无线传感器网络中移动目标的定位与跟踪

对侵入无线传感器网络中的目标,提出了一种移动节点和静态节点相结合的定位与跟踪方式.静态节点可以发现侵入传感器网络中的目标,移动节点与静态节点配合进一步确定目标的具体位置.仿真实验验证表明:该方法可以减少大规模的频繁移动节点,不需要过多地对移动节点的选择和运动进行特别复杂的计算,具有较好的定位精度和鲁棒性,对多目标的定位与跟踪研究有一定的启发作用.     

Performance modeling of the LEACH protocol for mobile wireless sensor networks

In many wireless sensor network applications, nodes are mobile, while many protocols proposed for these networks assume a static network. Thus, it is important to evaluate if a traditional protocol designed for a static network can tolerate different levels of mobility. This paper provides an analytic model to investigate the effect of mobility on a well-known cluster-based protocol, LEACH. The model evaluates data loss after construction of the clusters due to node mobility, which can be used to estimate a proper update interval to balance the energy and data loss ratio. Thus, the results can help the network designer to adjust the topology update interval given a value of acceptable data loss threshold. A practical approach to increase the mobility tolerance of the protocol is applying a buffer zone to the transmission ranges of the nodes. The model is extended in order to consider the effect of buffer zone. To validate the analytic evaluations, extensive simulations are conducted and correctness of the evaluations is tightly verified.     

无线传感器网络中一种新的分布式定位方案研究

Node localization in wireless sensor networks (WSN) is treated as a functional dual of target tracking from a novel perspective in the paper. Different from the traditional tracking problem in WSN, using the static location-ware node to estimate the moving target, the mobile node is used to help unknown nodes to accurately discover their positions. A new node localization scheme virtual beacons-energy ratios localization (VB-ERL) and its refinements for the WSN are presented. In the scheme, the mobile node moves in the surveillant field based on the Gauss-Markov mobility model and periodically broadcasts the information packets. Each static unknown node receives the virtual beacons and energy in its sensing range, and estimates its location by finding the intersection of a set of hyper-spheres. Simulation results show the proposed scheme is efficient.     

移动异构传感器网络分布式部署算法

针对移动异构传感器网络中的最大覆盖问题,论文提出了一种分布式部署算法.该算法依据节点坐标及其感知范围而更新目标划分子区间,使子区间内的各个节点能结合自身及其delaunay邻居节点当前的几何位置和剩余能量值确定速度向量,同时利用节点的移动特性,使调整后的网络最大化覆盖目标区域.仿真结果表明,该算法在提高网络覆盖率和协调速度的同时,能兼顾网络节点剩余能量的均衡.     

ASH: tackling node mobility in large-scale networks

With the increased adoption of technologies like wireless sensor networks by real-world applications, dynamic network topologies are becoming the rule rather than the exception. Node mobility, however, introduces a range of problems (communication interference, path uncertainty, low quality of service and information loss, etc.) that are not handled well by periodically refreshing state information, as algorithms designed for static networks typically do. To address specifically this problem, the main contribution of this paper is the introduction of a novel mechanism (called ASH) for the creation of a quasi-static overlay on top of a mobile topology. It is powered by simple, local interactions between nodes and exhibits self-healing and self-organization capabilities with respect to failures and node mobility. We show that the overlay mechanism works without assumptions about position, orientation, speed, motion correlation, and trajectory prediction of the nodes. A preliminary evaluation by means of simulation shows that ASH succeeds in tackling node mobility, while consuming only minimal resources.     

Sink节点移动的无线传感网生存时间优化算法

为提高网络最大生存时间,提出Sink节点移动的无线传感网生存时间优化算法(LOAMSN)。该算法分析Sink节点移动时的流量平衡约束、最大传输速率约束、节点能耗约束等约束条件,将生存时间优化问题转化成优化模型。提出Sink节点的移动方法,即Sink节点利用节点的度值构建其移动路径,按照此路径循环移动收集数据。将Sink节点的移动认为是离散运动,Sink节点移动的生存时间优化模型分解成若干个Sink节点静止的生存时间优化模型,采用牛顿法求解每个Sink节点静止的优化模型,获得网络最大生存时间和节点发送数据量的最优值。仿真结果表明:LOAMSN算法能减少Sink节点停留位置上的节点能耗,平衡网络负载和节点能耗,提高网络最大生存时间。在一定条件下,LOAMSN算法比Sink节点静止时更优。     

