Research On Key Technologies For Event-oriented Wireless Sensor Networks

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.