The traveling miser problem

Various monitoring and performance evaluation tools generate considerable amount of low priority traffic. This information is not always needed in real time and often can be delayed by the network without hurting functionality. This paper proposes a new framework to handle this low priority, but resource consuming traffic in such a way that it incurs a minimal interference with the higher priority traffic. Consequently, this improves the network goodput. The key idea is allowing the network nodes to delay data by locally storing it. This can be done, for example, in the Active Network paradigm. In this paper we show that such a model can improve the network's goodput dramatically even if a very simple scheduling algorithm for intermediate parking is used. The parking imposes additional load on the intermediate nodes. To obtain minimal cost schedules we define an optimization problem called the traveling miser problem. We concentrate on the on-line version of the problem for a predefined route, and develop a number of enhanced scheduling strategies. We study their characteristics under different assumptions on the environment through a rigorous simulation study. We prove that if only one link can be congested, then our scheduling algorithm is O(log/sub 2/B) competitive, where B is congestion time, and is 3-competitive, if additional signaling is allowed.     

Hardware-Software Implementation of a Sensor Network for City Traffic Monitoring Using the FPGA- and ASIC-Based Sensor Nodes

This paper presents a prototype sensor network for monitoring urban traffic. The sensor network node, equipped with a low-resolution camera, observes the street and detects moving objects. Object detection is based on the custom video segmentation algorithm, using dual background subtraction, edge detection and shadow detection, running on dedicated multi-processor SoC hardware. The number and the speed of the detected objects are transmitted using a low-power license-free radio transceiver to another neighboring node. All the nodes create a self-organized network, data are aggregated at the nodes and passed further to the nodes closer to data sinks. Finally, information about the traffic flow is collected from the sinks and visualized on a PC. The prototype sensor network node has been realized in two versions: FPGA and ASIC. The ASIC version consumes approximately 500 mW and it can be powered from a photovoltaic solar panel combined with a single cell Li-Po battery. The comparison of power consumption of both versions has also been made. Apart from collecting traffic data, the proposed sensor network can gather environmental data, such as the temperature, the acoustic noise or the intensity of the sunlight. The set of 26 prototype sensors has been mounted on street lamp-poles on streets and tested in real conditions.     

Set pair three-way overlapping community discovery algorithm for weighted social internet of things

There are many problems in Social Internet of Things(IoTs), such as complex topology information, different degree of association between nodes and overlapping communities. The idea of set pair information grain computing and clustering is introduced to solve the above problems so as to accurately describe the similarity between nodes and fully explore the multi-community structure. A Set Pair Three-Way Overlapping Community Discovery Algorithm for Weighted Social Internet of Things (WSIoT-SPTOCD) is proposed. In the local network structure, which fully considers the topological information between nodes, the set pair connection degree is used to analyze the identity, difference and reverse of neighbor nodes. The similarity degree of different neighbor nodes is defined from network edge weight and node degree, and the similarity measurement method of set pair between nodes based on the local information structure is proposed. According to the number of nodes' neighbors and the connection degree of adjacent edges, the clustering intensity of nodes is defined, and an improved algorithm for initial value selection of k-means is proposed. The nodes are allocated according to the set pair similarity between nodes and different communities. Three-way community structures composed of a positive domain, boundary domain and negative domain are generated iteratively. Next, the overlapping node set is generated according to the calculation results of community node membership. Finally, experiments are carried out on artificial networks and real networks. The results show that WSIoT-SPTOCD performs well in terms of standardized mutual information, overlapping community modularity and F1.     

无线传感网络坏点识别研究与应用

无线传感器网络中各传感器节点通过自组织的方式构成,协作地实时监测、感知和采集各种环境或监测对象的信息,一旦某个节点损坏或者被窃取,那么将可能影响整个网络并在网络中传递错误信息。该文针对区域监控网络中单跳网络损坏节点的检测问题,以图论分析为基础,采用特别的网络模型对无线传感网络加以描述,以基站产生虚拟报警机制和特殊报警源求因算法来定位损坏节点,以网络覆盖性能和损坏节点检测率作为算法性能评估标准。实验结果表明:基于二分图的损坏节点识别算法能很好地检测并剔除损坏节点,从而保证无线传感器网络正常工作。     

