New Modeling Procedure for Indoor/Outdoor Propagation Environments in Micro- and Pico-Cell Wireless Communication Systems

University Of Utah, Salt Lake City UT

Investigators

Abstract

0102253 Iskander With this proposal the PI's respectfully request NSF support to develop a detailed, accurate, and computationally efficient propagation model for wireless communications in micro- and pico-cell systems. A new 3D model [or alternatively a 2D model with advanced calculation capabilities such as the vertical-plane-launch (VPL) technique] will be developed based on integrating three new and innovative approaches to improve calculation accuracy and increase the computational efficiency. This includes the use of the following: 1. A new unstructured triangular grid ray tracing method (TGRM) to provide significant savings in computational time when modeling outdoor regions. Preliminary results show that CPU time for the TGRM method is approximately 30% of that of the visibility ray tracing. 2. A space division procedure based on a uniform rectangular grid method (URGM) for indoor regions and assuming that the reflection/transmission surfaces coincide with the grid lines. Preliminary results show that the CPU time for the proposed uniform grid method for indoor propagation regions is approximately 14% of that of the visibility ray tracing method. 3. An FDTD approach to calculate reflection (F ) and transmission (F ) coefficients of composite walls and incorporate these coefficients in the overall ray tracing code. This is important for short range signal prediction where average or effective values of materials properties of walls may provide inaccurate predictions. The multigrid Finite Difference Time Domain (multigrid FDTD) code will also be used to calculate diffraction coefficients from indoor and outdoor objects that are difficult to model analytically. Diffraction coefficient results will be incorporated with a 3D ray tracing code that implements the proposed procedures described above. Diffraction coefficients will be included as part of the program in the form of a database and look-up tables. 4. The development of the 3D version of the proposed ray tracing code will be based on using pyramidal or tetrahedral cells in the TGRM procedure, and solid rectangular cells in the URGM method. The proposed methods do not involve search algorithms and hence significant improvement in the computational efficiency is expected. The overall results from the developed new propagation model will be validated experimentally on scaled models in the 60'x40'x23' indoor antenna range available at the University of Utah. Scaled models will be carefully selected so as to present physical structures of interest, on the one hand, and an object that can be used as a building block towards the development of a fully understandable and physics-based propagation model, on the other. With the available experimental facilities (HP8510 up to 40 GHz), it will be possible to use scale factors as large as 20 to model realistic structures at the higher frequencies (2GHz) presently being used in terrestrial wireless communication systems. In addition to the development of the deterministic EM-based propagation model, the PI's propose to use the calculated EM power distribution pattern to determine statistical parameters that may be used in the simulation of wireless communications systems. This includes calculations of coverage, delay spread, bit error rate, and angle of arrival. The project will involve two graduate students to work on the simulation part of the project, and one additional graduate student together with a team of undergraduate senior students to work on building the scaled models and conducting the experimental verification part of the project.