LOS Detection in Cellular Networks via Ricean Factor and RMSE
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Solution Overview
Problem
Existing LOS detection mechanisms in cellular communications networks are unreliable, especially in complex environments with varying mobility, distance, and propagation scenarios, due to issues like multi-path propagation and the need for known transmitter and receiver locations.
Innovation Solution
A network node in the cellular communications network determines LOS by comparing the Ricean factor and Root Mean Squared Error (RMSE) of the wireless communications channel with predetermined thresholds, and optionally using best-fit analysis of Rayleigh PDFs and signal strength correlations to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TOA and DOA-based positioning techniques are used, then positioning accuracy is improved, but reliability deteriorates in multi-path propagation environments
Solution Approach 1:
The system performs preliminary LOS detection by analyzing signal characteristics (Ricean factor, RMSE) before executing TOA/DOA positioning. This preliminary assessment ensures that positioning calculations are only performed when LOS conditions are confirmed, preventing unreliable results in multi-path environments while maintaining high accuracy when conditions are favorable.
Solution Approach 2:
The patent introduces LOS detection as an intermediary mechanism between signal reception and positioning calculation. By using Ricean factor and RMSE as intermediate indicators to assess channel conditions, the system mediates between the raw signal data and the final positioning result, ensuring reliability by filtering out multi-path contaminated measurements.
2Measurement precision
If Ricean factor and RMSE comparisons are performed, then LOS detection accuracy is improved, but device complexity increases
Solution Approach 1:
The system transforms the complex problem of LOS detection into comparisons of two derived parameters (Ricean factor and RMSE) against predetermined thresholds. By changing the problem representation from direct geometric LOS verification to statistical parameter comparison, the system achieves high detection accuracy while maintaining relatively simple processing requirements.
Solution Approach 2:
The patent replaces complex geometric and spatial analysis mechanisms with statistical signal processing methods. Instead of mechanically tracking signal paths or performing complex channel modeling, the system substitutes these with computations of Ricean factor and RMSE, which are mathematically simpler to calculate and compare against thresholds.
3Ease of operation
If prior LOS detection mechanisms are used, then implementation is simplified, but reliability deteriorates in unknown location scenarios
Solution Approach 1:
The system enables the wireless device to perform self-service LOS detection using its own received signal measurements. The device independently calculates Ricean factor and RMSE from its received signals without requiring external assistance or pre-known location data, making the solution both easy to implement and reliable in scenarios where locations are unknown.
Data Source
AI summary
Systems and methods for detecting a Line of Sight (LOS) in a cellular communications network are provided. In one embodiment, a network node in the cellular communications network determines whether a wireless device is within LOS of a base station. In order do so, the network node compares a Ricean factor of a wireless communications channel between the base station and the wireless device and a predetermined Ricean factor threshold for LOS detection. In addition, the network node compares a Root Mean Squared Error (RMSE) between a Rayleigh probability density function and samples of received signal strength for radio signals transmitted between the base station and the wireless device and a predetermined RMSE threshold for LOS detection. The network node then determines whether the wireless device is within LOS of the base station based on results of the comparisons.