Fine Timing Measurement Protocol for Indoor Ranging
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Solution Overview
Problem
Current satellite positioning systems face challenges in accurately measuring range in indoor environments due to increased congestion and contention for wireless link resources, especially when using round-trip time (RTT) measurements, which can lead to measurement errors and vulnerability to spoofing attacks.
Innovation Solution
Implementing a method that uses fine timing measurement (FTM) messages and conditional authentication to measure time of flight (TOF) between wireless stations with fewer messages, reducing measurement errors and preventing spoofing by authenticating acknowledgement messages based on media access control (MAC) addresses and token exchanges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If round-trip time (RTT) measurements are used for range measurement in indoor environments, then positioning capability is enabled, but measurement errors increase due to wireless link congestion and contention
Solution Approach 1:
The patent extracts the timing measurement function from the standard RTT protocol and implements a dedicated Fine Timing Measurement (FTM) protocol. This separates the ranging function from general data communication, allowing optimized handling of timing-critical messages with dedicated resource allocation, thus reducing measurement errors caused by congestion
Solution Approach 2:
The patent implements preliminary authentication through token exchange before actual timing measurements. The initiator station sends a challenge token, the responder station returns a security token, and authentication is verified before FTM messages are exchanged. This preliminary security setup prevents spoofing attacks and ensures measurement reliability
2Adaptability or versatility
If standard RTT measurement protocols are used, then positioning functionality is provided, but vulnerability to spoofing attacks increases
Solution Approach 1:
The patent implements preliminary authentication through token exchange before actual timing measurements. The initiator station sends a challenge token, the responder station returns a security token, and authentication is verified before FTM messages are exchanged. This preliminary security setup prevents spoofing attacks and ensures measurement reliability
Solution Approach 2:
The patent incorporates authentication feedback mechanisms where each FTM message includes security tokens that are verified against previously exchanged challenge-response pairs. This continuous feedback verification ensures that only authenticated devices can participate in ranging measurements, preventing spoofing while maintaining positioning functionality
3Object-affected harmful factors
If more authentication and security messages are exchanged, then spoofing prevention is improved, but message congestion and contention increase
Solution Approach 1:
The patent merges authentication and timing measurement functions into a unified FTM protocol sequence. The challenge token, security token, and FTM measurement messages are exchanged in a single coordinated sequence rather than separate authentication and ranging phases. This integration reduces overall message count and protocol complexity while maintaining security
Solution Approach 2:
The patent creates a multi-functional FTM message structure that simultaneously carries authentication tokens and timing measurement data. The FTM request and response messages incorporate both security verification elements and ranging information, allowing a single message exchange to fulfill multiple functions and reduce overall communication overhead
Data Source
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AI summary
Disclosed are processes, devices and systems for exchanging messages between devices in support of measuring ranges between devices. In one particular implementation, a first wireless transceiver device may transmit one or more fine timing measurement (FTM) messages to a second wireless transceiver device, and receive a message acknowledging receipt of at least one of the one or more FTM messages. The first wireless transceiver device may authenticate the received message as being transmitted from the second wireless transceiver device.