引入移动节点的无线传感器网络

文章围绕引入移动节点可以节省无线传感器网络的能量消耗这一主题,对引入了移动节点的无线传感器网络的数据收集方式进行了一个全面合理的分类,并且结合相关文献对每类数据收集方式展开深入讨论,系统全面地论述了该主题的研究现状、存在的问题以及面临的挑战。     

Mobility Management for Hierarchical Wireless Networks

In this paper, we consider the mobility management in large, hierarchically organized multihop wireless networks. The examples of such networks range from battlefield networks, emergency disaster relief and law enforcement etc. We present a novel network addressing architecture to accommodate mobility using a Home Agent concept akin to mobile IP. We distinguish between the physical routing hierarchy (dictated by geographical relationships between nodes) and logical hierarchy of subnets in which the members move as a group (e.g., company, brigade, battalion in the battlefield). The performance of the mobility management scheme is investigated through simulation.     

Handling Mobility in Wireless Sensor and Actor Networks

In Wireless Sensor and Actor Networks (WSANs), the collaborative operation of sensors enables the distributed sensing of a physical phenomenon, while actors collect and process sensor data and perform appropriate actions. WSANs can be thought of as a distributed control system that needs to timely react to sensor information with an effective action. In this paper, coordination and communication problems in WSANs with mobile actors are studied. First, a new location management scheme is proposed to handle the mobility of actors with minimal energy expenditure for the sensors, based on a hybrid strategy that includes location updating and location prediction. Actors broadcast location updates limiting their scope based on Voronoi diagrams, while sensors predict the movement of actors based on Kalman filtering of previously received updates. The location management scheme enables efficient geographical routing, and based on this, an optimal energy-aware forwarding rule is derived for sensor-actor communication. Consequently, algorithms are proposed that allow controlling the delay of the data-delivery process based on power control, and deal with network congestion by forcing multiple actors to be recipients for traffic generated in the event area. Finally, a model is proposed to optimally assign tasks to actors and control their motion in a coordinated way to accomplish the tasks based on the characteristics of the events. Performance evaluation shows the effectiveness of the proposed solution.     

Exploiting Mobility for Efficient Coverage in Sparse Wireless Sensor Networks

Reliable monitoring of a large area with a Wireless Sensor Network (WSN) typically requires a very large number of stationary nodes, implying a prohibitive cost and excessive (radio) interference. Our objective is to develop an efficient system that will employ a smaller number of stationary nodes that will collaborate with a small set of mobile nodes in order to improve the area coverage. The main strength of this collaborative architecture stems from the ability of the mobile sensors to sample areas not covered (monitored) by stationary sensors. An important element of the proposed system is the ability of each mobile node to autonomously decide its path based on local information (i.e. a combination of self collected measurements and information gathered by stationary sensors in the mobile’s communication range), which is essential in the context of large, distributed WSNs. The contribution of the paper is the development of a simple distributed algorithm that allows mobile nodes to autonomously navigate through the field and improve the area coverage. We present simulation results based on a real sparse stationary WSN deployment for the coverage improvement scenario.     

Terminal-Controlled Mobility Management in Heterogeneous Wireless Networks

The coexistence of multiple access technologies deployed by different operators is fundamental for future fourth-generation mobile networks. In spite of this heterogeneity, seamless interoperator/intersystem mobility is a mandatory requirement. In this article we present a seamless mobility management approach that does not require changes to existing network infrastructure. The novelty of the proposed approach is that mobility management is fully controlled by the terminal, and network selection is user-centric, power-saving, cost-aware, and performance-aware. Total mobility management, including interface management, handover decision, and execution, is also detailed     

Exploiting Reactive Mobility for Collaborative Target Detection in Wireless Sensor Networks

Recent years have witnessed the deployments of wireless sensor networks in a class of mission-critical applications such as object detection and tracking. These applications often impose stringent Quality-of-Service requirements including high detection probability, low false alarm rate, and bounded detection delay. Although a dense all-static network may initially meet these Quality-of-Service requirements, it does not adapt to unpredictable dynamics in network conditions (e.g., coverage holes caused by death of nodes) or physical environments (e.g., changed spatial distribution of events). This paper exploits reactive mobility to improve the target detection performance of wireless sensor networks. In our approach, mobile sensors collaborate with static sensors and move reactively to achieve the required detection performance. Specifically, mobile sensors initially remain stationary and are directed to move toward a possible target only when a detection consensus is reached by a group of sensors. The accuracy of final detection result is then improved as the measurements of mobile sensors have higher Signal-to-Noise Ratios after the movement. We develop a sensor movement scheduling algorithm that achieves near-optimal system detection performance under a given detection delay bound. The effectiveness of our approach is validated by extensive simulations using the real data traces collected by 23 sensor nodes.     

