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Decreasing the Artificial Attenuation of the RCSIM Radio Channel Simulation Software. Abigail Snyder Research Alliance in Math and Science Computational Sciences and Engineering Mentor: Jim Nutaro, PhD August 13, 2008 Oak Ridge, Tennessee. Outline. Introduction Background

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decreasing the artificial attenuation of the rcsim radio channel simulation software

Decreasing the Artificial Attenuation of the RCSIM Radio Channel Simulation Software

Abigail SnyderResearch Alliance in Math and ScienceComputational Sciences and Engineering

Mentor: Jim Nutaro, PhD

August 13, 2008

Oak Ridge, Tennessee

outline
Outline
  • Introduction
  • Background
  • Research Objective
  • Implementation
  • Results
  • Conclusions
  • Future Research
introduction
Introduction

Oak Ridge National Laboratory is currently improving the accuracy of the radio channel simulation software RCSIM by reformulating the scattering junctions that it uses to propagate a simulated radio wave

UTBOG_Computing_0801

background
Background
  • Radio waves naturally experience path loss (attenuation) as they move outward from signal source
  • Certain level of artificial attenuation in computer simulations of radio wave propagation
  • Goal to increase overall accuracy of RCSIM software in part by decreasing artificial attenuation
background1
Background
  • Radio waves (all waves) propagate in the shape of a sphere
  • Using Transmission Line Matrix method (TLM) signal is propagated forward and backward along set geometry at scattering junctions to specific number of neighboring nodes (based on geometry chosen) according to:

2/(Number of Directions)*(State of Node)-InputoppN

background2
Background
  • Three geometries for scattering junction were compared to the original rectilinear scheme:
    • tetrahedral
    • cubic-close packed
    • octahedral
background3
Background
  • Ideally, the more directions (the more neighboring nodes) to a displaced node, the more sphere-like propagation will be
  • Sphere-like propagation is denoted by lack (or at least decrease from rectilinear scheme) of directional dependencies in propagation

From Nutaro: An Event Driven Simplified TLM Method for Predicting Path-Loss

research objective
Research Objective

Find a geometry that will improve the overall accuracy of the RCSIM radio channel simulation software by decreasing the artificial attenuation from geometry by more closely mirroring the sphere shape of actual radio wave propagation

implementation
Implementation
  • Determine schemes to find neighboring nodes to displaced node for each geometry
  • Marshmallows = Science
implementation1
Implementation
  • Build free-space simulators for each geometry using C++
  • Choose points for each direction from the displacement (100, 110, 111)
  • Compare maximum states for each data point to determine error values
conclusions
Conclusions
  • Error value for the tetrahedral scheme is better than rectilinear scheme, but directional dependencies too great for practical use
  • Error value for octahedral scheme is best, though experiences inaccuracies in111 direction as edge is approached
  • Error for cubic-close packed scheme is close enough to octahedral to make it possible to implement as well, but inconsistent data presents problems
conclusions1
Conclusions
  • Goal was to determine scheme for scattering junctions that would more closely imitate sphere of wave propagation than current rectilinear scheme
  • Initially believed would be cubic-close packed scheme since has most directions/neighboring nodes using TLM method (12 compared to six for rectilinear, four for tetrahedral and eight for octahedral)
conclusions2
Conclusions
  • In reality, the octahedral scheme provided better results
  • This is most likely because octahedral scheme provides most directions while still maintaining a square, computer-friendly geometry

Cubic-Close Packed Grid

Regular Grid

future research
Future Research

Implement the octahedral scheme into RCSIM software to determine the overall improvement to results

acknowledgments
Acknowledgments

The Research Alliance in Math and Science program is sponsored by the Office of Advanced Scientific Computing Research, U.S. Department of Energy.

The work was performed at the Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC under Contract No. De-AC05-00OR22725. This work has been authored by a contractor of the U.S. Government, accordingly, the U.S. Government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes.

Thanks to Jim Nutaro, Kara Kruse and Richard Ward for their roles as mentors. Thanks to Debbie McCoy and Jacki Isaacs.

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QUESTIONS?

Questions

UTBOG_Computing_0801