Abstract: Shadow fading effects caused by obstacles，complex terrain and so on，affect the sensing ability of sensor nodes a lot，while the wireless signals are transmitted through the air.This paper studies the coverage problem of wireless sensor networks by introducing point coverage，and the so-called lognormal shadow fading model.Through the analysis of mathematical models and simulation experiments，it is proved that shadow fading increases the coverage ratio of sensor network which is randomly deployed according to the homogeneous Poisson process.And the simulation results also show that greater fading factor means greater impacts.

Key words: wireless sensor networks, shadow fading, point coverage

摘要： 在无线传感器网络节点关联过程中，各种障碍物和复杂地形等因素所引起的阴影衰落效应将影响传感器节点感知能力，从而影响无线传感器网络的覆盖范围。引入点覆盖的概念，使用对数正态阴影衰落模型，研究无线传感器网络的阴影覆盖问题。通过对阴影衰落感知数学模型的分析和仿真实验，论证了在采用相同泊松过程随机部署的传感器网络中，阴影衰落效应在一定程度上可以提高网络的覆盖率。仿真结果还显示越大的衰落因子对覆盖率的提高幅度越大。

关键词: 无线传感器网络, 阴影衰落, 点覆盖