Study On The FDTD Analysis Method Of Propagation Characteristics Inside The Tunnels

The tunnel is a special kind of confined space, and generally has a complex structure and electrical parameters. The wireless signal propagation is affected by cross-section shapes, sizes, electrical parameters of the surrounding rock materials, radio operating frequencies and other factors. The radio channel is completely different from the wireless channel and we can not copy the theories on the ground. So, to carry out the study of FDTD analysis methods of the radio wave propagation characteristics inside the tunnels and other limited space, and find out the effects of the cross-section shapes, sizes, electromagnetic parameters of surrounding rock, wireless radio operating frequencies, not only can expand the way of radio wave propagation characteristics analysis inside the tunnels, broaden the application scope of the FDTD method, the research results also can be further used to numerical analyze electromagnetic problems inside the related confined space, but also has an important theoretical significance and practical value to perfect wireless transmission theory in tunnel and guide the tunnel construction of mobile communication system and transportation safety, coal and mine rescue works. The main works of this paper are as follows:works of this paper are as follows: 1. Studying a new waveguide excitation added method, this method is verified that has good waveform fidelity and universality by the calculation example.2. Studying the main modes’ attenuation rate inside the circular, rectangular and arched tunnels respectively based on the theoretical approach, and analyzing the attenuation characteristics about the tunnel cross-section shapes, sizes, radio operating frequencies and the relative dielectric constants.3. Researching the Compact-2D-FDTD algorithm, and using real-variables Compact-2D-FDTD method to analyze the wireless radio propagation characteristics of the circular, rectangular and arched tunnels. By comparing the results with the analytical solutions and verify the validity of the method.4. Researching the MPI-OpenMP hybrid parallel technology, achieving a threedimentional parallel FDTD algorithm which can be used to analyze the radio propagation characteristics inside the tunnel based on MPI-Open MP hybrid platform. To prove the correctness and effectiveness of the method.