一种基于跨层设计和蚁群优化的自组网负载均衡路由协议

针对大部分现有替代路径共同存在的替代路径老化和构建效率问题,本文提出了一种基于跨层设计和蚁群优化的负载均衡路由协议(CALRA),利用蚁群优化算法特有的信息素挥发方法实现对替代路径的老化问题,将蚁群优化和跨层优化方法结合起来解决自组网中的负载均衡问题,通过双向逐跳更新的方式较好的解决了替代路径构建效率问题,并将蚂蚁在所经过的各中间节点为路由表带来的信息素增量映射为蚂蚁离开源节点的距离、移动过程中所遇到的节点拥塞程度、节点当前信息素浓度和节点移动速度等各协议层的统计信息的函数,通过对各种信息所对应的参数赋予不同加权值的方法对概率路由表进行控制,改善了自组网中现有基于蚁群优化的路由协议中普遍存在的拥塞问题、捷径问题、收敛速度问题和引入的路由开销问题.仿真表明,CALRA在分组成功递交率、路由开销、端到端平均时延等方面具有优良性能,能很好地实现网络中的业务负载均衡.     

基于ZigBee的环境检测系统设计

环境检测系统主要由传感检测网络、网关、服务器以及终端应用组成。传感检测网络基于ZigBee协议,EB分布于各个待检测区域的环境检测节点组成。传感器节点分为父节点和子节点,上电后父节点建立的网络,子节点加入网络。经测试,子节点可向父节点周期性地上传环境数据。用户通过手机或平板电脑接入移动网络随时掌握被测网络的环境信息。     

Unveiling the underlying relationships over a network for monitoring purposes

Nowadays traffic monitoring and analysis tools provide poor information about traffic volume without giving any clear view of what the hidden rules and relationships that govern these flows are. Since the majority of flows is generated by services (web browsing, email, p2p) and most of these applications are dependent on many network assets (servers and databases) we should discover the underlying relationships of every application. We present a technique that discovers the hidden relationships among components of a network that consist of parts of specific applications. From time information and flow attributes, such as IP addresses and service ports, our method using a novel hybrid genetic algorithm produces a small set of fuzzy rules that can reveal the underlying relationships over a network without any guidance. These dependencies build a service graph which can become a useful tool for fault localization, monitoring service performance, designing changes and anomaly detection. Copyright © 2009 John Wiley & Sons, Ltd.     

考虑排队时延的系统保护通信网络路由选择算法

目前满足系统保护通信网络的路由算法是在综合时延和可靠性的要求下,计算一条快速且可靠传输的路径,而没有考虑到当电网发生故障或网络中通信量过大时,通信网络中许多节点的排队时延会极大地增加,忽略排队时延对路径传输总时延的影响会导致路径的错误选择,从而影响系统保护的实时性。针对此问题,提出了一种考虑排队时延的路由选择算法,用于计算信息传输总时延最小的最优路径,以提高系统保护通信的实时性。实验结果表明,通过本文提出的路由选择算法计算得到的路径在满足系统保护可靠性要求的基础上信息传输总时延最小。     

基于邮件路径地理属性分析的垃圾邮件过滤算法

提出一种基于邮件路径地理属性分析的邮件过滤算法GEPA（geographic E—mail path analysis）。首先提取邮件命令报文包含的路由信息，并以此为基础构建邮件路径子集；其次采用一种高效的地理属性映射方法进行地理信息映射；接着对路径中节点的地理逻辑关系背离情况进行分析用于过滤垃圾邮件；最后从中国大陆某骨干网边界路由器的一条链路上（该链路跨越地理边界）采集邮件流量以验证算法性能。研究表明，GEPA识别的垃圾邮件约占邮件总量的13．9％，且算法在执行速度和内存开销等方面具有较好的性能，能够满足实时邮件过滤的需求。     

Bayonet-corpus: a trajectory prediction method based on bayonet context and bidirectional GRU

Predicting travel trajectory of vehicles can not only provide personalized services to users, but also have a certain effect on traffic guidance and traffic control. In this paper, we build a Bayonet-Corpus based on the context of traffic intersections, and use it to model a traffic network. Besides, Bidirectional Gated Recurrent Unit (Bi-GRU) is used to predict the sequence of traffic intersections in one single trajectory. Firstly, considering that real traffic networks are usually complex and disorder and cannot reflect the higher dimensional relationship among traffic intersections, this paper proposes a new traffic network modeling algorithm based on the context of traffic intersections: inspired by the probabilistic language model, a Bayonet-Corpus is constructed from traffic intersections in real trajectory sequence, so the high-dimensional similarity between corpus nodes can be used to measure the semantic relation of real traffic intersections. This algorithm maps vehicle trajectory nodes into a high-dimensional space vector, blocking complex structure of real traffic network and reconstructing the traffic network space. Then, the bayonets sequence in real traffic network is mapped into a matrix. Considering the trajectories sequence is bidirectional, and Bi-GRU can handle information from forward and backward simultaneously, we use Bi-GRU to bidirectionally model the trajectory matrix for the purpose of prediction.     

