中文摘要：

无线传感网的一个基本挑战是能量受限，因此网络生存期是无线传感网最关心的课题．考虑了随机分布在面积为Sn=λn的正方形上的，2个传感节点和1个基站组成的跳时冲击无线电超宽带（TH-IR UWB）传感网．分别推导了完全分簇和常规分簇的扩展TH—IR UWB传感网生存期的渐近下界．结果表明，完全分簇的静态扩展网络生存期下界比常：观分簇的提高了λn／（log（λn））^2倍，而理想情形下的完全分簇的扩展网络生存期下界则比常规分簇的提高了（λn）^1/2／（log（λn））^3／2倍，因此完全分簇能极大地提高网络生存期．研究也表明对于常规分簇的扩展TH—IR UWB传感网，理想情形下生存期的下界比静态网络提高了（λn/log（λn））^1/2倍，因此节点或基站在部署区域内随机移动能提高常规分簇传感网的生存期．下界公式也揭示了生存期与节点数n或部署区域面积成反比，因此大规模扩展TH—IR UWB传感网不实用．

英文摘要：

A fundamental challenge for wireless sensor networks lies in energy constraint, hence the network lifetime becomes a critical concern in the design of wireless sensor networks under energy constraint. Considering time hopping impulse radio ultra wide band（TH-IR UWB） sensor networks with n sensor nodes randomly located on a disk of area Sn =λn and a base station, the asymptotic lower bounds on the lifetime of complete clustering and ordinary clustering extended TH-IR UWB sensor networks are derived respectively. The results indicate that the lower bound on the lifetime of complete clustering static extended network is λn/（log（An））2 times longer than that of ordinary clustering static network, and that the lower bound on the lifetime of complete clustering extended network in the ideal case is （An）l/2/（log（λn））^3/2 times longer than that of ordinary clustering network in the ideal case, and thus complete clustering can significantly improve the network lifetime. The results also reveal that for ordinary clustering extended TH-IR UWB sensor network the lower bound on the lifetime in the ideal case is longer than that of static network by a factor of（λn/log（λn））^1/2, therefore, sensor nodes or base station moving randomly in the deployment area can improve the lifetime of ordinary clustering sensor network. The formulas for lower bounds also reveal that the network lifetime is in inverse proportion to the node number n or the size of deployment area, and thus the large-scale extended TH-IR UWB sensor network is not practical.