Local Maps for Indoor Wireless Positioning
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Solution Overview
Problem
In areas where Satellite Positioning System (SPS) navigation signals are not available, such as indoors, existing methods for mobile device location estimation using wireless network elements face inaccuracies due to processing delays and signal strength variations caused by physical structures, leading to unreliable range calculations.
Innovation Solution
A system and method that utilize wireless network elements to provide local maps and annotations, allowing mobile devices to estimate their location by receiving signals from these elements, accounting for processing delays and signal strength variations through predefined relationships, and triangulating their position using a local coordinate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal strength measurement is used to estimate range to access point, then location estimation can be performed in areas without SPS signals, but signal strength varies due to physical structures causing inaccurate range estimates
Solution Approach 1:
The system performs preliminary characterization of the wireless environment by collecting signal strength measurements at known locations and storing them in a database. This pre-established database of signal characteristics is then used to compensate for variations caused by physical structures during actual location estimation, improving accuracy without requiring real-time environmental sensing.
2Measurement precision
If time of flight measurement is used to determine range to access point, then location estimation can be performed, but processing delay at access point causes inaccurate measurements
Solution Approach 1:
The system implements feedback by having the mobile device transmit a measurement message to the access point, which then provides feedback about its processing delay. The mobile device uses this feedback information to compensate for the processing delay in subsequent range calculations, transforming the delay from an error source into a correctable parameter.
3Measurement precision
If local maps with annotations are implemented to improve location accuracy, then location determination precision improves in areas without SPS signals, but system complexity increases
Solution Approach 1:
The system creates simplified copies of the physical environment in the form of local maps with annotations stored in a database. These maps contain pre-characterized information about access points, signal strengths, and processing delays for specific locations. The mobile device uses these copied environmental representations to determine location without needing to perform complex real-time environmental analysis, reducing computational complexity while maintaining 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
Enables accurate location determination within areas without SPS signals by using local maps and annotations to account for processing delays and signal strength changes, improving location estimation precision and reducing errors.
Implementation Method 1
signal strength of a signal received from the access point may be measured and a range from the mobile device to the access point may by estimated based on the measured signal strength
Implementation Method 2
A mobile device may transmit a signal to an access point and measure a length of time until a response signal from the access point is received. A range from the mobile device to the access point may be determined based upon the measured length of time
Data Source
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AI summary
The subject matter disclosed herein relates to a system and method for retrieving a local map for a given area. One or more signals wirelessly transmitted from one or more wireless network elements may be received by a mobile device. The mobile device may identify an associated local map based at least in part on the received one or more signals. The associated local map and annotations associated with the associated local map may subsequently be obtained. The associated local map utilizes a predefined coordinate system.