Simplified ray models "Simplified ray models"are derived from deterministic ray models.however, the geometry of the multipath pattern is somehow simplified to ease the computational burden while still taking major rays into account Usually,the problem is simplified by identifying planes where most rays lie, thus resorting to a 2-dimensional(2D)approach.Such simplifications however are not rigorous since multipath propagation in urban environment is intrinsically 3D Of course 2D computation is much simpler and faster than 3D computation 2 different approaches can be identified:2D+2D (lateral plane+vertical plane ray tracing)and quasi-3D(Vertical Plane Launch,VPL ray tracing) 8 Simplified ray models • “Simplified ray models” are derived from deterministic ray models. however, the geometry of the multipath pattern is somehow simplified to ease the computational burden while still taking major rays into account • Usually, the problem is simplified by identifying planes where most rays lie, thus resorting to a 2-dimensional (2D) approach. Such simplifications however are not rigorous since multipath propagation in urban environment is intrinsically 3D • Of course 2D computation is much simpler and faster than 3D computation • 2 different approaches can be identified: 2D+2D (lateral plane+vertical plane ray tracing) and quasi-3D (Vertical Plane Launch, VPL ray tracing) 8