Deterministic broadcasting in ad hoc radio networks

We consider the problem of distributed deterministic broadcasting in radio networks of unknown topology and size. The network is synchronous. If a node u can be reached from two nodes which send messages in the same round, none of the messages is received by u. Such messages block each other and node u either hears the noise of interference of messages, enabling it to detect a collision, or does not hear anything at all, depending on the model. We assume that nodes know neither the topology nor the size of the network, nor even their immediate neighborhood. The initial knowledge of every node is limited to its own label. Such networks are called ad hoc multi-hop networks. We study the time of deterministic broadcasting under this scenario. For the model without collision detection, we develop a linear-time broadcasting algorithm for symmetric graphs, which is optimal, and an algorithm for arbitrary n-node graphs, working in time . Next we show that broadcasting with acknowledgement is not possible in this model at all. For the model with collision detection, we develop efficient algorithms for broadcasting and for acknowledged broadcasting in strongly connected graphs. Received: January 2000 / Accepted: June 2001     

Tracking a moving object via a sensor network with a partial information broadcasting scheme

Tracking a moving object is one of the key applications of wireless sensor networks (WSNs) for facility management, logistics, healthcare, etc. The quantitative relationship between tracking accuracy and resource consumption is crucial for designing a WSN-based tracking system. A partial information broadcasting scheme (PIBS) is developed as a decentralized tracking strategy in this paper, where only a part of the nodes broadcast their tracking estimation results to their neighbors. The relationship between tracking accuracy and resource consumption is quantified with this scheme. Two broadcasting policies are proposed by balancing the residual energy among sensors and reducing time delay, where the “Randomly Broadcast” (RB) policy takes energy consumption as a first priority and the “Good Estimates Broadcast First” (GEBF) policy consider time delay first. Both of them can be implemented as a decentralized tracking strategy. It is shown that the PIBS with RB or PIBS with GEBF can reduce required resources with minor degradation in tracking accuracy in comparison with the centralized tracking strategy. The finite sensing range of a sensor node is considered and a node activation scheme with variable activation radius is introduced for energy saving. The activation radius is adjusted to guarantee tracking coverage with trade-off between tracking accuracy and resource consumption. The analytical conditions on tracking coverage and the bounds on tracking accuracy are obtained. The numerical experiments demonstrate that this activation scheme outperforms the existing schemes.     

Deterministic network exploration by a single agent with Byzantine tokens

A mobile agent has to explore an unknown network with unlabeled nodes: it must visit all nodes by walking along the links of the network, and eventually stop. If no upper bound on the size of the network is known and nodes of the network cannot be marked, then this exploration task cannot be accomplished for arbitrary networks by a deterministic terminating algorithm. On the other hand, it is feasible, if there is one unmovable token at the starting node of the agent. We investigate the exploration problem in arbitrary networks in the presence of identical unmovable tokens, some of which are Byzantine. A Byzantine token can be visible or invisible to the agent whenever the latter visits the node where the token is located, and visibility is decided by the adversary at each visit of the agent. If no upper bound on the number of tokens is known to the agent, deterministic exploration of all networks is impossible, even if all tokens are fault free. It is also impossible if all tokens are Byzantine, even if their number is known. Our main result is a deterministic exploration algorithm with cost polynomial in the (unknown) size of the network, which works in arbitrary networks, provided that the agent knows some upper bound on the total number of tokens, and that at least one token is fault free.     

一种新型的无线广播网复用技术分析

介绍了一种新型的、适用于中国移动多媒体广播网的复用技术,对其中涉及的关键点给予了详细分析.新型的广播复用技术引入了模式适配、逻辑管道映射、包分组管理、统计复用、时频资源调度的概念,对有效提高无线资源利用率、提升多媒体业务传输的质量和数量均有明显作用.     

