【作者】 郭瑛；

【导师】 郭忠文；

【作者基本信息】 中国海洋大学 ， 计算机应用技术， 2010， 博士

【摘要】 无线传感器网络(Wireless sensor networks,简称WSN)是由随机撒布的大量传感器节点组成的无线自组织网络,其目的是协作地感知、采集和处理网络覆盖的地理区域内感知对象的信息,并发布给观察者。事件监测是无线传感器网络的一个重要应用,事件监测时无线传感器网络具有事件触发的特点,事件触发的无线传感器网络具有阶段性、突发性、数据量大、冗余度高等特点。本文对事件触发的无线传感器网络进行了分析,主要在节点定位算法、数据融合技术、干扰避免协议、休眠机制和信息汇报方法这几个方面进行了研究,主要工作及创新点包括：1.研究了适用于事件触发传感器网络的节点定位算法,提出了移动节点辅助的垂直相交定位算法(Perpendicular Intersection,简称PI)。PI通过比较传感器节点接收信号强度(Received Signal Strength Indicator,简称RSSI),得到传感器节点间的几何关系,来计算传感器节点的位置,避免了传统方法中把RSSI直接转化成物理距离带来的误差。还设计了PI定位算法中移动信标节点的最优运动轨迹,提出了移动信标节点采用任意轨迹时的扩展PI定位算法。并在各种真实环境下进行实验来验证PI定位算法的性能,大量的实验数据充分表明了该算法的优越性。2.设计了事件触发的数据融合技术(Event-oriented Data Aggregation,简称EDA)。EDA利用模糊数学里的隶属云模型来描述同一物理事件的采样信息之间的逻辑关系,把各个传感器节点采集的信息形成事件特征,只要把包含事件特征的融合数据包传回基站,基站就可以恢复全部事件信息。EDA分布式算法可以处理多个相邻事件同时发生和事件信息非正态分布的情况。通过理论分析、仿真和海上试验平台的历史数据,证明了EDA的可行性和有效性。3.提出了事件触发的干扰避免传输协议(Event-oriented Interference Avoidance,简称EIA)。EIA通过对传感器节点的频率分配和时间调度,来避免事件信息传输过程中的干扰和冲突,实现相邻节点无干扰的并行传输。同时给出了在监测事件动态变化的时候,信息传输路径的动态调整策略。理论分析和仿真实验证明EIA明显减少了传输过程中的干扰和冲突,提高了网络效率。4.给出了事件触发的节点休眠机制(Sleep Scheduling Algorithm,简称SSA)并设计了与之对应的信息汇报方法(Gradient Query Algorithm,简称GQA)。对于目标事件监测这类应用,不需要一直保持完全覆盖监测区域,只需要让检测到目标事件的传感器节点保持活动就可以了。SSA可以找出每个传感器节点的最优休眠时间,让大部分传感器节点处于休眠状态,在节省能量的同时确保始终能监测到移动的目标事件。GQA针对SSA休眠机制,由查询事件触发,通过梯度路径汇报目标事件信息,信息汇报梯度基于传感器节点的休眠周期,这也是从用户到目标事件信息源最短的路径。通过理论分析和仿真证明了SSA和GQA在节省网络能量上的性能。事件触发的无线传感器网络在军事、环境监测、健康、家庭和商业领域等各个方面得到了非常广泛的使用。对其进行深入的研究必将进一步提高无线传感器网络的性能,使其具有更加广阔的应用前景。更多还原

【Abstract】 Wireless sensor networks (WSN) is a wireless self-organized network, which is composed by numerous sensors deployed randomly in a geographical scenario, and is used to sense, collect and process sensed information collaboratively, and then sending the information to the observer. One of the most important applications of WSN is monitoring events, in which WSN is event-oriented. The event-oriented WSN has the characteristics of multi-phase, paroxysm, and large number of data with high redundancy. This paper based on event-oriented WSN, and referred several topics which are localization algorithm, data aggregation approach, interference avoidance protocol, sleep scheduling and information report method. The main work and innovations are as follows.1. This paper studies on the localization algorithm of event-oriented WSN, and proposes a mobile-assisted localization scheme called Perpendicular Intersection (PI). PI locates the nodes by contrasting the RSSI values and utilizing the geometric relationship among the nodes, so as to avoid the errors brought by the translations from RSSI values to physical distances. This paper also designs the optimal trajectory of the mobile beacon, and extended PI algorithm for random trajectory. Comprehensive experiments show that PI significantly outperforming the existing localization schemes.2. This paper designs an Event-oriented Data Aggregation algorithm (EDA). EDA exploits Cloud Membership model of fuzzy logic to aggregate the information of events in the WSN, and uses the information sampled by sensor nodes produce event features. The base station will restore the whole event information when receiving the aggregated packets of event features. It also presents a distributed algorithm which can handle the situations of multiple events happening nearby and the event information of none Normal distribution. The performance has been evaluated through theoretical analysis, simulations and the traces of offshore sensor network test-bed.3. This paper proposes an Event-oriented Interference Avoidance protocol (EIA). EIA makes use of frequency assignment and time scheduling to avoid the interference and collision in the data transmission process. It can realize non interference parallel transmission between neighbor nodes. EIA also includes dynamic adjustment strategy of information transmission path when the monitoring event changing dynamically. Theoretical analysis and simulations show that EIA reduces the interference and collision in the data transmission process greatly, and improves the efficiency of WSN.4. This paper proposes a duty cycling design for the event-oriented sensor networks of target monitoring, called Sleep Scheduling Algorithm (SSA) and designs the information report method correspond to SSA, which is called Gradient Query Algorithm (GQA). For the applications of target monitoring, however, it is not necessary anymore to keep the whole sensory coverage of the sensor networks. It only needs to make sure that such kinds of nodes are active which can perceive the activities of the monitored targets. Under SSA most of the sensor nodes can be in sleep, while still keep the functions of target monitoring in WSN. GQA is oriented by query event, and it reports information through gradient paths. The gradient of GQA is based on the sleep periods decreased path of the sensor nodes, meanwhile, this route is the shortest path from the user to the information source. The performance of SSA and GQA has been evaluated through theoretical analysis and simulations.Event-oriented WSN has wide application in military affairs, environment detecting, health affairs, home network, commercial areas and so on. An in-depth study will enhance the performance of WSN and mak it has a broad application prospects.更多还原