Modeling of Shadow Fading Correlation in Urban Environments Using the Uniform Theory of Diffraction
Résumé
Shadow fading is a well known problem in wireless sensor networks (WSN) and ad hoc networks since the communicating devices often are at street-level where the surrounding buildings often obstruct incoming radio waves. Therefore, accurately modeling shadow fading is an important requirement for the optimal design of such networks. Because the height of building is the most important parameter to calculate diffraction loss, the correlation of building heights on two close paths may influence the correlation of shadow-fading. In this paper, we first assume that the building heights follow an exponentially correlated Gaussian distribution, and then investigate shadow-fading correlation through the uniform theory of diffraction (UTD). The result shows that the correlation of shadow-fading stems from multiple exponential decay functions. Considering that the buildings near RX and TX are dominant contributors to shadow fading, a multiple (double in particular) exponential decay function is expected to better model the correlation than a single exponential.