一种移动终端辅助的传感器网络数据收集协议

提出了一种利用具有传感器通信接口的移动终端设备（如手机、手提电脑、个人数字助理等）进行辅助数据获取的传感器网络数据收集协议。网络中固定汇聚节点与移动终端共存,全部传感器节点都维护到固定汇聚节点的路由,移动终端进入网络后定期向其附近小范围内的传感器节点扩散自己的存在信息,传感器节点向距自己跳数最小的汇聚节点或移动终端发送或转发数据包,移动终端和传感器节点之间通过应答和重传的机制来保证数据的可靠传输。仿真研究证明,该协议在延长网络生存时间的同时可以获得较高的数据传输成功率和较短的数据传输延迟,而且可靠性、灵活性、可扩展性较强。     

TBMC:一种基于多探测器协同的DTNs目标追踪策略

延迟容忍网络中的目标追踪问题一直被广泛关注,目前的相关策略主要围绕单探测器追踪单个目标问题。有些搜索策略利用节点相遇的可能性,有些利用节点的地理位置信息,有些采用更加新颖的方法,比如利用目标节点留下的移动方位信息和时间。这些策略都直接或者间接地利用了目标节点的信息进行目标搜索,但是普遍不高的成功率使得这些搜索策略应用范围受到一定限制。设计了一套基于多探测器协同的分布式目标追踪策略,通过远距离协同探测机制DTRs与直接协同机制TRs进行多探测器协同追踪,有效避免探测冲突与冗余步骤,提高追踪效率。理论分析与实验表明,该策略相比传统策略能有效减少追踪步数,提高目标追踪成功率。     

An improved ant colony optimization-based approach with mobile sink for wireless sensor networks

Traditional wireless sensor networks (WSNs) with one static sink node suffer from the well-known hot spot problem, that of sensor nodes near the static sink bear more traffic load than outlying nodes. Thus, the overall network lifetime is reduced due to the fact some nodes deplete their energy reserves much faster compared to the rest. Recently, adopting sink mobility has been considered as a good strategy to overcome the hot spot problem. Mobile sink(s) physically move within the network and communicate with selected nodes, such as cluster heads (CHs), to perform direct data collection through short-range communications that requires no routing. Finding an optimal mobility trajectory for the mobile sink is critical in order to achieve energy efficiency. Taking hints from nature, the ant colony optimization (ACO) algorithm has been seen as a good solution to finding an optimal traversal path. Whereas the traditional ACO algorithm will guide ants to take a small step to the next node using current information, over time they will deviate from the target. Likewise, a mobile sink may communicate with selected node for a relatively long time making the traditional ACO algorithm delays not suitable for high real-time WSNs applications. In this paper, we propose an improved ACO algorithm approach for WSNs that use mobile sinks by considering CH distances. In this research, the network is divided into several clusters and each cluster has one CH. While the distance between CHs is considered under the traditional ACO algorithm, the mobile sink node finds an optimal mobility trajectory to communicate with CHs under our improved ACO algorithm. Simulation results show that the proposed algorithm can significantly improve wireless sensor network performance compared to other routing algorithms.     

Performance evaluation of selective and adaptive heads clustering algorithms over wireless sensor networks

Target tracking in wireless sensor networks can be considered as a milestone of a wide range of applications to permanently report, through network sensors, the positions of a mobile target to the base station during its move across a certain path. While tracking a mobile target, a lot of open challenges arise and need to be investigated and maintained which mainly include energy efficiency and tracking accuracy. In this paper, we propose three algorithms for tracking a mobile target in wireless sensor network utilizing cluster-based architecture, namely adaptive head, static head, and selective static head. Our goal is to achieve a promising tracking accuracy and energy efficiency by choosing the candidate sensor nodes nearby the target to participate in the tracking process while preserving the others in sleep state. Through Matlab simulation, we investigate the performance of the proposed algorithms in terms of energy consumption, tracking error, sensor density, as well as target speed. The results show that the adaptive head is the most efficient algorithm in terms of energy consumption while static and selective static heads algorithms are preferred as far as the tracking error is concerned especially when the target moves rapidly. Furthermore, the effectiveness of our proposed algorithms is verified through comparing their results with those obtained from previous algorithms.     