Sensing Coverage for Wireless Sensor Networks in Shadowed Rician Fading Environments

Wireless Personal Communications - The effect of shadowing and multipath fading on sensing coverage has been studied in this paper. Rician fading is one of the most widely occurring type of...     

UMTS全IP无线网络的移动性管理

文章讨论了3GPP UMTS全IP无线网络中的两种运行模式:传输模式和本机模式,3个不同层次移动性支持:接入移动性、宽域移动性和微移动性.对基于路由和基于隧道两种移动性管理协议进行了比较,并介绍了基于多协议标志交换(MPLS)的分级移动性管理方案,该方案利用标志边界移动性代理的增强MPLS路由器,使网络具有灵活性、可升级性和无隙缝移动性.     

Policy Based Mobility &; Flow Management for IPv6 Heterogeneous Wireless Networks

We propose a dynamic mobility management framework for Internet Protocol version 6 (IPv6) and policy enforcement enabled heterogenous wireless networks. Policies and policy rules are defined depending on network infrastructure facilities, service agreements and negotiation results. Each traffic is coupled with an identifiable traffic flow while the heterogenous interface flow bindings are regulated by polices. The network selection, flow distribution, handovers and mobility procedures are flexible and we propose to improve the decision making via Multiple Attributes Decision Making (MADM). Techniques considered in the framework include the IPv6 based Network Mobility (NEMO), multihoming capability, transparent vertical handovers, horizontal handovers and dynamic policy enforcement matching process to improve the Quality of Service (QoS), Quality of Experience (QoE) and ubiquitous connectivity. A experiment testbed and simulation models have been constructed to verify the mobility framework performance in a heterogeneous WiFi, WiMax and UMTS hybrid environment.     

Distributed Mobility Management for Target Tracking in Mobile Sensor Networks

Mobility management is a major challenge in mobile ad hoc networks (MANETs) due in part to the dynamically changing network topologies. For mobile sensor networks that are deployed for surveillance applications, it is important to use a mobility management scheme that can empower nodes to make better decisions regarding their positions such that strategic tasks such as target tracking can benefit from node movement. In this paper, we describe a distributed mobility management scheme for mobile sensor networks. The proposed scheme considers node movement decisions as part of a distributed optimization problem which integrates mobility-enhanced improvement in the quality of target tracking data with the associated negative consequences of increased energy consumption due to locomotion, potential loss of network connectivity, and loss of sensing coverage.     

Hierarchical Architecture for Multi-Technology Wireless Sensor Networks for Critical Infrastructure Protection

A hierarchical architecture for wireless sensor network (WSN) consisting of heterogeneous devices is introduced in this paper. Proposed architecture is well suited for surveillance of critical infrastructures and it is designed to be scalable for various different scenarios. Low power consumption will be achieved by utilizing a wake-up radio concept which enables to keep the most power consuming devices at the sleep mode as long as possible. A WSN OpenAPI gateway (WOAG) component of the architecture supports high scalability by enabling data collection and sharing from networks deployed using multiple different technologies. WOAG facilitates WSNs information availability to local and remote end-users. Analytical energy efficiency optimization model for the architecture is developed. Results show energy efficiency gains that can be achieved with the proposed wake-up concept based intelligent hierarchical architecture design. For low event frequency case the energy efficiency is found to be one order of magnitude better than for duty cycle (1 %) radio based network.     

Fuzzy Rule-Based Mobility and Load Management for Self-Organizing Wireless Networks

Mobility management in a cluster-based, multihop ad hoc network is studied. It is shown that the process of clustering the network into groups of stations has similarities to data analysis, in particular, pattern recognition. In data analysis, the term clustering refers to the process of unsupervised learning, which also describes the situation in a mobile ad hoc network.In this paper, existing data-clustering algorithms are first classified into different categories. Some of the most important types of algorithms are afterwards described, and their applicability to the problem of mobility management in an ad hoc network is studied. It is shown that most of the pattern-recognition algorithms are not suited to the application under consideration.This is why we have developed a new clustering scheme that incorporates some of the ideas of the data classification schemes. The new clustering scheme is based on a rule-based fuzzy inference engine. The main idea consists of the consideration of dynamic clustering events chosen as a consequence of the fuzzy rules. Four types of clustering events are considered.The performance of the clustering algorithm has been evaluated by computer simulation.     

Fault Recovery in Time-Synchronized Mission Critical ZigBee-Based Wireless Sensor Networks

Reliability and precise timestamping of events that occur are two of the most important requirements for mission critical wireless sensor networks. Accurate timestamping is obtained by synchronizing the nodes to each other while reliability can be obtained by eliminating single points of failure (SPF). In this paper, we address the SPF problem of a ZigBee-based wireless sensor network by means of using multiple coordinators with different personal area network identifiers (PAN IDs). We propose a solution where members of a network switch from one coordinator to another in case of failure by changing their respective PAN ID. We verify experimentally that our solution provides gains in terms of recovery speed and, therefore, synchronization accuracy with respect to a solution proposed in the literature.     

