WLAN Positioning via Ping Event Sorting
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Solution Overview
Problem
Current location determination methods in WLANs, such as GPS, are vulnerable to outages and may not provide the desired level of accuracy or are overly expensive, especially in satellite-based systems.
Innovation Solution
The method involves generating and sorting ping event values from transmit and receive count stamps in a WLAN to determine clock rate and location solutions, using a space-time calibration unit to track transmit and receive delays, thereby providing precise positioning solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If satellite-based GPS systems are used for location determination, then global coverage and navigation capability are provided, but vulnerability to outages and high cost occur
Solution Approach 1:
The patent introduces an intermediary wireless local area network (WLAN) infrastructure as a mediator between satellite-based GPS systems and mobile devices. The WLAN-based positioning system uses access points and wireless nodes to provide location determination independently of satellite systems, thereby reducing vulnerability to GPS outages while maintaining reliable location services through a alternative communication pathway
Solution Approach 2:
The patent segments the monolithic satellite-based positioning approach into a distributed WLAN-based positioning system. Instead of relying on a single satellite constellation, the system divides positioning functionality across multiple wireless access points and nodes within local networks, creating redundant pathways for location determination that enhance reliability and reduce dependency on any single infrastructure
2Measurement precision
If satellite-based GPS systems are used for location determination, then global navigation service is provided, but high cost occurs
Solution Approach 1:
The patent replaces expensive satellite-based positioning infrastructure with relatively inexpensive WLAN-based infrastructure. The system uses standard wireless access points and mobile device wireless interfaces that are already widely deployed, eliminating the need for costly satellite receivers and reducing system implementation costs while maintaining sufficient location accuracy for local positioning applications
Solution Approach 2:
The patent makes the WLAN infrastructure serve multiple functions: it provides both wireless communication for data transmission and positioning for location determination. By utilizing the existing wireless network infrastructure for dual purposes, the system eliminates the need for separate dedicated positioning hardware, thereby reducing overall system cost while maintaining measurement precision through the same multi-functional wireless channels
3Measurement precision
If ping event values are sorted and processed to determine clock rate and location solutions, then precise positioning solutions are achieved, but increased computational processing is required
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing clocks among WLAN nodes using ping event exchanges before actual positioning measurements are taken. This preliminary clock synchronization establishes a common time reference that simplifies subsequent positioning calculations, reducing the computational complexity of determining location solutions while maintaining high positioning accuracy through pre-established temporal coordination
Data Source
AI summary
The location of one or more mobile nodes in a wireless local area network (WLAN) is determined. Nodes in the WLAN include respective ping drivers to generate ping event values related to transmit count stamps and receive count stamps for wireless messages exchanged between the nodes. Each wireless message is associated with a transmit offset corresponding to an expected transmit time. A sorting module groups the ping event values and produces a difference between the respective receive count stamps and the transmit count stamps for each wireless message. Based on the sorted ping event values, the sorting module generates transmit offset values relating to the transmit offsets. A space-time calibration unit generates, from the sorted differences and the transmit offset values, a clock rate solution and a location solution for at least one of the nodes in the WLAN.