Configuring wide area computer networks

Summary Modern computer networks consist of wide area backbone networks which serve as major highways to transfer large volumes of communication traffic between access points, and local access networks which feed traffic between the backbone network and end user nodes. The topological design of wide area computer communication networks consists of selecting a set of locations for network control processors (NCPs) placement, deciding on backbone links and their capacities to connect the NCPs, linking end user nodes to the NCPs and selecting routes for routing messages between communicating end user pairs. This paper presents some of the problems faced by network designers starting from the capacity assignment problem, moving to routing and capacity assignment, followed by the topological design and capacity assignment problem; the last problem presented is the topological design and capacity expansion over time. The problems are complex combinatorial optimization problems, which require developing new solution procedures. The paper presents the problems and discusses models and solution procedures. The paper concludes with a discussion and directions for further research.This research was partially supported by a Dean's grant for faculty research at the Owen Graduate School of Management, Vanderbilt University, Nashville, TN 37203, USA.     

Lifetime improvement in wireless sensor networks via collaborative beamforming and cooperative transmission

Collaborative beamforming (CB) and cooperative transmission (CT) have recently emerged as communication techniques that can make effective use of collaborative/cooperative nodes to create a virtual multiple-input/multiple-output system. Extending the lifetime of networks composed of battery-operated nodes is a key issue in the design and operation of wireless sensor networks. The effects on network lifetime of allowing closely located nodes to use CB/CT to reduce the load or even to avoid packet-forwarding requests to nodes that have critical battery life are considered. First, the effectiveness of CB/CT in improving the signal strength at a faraway destination using energy in nearby nodes is studied. Then, the performance improvement obtained by this technique is analysed for a special 2D disc case. Further, for general networks in which information-generation rates are fixed, a new routing problem is formulated as a linear- programming problem, whereas for other general networks, the cost for routing is dynamically adjusted according to the amount of energy remaining and the effectiveness of CB/CT. From the analysis and the simulation results, it is seen that the proposed method can reduce the payloads of energy-depleting nodes by about 90% in the special case network considered and improve the lifetimes of general networks by about 10%, compared with existing techniques.     

水下网络移动节点分布式定位算法

随着水下网络系统的发展,水下移动节点的分布式定位技术的研究受到关注。提出了一种自组织、可容忍节点失效与测距误差、计算量和通信开销小的分布式水下节点定位算法,该算法利用自适应加权、循环三角组合测量法提高定位精度。对基于TOA测距的循环三角组合算法的定位精度进行了仿真,分析参考节点数对平均定位误差的影响,并与三边测量法的定位精度进行了比较。仿真结果表明,该算法具有较高的定位精度,对节点失效和测距误差的鲁棒性高,并且降低了水下网络对参考节点的密度要求。     

Benefit distribution mechanism in the team members’ scientific research collaboration network

Scientific research collaboration networks are well-established research topics, which can be divided into two kinds of research paradigms: (1) The topological features of the whole scientific collaboration networks and the collaboration representations in some given fields. (2) The individual nodes’ characteristics in the collaboration networks and their endorsements in the networks. However, in the above studies, all the nodes’ roles in the scientific collaboration network are the same, all of whom are called collaborators, thus the relationships among all the nodes in the scientific collaboration network are symmetric, and the scientific collaboration network is undirected. Such symmetric roles and relationships in the undirected networks have no incentive effects on the members’ participations and efforts in the team’s scientific research. In this paper, the roles of team members in the scientific research collaborations are defined, including the scientific research pioneers and contributors, their collaboration relationships are considered from the viewpoint of principal-agent theory, and then the directed scientific collaboration network is built. Then the benefit distribution mechanism in the team members’ networked scientific research collaborations is presented, which will encourage the team members with different roles to make their efforts in their scientific research collaborations and improve the quality of scientific research outputs. An example is used to test the above ideas and conclude that the individual member’s real outputs not only lie in his/her real scientific research efforts, but also rest with his/her contributions to other members’ scientific research.     

