WLAN Speed Estimation via Dynamic Signal Strength Variation
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Solution Overview
Problem
Current WLAN positioning systems are ineffective in wide-area deployments due to the inability to conduct detailed site surveys and reliance on constant communication channels, and they struggle with accurately estimating speed and direction of travel due to shadowing and multi-path effects, especially in outdoor environments.
Innovation Solution
A method for estimating speed and direction of travel using WLAN access points, which involves receiving and analyzing signal strengths and characteristics from multiple access points, accessing a reference database to determine geographical locations, and calculating speed and direction based on signal variations and position estimations over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If indoor WLAN positioning algorithms are used for outdoor wide-area deployment, then positioning functionality is provided, but accuracy deteriorates due to fundamentally different outdoor radio propagation characteristics
Solution Approach 1:
The patent changes the fundamental parameters of the positioning algorithm from indoor to outdoor environments. Instead of using indoor algorithms that rely on detailed site surveys and constant communication channels, the patent uses outdoor-appropriate algorithms that work with metropolitan-wide WLAN access points and account for outdoor radio propagation characteristics, thereby resolving the contradiction between adaptability and precision
2Measurement precision
If detailed site surveys are conducted for every square foot of the campus, then positioning accuracy is improved to 1-3 meters, but deployment complexity and cost increase significantly for wide-area scenarios
Solution Approach 1:
The patent extracts the requirement for detailed site surveys from the positioning system. Instead of requiring comprehensive indoor site surveys for every square foot, the patent uses a simplified approach that leverages existing metropolitan WLAN access points and their broadcast information, eliminating the need for extensive manual surveying while maintaining positioning functionality
Solution Approach 2:
The patent makes the positioning system universal by using widely-deployed WLAN access points that already exist throughout the metropolitan area. These access points serve multiple functions: they provide wireless networking and simultaneously serve as positioning references, eliminating the need for dedicated positioning infrastructure and reducing deployment complexity
3Reliability
If constant communication channels are required between access points and client radios, then synchronization information can be exchanged, but system reliability deteriorates in wide-area deployments where such constant connection cannot be guaranteed
Solution Approach 1:
The patent performs preliminary actions by using WLAN access points that continuously broadcast their information (SSID, BSSID, signal strength) regardless of whether a client is present. This preliminary broadcasting ensures that synchronization and positioning information are always available when needed, without requiring constant bidirectional communication channels
Solution Approach 2:
The positioning system is self-service in that it uses the inherent broadcast capabilities of WLAN access points to provide positioning information. The access points automatically transmit their identification and signal strength information without needing to be prompted or maintained by client devices, ensuring continuous availability of positioning data
4Ease of operation
If indoor positioning algorithms are used for speed and bearing estimation, then speed estimation can be provided, but accuracy deteriorates due to shadowing and multi-path effects in outdoor environments
Solution Approach 1:
The patent changes the parameters used for speed and bearing estimation from indoor-appropriate metrics to outdoor-appropriate metrics. Instead of relying on signal strength variations that are heavily affected by indoor shadowing and multi-path effects, the patent uses observation periods and signal strength variations that are specifically suited for outdoor metropolitan environments, improving both ease of operation and 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 and continuous estimation of speed and direction of travel in a WLAN-based location service, even in metropolitan areas, by leveraging the proliferation of WLAN access points and their radio wave propagation characteristics, improving upon existing methods that are limited by indoor radio propagation algorithms and require constant communication channels.
Implementation Method 1
receiving signals transmitted by Wi-Fi access points in range of the Wi-Fi enabled device
Implementation Method 2
using the dynamic signal strength variation of multiple WLAN access points to estimate a speed of travel
Data Source
AI summary
A method for estimating the speed and bearing of a Wi-Fi enabled device using WLAN radio signals in a WLAN based location service is provided. A method used to estimate a speed of travel of a Wi-Fi enabled device comprises the Wi-Fi enabled device receiving signals transmitted by Wi-Fi access points in range of the Wi-Fi enabled device, and using the signals to estimate the speed of and/or direction of travel of the Wi-Fi enabled device.