A Hybrid Trust Management Scheme for Wireless Sensor Networks

Wireless sensor network (WSN) consists of wireless small sensor nodes deployed in the terrain for continuous observation of physical or environmental conditions. The data collected from the WSN is used for making decisions. The condition for making critical decision is to assure the trustworthiness of the data generated from sensor nodes. However, the approaches for scoring the sensed data alone is not enough in WSN since there is an interdependency between node and data item. If the overall trust score of the network is based on one trust component, then the network might be misguided. In this work, we propose the hybrid approach to address the issue by assigning the trust score to data items and sensor nodes based on data quality and communication trust respectively. The proposed hybrid trust management scheme (HTMS) detects the data fault with the help of temporal and spatial correlations. The correlation metric and provenance data are used to score the sensed data. The data trust score is utilized for making decision. The communication trust and provenance data are used to evaluate the trust score of intermediate nodes and source node. If the data item is reliable enough to make critical decisions, a reward is given by means of adding trust score to the intermediate nodes and source node. A punishment is given by reducing the trust score of the source and intermediate nodes, if the data item is not reliable enough to make critical decisions. Result shows that the proposed HTMS detects the malicious, faulty, selfish node and untrustworthy data.     

基于6LoWPAN的IPv6传感器网络报头压缩方案的设计与实现

无线传感器网络节点的资源非常有限,如果能够对IPv6报头进行压缩可以在较大程度上减小数据传输量,提高IPv6传感器网络的整体性能。通过对6LoWPAN报头压缩方案的研究,并结合无线传感器网络的特点和实际需求,在已有无线传感器网络底层协议和基本IPv6协议栈基础上,设计并实现了一种支持对跳数限制压缩的IPv6报头压缩方法。实验结果表明,报头压缩可以有效节省网络能耗,降低丢包率,减小数据传输时延。     

Optimized Congestion Management Protocol for Healthcare Wireless Sensor Networks

The application of Wireless Sensor Networks (WSNs) in healthcare is dominant and fast growing. In healthcare WSN applications (HWSNs) such as medical emergencies, the network may encounter an unpredictable load which leads to congestion. Congestion problem which is common in any data network including WSN, leads to packet loss, increasing end-to-end delay and excessive energy consumption due to retransmission. In modern wireless biomedical sensor networks, increasing these two parameters for the packets that carry EKG signals may even result in the death of the patient. Furthermore, when congestion occurs, because of the packet loss, packet retransmission increases accordingly. The retransmission directly affects the lifetime of the nodes. In this paper, an Optimized Congestion management protocol is proposed for HWSNs when the patients are stationary. This protocol consists of two stages. In the first stage, a novel Active Queue Management (AQM) scheme is proposed to avoid congestion and provide quality of service (QoS). This scheme uses separate virtual queues on a single physical queue to store the input packets from each child node based on importance and priority of the source’s traffic. If the incoming packet is accepted, in the second stage, three mechanisms are used to control congestion. The proposed protocol detects congestion by a three-state machine and virtual queue status; it adjusts the child’s sending rate by an optimization function. We compare our proposed protocol with CCF, PCCP and backpressure algorithms using the OPNET simulator. Simulation results show that the proposed protocol is more efficient than CCF, PCCP and backpressure algorithms in terms of packet loss, energy efficiency, end-to-end delay and fairness.     

Centralized Key Management Scheme in Wireless Sensor Networks

Today, key management is widely recognized as an important aspect of security in wireless sensor networks. In these networks, sensor nodes can be either mobile or static. Therefore, supporting the mobility of the nodes can be regarded as a purpose of key management schemes. In our previous work, we presented a key management scheme that was more efficient with respect to security and connectivity compared to the other ones. In that scheme, it is assumed that the nodes are static. In this paper we are going to present a scheme that supports the mobility of the nodes and makes the initial scheme more flexible. The basic criterion for the evaluation of the scheme is the communication overhead. First, the nodes establish a secure link with the cluster heads and then establish a secure link among themselves with the help of the cluster heads. We have analyzed this scheme with regards to the communication overhead and we will compare it with the other schemes.     

一种基于位置的WSN密钥管理方案

针对当前无线传感器网络（WSN）随机密钥预分布方案中网络只能概率连通且密钥不能作为认证的问题，文中提出了一种基于节点位置的密钥管理方案LBK-KMS，文中详细介绍LBK-KMS方案的建立过程；并从安全抵抗性，网络连通性，扩展性以及通信计算性能等方面与E-G以及q-Composite方案进行了比较分析；最后探讨了下一步可研究的工作．