Medium access control layer management for saving energy in wireless sensor networks routing algorithms

Wireless sensor networks (WSNs) consist of small nodes that are capable of sensing, computing, and communication. One of the greatest challenges in WSNs is the limitation of energy resources in nodes. This limitation applies to all of the protocols and algorithms that are used in these networks. Routing protocols in these networks should be designed considering this limitation. Many papers have been published examining low energy consumption networks. One of the techniques that has been used in this context is cross-layering. In this technique, to reduce the energy consumption, layers are not independent but they are related to each other and exchange information with each other. In this paper, a cross-layer design is presented to reduce the energy consumption in WSNs. In this design, the communication between the network layer and medium access layer has been established to help the control of efforts to access the line to reduce the number of failed attempts. In order to evaluate our proposed design, we used the NS2 software for simulation. Then, we compared our method with a cross-layer design based on an Ad-hoc On-demand Distance Vector routing algorithm. Simulation results show that our proposed idea reduces energy consumption and it also improves the packet delivery ratio and decreases the end-to-end delay in WSNs.     

Architectural design of a sensory node controller for optimized energy utilization in sensor networks

The increasing complexity of manufacturing machines and the continued demand for high productivity have led to growing applications of sensor networks to enable more reliable, timely, and comprehensive information gathering from the machines being monitored. An effective and efficient utilization of sensor networks requires new sensor designs that enable adaptive event-driven information gathering based on the condition of the machines, as well as a coordinated information distribution adjusted to the available communication bandwidth of the network. This paper investigates several fundamental aspects regarding the architectural design of a sensory node controller (SNOC). The SNOC is the key element in a large-scale sensor network that coordinates the operation of individual sensors and the communication among various sensing clusters to realize distributed intelligent sensing. A parametric SNOC design that dynamically adjusts the power supply and the data-acquisition procedure to reduce the overall energy consumption of the sensor network is presented. Considerations on both the hardware and software aspects of the design to achieve energy efficiency are described, and analytical formulations are derived. Simulation results for a sensor network consisting of 40 SNOCs, each coordinating eight physical sensors, have shown that the design is able to reduce the energy consumption by about 43%, as compared to traditional techniques. A prototype SNOC was designed and implemented, based on the platform of a commercially available microcontroller, and experimentally tested for its ability to dynamically adjust the power consumption. The study has provided a concrete input to the design optimization and experimental realization of an SNOC-based sensor network for machine-system monitoring.     

Reliability and fault-tolerance in multistage interconnection networks

Reliability and fault-tolerance issues are important in the study of interconnection networks used in large multiprocessor systems because of the large number of components involved. In this paper we study these issues with respect to multistage networks which are typically built forN inputs andN outputs using 2 × 2 switching elements and log₂ N stages. In such networks, the failure of a switching element or connecting link destroys the communication capability between one or more pair(s) of source and destination terminals. Many techniques exist for designing multistage networks that tolerate switch and/or link failures without losing connectivity. Several approaches for achieving fault-tolerance in multistage interconnection networks are described in this paper. The techniques vary from providing redundant components in the network to making multiple passes through the faulty network. Quantitative measures are introduced for analysis of the reliability of these networks in terms of the component reliabilities. Several examples are given to illustrate the techniques. This research is supported by thensf Presidential Young Investigator Award No.dci-8452003, a grant from AT&T Information Systems, and a grant fromtrw.     

Sensor network algorithms and applications

A sensor network is a collection of nodes with processing, communication and sensing capabilities deployed in an area of interest to perform a monitoring task. There has now been about a decade of very active research in the area of sensor networks, with significant accomplishments made in terms of both designing novel algorithms and building exciting new sensing applications. This Theme Issue provides a broad sampling of the central challenges and the contributions that have been made towards addressing these challenges in the field, and illustrates the pervasive and central role of sensor networks in monitoring human activities and the environment.     

