Raytracing in Channel Model Development

Sammanfattning: The fifth generation of mobile internet is upon us, but still, there is work to do before the new technology is fully utilized. The new generation of cellular network promises frequencies ranging from the sub – 6 GHz to 39 GHz, the latter being in the mmWave spectrum. At these frequencies, we can utilize geometrical optics to calculate the radio wave propagations. The purpose of this work is to explore how raytracing can be used to predict wireless radio wave channels and pathloss in indoor and urban environment settings. The model presented in this work explores line of sight, reflection, refraction, diffraction and scattering. The model utilizes Frii’s pathloss model for pathloss in the line-of-sight case. For reflection and refraction, Snell’s laws of reflection and refraction were used. For diffraction, the uniform theory of diffraction was used, and the scattering explored in this work was created using a physics based bidirectional reflectance diffusion function. With this we create a basic raytracing program for simple environments with potential for expansion in future work. The simple environment is a cube made in an STL file. The algorithms for the different parameter were a hybrid method of shoot- and bounce and image method for reflection, a double counting method for refraction. The transitions between different shadow boundaries were smooth. While scattering was explored, more work needs to be done to implement scattering into the code.