FTM Communication Device NLOS Positioning
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Solution Overview
Problem
Current indoor positioning systems face challenges in accurately estimating the position of communication devices within buildings due to the inability of satellite-based systems to penetrate concrete walls and the limitations of existing methods in handling non-line-of-sight (NLOS) conditions, especially in scenarios with multiple propagation paths and obstacles.
Innovation Solution
The implementation of a communication device and method that utilizes Fine Timing Measurement (FTM) procedures to determine the time of flight for multiple paths, including non-line-of-sight paths, by selecting specific taps of the channel impulse response and using phased array antennas to steer beams and improve positioning accuracy, even in the absence of a global angular reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If satellite-based positioning systems are used, then positioning can be achieved in open environments, but they cannot penetrate concrete walls and fail in indoor scenarios
Solution Approach 1:
The patent introduces WLAN infrastructure (access points) as intermediary devices to enable indoor positioning. These access points transmit radio signals that can penetrate walls and propagate through indoor environments, serving as mediators between the positioning system and indoor locations where satellite signals cannot reach
Solution Approach 2:
The patent replaces satellite-based electromagnetic positioning with a ground-based radio signal positioning system using WLAN infrastructure. This substitution enables positioning in indoor environments by using locally deployed access points instead of distant satellites
2Ease of manufacture
If RSSI-based fingerprinting or path loss models are used, then positioning can be implemented without dedicated infrastructure, but accuracy is limited and requires elaborate mapping or assumptions
Solution Approach 1:
The patent replaces RSSI-based estimation methods with Time of Flight (ToF) measurement using the FTM protocol. This substitution provides direct distance measurements based on signal propagation time rather than signal strength, eliminating the need for path loss models and fingerprinting databases while improving accuracy
Solution Approach 2:
The patent implements preliminary beamforming training between the initiator and responder to establish optimal beam pairs before performing FTM measurements. This preliminary action ensures that the strongest propagation paths are used for timing measurements, improving accuracy without requiring elaborate environmental mapping
3Ease of operation
If FTM procedure uses only the first tap of channel impulse response, then Line of Sight path measurement is simple, but positioning fails in NLOS conditions with obstacles
Solution Approach 1:
The patent segments the channel impulse response into multiple taps and evaluates each tap independently to identify valid propagation paths. Instead of relying on a single first tap, the system examines multiple taps to find paths that satisfy timing and consistency criteria, enabling reliable positioning in NLOS conditions
Solution Approach 2:
The patent dynamically selects which tap to use for FTM measurement based on real-time channel conditions. The system can switch between using the first tap (when LOS is available) and subsequent taps (when NLOS paths are dominant), adapting to changing environmental conditions to maintain positioning reliability
4Reliability
If phased array antennas are used to counteract path loss in mmWave, then communication reliability improves, but device complexity increases
Solution Approach 1:
The patent merges the communication and positioning functions into a single integrated system. The phased array antennas perform beamforming for both data communication and FTM measurements, eliminating the need for separate antenna systems and reducing overall device complexity despite the advanced antenna requirements
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 approach enhances the reliability and accuracy of position estimation by incorporating information from multiple paths, enabling valid positioning in various conditions, including those with reflections and no line-of-sight, and supports both Single Input Single Output and Hybrid MIMO systems.
Implementation Method 1
From the TOF, the corresponding distance between two devices can be computed using the speed of light in the communication medium (e.g., free space)
Implementation Method 2
One of these new concepts is the usage of Phased Array Antennas (PAAs), which increase the antenna gain, allow dynamic adaption to the channel and therefore counteract the huge path loss and angular sparsity of mmWave channels
Implementation Method 3
using phased array antennas to steer beams and improve positioning accuracy, even in the absence of a global angular reference
Data Source
AI summary
A communication device for RF based communication with another communication device, said communication device comprising circuitry configured to apply a fine timing measurement, FTM, procedure. The circuitry is configured to determine an FTM mode out of at least two different FTM modes, and to perform an FTM procedure to determine the round trip time, RTT, between the communication device and the other communication device, wherein the RTT is determined by evaluating a time information of a tap of the channel impulse response, wherein the tap used for the evaluation depends on the determined FTM mode.