Sealing borders with wireless sensors.

摘要

Wireless sensor networks, which have numerous potential applications such as monitoring environment and security detection, are an active research area in recent years. One of the fundamental research issues in wireless sensor networks is coverage, which determines how well an area is monitored by a sensor network. In this dissertation, we study the fundamental coverage problems for the intrusion detection applications such as international border guarding.;(Global) barrier coverage is known to be an appropriate model of coverage for movement detection applications such as intrusion detection. However, it has been proved that given a sensor deployment, sensors can not locally determine whether the deployment provides global barrier coverage, making it impossible to develop localized algorithms, thus limiting its use in practice. In this dissertation, we introduce the concept of local barrier coverage to address this limitation. Local barrier coverage guarantees the detection of all movements whose trajectory is confined to a slice of the belt region of deployment. We prove that it is possible for individual sensors to locally determine the existence of local barrier coverage. Although local barrier coverage does not deterministically guarantee global barrier coverage, we show that for thin belt regions, local barrier coverage almost always provides global barrier coverage.;Sensors may fail due to various reasons such as heat, malicious activity, environmental hazards, and lack of power. As more and more sensors fail, certain desired properties such as barrier coverage will diminish and eventually fall below a desired level. In such a case, the network will have to be repaired. It is therefore desirable to have mechanisms to monitor network properties. In this dissertation, we are interested in measuring the quality of barrier coverage. In the literature, researchers only consider whether or not a sensor network provides barrier coverage. This is equivalent to measuring its quality as either 0 or 1. We believe quality of barrier coverage is not binary and propose a metric for measuring it. If the measured quality is short of a desired value, we further identify all local regions that need to be repaired. We also discuss how to actually repair a region.;For some intrusion detection applications, it may be the case that only one direction of crossing (the belt) is illegal. Therefore, we introduce a new coverage model called one-way barrier coverage. We investigate necessary conditions and sufficient conditions for one-way barrier coverage. We then study how to make a sensor network provide one-way barrier coverage with different barrier models or sensor models.