Distributed Space-Time Communication For Wireless Sensor Networks

无线传感器网络具有广泛的潜在应用，包括环境监测、家庭和工厂自动化以及国土安全。本研究致力于从传感器网络中高效地收集数据，这是大规模部署低成本传感器节点的根本瓶颈之一。两个关键困难是规模(如何管理大量相对简单的节点)和能源(通信是能源密集型的，但传感器节点必须依靠电池或从环境中收集能量来运行数月或数年)。这项研究有两个互补的研究推动力，都是研究从传感器网络收集数据的新技术，利用传感器节点在空间中的自然分布。第一种称为虚拟雷达，通过将复杂的数据收集节点转移到复杂的数据收集节点，可以部署非常简单的传感器节点，这些节点不需要联网或定位功能。第二种方法需要更复杂的节点，通过相邻(单天线)传感器节点之间的智能协调来获得多天线传输的功能，从而提高能量效率和射程。在第一种推力中，称为虚拟雷达的传感器节点通过电子方式报告报告，反映由“驾车经过”或“飞越”收集器节点发射的信标，从而形成类似雷达的几何结构。采集器使用复杂的合成孔径雷达之类的信号处理技术来获得传感器领域内活动的“图像”，跟踪穿过传感器领域的事件，并在采集器上利用多个天线。第二个推力称为分布式传输，涉及作为节点间实现的同步水平的函数的波束形成、分集和通过相邻节点之间的协调而获得的功率增益的研究。文中还讨论了实现这种同步的方法。

Wireless sensor networks have a large array of potential applications,including environmental monitoring, home and factory automation, andhomeland security. This research addresses efficient data collectionfrom sensor networks, which is one of the fundamental bottlenecks tolarge-scale deployment of low-cost sensor nodes. Two key difficultiesare scale (how to manage very large numbers of relativelyunsophisticated nodes) and energy (communication is energy-intensive,but sensor nodes must operate for months or years on battery, or byscavenging energy from the environment). This research has twocomplementary research thrusts, both investigating novel techniquesfor data collection from sensor networks, exploiting the naturaldistribution of sensor nodes in space. The first, termed virtualradar, enables deployment of extremely simple sensor nodes which donot need networking or position location functionality, by moving thecomplexity to a sophisticated data collection node. The secondapproach requires more sophisticated nodes, and increases energyefficiency and range by obtaining the functionality of multi-antennatransmission by intelligent coordination between neighboring(single-antenna) sensor nodes.In the first thrust, termed virtual radar, sensor nodes with activityto report electronically reflect a beacon transmitted by a"driveby" or "flyby" collector node, thuscreating a radar-like geometry. The collector employs sophisticatedsynthetic aperture radar like signal processing techniques to obtainan "image" of the activity in the sensor field.Tracking of events moving across the sensor field, and exploitingmultiple antennas at the collector, are investigated. The secondthrust, termed distributed transmission, involves investigation ofbeamforming, diversity and power gains obtained by coordinatingbetween neighboring nodes, as a function of the level ofsynchronization achieved among the nodes. Methods of achieving suchsynchronization are also considered.