• 
  • News
  • About
  • Contact
  • Location
• 
  • Alumni
  • People
• 
  • Projects
  • Software
  • Gallery
• 
  • Articles
  • Libraries
• 
  • Topics for Student Projects
  • Lectures
  • Computer-Aided Geometric Design
  • - Photorealism
  • - Design and Implementation
  • - Simulation and Animation
  • - Digital Libraries
  • - AK Computer Graphics
• 
  • Dave
  • HEyeWall
  • Davelib
  • Multitouch

• 
  • Extended Search

User: anonymous

---

some links

Radio Wave Propagation (CARPET)

Prof. Dr. D. Fellner, Norbert Schenk

Computer Graphics and Knowledge Visualization, Graz University of Technology, Austria

The Idea

The CARPET project (CAlculation of Radio Propagation Employing a Threedimensional model) investigates whether and how modern methods of computer graphics can be employed to improve existing simulation models for radio wave propagation in the GHz band. While the frequency of light is almost a million times larger, there are some common features:

• The wave length is still small enough to justify the ray model. Effects like reflection and transmission can thus be simulated in a similar way.
• To achieve a high simulation speed, the model should be as simple as possible. Many advances in computer graphics are based on simplifying the light propagation model in the right places. The basic ideas should prove useful for other wave lengths, too.
• 3-D simulation models are based on a geometrical description of the environment. Suitable data structures have been developed in computer graphics which also meet the requirements of radio wave propagation.

Yet the different wave lengths and applications prevent a direct transfer of the results:

• Diffraction cannot be neglected with wavelengths of several inches. Sometimes even polarization and phase have to be considered.
• The relevant surface properties differ. As a consequence, scene descriptions developed for visualization cannot be used in radio wave propagation without proper extensions.
• Instead of the image of a virtual camera the desired output is the resulting field strength distribution. This affects the way rays are being traced.

Thus solutions from computer graphics have to be adapted and new algorithms have to be developed to meet the requirements. On the other hand methods of geometric modeling and ray intersection computation can be used with little or no modifications.

The Results

By improving the simulation model and employing modern rayacceleration techniques the simulation speed has been brought to a point where a usual PC can compute the field strength distribution for a typical citymodel in a few minutes. With the antenna below the average roof top -- which is a usual case in reality -- computation times are in the near-interactive rates.

On top of that the gain in simulation speed allows for a larger number of propagation paths to be considered, which often eliminates the need to supplement the results with a less exact, two-dimensional approximation model as it is used in most existing solutions.

The modular architecture makes CARPET a tool box that significantly simplifies the improvement of the simulation model and the realization of new methods. Though important goals have already been reached, CARPET is first of all a starting point -- a base has been designed for future ideas to build upon.

Nevertheless together with our project partner T-Mobile we have sucessfully applied for a patent and CARPET is currently a part of the widely used Mobile Radio Network Planning System Pegasos.