An Asynchronous Clustering and Mobile Data Gathering Schema Based on Timer Mechanism in Wireless Sensor Networks

Recently, Wireless sensor networks (WSNs) have become very popular research topics which are applied to many applications. They provide pervasive computing services and techniques in various potential applications for the Internet of Things (IoT). An Asynchronous Clustering and Mobile Data Gathering based on Timer Mechanism (ACMDGTM) algorithm is proposed which would mitigate the problem of “hot spots” among sensors to enhance the lifetime of networks. The clustering process takes sensors’ location and residual energy into consideration to elect suitable cluster heads. Furthermore, one mobile sink node is employed to access cluster heads in accordance with the data overflow time and moving time from cluster heads to itself. Related experimental results display that the presented method can avoid long distance communicate between sensor nodes. Furthermore, this algorithm reduces energy consumption effectively and improves package delivery rate.     

Automatic Classification of Acoustic Emission Patterns

Abstract: The problem of automatic classification of acoustic emission signals using techniques derived from pattern recognition is addressed in this paper. The data were taken from laboratory experimental work on a box girder of a bridge in which the acoustic emission (AE) generation mechanism and location were monitored. Two statistical methods and a neural network procedure have been used to classify the data into groups representing different AE generation mechanisms. The classifiers are constructed using the traditional AE features – four parameters from each burst. Principal component analysis is used to reduce the dimension of the AE data feature vectors to two dimensions, resulting in simple visualisations of the data.     

An Energy-Efficient Wireless Power Transmission-Based Forest Fire Detection System

Compared with the traditional techniques of forest fires detection, wireless sensor network (WSN) is a very promising green technology in detecting efficiently the wildfires. However, the power constraint of sensor nodes is one of the main design limitations of WSNs, which leads to limited operation time of nodes and late fire detection. In the past years, wireless power transfer (WPT) technology has been known as a proper solution to prolong the operation time of sensor nodes. In WPT-based mechanisms, wireless mobile chargers (WMC) are utilized to recharge the batteries of sensor nodes wirelessly. Likewise, the energy of WMC is provided using energy-harvesting or energy-scavenging techniques with employing huge, and expensive devices. However, the high price of energy-harvesting devices hinders the use of this technology in large and dense networks, as such networks require multiple WMCs to improve the quality of service to the sensor nodes. To solve this problem, multiple power banks can be employed instead of utilizing WMCs. Furthermore, the long waiting time of critical sensor nodes located outside the charging range of the energy transmitters is another limitation of the previous works. However, the sensor nodes are equipped with radio frequency (RF) technology, which allows them to exchange energy wirelessly. Consequently, critical sensor nodes located outside the charging range of the WMC can easily receive energy from neighboring nodes. Therefore, in this paper, an energy-efficient and cost-effective wireless power transmission (ECWPT) scheme is presented to improve the network lifetime and performance in forest fire detection-based systems. Simulation results exhibit that ECWPT scheme achieves improved network performance in terms of computational time (12.6%); network throughput (60.7%); data delivery ratio (20.9%); and network overhead (35%) as compared to previous related schemes. In conclusion, the proposed scheme significantly improves network energy efficiency for WSN.     

Molecular communication and networking: opportunities and challenges

The ability of engineered biological nanomachines to communicate with biological systems at the molecular level is anticipated to enable future applications such as monitoring the condition of a human body, regenerating biological tissues and organs, and interfacing artificial devices with neural systems. From the viewpoint of communication theory and engineering, molecular communication is proposed as a new paradigm for engineered biological nanomachines to communicate with the natural biological nanomachines which form a biological system. Distinct from the current telecommunication paradigm, molecular communication uses molecules as the carriers of information; sender biological nanomachines encode information on molecules and release the molecules in the environment, the molecules then propagate in the environment to receiver biological nanomachines, and the receiver biological nanomachines biochemically react with the molecules to decode information. Current molecular communication research is limited to small-scale networks of several biological nanomachines. Key challenges to bridge the gap between current research and practical applications include developing robust and scalable techniques to create a functional network from a large number of biological nanomachines. Developing networking mechanisms and communication protocols is anticipated to introduce new avenues into integrating engineered and natural biological nanomachines into a single networked system. In this paper, we present the state-of-the-art in the area of molecular communication by discussing its architecture, features, applications, design, engineering, and physical modeling. We then discuss challenges and opportunities in developing networking mechanisms and communication protocols to create a network from a large number of bio-nanomachines for future applications.     

