Channel characteristics in tunnels: FDTD simulations and measurement

this paper presents the results of measurements and simulations of the characteristics of 900 mhz band radio propagation channels in a tunnel environment. the simulations were made using the fdtd method (with companion upml) and measurements made use of the swept frequency technique. another method, the metaheuristic simulated annealing, was implemented for estimating the values of characteristic parameters of materials. the fdtd code was reformulated for use with cuda with the objective of decreasing program running time.