Direction-based adaptive data propagation for heterogeneous sensor mobility

We consider sensor networks where the sensor nodes are attached on entities that move in a highly dynamic, heterogeneous manner. To capture this mobility diversity we introduce a new network parameter, the direction-aware mobility level, which measures how fast and close each mobile node is expected to get to the data destination (the sink). We then provide local, distributed data dissemination protocols that adaptively exploit the node mobility to improve performance. In particular, “high” mobility is used as a low cost replacement for data dissemination (due to the ferrying of data), while in the case of “low” mobility either (a) data propagation redundancy is increased (when highly mobile neighbors exist) or (b) long-distance data transmissions are used (when the entire neighborhood is of low mobility) to accelerate data dissemination toward the sink. An extensive performance comparison to relevant methods from the state of the art demonstrates significant improvements, i.e. latency is reduced by even four times while keeping energy dissipation and delivery success at very satisfactory levels.     

基于无线传感器网络的同时定位与跟踪

研究无线传感器网络在位置信息不确定时,同时定位无线传感器网络节点并跟踪移动目标。利用RSSI测量节点对之间的距离,多维定标技术根据距离矩阵完成传感器网络的初始定位。估计与更新阶段提出了压缩EKF滤波确定传感器节点位置和目标位置。仿真结果显示:算法在较低的网络覆盖率下有较高的定位和跟踪准确度,在初始定位误差为5m时,节点和跟踪误差均小于3m,特别是在长距离的跟踪任务中有很好的精度和实时性。     

一种结合移动IP和SIP实现IP网络移动性管理的优化方案

本文提出了一种网络层和应用层相结合实现IP网络移动性管理的新方案。移动终端的固定IP地址作为数据传输的地址；当终端和所在子网使用的是不同的IP子网前缀时，使用转交地址形成隧道对数据进行收发；SIP地址作为用户帐号，是在应用层使用服务的地址，通过把它动态地和移动终端绑定来使用终端。方案中还提出了以SIP地址域的分级方式进行组织管理的用户数据库系统，定义了为子网中移动终端服务的区域代理。新方案能够对现役设备和协议改动较小的程度下，为下一代网络提供移动性管理。     

Design,implementation and experimental evaluation of an end-to-end vertical handover scheme on NCTUns simulator

This paper presents the simulation study of “Host based autonomous Mobile Address Translation” using NCTUns simulator. It is a network layer, end-to-end vertical handover solution, based upon modification of “Mobile IP with address Translation”. Vertical handover approaches generally require new network elements, a new layer in TCP/IP stack, or fixing a protocol at a particular layer. To enhance handover experience, recent approaches focus on reducing signalling, localizing the registration, creating hierarchies, using proxy, preparing handover in advance, predicting target network, or exploiting multicasting and path extension techniques. These approaches, however, demand change in the network infrastructure to support mobility and limit the scope of mobility. Despite end-to-end signalling, the Host based autonomous Mobile Address Translation scheme ensures minimum service disruption and distinctly allows global mobility of the mobile node without requiring any modification in the network. We have simulated the mobility of a multi-interface mobile node in a heterogeneous network environment composed of WiFi (IEEE802.11a, IEEE802.11b) and WiMAX (IEEE802.16e) access networks. Performance of the scheme is evaluated taking into account wide range of end-to-end delays between mobile node and the correspondent node, various speeds of the mobile node and different packet loss rates of the network. Based on our detailed simulation study, it has been observed that this scheme offers reduced service disruption time, packet loss and packet latency. The service disruption time is found to be significantly low (typically in the range of 10 ms) compared to that of Mobile IP (which is in the order of 100 ms); this makes this new scheme perfectly suitable for real time applications. Low service disruption time consequently reduces the packet loss by manyfold and the packet latency remains unaffected during and after handover due to translation of address at the source. The results suggest that this protocol is a viable vertical handover solution due to its simplicity, scalability, low overhead and ready deployability.     