广电网络中云计算技术的应用分析简

随着我国现代化经济的不断发展,我国的信息网络技术也在产生着日新月异的变化,与此同时对我国的信息网络的要求也在不断提高,尤其是对我国的广电网络的要求。目前,我国的广电网络中出现了一种新型的云计算技术,它不仅提高了广电网络的发展水平,而且还对世界上很多发达国家产生深远的影响。同时,在人们的日常生活中产生了许多的“云”系类的技术产品。提高了人们的生活水平,促进了我国广电网络事业的发展。     

基于广播SNMP的网络管理并行轮询算法*

面对网络融合环境下网络规模大、分布广、设备多的实际需求,传统网络管理系统通过依次轮询设备进行数据采集存在轮询周期长、实时性低、轮询数据量多等缺点,提出了一种基于广播SNMP的数据采集并行轮询算法。该算法在轮询时,通过向每个网段发送广播SNMP数据包的方式并行轮询被管设备,减少轮询数据包的数量,减轻管理站的负担,缩短轮询周期;在接收设备回复数据包时,针对接收和处理速度不匹配的情况,采用多线程自适应并行处理环形缓存的方法,达到高速数据接收的目的。系统测试结果表明,通过广播方式的轮询可以有效缩短轮询周期,减少轮     

SDN在广电网中的应用与优化

在信息技术日渐成熟的今天,业务带宽成为提高用户体验的首要因素,不断改进升级,促进广电网络信息化、智能化并保证网络安全、稳定成为广电运营商必不可少的一项工作。将SDN(Software Defined Network)网络架构运用于广电网,可以减少对原有网络服务器的压力,更加方便网络管理人员对网络进行管理。针对现有广电网络模型,提出了将SDN设备接入在网络边缘,再将所有边缘业务逐渐迁移到SDN业务体系中,待业务完善后将SDN部署到核心业务中,并对改进模型进行了实际应用的模拟实验。实验结果表明,SDN通过不断地更新软件策略,对DDoS的威胁采取屏蔽、丢弃数据包等方式,及时发现威胁,定期清洗流量等实现了软件定义安全。     

基于网络编码的确定性逐层构造算法

为了解决适用于多源组播通信的网络编码构造算法存在收敛时间较长的问题,提出一种基于网络编码的确定线性逐层构造算法。在已有研究基础上,利用虚拟信源点进行虚拟试播：首先,根据决策树算法逐层确定获得非满秩局部编码矩阵的节点;然后,重构与该节点对应的上层变换节点的局部编码系数,生成新的编码向量;最后,重传这些编码向量至对应节点,使该节点的局部编码矩阵满秩,从而得到可行的编码方案。在试播过程中允许对出现数据冗余的链路进行修剪枝,以提高带宽利用率。与基于信宿反馈的确定网络编码（SNFDNC）算法相比,该算法只需进行一次虚拟试播。仿真测试结果表明该算法在中等规模网络中收敛时间更短,能进一步提高多源组播通信的平均传输速率。     

Deterministic fuzzy time series model for forecasting enrollments

The fuzzy time series has recently received increasing attention because of its capability of dealing with vague and incomplete data. There have been a variety of models developed to either improve forecasting accuracy or reduce computation overhead. However, the issues of controlling uncertainty in forecasting, effectively partitioning intervals, and consistently achieving forecasting accuracy with different interval lengths have been rarely investigated. This paper proposes a novel deterministic forecasting model to manage these crucial issues. In addition, an important parameter, the maximum length of subsequence in a fuzzy time series resulting in a certain state, is deterministically quantified. Experimental results using the University of Alabama’s enrollment data demonstrate that the proposed forecasting model outperforms the existing models in terms of accuracy, robustness, and reliability. Moreover, the forecasting model adheres to the consistency principle that a shorter interval length leads to more accurate results.     

时间触发光纤通道调度算法确定性分析

光纤通道以其优良性能,成为下一代航电系统的必然选择。但是基于事件触发的消息调度形式限制了对航电系统性能的分析,为提高消息在网络中传输时间确定性,在时间触发协议的基础上,针对光纤通道提出一种时间触发的消息调度算法。通过对交换式网络建模,采用理论和仿真相结合的方法,对先来先服务调度策略和时间触发调度策略进行分析,结果表明时间触发调度算法可以很好地提高网络消息传输的确定性,满足航电系统安全关键消息的传输要求。     

