Wireless LAN Location Inference via Association Requests
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Solution Overview
Problem
Existing wireless local area networks (WLANs) face challenges in accurately determining the location of mobile units seeking association, which hinders secure access control and efficient resource allocation within designated service areas.
Innovation Solution
A method is introduced where association requests from mobile units are recorded across multiple access points, using signal strength and time-based measurements to infer the mobile unit's location, allowing authorized access only if within the designated area, and employing NACK signals to determine range, thereby controlling access and denying unauthorized attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If association requests are denied to determine location, then security is improved, but access control efficiency deteriorates
Solution Approach 1:
The system performs preliminary location inference by recording association requests from multiple access points before making an access decision. This preliminary action of gathering location data from multiple APs enables the system to determine whether the mobile unit is within the service area, allowing authorized units to eventually gain access while denying unauthorized ones, thus resolving the contradiction between security and access control efficiency.
2Measurement precision
If location inference uses multiple access points, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The cell controller performs multiple functions: it manages association requests, records location information from multiple access points, infers mobile unit locations, and makes access decisions. By making the cell controller universal and multi-functional, the system achieves precise location measurement through multiple APs without proportionally increasing overall network complexity, as these functions are integrated into the existing controller architecture.
3Measurement precision
If NACK signals are used to determine range, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system uses the association request message itself as a carrier for location information. By recording the association requests that mobile units send to multiple access points, the system extracts location data without requiring separate measurement messages. This copying approach allows range determination through the existing association protocol, achieving measurement precision while minimizing additional time loss compared to dedicated measurement procedures.
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 method effectively denies access to unauthorized units outside the service area, enhances security, and optimizes access point assignment by accurately determining mobile unit locations without requiring hardware changes, using software updates in access points, RF Ports, and cell controllers.
Implementation Method 1
The time between the directed signal and the ACK signal is determined thereby to determine range to the mobile unit from the access point
Implementation Method 2
determining received signal strength, wherein recording includes recording data corresponding to signal strength, and wherein inferring a location comprises inferring location based on the signal strength data
Data Source
AI summary
Association request messages received by one or more access points of a wireless local area network are used to infer the location of a mobile unit requesting association. Association may be refused for security purposed if it is determined that the mobile unit is not within an area services by the wireless network. In addition the inferred location can be used to assign the mobile unit to an access point for association.