Impact of mobility on the performance of relaying in ad hoc networks – Extended version

We consider a mobile ad hoc network consisting of three types of nodes: source, destination, and relay nodes. All the nodes are moving over a bounded region with possibly different mobility patterns. We introduce and study the notion of relay throughput, i.e. the maximum rate at which a node can relay data from the source to the destination. Our findings include the results that (a) the relay throughput depends on the node mobility pattern only via its (stationary) node position distribution, and (b) that a node mobility pattern that results in a uniform steady-state distribution for all nodes achieves the lowest relay throughput. Random waypoint and random direction mobility models in both one and in two dimensions are studied and approximate simple expressions for the relay throughput are provided. Finally, the behavior of the relay buffer occupancy is examined for the random walk and random direction mobility models. For both models, the explicit form of the mean buffer is provided in the heavy-traffic case.     

基于移动锚节点无线传感器网络定位的算法

无线传感器网络应用在很多场合中,监测目标进行定位和跟踪是最基本的应用。在无线传感器网络中基于移动锚节点的定位算法进行设计仿真,网络部署成本显著减少。节点能耗减少,运行时间延长,而且在网络边缘上的节点100％都能获得节点位置．该设计算法能得到完整的网络信息,即使在网络节点出现故障后,通过移动锚节点来重新确认所有无故障节点的位置,进行重新定位。     

物联网感知层移动自组织网可靠性评估方法

移动自组织网可靠性是影响物联网应用的数据采集和设备控制的关键因素之一。为解决移动自组织网络可靠性的不确定性分析和量化评估的问题,综合考虑节点移动性引起的动态连接以及网络组件故障的因素,提出了一种基于节点移动的Ad_hoc网的可靠性计算方法。在两个节点移动时都保持速度和方向不变的条件下,首先预测其中一个节点有效链路保持的持续时间,然后考虑此节点某段时间内在速度和方向上的变化来评估此链路的有效性,进而间接地计算自组织网的可靠性。实验结果表明,移动自组织网的可靠性不仅依赖节点、链路可靠性,还依赖于网络拓扑的冗余度和节点在网络中的分布。     

基于簇结构的无线传感器网络移动目标 精确跟踪

对于移动目标跟踪,需要利用加速度或速度恒定的模型对其连续轨迹进行推断.在传感器网络环境下,利用无线传感器网络的冗余特点,提出了一种分簇结构和分时机制下采用流水线工作模式进行跟踪探测的方法,减少两次探测值之间的时间差,通过分析和仿真验证,该方法能够有效地降低对移动目标的跟踪误差.所设计的算法计算复杂度低,实现简单,满足无线传感器网络节点的计算能力要求.     

三维曲面多移动节点的传感器网络部署算法

目前大多数传感器网络部署研究主要集中在二维平面和三维全空间区域,然而,许多现实世界的应用领域是一个复杂的三维空间曲面,现有的覆盖方法不能取得较好的结果。本文研究三维空间曲面传感器网络部署方法,提出一种三维曲面多移动节点的传感器网络部署算法,采用静态节点和动态节点组成的混合传感器网络,由静态节点估算覆盖空洞的位置和面积,再通过移动节点对覆盖空洞进行依次修复。仿真结果表明,该算法的最终网络覆盖率达到了99%,比3DGA算法提高了6个百分点,比Delaunay算法提高了8.5个百分点,同时降低了网络整体能耗。     

移动场景下的节点高效寻路RPL路由算法优化

在低功耗有损网络(low power and lossy networks)中,现有的移动性支持路由算法存在控制消息冗余,应用场景不具有普适应,网络丢包率和移动节点能耗较高等问题.针对这些问题,提出一种移动场景下的节点高效寻路RPL路由算法(efficient pathfinding RPL routing algorithm for nodes in mobile scenarios,MSE-RPL).该算法提出的优化思路如下:首先,精简了移动节点的控制消息,并采用自适应黑名单机制建立备选父节点集,从而降低了移动节点的能耗;其次,基于移动节点的移动速度和方向,从备选父节点集中选择移出通信范围预估时间最短的节点作为最优父节点,不但适用于随机移动场景,还降低了平均端到端时延;最后,在链路中断前,利用DIS计时器及时通告DIS消息以快速重构拓扑,降低了丢包率.仿真结果表明,MSE-RPL算法在平均端到端时延、移动节点能耗、丢包率等性能指标方面均有明显改善.