建路协议,在链路各节点间按照选频通信的方式搭建传输链路;并在“全节点比例定时交替传输协议”基础上加入选频通信,设计选频传输协议,避免数据包间的相互碰撞。经仿真测试,设计的协议按照选频通信方式搭建了传输链路并实现了数据的无碰撞双向传输。 相似文献
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Performance Analysis of a Bandwidth Guaranteed Medium Access Control Protocol for WDM Local Networks
In this paper, we propose and analyze a bandwidth guaranteed medium access control protocol for broadcast-and-select WDM local networks with a star topology. The proposed protocol is based on a combination of contention and dedicated reservation mechanisms for time slotted WDM networks. Every node accesses the data channel by transmitting request packets in minislots on a separate control channel. There are two types of minislots; dedicated minislots and contention minislots. Nodes requiring bandwidth guarantees, called guaranteed nodes, use dedicated minislots that are assigned by the centralized control node. The remaining nodes, called random-access nodes, share contention minislots using a distributed random access mechanism. The dedicated minislots can guarantee a minimum bandwidth for the guaranteed nodes. The contention minislots enable on-demand services at the optical layer and achieve good fairness for the remaining bandwidth. Here, the data channels are dynamically assigned to the minislots successfully returned on a first-come-first-served (FCFS) basis. This protocol can combine the best of centralized and distributed access protocols such as simplicity, efficiency, and flexibility. We analyze the maximum throughput and verify the results by simulation. 相似文献
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To reduce excessive computing and communication loads of traditional fault detection methods, a neighbor-data analysis based node fault detection method is proposed. First, historical data is analyzed to confirm the confidence level of sensor nodes. Then a nodes reading data is compared with neighbor nodes which are of good confidence level. Decision can be made whether this node is a failure or not. Simulation shows this method has good effect on fault detection accuracy and transient fault tolerance, and never transfers communication and computing overloading to sensor nodes. 相似文献
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摘要:针对车辆自组织网络(vehicular Ad Hoc network,VANET)中紧急消息的传输,提出一个改进的二元分割广播(MBPAB)协议。协议将通信范围迭代划分成小的区域,寻找离发送节点最远区域内的车辆,对紧急消息执行转发,通过减少转发跳数,提高消息传播速度。通过引入MAC(medium access control)子层的微型分布式帧间间隔(mini-DIFS),赋予对紧急消息以更高的优先级接入通信信道。仿真结果表明,在VANET 中, MBPAB协议与现有的广播协议相比,在通信时延和消息传播速度方面有更好的性能表现。 相似文献
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A group-based network architecture provides many benefits for the whole network increasing the content availability, providing
fault tolerance and giving more scalability. Many grid architectures have been developed since the first proto-grid systems
in the early 70’s, but no one of them is based on groups. This paper proposes a group-based grid architecture using an efficient
neighbor node selection. The architecture organizes logical connections between nodes from different groups of nodes allowing
sharing resources, data or computing time between groups. Connections are used to find and share available resources from
other groups and they are established based on node’s available capacity. Suitable nodes have higher roles in the architecture
and their function is to organize connections based on a node selection process. Nodes’ logical connections topology changes
depending on some dynamic parameters. The architecture is scalable and fault-tolerant. The designed protocol, its management
and real measurements are shown. It could be used as an intergrid protocol. 相似文献
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超低功耗粮仓无线实时监测系统设计 总被引:2,自引:1,他引:1
针对在粮库温度智能监测领域,采用电线电缆传输数据的不便以及目前无线传感网络节点寿命短的问题,利用MSP430超低功耗单片机设计了超低功耗无线温度监测系统。基于超低功耗设计了系统的整体框架以及各模块硬件,其中包括节点、温度传感器模块、无线通信模块、通信协议、桌面实时显示程序,通信协议解决了多个节点同时介入时的碰撞问题并设计了节能算法。最后对整个系统的可靠性以及节点的使用寿命进行了实验验证,经过试验的检验本系统具有超低功耗的特点,基本满足超低功耗粮仓无线实时监测系统的设计需求。 相似文献
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Gurewitz O. de Baynast A. Knightly E.W. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(10):3596-3614
In this paper, a low-complexity cooperative protocol that significantly increases the average throughput of multihop upstream transmissions for wireless tree networks is developed and analyzed. A system in which transmissions are assigned to nodes in a collision free, spatial time division fashion is considered. The suggested protocol exploits the broadcast nature of wireless networks where the communication channel is shared between multiple adjacent nodes within interference range. For any upstream end-to-end flow in the tree, each intermediate node receives information from both one-hop and two-hop neighbors and transmits only sufficient information such that the next upstream one-hop neighbor will be able to decode the packet. This approach can be viewed as the generalization of the classical three node relay channel for end-to-end flows in which each intermediate node becomes successively source, relay and destination. The achievable rate for any regular tree network is derived and an optimal schedule that realizes this rate in most cases is proposed. Our protocol is shown to dramatically outperform the conventional scheme where intermediate nodes simply forward the packets hop by hop. At high signal-to-noise ratio (SNR), it yields approximately 66% throughput gain for practical scenarios. 相似文献
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针对传统AODV路由协议在路由发现过程中采用洪泛机制会带来很大的通信开销这一问题,提出了一种基于路径深度的AODV路由协议,减少了参与路由发现过程的节点数,以减少通信开销。在节点转发路由请求时,引入一个时间延时,最大可能地选择最短路径实现通信。实验结果表明:改进的协议有效地减少了能量消耗,减少通信冲突。 相似文献
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In order to improve the organizing performance and fault tolerance of the wireless network protocol GEAR based on the geographical location information in the Internet of things and achieve better energy distribution and conservation effects. This paper proposes a new multipath routing organizing protocol (SMG, Self-organized Multipath GEAR) based on the basic geographic routing protocol GEAR. By two-step organizing, communication empty nodes and communication hole can join the network respectively and energy spreading out and mechanism of dormancy of the multi-path are utilized to spread out and save energy. Meanwhile, this paper presents an approximate estimation algorithm to estimate the number of the nodes in the monitoring region with a certain size and regular shape. The critical path node goes to failure in different times while received packet rate is monitored using the experiment of NS2 simulation and actual hardware. The experiment results show that the improved protocol increases the fault tolerance of the network, reduces the paralysis rate of the network and achieves the effect of energy spreading out and saving, increases the lifetime of the network through a multi-path strategy. 相似文献
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在无线传感器网络中,信息的传输需要保证通信双方的节点是本次通信的节点,而不是网络中的其他节点或者一些恶意节点,这就需要对通信双方的身份进行身份鉴别。提出了一种基于共享密钥的节点鉴别机制,实现了网内节点间在通信前确认彼此身份的合法性和有效性。分析表明,该方案有效抵御了传感器网络中一些常见的安全威胁,例如女巫攻击等。同时,该方案还具有很强的攻击容忍性。 相似文献