LOS Signal Detection Using Polarization Intensity Measurements
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Solution Overview
Problem
Existing methods for determining line of sight (LOS) in communication systems face inaccuracies when signal propagation occurs through non-line of sight (NLOS) paths, leading to errors in distance estimation and location triangulation due to multiple signal reflections.
Innovation Solution
A method and system for determining LOS by exchanging reference signals with different polarizations, measuring channel impulse responses, and comparing intensities of first arrival paths to distinguish between LOS and NLOS transmissions, using binary or multiple level indicators for confidence assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ToF-based distance estimation is used, then distance can be calculated from signal propagation time, but location estimation becomes inaccurate when NLOS paths are present
Solution Approach 1:
The system performs preliminary LOS determination before distance estimation by analyzing polarization characteristics of received signals. This preliminary classification allows the system to identify reliable LOS paths and exclude unreliable NLOS paths from subsequent distance calculations, thereby improving overall location estimation reliability
Solution Approach 2:
The system changes the parameter used for path characterization from simple time-based metrics to polarization-based metrics. By measuring polarization intensity differences across multiple receiving resources and comparing them against thresholds, the system can distinguish LOS from NLOS paths more reliably, resolving the contradiction between measurement precision and reliability
2Adaptability or versatility
If multiple signal copies from different paths are received, then signal reception is possible in NLOS conditions, but distance estimation errors increase due to reflected paths
Solution Approach 1:
The system segments the received signal copies into distinct LOS and NLOS categories based on polarization characteristics. By separating these path types and applying different processing rules (using only LOS paths for distance estimation), the system maintains signal reception versatility while eliminating distance estimation errors from NLOS paths
Solution Approach 2:
The system introduces polarization intensity analysis as an intermediary mechanism between signal reception and distance estimation. This intermediary step classifies signal paths and filters out NLOS copies before they can corrupt distance calculations, allowing the system to benefit from multiple signal copies while maintaining accuracy
3Measurement precision
If LOS determination procedures are implemented, then accurate distance estimation is achieved, but device complexity increases due to additional measurements and processing
Solution Approach 1:
The system uses polarization measurements that serve multiple functions: they characterize the channel for LOS determination, provides information for signal processing, and enable distance estimation. This multi-functionality reduces the need for separate dedicated LOS detection mechanisms, thereby limiting the increase in device complexity while achieving accurate distance estimation
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 ranging and positioning accuracy by correctly identifying LOS signals, reducing errors in distance estimation and enabling precise location determination through triangulation.
Implementation Method 1
a first set of electromagnetic (EM) wave signals with a first polarization and a second set of EM wave signals with a second polarization different from the first polarization are transmitted by the transmitter
Implementation Method 2
measuring an intensity of a first received EM wave signal from a first direction and an intensity of a second received EM wave signal from a second direction
Data Source
AI summary
A method performed by a first device includes communicating, by the first device, with a second device, a line of sight (LOS) determination request including a LOS indicator indicating that a LOS procedure is used in LOS characterization of a transmission between the first device and the second device; transmitting, by the second device, a first set of reference signals, via a first plurality of transmitting resources; and measuring, by the first device, a second set of reference signals, transmitted by the second device, via a second plurality of receiving resources. This method comprises of both embodiments when there is LOS characterization transmission between the first device and the second device, and when there is no LOS characterization transmission between the first device and the second device.