Time-of-Flight Location with Unmanaged WLAN Access Points
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Solution Overview
Problem
Indoor navigation systems face challenges in accurately determining location due to satellite signal inhibition and slow start-up times, especially in environments like buildings or vehicles, where traditional GPS methods are inefficient.
Innovation Solution
Implementing Time-of-Flight (ToF) measurements using unmanaged wireless local area networks (WLANs) to supplement or replace satellite signals, enabling accurate location determination through enhanced Assisted GNSS (A-GNSS) protocols that include modifications to support WLAN ToF positioning, such as OMA SUPL and OMA LPPe protocols, allowing devices to initiate ToF measurements with multiple WLAN access points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional GPS methods are used for indoor navigation, then satellite signal reception is required, but signal inhibition occurs in indoor environments
Solution Approach 1:
The patent introduces WLAN access points as intermediary objects to enable location determination in indoor environments. Instead of directly relying on satellite signals that are blocked by buildings, the system uses WLAN APs as mediators that can be received indoors. The mobile device measures ToF to multiple WLAN APs, and a server calculates the location based on these measurements, thus solving the signal inhibition problem through an intermediary positioning infrastructure.
Solution Approach 2:
The patent replaces the satellite-based mechanical positioning system with a WLAN-based electromagnetic signal system for indoor location determination. By substituting GPS satellite signals with WLAN access point signals, the system can operate effectively indoors where satellite signals are blocked, while maintaining location determination functionality through a different physical mechanism.
2Reliability
If traditional GPS methods are used, then location acquisition is possible, but start-up time is long
Solution Approach 1:
The patent implements preliminary action by having the mobile device continuously scan and maintain a list of available WLAN access points and their signal characteristics in the background, even before location determination is requested. This preliminary gathering of WLAN information allows the ToF-based location calculation to start immediately when needed, significantly reducing the start-up time compared to traditional GPS that requires satellite signal acquisition from scratch.
3Productivity
If WLAN ToF measurements are implemented, then location determination speed is improved, but device complexity increases
Solution Approach 1:
The patent extracts the complex location calculation algorithms and WLAN network management functions from the mobile device and places them on a remote server. The mobile device only needs to perform relatively simple ToF measurements and send the data to the server, which handles the computationally intensive trilateration and location calculation. This extraction of complexity reduces the burden on the mobile device while maintaining fast location determination capability.
4Adaptability or versatility
If unmanaged WLANs are used for positioning, then infrastructure requirements are reduced, but measurement precision may be affected
Solution Approach 1:
The patent implements feedback mechanisms where the mobile device measures signal characteristics (such as signal strength, timing information) from WLAN access points and reports them to the server. The server uses this feedback information to refine location calculations and compensate for variations in unmanaged WLAN environments. The system continuously receives feedback from multiple WLAN APs to improve measurement precision while maintaining compatibility with unmanaged networks.
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
This approach provides faster and more accurate location determination in indoor and challenging outdoor environments by leveraging WLAN ToF measurements, enhancing A-GNSS performance and expanding carrier/operator Location Based Services (LBS) facilities, including emergency location services.
Implementation Method 1
SETs for use outdoors typically measure the time needed for a signal to travel from a plurality of satellites that are orbiting the Earth to the device
Implementation Method 2
perform, using the information, the ToF measurements with a plurality of WLAN access points (APs) including transmitting an initiator message
Data Source
AI summary
Systems and techniques for time-of-flight (ToF) location determination with unmanaged WLAN are described herein. Information for ToF measurements may be received. The ToF measurements may be performed with a plurality of WLAN access points (APs), including transmitting an initiator message from the SET (e.g., navigation device) to the plurality of WLAN APs. Results for the ToF measurements may be gathered. The gathered results may be communicated to a position calculator to calculate a position of the SET.