Indoor WLAN Positioning Signal Reflection Filtering
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Solution Overview
Problem
WLAN positioning methods in indoor environments are vulnerable to signal reflection, leading to significant errors in positioning precision due to the impact of reflections on signal propagation.
Innovation Solution
A method and system that determine whether signals between access points and terminals are affected by reflection by comparing measured and calculated RSSI or signal propagation values within a preset threshold, using a propagation model to select reliable access points for accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If WLAN positioning methods (TOA, TDOA, RSSI-based) are used in indoor environments, then positioning service can be provided, but positioning precision deteriorates due to signal reflection impact
Solution Approach 1:
The patent applies preliminary action by pre-calculating expected RSSI values using a propagation model before actual positioning. The system compares measured RSSI values with these pre-calculated expected values to identify and exclude reflected signals, thereby improving positioning precision while maintaining service availability
Solution Approach 2:
The patent introduces an intermediary mechanism - a propagation model - that acts as a mediator between the measured signal values and the positioning calculation. This model provides expected signal strength values that help distinguish direct signals from reflected signals, resolving the contradiction between service availability and precision
2Ease of operation
If signal propagation time information is used for positioning calculation, then positioning can be performed, but positioning accuracy deteriorates when signals are affected by reflection
Solution Approach 1:
The patent implements feedback by comparing measured RSSI values with expected RSSI values calculated from propagation models. This feedback mechanism identifies signals affected by reflection, allowing the system to exclude these signals from positioning calculations, thereby maintaining operational simplicity while improving accuracy
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
Improves the precision of terminal positioning by identifying and excluding signals affected by reflection, thereby enhancing the accuracy of indoor WLAN positioning.
Implementation Method 1
The difference between the two time values is the propagation duration of radio waves in the air. The speed of radio waves propagated in the air is the light velocity c.
Implementation Method 2
WLAN positioning methods are vulnerable to impact of reflection indoors, which affects positioning precision and leads to considerable errors in positioning results.
Data Source
AI summary
The present invention provides a positioning method, device and system, which are applied to indoor WLAN positioning. A positioning server obtains location service information of APs in a set of APs to be measured; selects three APs to be measured in the set of APs to be measured according to a preset rule, and calculates a first coordinate of a terminal; if a calculated RSSI value of an unmeasured AP is not smaller than a difference between the measured RSSI value and a preset threshold, determines that signals of the unmeasured AP are not affected by reflection; and uses the first coordinate as a location coordinate of the terminal if all the three APs to be measured have been measured, thereby positioning the terminal.