WLAN Access Point Selection via MMSE Variance Exclusion
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Solution Overview
Problem
Satellite-based positioning systems are ineffective for indoor positioning due to the requirement of a clear line of sight and increased costs, while existing WLAN-based systems face performance issues when access points fail to conform to applied channel models.
Innovation Solution
A WLAN positioning system that computes likelihood values and minimum mean squared error (MMSE) estimates for each access point, excluding those that increase MMSE variance, thereby selecting the most accurate set of access points for positioning based on channel model conformance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all visible access points are used for positioning, then the quantity of positioning data increases, but positioning accuracy deteriorates due to non-conforming access points increasing MMSE variance
Solution Approach 1:
The system performs preliminary evaluation of each access point by computing likelihood values and MMSE variance contributions before final positioning. This preliminary action identifies and excludes access points that would degrade positioning accuracy, ensuring only high-quality access points are used in the final position calculation.
Solution Approach 2:
The positioning system automatically evaluates and selects appropriate access points without external intervention. The system computes likelihood values, determines MMSE variance contributions, and autonomously excludes problematic access points, making the selection process self-service and eliminating manual configuration requirements.
2Measurement precision
If access points are selectively excluded based on MMSE variance, then positioning accuracy improves, but computational complexity increases
Solution Approach 1:
The system computes likelihood values and MMSE variance for only the necessary subset of access points rather than all possible access points. By performing partial evaluation focused on visible access points and using probabilistic filtering, the system achieves accurate positioning while reducing unnecessary computational energy consumption.
Solution Approach 2:
The system dynamically changes the parameter set used for positioning by computing likelihood values and MMSE variance contributions for each access point. Based on these computed parameters, the system adaptively selects which access points to include or exclude, optimizing the balance between positioning accuracy and computational energy consumption.
3Measurement precision
If satellite positioning systems are used, then positioning accuracy improves, but indoor positioning capability deteriorates due to line of sight requirements
Solution Approach 1:
The system provides universal positioning capability that works both indoors and outdoors by using WLAN access points instead of satellite signals. The access point selection mechanism with likelihood computation and MMSE variance evaluation enables accurate positioning in indoor environments where satellite signals are blocked, while maintaining compatibility with outdoor positioning scenarios.
Data Source
AI summary
Apparatus and method for positioning a device based on wireless local area network signals. In one embodiment, a wireless local network positioning system includes access point selection logic. The access point selection logic includes likelihood computation logic, minimum mean squared error (MMSE) estimation logic, variance computation logic, and access point exclusion logic. The likelihood computation logic is configured to compute a likelihood value for each access point and point of a positioning grid. The MMSE estimation logic is configured to compute an MMSE estimate based on the likelihood values. The variance computation logic is configured to compute an MMSE variance for the MMSE estimate. The access point exclusion logic is configured to determine whether excluding a selected one of the access points reduces the MMSE variance, and to exclude the selected access point from the access points used for positioning, based on the exclusion reducing the MMSE variance.