Propagation Loss Modeling With Terrain and Clutter for Spectrum Sharing
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Solution Overview
Problem
Existing radio frequency propagation models fail to account for clutter heights, leading to inaccurate interference predictions and inefficient spectrum allocation in shared spectrum wireless systems, particularly in environments with significant clutter such as buildings and vegetation.
Innovation Solution
Incorporating high-fidelity obstruction height values by combining terrain and clutter information to determine diffraction and tropo-scattering losses, enabling more accurate propagation path loss calculations and spectrum usage decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If terrain-only models are used for propagation loss calculation, then the calculation process is simple, but the interference prediction accuracy deteriorates
Solution Approach 1:
The patent combines terrain height data with clutter height data to create a composite propagation loss model. This merging of multiple data sources (terrain and clutter) resolves the contradiction by maintaining computational simplicity while significantly improving interference prediction accuracy through the inclusion of additional environmental factors that were previously ignored.
Solution Approach 2:
The patent creates a composite propagation model that integrates multiple components: free space path loss, terrain-based diffraction loss, and clutter-based obstruction loss. This composite approach allows the system to maintain the mathematical simplicity of individual models while achieving superior predictive accuracy through the synergistic combination of multiple physical phenomena.
2Device complexity
If clutter heights are not accounted for in propagation models, then the model structure remains simple, but the spectral efficiency deteriorates
Solution Approach 1:
The patent performs preliminary characterization of clutter environments by collecting and storing clutter height data before propagation loss calculations are performed. This advance preparation allows the model to quickly incorporate clutter effects during spectrum allocation decisions without adding significant computational complexity to the real-time operation, thereby improving spectral efficiency.
Solution Approach 2:
The patent applies clutter height considerations selectively at specific locations along the propagation path where clutter objects are present, rather than uniformly across the entire environment. This localized approach maintains model simplicity in open areas while accurately accounting for clutter effects in built-up or vegetated regions, optimizing spectral efficiency without excessive complexity.
3Loss of time
If terrain-only models are used for spectrum allocation, then the allocation process is fast, but the network capacity deteriorates
Solution Approach 1:
The patent divides the propagation loss calculation into distinct segments: free space loss component, terrain-based diffraction component, and clutter-based obstruction component. This segmentation allows each component to be calculated using optimized algorithms appropriate to its physical basis, maintaining overall computational speed while improving the accuracy of interference predictions that directly impact network capacity decisions.
4Power
If diffraction and tropo-scattering losses are not calculated for large scattering angles, then the computational load is reduced, but the interference prediction accuracy deteriorates
Solution Approach 1:
The patent modifies the diffraction and tropo-scattering loss calculations to accommodate large scattering angles by transforming the input parameters (scattering angles greater than one degree) into a form suitable for the ITM propagation model equations. This parameter transformation allows the use of established computational methods while accurately capturing the physics of large-angle scattering effects that occur in cluttered environments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances network capacity and spectral efficiency by allowing more precise interference predictions and optimized spectrum allocation, reducing conservative access decisions based on inaccurate terrain-only models.
Implementation Method 1
determining a third radio frequency propagation loss for a second portion of the first radio frequency propagation path, said third radio frequency propagation loss including: (i) a loss from radio frequency propagation diffraction
Implementation Method 2
determining a third radio frequency propagation loss for a second portion of the first radio frequency propagation path, said third radio frequency propagation loss including: (ii) a loss from radio frequency propagation tropo-scattering
Data Source
AI summary
The present invention relates to methods and apparatus for determining propagation loss between a transmitter and a receiver using terrain and clutter data and/or the utilization of the determined propagation loss for managing spectrum usage. An exemplary method includes the steps of: determining a free space loss (FSL) for a propagation path extending from a first endpoint to a second endpoint, determining a clutter loss for a first portion of the propagation path, the first portion of the propagation path extending from the first endpoint to a horizon point which is located atop of clutter, determining a diffraction or tropo-scattering loss for a second portion of the propagation path extending from the horizon point to the second endpoint; generating a total loss for the propagation path based on the FSL, the clutter loss, and the diffraction or tropo-scattering loss; and making a spectrum usage decision based on the total loss.