Basic Research Related to Spread Use of Sensor Network

目前的研究项目研究了传感器网络物理层无线通信在沙漠或森林山丘等粗糙表面上的传播特性。在数值分析中，我们采用了FVTD方法，研究了粗糙表面的平均高度和相关长度等参数对传播特性的影响。已经证明，衰减特性很好地表示为从源到目的地的直线距离的功率。其次，我们提出了一个简化形式的外推吸收边界条件（EABC），以便在将其应用于沿粗糙表面的传播问题时减少计算机内存。结果表明，EABC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，我们提出了一种估计在城市地区或家庭中观测到的接收衰落电磁波包络统计特性的算法。该算法已应用于一些实验和理论数据中，用于估算入射波与散射波的比值。

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.