Using cubic B-spline interpolation for efficient ray-tracing-based ultrawideband propagation modeling

Site-specific ultrawideband propagation modeling involves dealing with frequency variations of the propagation mechanisms and antenna patterns in the ray tracing program. Typically, electromagnetic field calculations have to be performed in a lot of frequencies to accurately construct the frequency response of the channel at a receiving point. This imposes a heavy computational burden on ray tracing specially in calculating the coverage map or finding the statistics of channel parameters where the number of receiving locations is large. In this paper, the computational complexity of ray tracing in ultrawideband propagation modeling is reduced by using cubic B-spline interpolation. The frequency response of the channel at each receiving point is obtained by calculating the electromagnetic fields at a limited number of frequencies and then interpolating the results using cubic B-splines. A speedup of about four times in simulating a typical residential environment is achieved. Besides, the accuracy of the results is maintained due to excellent characteristics of the cubic B-spline interpolation.