Study On The Propagation Characteristics Of Mobile Communication Radio Waves In Tunnels Based On The Method Of SBR/Image

Mobile communication technology is developing rapidly, and it is playing an increasinglyimportant role in our daily life. The studies of radio wave propagation characteristics in the mobilecommunication frequency bands are causing more and more attention, and it becomes one of thehotspots in the field of radio wave propagation. Tunnels are common environments in daily life, andthe propagation characteristics of mobile communication frequency bands in tunnels has importanttheoretical significance and practical value. In this thesis, the propagation characteristics of mobilecommunication frequency bands in complex tunnel are studied based on the method of Shootingand Bouncing Ray/Image. Using the Wireless InSite software to model and simulate, then thepropagation characteristics of mobile communication frequency bands are obtained, such asreceived power, delay spread, multipath propagation, Doppler frequency shift and so on. This canprovide an effective theoretical basis for the design and coverage of mobile communication systemsin tunnels.The main contents and contributions of this thesis are as follows:(1) The basic theory of ray tracing methods is described, and the realizations of the propagationcharacteristics of waves in tunnels based on the method of SBR/Image are introduced in detail.At the same time, the formula of field strength considering polarization is given.(2) Using Wireless InSite software based on the method of SBR/Image, the simulation is carriedout successfully. And the measurement results of wave propagation characteristics in theliteratures are compared with it in good agreement, then the correctness of SBR/Image has beenvalidated.(3) The propagation characteristics of mobile communications frequency bands in a typical long,straight tunnel have been simulated, and the propagation characteristics are obtained, such asreceived power, delay spread, multipath propagation, Doppler shift and so on.(4) Considering the practicability of the simulation, the propagation characteristics of radio wave intunnels with cars are studied.The results of simple tunnels and tunnels with cars are comparedwith each other. Meanwhile, the signals of900MHz and2400MHz in two different frequencybands are compared and analyzed.(5) In the curved tunnels, the distribution of received power and the angle of arrival are studied, onthe condition of non-line-of-sight propagation. Then the horizontally polarized wave andvertically polarized wave are simulated and compared with each other. The bending of tunnels and polarization effects on the tunnel signal quality are researched.