Throughput Evaluation of a Novel Scheme to Mitigate the Congestion over WSNs

In recent years, due to fast development of wireless sensor networks (WSNs), the numbers of nodes are increasing, and their scope of applications is continuously expanding, including environmental monitoring, military and smart home applications. The power supply, memory and computing power of wireless sensor nodes are greatly hampered in WSNs so that the WSNs are classified as a task-oriented framework. This study focused on exploring problems caused by traffic congestion on the WSNs with a large amount of flow, such as packet loss, bandwidth reduction, and waste of energy on the sensor nodes. On the other hand, a cooperative strong node mechanism is presented and named as Cooperative Strong Node Mechanism, in which a threshold is set to determine whether the node traffic is over or not. When the load exceeds, the privilege of corresponding sensor nodes is upgraded so that it can command its child nodes to change the transmission path to distribute the traffic effectively. Furthermore, when the traffic exceeds preset overall network flow, new sensor nodes are added in the network to relieve the traffic. This novel proposed mechanism can not only increase network throughput and effectively prevent the occurrence from congestion problems, but is suitable for a variety of routing protocols.     

大型IP网络时延的主成分分析

网络时延是评估网络性能的关键指标之一。主成分分析(PCA)是数据挖掘领域常用的一种多变量分析和降维算法。通过对大型IP网络时延进行PCA分析,旨在挖掘网络时延的深层原因及网络各节点间的相互依赖关系,并搭建一个科学合理的网络时延评价体系,最终得到IP网络建设、优化改造的有效建议。对历史网络时延进行离线分析只是主成分分析方法的一种初步应用,今后可结合网络拓扑结构、现网流量流向、路由、距离等相关因素,将主成分分析方法应用到针对网络流量、网络时延、网络丢包等网络性能的实时在线监测分析中,进一步提升网络运营的效率和质量。     

一种改进的基于连通支配集的P2P搜索算法

为了避免由洪泛搜索方法引起的大量网络流量问题．基于连通支配集的广播算法BCDS通过减少转发节点来减少查询消息数。文章对BCDS算法进行改进，选择转发节点时考虑节点间的距离．简化选择转发节点的操作，且不用维持局部两跳拓扑信息。实验结果表明当搜索结果相同时，改进的BCDS算法的消息数量平均仅为洪泛搜索方法的35％。     

DNS‐Class: immediate classification of IP flows using DNS

Nowadays we see a tremendous growth of the Internet, especially in terms of the amont of data being transmitted and new network protocols being introduced. This poses a challenge for network administrators, who need adequate tools for network management. Recent findings show that DNS can contribute valuable information on IP flows and improve traffic visibility in a computer network. In this paper, we apply these findings on DNS to propose a novel traffic classification algorithm with interesting features. We experimentally show that the information carried in domain names and port numbers is sufficient for immediate classification of a highly significant portion of the traffic. We present DNS‐Class: an innovative, fast and reliable flow‐based traffic classification algorithm, which on average yields 99.8% of true positives and < 0.1% of false positives on real traffic traces. The algorithm can work as a major element of a modular system in a cascade architecture. Additionally, we provide an analysis on how various network protocols depend on DNS in terms of flows, packets and bytes. We release the complete source code implementing the presented system as open source. Copyright © 2014 John Wiley & Sons, Ltd.     

Some principles for designing a wide-area WDM optical network

We explore design principles for next-generation optical wide-area networks, employing wavelength-division multiplexing (WDM) and targeted to nationwide coverage. This optical network exploits wavelength multiplexers and optical switches in routing nodes, so that an arbitrary virtual topology may be embedded on a given physical fiber network. The virtual topology, which is used as a packet-switched network and which consists of a set of all-optical “lightpaths”, is set up to exploit the relative strengths of both optics and electronics-viz. packets of information are carried by the virtual topology “as far as possible” in the optical domain, but packet forwarding from lightpath to lightpath is performed via electronic switching, whenever required. We formulate the virtual topology design problem as an optimization problem with one of two possible objective functions: (1) for a given traffic matrix, minimize the network-wide average packet delay (corresponding to a solution for present traffic demands), or (2) maximize the scale factor by which the traffic matrix can be scaled up (to provide the maximum capacity upgrade for future traffic demands). Since simpler versions of this problem have been shown to be NP-hard, we resort to heuristic approaches. Specifically, we employ an iterative approach which combines “simulated annealing” (to search for a good virtual topology) and “flow deviation” (to optimally route the traffic-and possibly bifurcate its components-on the virtual topology). We do not consider the number of available wavelengths to be a constraint, i.e., we ignore the routing of lightpaths and wavelength assignment for these lightpaths. We illustrate our approaches by employing experimental traffic statistics collected from NSFNET     