Control chart pattern recognition using back propagation artificial neural networks

In this paper, control chart pattern recognition using artificial neural networks is presented. An important motivation of this research is the growing interest in intelligent manufacturing systems, specifically in the area of Statistical Process Control (SPC). Online automated process analysis is an important area of research since it allows the interfacing of process control with Computer Integrated Manufacturing (CIM) techniques. Two back-propagation artificial neural networks are used to model traditional Shewhart SPC charts and identify out-of-control situations as specified by the Western Electric Statistical Quality Control Handbook , including instability patterns, trends, cycles, mixtures and systematic variation. Using back propagation, patterns are presented to the network, and training results in a suitable model for the process. The implication of this research is that out-of-control situations can be detected automatically and corrected within a closed-loop environment. This research is the first step in an automated process monitoring and control system based on control chart methods. Results indicate that the performance of the back propagation neural networks is very accurate in identifying control chart patterns.     

Communication Reliability Analysis of Wireless Sensor Networks Using Phased‐Mission Model

Communication reliability of wireless sensor networks (WSNs) is essential to ensure the correct and reliable operation of the network. Two distinct communication paradigms exist in WSNs: infrastructure communication and application communication, and a practical communication task typically involves both types of communications. To the best of our knowledge, no reliability studies on WSNs have been dedicated to combining the two communication paradigms. In this paper, we advance the state‐of‐the‐art by proposing a phased‐mission framework to analyze the communication reliability of WSNs considering both infrastructure communication and application communication, as well as K‐coverage requirements. WSNs containing two types of sensor nodes (energy harvesting sensor nodes and battery‐powered sensor nodes) are modeled. Corresponding to the two types of sensor nodes, two different link reliability models are first presented. Binary decision diagram (BDD) based algorithms are then developed for the phased‐mission communication reliability analysis of WSNs. Case studies are given to illustrate the application of the proposed algorithms. Copyright © 2016 John Wiley & Sons, Ltd.     

EAMTR: energy aware multi-tree routing for wireless sensor networks

IEEE 802.15.4 is the prevailing standard for low-rate wireless personal area networks. It specifies the physical layer and medium access control sub-layer. Some emerging standards such as ZigBee define the network layer on top of these lower levels to support routing and multi-hop communication. Tree routing is a favourable basis for ZigBee routing because of its simplicity and limited use of resources. However, in data collection systems that are based on spanning trees rooted at a sink node, non-optimal route selection, congestion and uneven distribution of traffic in tree routing can adversely contribute to network performance and lifetime. The imbalance in workload can result in hotspot problems and early energy depletion of specific nodes that are normally the crucial routers of the network. The authors propose a novel light-weight routing protocol, energy aware multi-tree routing (EAMTR) protocol, to balance the workload of data gathering and alleviate the hotspot and single points of failure problems for high-density sink-type networks. In this scheme, multiple trees are formed in the initialisation phase and according to network traffic, each node selects the least congested route to the root node. The results of simulation and performance evaluation of EAMTR show significant improvement in network lifetime and traffic distribution.     

