Trigger-Based FTM Grouping for Dense Wi-Fi Ranging

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Solution Overview

Problem

Large-scale Fine Time Measurement (FTM) exchanges in wireless networks cause network performance issues due to collisions, missed frames, and excessive bandwidth consumption, particularly in high client density scenarios.

Innovation Solution

Implementing trigger-based FTM improvements by efficiently grouping initiators based on Received Signal Strength Indication (RSSI), Channel State Information (CSI), and Line of Sight (LOS)/Non Line of Sight (NLOS) relationships to optimize FTM exchanges and reduce network airtime consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If large-scale FTM exchanges are performed in high client density scenarios, then positioning accuracy is improved, but network performance deteriorates due to collisions, missed frames, and excessive bandwidth consumption

Engineering Contradiction:

Improvepositioning accuracyVSAvoidnetwork performance

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent segments initiators into different groups based on their RSSI, CSI, and LOS/NLOS relationships with responders. This grouping divides the large-scale FTM exchanges into smaller, manageable subsets that can be processed separately, reducing collisions and network congestion while maintaining positioning accuracy for each group

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary classification of initiators into groups based on their signal characteristics (RSSI, CSI) and geometric relationships (LOS/NLOS) before executing FTM exchanges. This preliminary organization optimizes the sequence and timing of FTM measurements, preventing network overload and frame collisions during high-density scenarios

Inventive Principle:

Principle #10Preliminary action

2Area of stationary object

If FTM exchanges are performed with all initiators simultaneously, then comprehensive positioning coverage is achieved, but bandwidth consumption increases excessively

Engineering Contradiction:

Improvepositioning coverageVSAvoidbandwidth consumption

Core Design Contradiction:

Area of stationary objectVSQuantity of substance

Solution Approach 1:

Initiators are segmented into multiple groups based on their spatial relationships and signal characteristics. Each group performs FTM exchanges in a coordinated manner, ensuring comprehensive coverage across all areas while controlling the bandwidth consumption of each individual group, thereby reducing overall network load

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic FTM exchanges organized in measurement opportunities (MEOPs) structured as discovery, measurement, and exit phases. Initiator groups perform measurements in periodic intervals rather than simultaneously, maintaining comprehensive positioning coverage while distributing bandwidth consumption over time

Inventive Principle:

Principle #19Periodic action

3Productivity

If more initiators are grouped together for FTM measurements, then measurement efficiency is improved, but collision probability increases

Engineering Contradiction:

Improvemeasurement efficiencyVSAvoidcollision probability

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating groups with heterogeneous characteristics - each group contains initiators with similar RSSI ranges, CSI profiles, and LOS/NLOS relationships. This local homogeneity within groups optimizes measurement efficiency, while the heterogeneity between groups reduces collision probability by diversifying the measurement patterns across different spatial and signal conditions

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12519524B2Trigger based fine time measurement improvement via efficient grouping

Publication Date: 2026.01.06 CISCO TECHNOLOGY INC

AI summary

Fine Time Measurement (FTM) improvement and, specifically, trigger based FTM improvements via efficiently grouping initiators may be provided. A plurality of probe requests transmitted by a plurality of initiators is received. For each probe request, a Received Signal Strength Indication (RSSI) and Channel State Information (CSI) is determined, and a distance between an initiator and an associated responder associated with the probe request is determined based on the RSSI and the CSI. Line of Sight (LOS) or Non Line of Sight (NLOS) relationships between the plurality of initiators and one or more responders is determined based on the CSI. One or more groups of initiators is determined from the plurality of initiators based on the LOS or NLOS relationships and the distances determined for each probe request, wherein the responders and the initiators perform FTM based on the one or more groups of initiators.