Tomographic Signal Loss Estimation for Shared Spectrum Allocation
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Solution Overview
Problem
Accurately determining RF signal power loss in wireless communication is challenging due to environmental variables, leading to inefficient resource allocation in shared spectrum systems, especially when signals propagate through structures like buildings, where free space estimates are often inaccurate.
Innovation Solution
Generating attenuation profiles based on measured RF signal losses using sounding signals from known transmitters, such as GPS satellites, to estimate signal loss values in three-dimensional models, allowing for more precise allocation of shared spectrum resources and improved radio coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If free space estimates are used for RF signal propagation, then device complexity is reduced, but measurement precision deteriorates due to inaccurate power loss determination
Solution Approach 1:
The system uses measured RF signal power levels from the environment as feedback to generate attenuation profiles. These profiles are then applied to adjust free space propagation estimates, creating a feedback loop that improves accuracy without significantly increasing system complexity. The measured data from the receiver is fed back into the propagation model to refine predictions.
Solution Approach 2:
The patent applies attenuation profiles selectively to specific frequency ranges and propagation scenarios where structural interference is significant. Rather than completely replacing free space estimates, the system applies partial corrections based on measured data, achieving improved accuracy only where needed while maintaining the simplicity of free space modeling for other cases.
2Measurement precision
If measured RF signal losses are used to generate attenuation profiles, then measurement precision is improved, but loss of time increases due to extended measurement and processing requirements
Solution Approach 1:
The system performs preliminary measurements of RF signal power levels from multiple directions to pre-generate attenuation profiles before actual spectrum allocation decisions are made. This preliminary action allows the profiles to be ready in advance, reducing the time required during actual resource allocation operations. The measurement phase is separated and completed beforehand.
Solution Approach 2:
The patent combines measurements from multiple sounding signals and directions into a single integrated attenuation profile. By merging multiple data sources and measurements into one comprehensive profile, the system reduces the total number of separate measurements needed and consolidates processing time, achieving accurate profiles more efficiently.
3Productivity
If free space propagation estimates are used, then productivity is maintained through quick resource allocation, but reliability deteriorates due to inaccurate interference predictions
Solution Approach 1:
The system applies attenuation profiles selectively to frequency ranges and propagation conditions where structural interference is significant, rather than applying corrections universally. This partial application maintains quick allocation for cases where free space estimates are sufficient while improving reliability only where needed, preserving productivity while enhancing accuracy for critical scenarios.
Solution Approach 2:
The attenuation profile acts as an intermediary between the simple free space propagation model and the complex reality of environmental interference. Rather than directly using complex measurements for every allocation decision, the profile serves as a pre-processed mediator that captures environmental effects, allowing quick allocations with improved reliability through this intermediate representation.
Data Source
AI summary
Determination of a signal loss profile relative to a receiver based on measured signal power of a sounding signal from a sounding transmitter having a known signal power in free space relative to the receiver. The signal loss profile may include a plurality of signal loss values corresponding to a plurality of received sounding signals at the receiver. In an embodiment, the sounding signal may comprise a GNSS navigational signal (e.g., a GPS signal). The signal loss profile may be used to extrapolate signal loss for a transmitter collocated with the receiver. In turn, the signal loss profile may be used in conjunction with a shared spectrum system to model a signal propagation from the collocated transmitter when determining allocation of a shared spectrum resource of the shared spectrum system.