面向混合业务的无线传感器网络能量有效接入策略

研究了在实时业务和非实时业务同时存在的混合背景下,非实时业务的无线传感器节点自适应侦听和睡眠的动态接入机制。网络节点处于睡眠状态时所需的能量很低,节约了无线传感器网络节点的平均能量消耗;但是,过长的睡眠时间可能使得网络节点错失传输机会。因此,根据信道的使用情况,合理地设定无线传感器网络节点的睡眠时间,能够在网络能量消耗和传输效率之间进行调整,从而最大化无线传感器网络的能量传输效率。首先,利用连续时间 Markov 方法对问题进行建模,并利用基于摄动分析理论对系统模型进行分析,获得求解无线传感器网络能量效率最大化的最优睡眠时间梯度算法。最后通过理论结果和计算机仿真模拟的对比,验证了推荐方法的可行性。     

Design and deployment of a smart system for data gathering in aquaculture tanks using wireless sensor networks

The design of monitoring systems for marine areas has increased in the last years. One of the many advantages of wireless sensor networks is the quick process in data acquisition. The information from sensors can be processed, stored, and transmitted using protocols efficiently designed to energy saving and establishing the fastest routes. The processing and storing of data can be very useful for taking intelligent decisions for improving the water quality. The monitoring of water exchange in aquaculture tanks is very important to monitor the fish welfare. Thus, this paper presents the design, deployment, and test of a smart data gathering system for monitoring several parameters in aquaculture tanks using a wireless sensor network. The system based on a server is able to request and collect data from several nodes and store them in a database. This information can be postprocessed to take efficient decisions. The paper also presents the design of a conductivity sensor and a level sensor. These sensors are installed in several aquaculture tanks. The system was implemented using Flyport modules. Finally, the data gathering system was tested in terms of consumed bandwidth and the delay Transmission Control Protocol (TCP) packets delivering data from the sensors.     

基于3G网络的智能交通视频监控系统

设计了一款基于3G网络的智能交通视频监控系统,包括前端视频采集部分、3G无线网络传输部分和后端监控管理服务平台三个部分。系统对实时路况车辆进行视频采集、经过无线传输,最终在PC终端界面上进行实时播放、存储,并实现了车辆违规判断、报警等功能。本系统有轻巧便捷、安装简易、运营成本低等优势,具有广阔的应用前景,是智能交通监控系统的新型发展模式。     

A scalable monitoring approach based on aggregation and refinement

Network monitoring is an integral part of any network management system. In order to ensure end-to-end service quality stated in service level agreements (SLAs), managers of a service provider network need to gather quality-of-service (QoS) measurements from multiple nodes in the network. For a large network with over thousands of flows with end-to-end SLAs, the information exchanged between network nodes and a central network management system (NMS) could be substantial. We propose a mechanism called aggregation and refinement based monitoring (ARM) to reduce the amount of information exchange. ARM is a generic mechanism that can be configured to run with different objectives, including threshold-based, rank-based and percentile-based. The mechanism enables the NMS to collect data from network nodes using a dynamic QoS data aggregation/refinement technique, and to process these information differently depending on its measurement objective. Our simulation results show that for these various objectives, the selective refinement process is able to validate SLAs quickly, is an order of magnitude more efficient than a simple polling scheme, and performs well across a wide range of traffic loads     

Maximum lifetime routing in wireless sensor networks

A routing problem in static wireless ad hoc networks is considered as it arises in a rapidly deployed, sensor based, monitoring system known as the wireless sensor network. Information obtained by the monitoring nodes needs to be routed to a set of designated gateway nodes. In these networks, every node is capable of sensing, data processing, and communication, and operates on its limited amount of battery energy consumed mostly in transmission and reception at its radio transceiver. If we assume that the transmitter power level can be adjusted to use the minimum energy required to reach the intended next hop receiver then the energy consumption rate per unit information transmission depends on the choice of the next hop node, i.e., the routing decision. We formulate the routing problem as a linear programming problem, where the objective is to maximize the network lifetime, which is equivalent to the time until the network partition due to battery outage. Two different models are considered for the information-generation processes. One assumes constant rates and the other assumes an arbitrary process. A shortest cost path routing algorithm is proposed which uses link costs that reflect both the communication energy consumption rates and the residual energy levels at the two end nodes. The algorithm is amenable to distributed implementation. Simulation results with both information-generation process models show that the proposed algorithm can achieve network lifetime that is very close to the optimal network lifetime obtained by solving the linear programming problem.