Environment databases 。 Deterministic models require detailed environment databases Geometric Terrain Buildings Material param's Electro (vegetation) magnetic 2467500 Hong Kong Paris
Environment databases • Deterministic models require detailed environment databases Hong Kong Paris Terrain Buildings (vegetation) Material param’ s 6
Environment database issues Good environment databases can be expensive(not true for the future) Environment databases are difficult to handle by non-expert personnel Environment databases are often not very accurate(precision of 0.5m for horizontal coordinates and 1 to 5 m for vertical coordinates) Major limitation for ray models
Environment database issues • Good environment databases can be expensive (not true for the future) • Environment databases are difficult to handle by non-expert personnel • Environment databases are often not very accurate (precision of 0.5m for horizontal coordinates and 1 to 5 m for vertical coordinates) Major limitation for ray models 7
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
Ex:2D+2D ray model In the vertical plane either a real 2D ray BS tracing or an ORT model is applied Mobile BS In the lateral plane a 2D ray tracing is performed Mobile 9
Mobile BS BS Mobile Ex: 2D+2D ray model • In the vertical plane either a real 2D ray tracing or an ORT model is applied • In the lateral plane a 2D ray tracing is performed 9
Deterministic ray models:trends Speed up techniques to decrease CPU time,e.g.parallelization on Graphical Processing Units A-priori determination of computation parameters,"active"database area and ray selection Exploitation of the multidimensional prediction potential Integration of statistical elements into the deterministic model such as diffuse scattering 10
• Speed up techniques to decrease CPU time, e.g. parallelization on Graphical Processing Units • A-priori determination of computation parameters, “active” database area and ray selection • Exploitation of the multidimensional prediction potential • Integration of statistical elements into the deterministic model such as diffuse scattering Deterministic ray models: trends 10