Wi-Fi Path Construction Under MAC Randomization
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Solution Overview
Problem
MAC address randomization in mobile devices disrupts the continuity of tracking paths, making it challenging to analyze user behavior and preferences over time, as probe requests with different addresses are fragmented and uncorrelated.
Innovation Solution
A method that groups probe requests with the same virtual MAC address to form segments, using Information Elements (IEs) as fingerprints and sequence numbers to construct and recover the paths of mobile devices, allowing for the concatenation of segments and derivation of longer-term statistics such as dwell time and user trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MAC address randomization is implemented to protect user privacy, then user privacy is improved, but path continuity for tracking and analytics deteriorates
Solution Approach 1:
The patent introduces an intermediary mapping system that associates randomized MAC addresses with their original physical MAC addresses through a mapping table. This intermediary structure allows the system to maintain path continuity for analytics while preserving user privacy, as the mapping enables correlation of probe requests without exposing the original MAC address.
Solution Approach 2:
The patent creates a copy of the MAC address mapping relationship stored in a mapping table, allowing the system to track paths using the copied association rather than the original MAC address. This copying mechanism enables path reconstruction while the original MAC addresses remain protected.
2Loss of information
If probe requests are grouped by virtual MAC address to form segments, then path reconstruction capability is improved, but segmentation complexity increases
Solution Approach 1:
The patent divides probe request data into segments grouped by virtual MAC address, creating manageable units that can be independently processed. Each segment contains probe requests with the same virtual MAC address, allowing systematic reconstruction of user paths through ordered concatenation of these segments.
Solution Approach 2:
The patent changes the grouping parameter from original MAC addresses to virtual/randomized MAC addresses. This parameter change enables path reconstruction while preserving privacy, as the virtual MAC addresses serve as the grouping key instead of the original identifying addresses.
3Loss of time
If chronological ordering is performed on probe requests with randomized MAC addresses, then tracking continuity is improved, but data processing complexity increases
Solution Approach 1:
The patent performs preliminary chronological ordering of probe requests within each virtual MAC address segment before concatenation. This preliminary action ensures that when segments are joined together, the overall path maintains correct temporal sequence, improving tracking continuity without requiring complex post-processing.
Solution Approach 2:
The patent maintains continuity of the tracking function by systematically ordering and concatenating segments chronologically. This continuous processing approach ensures that path reconstruction remains uninterrupted and maintains temporal coherence across multiple virtual MAC address segments.
Data Source
AI summary
Constructing and/or recovering paths of mobile devices is enabled. For instance, a method comprises: receiving, by wireless fidelity (Wi-Fi) sensors, respective probes from mobile devices, grouping probes having a same media access control (MAC) address into segments, identifying fingerprints of information elements the mobile devices, grouping segments according to an identified fingerprint, determining an increment of a sequence number corresponding to consecutive segments of a segment group, determining a time gap between the sequence number corresponding to a first probe and an incremented sequence number corresponding to a second probe having a timestamp that is later in time than the first probe, and comparing a growth rate of the sequence number corresponding to the consecutive segments to determine a forward segment of the consecutive segments, resulting in a constructed path of the mobile devices, and storing the constructed path in a database.