基于DSP的智能家居无线网络节点的设计

 将无线传感器网络技术融入智能家居系统中,设计合理的网络节点成为智能家居系统的核心问题．在分析无线传感器网络节点结构基础上,提出以DSP 芯片TMS320F206为处理器、AT86RF230为无线通信芯片的无线传感器网络节点．充分考虑节能和扩展性的需求,采用节点定时打开与关闭的协议且打开与关闭的时间比为1∶99．试验表明该无线网络节点能满足低功耗、长传输距离、准确定位、抗干扰的要求．     

Quantum Artificial Intelligence Based Node Localization Technique for Wireless Networks

Artificial intelligence (AI) techniques have received significant attention among research communities in the field of networking, image processing, natural language processing, robotics, etc. At the same time, a major problem in wireless sensor networks (WSN) is node localization, which aims to identify the exact position of the sensor nodes (SN) using the known position of several anchor nodes. WSN comprises a massive number of SNs and records the position of the nodes, which becomes a tedious process. Besides, the SNs might be subjected to node mobility and the position alters with time. So, a precise node localization (NL) manner is required for determining the location of the SNs. In this view, this paper presents a new quantum bird migration optimizer-based NL (QBMA-NL) technique for WSN. The goal of the QBMA-NL approach is for determining the position of unknown nodes in the network by the use of anchor nodes. The QBMA-NL technique is mainly based on the mating behavior of bird species at the time of mating season. In addition, an objective function is derived based on the received signal strength indicator (RSSI) and Euclidean distance from the known to unknown SNs. For demonstrating the improved performance of the QBMA-NL technique, a wide range of simulations take place and the results reported the supreme performance over the recent NL techniques.     

Energy-efficient directional routing between partitioned actors in wireless sensor and actor networks

Actor?actor communication is an important part of the functioning of wireless sensor?actor networks and enables the actor nodes to take coordinated action on a given event. Owing to various reasons such as actor mobility and low actor density, the actor network tends to get partitioned. The authors propose to use the underlying sensor nodes, which are more densely deployed, to heal these partitions. In order to maximise the utilisation of the limited energy available with the sensor nodes, a new routing protocol for actor?actor communication using directional antennas on the actor nodes is proposed. The authors contribution is threefold. First, using simulations they show that the problem of partitioning in the actor networks is significant and propose an architecture with directional antennas on actor nodes and sensor bridges to heal these partitions. Second, they identify the routing problem for this architecture based on a theoretical framework and propose centralised as well as distributed solutions to it. Third, they develop a routing protocol based on the distributed solution and show, using network simulations, that the proposed protocol not only heals the network partitions successfully, but also achieves high throughput and fairness across different flows, in addition to maximising the network lifetime.     

基于贪心遗传的地下物流节点选择规划研究

以国内某地区物流概况为研究背景,结合国内外地下物流系统研究成果,将集合覆盖的思想引入地下物流网络节点选址规划,建立以物流节点数量最少及物流节点转运率最低为优化目标的双层多目标规划模型,并结合贪心算法和遗传算法进行优化求解。研究表明：通过将集合覆盖的思想对城市地下物流系统节点规划进行初步探讨是可行有效的;基于贪心遗传算法进行优化求解,使得该地区地下物流网络节点选择达到全局最优,有效控制了物流节点的数量及节点转运率的大小;地下物流网络节点表现出明显的区域集中性,即服务节点均集中在物流需求点附近,且二级节点服务区域总是邻近某个一级节点。     

Efficient solutions to various routing issues involved in mobile ad hoc bio-sensor networks: applying appropriate motion trajectories

Ad hoc bio-sensor networks have a very characteristic structure with three types of nodes: the command centre, the sensor nodes (animals such as rats) and the relaying nodes. We have taken up such networks and measured the throughput of such systems and suggest ways in which the throughput can be increased. It was also found that to increase the throughput of such systems, no sophisticated routing techniques or expensive transmission techniques are needed. This can be achieved by simply adopting the appropriate motion trajectories of the nodes. We have also explained the structure of these networks in detail and the routing issues involved in these networks. A Hot-Spot problem at the command centre has also been discussed. The suggestions of appropriate motions target this problem and show how an even distribution of nodes can alleviate this problem to a large extent. In addition to this, a constraint on the number of messages the sensor node can send per unit time can also make the network more efficient.