Basic Research Related to Spread Use of Sensor Network

本研究课题是在传感器网络的物理层中，对与无线通信相关的沙漠、森林山丘等沿着粗糙表面的传播特性进行研究。在数值分析中，我们使用了FVTD方法，我们研究了粗糙表面参数，如粗糙表面的平均高度和相关长度，对传播特性的影响。它已被证明，衰减特性很好地表示在功率的直线距离从源到destination.Second，我们提出了一个外推吸收边界条件（EABC）的FVTD方法的简化形式，以减少计算机内存时，将其应用于传播问题沿着粗糙表面。结果表明，EABC方法对于一些需要大量计算机内存的电磁问题的数值分析是有效的。第三，我们提出了一种算法来估计通常在城市地区或住宅中观测到的接收衰落电磁波包络的统计特性。该算法已被应用到一些实验和理论数据，以估计入射波散射波比。

The present research project studied propagation characteristics along rough surfaces such as a desert or a forest hill in connection with wireless communications in the physical layer of a sensor network. In the numerical analyses, we have used the FVTD method, and we have investigated the effect of the rough surface parameters, such as average height and correlation length of the rough surface, on the propagation characteristics. It has been demonstrated that the attenuation characteristics are well expressed in terms of power of the straight distance from source to destination.Second, we have proposed an Extrapolated Absorbing Boundary Condition (EABC) for the FVTD method in a simplified form in order to reduce computer memory when applying it to propagation problems along rough surfaces. It has been shown that the EABC is effective for the numerical analysis of some electromagnetic problems which require much computer memory.Third, we have proposed an algorithm to estimate statistic properties of the envelope of received fading electromagnetic waves usually observed in urban areas or in houses. The algorithm has been applied to some experimental and theoretical data to estimate the incident wave to scattered wave ratio.