Geometry-Based Channel Modeling For Visible Light Communication In Tunnel Scenarios

With the explosive growth of the number of mobile users,there is an increasing demand of bandwidth among people.Next-generation wireless communication systems should provide higher capacity to support various wireless services.However,traditional wireless spectrum resources are almost exhausted,and new spectrum resources are urgently needed.Visible light communication can provide a bandwidth of 400THz which is about 104 times as much as the RF spectrum.That is enough to alleviate this problem.The visible light communication has indoor scenarios,mine scenarios,underwater scenarios,tunnel scenarios and so on.Due to the structure characteristics of the tunnel itself,the transmission of visible light signal in the tunnel is different from other scenarios.In order to evaluate the characteristics of the tunnel visible light communication system,it is indispensable to design a concise and accurate tunnel visible light communication model.Visible light communication has a great development prospects.As one of the most irrmportant scenarios of visible light communication,the indoor scenarios have been studied by many domestic and foreign research institutions,which can lay a solid foundation for outdoor scenarios or special scenarios of visible light communication.Firstly,the paper use regular-shaped geometry-based multiple bounce(RS-GBMB)contained two single-ring and one ellipse for 2D indoor scenarios visible light communication channel modeling.The LED is modeled as Lambertian radiation model,the PD is modeled as a field of view,the two-ring is proposed to model the scatterers around the LED and PD while the ellipse is proposed to model the walls within indoor environments.Through calculate the transmission length of line-of-sight,non-line-of-sight and analysis the power delay profile,delay and other parameters of the system.The results show that the power carried by the line-of-sight in the received power accounts for a large proportion,while the on-line-of-sight accounts for a small proportion.Finally the model is verified to be practical by comparison with infrared communication experimental data.Secondly,the paper use geometry-based stochastic model for 3D tunnel scenarios visible light communication channel modeling.In order to more accurately describe the tunnel scenarios,it is necessary to consider the influence of elevation angels.Multiple LEDs are respectively modeled as Lambertian radiation models,multiple PDs are respectively modeled as a field of view,the scatterers can be classified as a series of clusters randomly distributed inside tunnel.The position of cluster can be determined by setting the mean angle of cluster and the limited cylinder itself.The elevation angels,azimuth angles and transmission distance parameters of the visible light channel can be obtained by using the position of the LED,PD and clusters.For simulation purposes,method of equal volume is applied to calculate discrete angular parameters.The results show that line-of-sight carrying power in the received power accounts for a large proportion and the non-line-of-sight ratio is small;Channel capacity increases with the growth of SNR,indicating that MIMO visible light has the possibility of large-capacity communication.The spatial correlation decreases with the rising of the transmitter or receiver array spacing,which can provides a theoretical basis for the light source layout of visible light communication.And then using OOK and PPM to estimate the error performance of the system.Finally,in terms of power delay profile and root mean square delay spread and K factor,the tunnel model is compared with indoor model.