基于网络编码的多节点无线广播重传策略研究

重传是无线网络广播实现错误处理的重要技术。将网络编码理论和无线网络重传技术的结合推广到了多个节点的情况,研究了多个节点情况下基于网络编码的重传组合策略,并运用该策略编码组合多个信息包发送,一次组合包重传操作可以实现原有策略多次操作的目的。模拟测试结果表明：与原有策略相比,该策略可以有效地减少信息包的传输次数,并且具备一定的可行性和有效性。     

一种改进的井下无线传感器网络广播算法

针对现有的井下无线传感器网络广播算法能耗较高的问题,提出了一种改进的无线传感器网络前向广播算法。该算法中,转发节点可根据自身位置,选择优先节点转发信息,大大减少了无线传感器网络中需要转发的冗余信息量,从而降低了网络能耗。仿真结果表明,该算法在网络节点密度达到一定值时,满足网络接收率要求,且能够限制转发的信息总量,有效降低了无线传感器网络能耗。     

The minimum bandwidth required at each time slot of the fast broadcasting scheme

In this paper, we show that the Fast broadcasting scheme (L.-S. Juhn and L.-M. Tseng, 1998 [4]), abbreviated the FBR scheme, is also suitable for heterogeneous clients of different communication capabilities although it is originally designed for homogeneous clients of the same bandwidth. Given α channels of total bandwidth α⋅b Mbps to deliver a video of the consumption rate b Mbps, we first show that the FBR scheme can be employed to serve clients with communication capabilities ranging from b to α⋅b Mbps. Furthermore, we propose a simple way to determine the minimum bandwidth required at any given time slot.     

Distributed topology control algorithm on broadcasting in wireless sensor network

Topology control can enhance energy efficiency and prolong network lifetime for wireless sensor networks. Several studies that attempted to solve the topology control problem focused only on topology construction or maintenance. This work designs a novel distributed and reliable energy-efficient topology control (RETC) algorithm for topology construction and maintenance in real application environments. Particularly, many intermittent links and accidents may result in packet loss. A reliable topology can ensure connectivity and energy efficiency, prolonging network lifetime. Thus, in the topology construction phase, a reliable topology is generated to increase network reachable probability. In the topology maintenance phase, this work applies a novel dynamic topology maintenance scheme to balance energy consumption using a multi-level energy threshold. This topology maintenance scheme can trigger the topology construction algorithm to build a new network topology with high reachable probability when needed. Experimental results demonstrate the superiority of the RETC algorithm in terms of average energy consumption and network lifetime.     

基于动态膜计算系统的自组织网络广播算法

应用仿生学原理设计了一种新型的广播算法——基于动态膜计算系统的广播算法,提出了动态膜计算系统,并给出了解决自组织网络中广播问题的规则集。系统中节点转播信息的优先权通过节点间距离及邻居个数确定,适合不同密度的网络;并根据信息数与门限值的比较,取消部分节点的转播权,从而提高了可达率和转播节省率。仿真测试验证了此系统用于广播是可行的、高效的,为设计无线自组织网络中的广播算法提供了新思路。     

小波神经网络模型的确定性预测及应用

针对神经网络模型预测结果的随机性,构建了一种紧致性小波神经网络工具箱。该方法将小波函数移植到BP网络隐层,并采用一种随机确定状态命令获得确定的预测结果。与编程实现的小波神经网络和BP网络比较,该方法适合于大批量数据训练,对数据样本的适应能力和鲁棒性强,尤其对高频随机时间序列有更好的适应能力,具有预测结果确定及实用性强等特点,可显著提高模型的训练速度、预测精度和预测效率。基于小波包变换和小波神经网络的瓦斯涌出量预测实验证明了所提方法的有效性。     

蜂窝广播网络中基于连接优先级控制的多播应用

多播中,网络节点在耗费代价很小的情况下发送和接收数据包,这种通讯的优势使多播在各种类型的网络应用中迅速增长,本文介绍了一种无线广播网络中的多播应用,其根据连接优先级控制网络通讯,通讯链路上的参数SIR决定连接优先级,在确定连接优先级的情况下,网络应尽可能多的提供符合SIR要求的连接,以提高通讯的效率。