Convergence Analysis Of Indoor Ray Tracing

As a classical radio wave propagation prediction algorithm,ray tracing is often used not only in large size electromagnetic environment prediction,but also in indoor scenario electromagnetic environment simulation.Computation burden of indoor ray tracing sharply increases with the upper limit value of reflection rises.The upper limit of reflection number is closely related to accuracy and efficiency of indoor ray tracing.Therefore,the convergence of reflection number of indoor ray.tracing has become a research topic which is of great significance.Different from some foreign studies on convergence through analysis of ray tracing simulation results,this paper presents a theoretical convergence study of indoor ray tracing based on statistical analysis of indoor scene data.Firstly,the preprocessing model statistically analyzes the 3D data of indoor scenario and extracts parameters which could represent the distribution characteristics of indoor scene.Secondly,based on the parameters of preprocessing model and the basic electromagnetic theory of ray tracing,the power of propagation path with different reflections is deduced.In order to derive the probability of propagation path with different reflections,this paper defines a conditional probability model and simplifies the 3D geometric scene corresponding to this conditional probability event.Based on the hybrid ray tracing algorithm,this paper studies the geometric scene of image method refining obtained path and analysis the case when misjudgment of conditional probability event above happens.So misjudgment probability model is defined to deal with the misjudgment of conditional probability event,and misjudgment probability is derived on the basis of reasonable geometric scene simplification.Finally,on the basis of the power and probability of propagation path,convergence model computes the power ratio which is the power of the path that experienced exactly upper limit of reflections divided by the total power.By comparing the ratio with the ray tracing computational accuracy,this convergence model outputs the most reasonable reflection threshold value which could improve the efficiency of indoor ray tracing without losing the computational accuracy.Last but not least,several groups of experiments are carried out to compare the convergence of ray tracing simulation results.The results of the experiments show that the convergence results of the convergence model are basically consistent with ray tracing simulation.Under the same calculation precision,the average difference of the upper limit value of reflection between convergence model and simulation is only 5.19%.By comparing the results of the model with misjudgment and the model without misjudgment in the underground parking scene,it can be revealed that misjudgment model improves the accuracy of the convergence model.The feasibility of convergence model and misjudgment model are verified by synthesizing all the experimental comparison results.