Time-of-Flight Ranging Using Impulse Radio and Phase Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ranging technologies face challenges in achieving high-precision time-of-flight (TOF) and downlink time difference of arrival (DL-TDOA) estimates, particularly in impulse radio systems, due to the need for carrier frequency offset compensation and synchronization.
Innovation Solution
The methods involve single-sided two-way ranging (SS-TWR) and double-sided two-way ranging (DS-TWR) techniques that utilize phases of arrival and response delays to calculate TOF and DL-TDOA, eliminating the need for relative carrier frequency offset estimation, enabling accurate ranging by considering first path angles and delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If classic phase-based ranging uses multiple tones or carrier frequency sweeps, then TOF measurement precision is improved, but carrier frequency synchronization and offset compensation complexity increases
Solution Approach 1:
The patent extracts and eliminates the carrier frequency offset compensation step from the ranging process. By using impulse radio technology with ultra-wideband signals, the system obtains TOF measurements that are inherently insensitive to carrier frequency offsets, removing the need for complex synchronization mechanisms while maintaining high precision.
Solution Approach 2:
The patent replaces the mechanical carrier frequency locking and phase measurement system with an impulse-based time-domain measurement system. Instead of using continuous wave carriers and measuring phase differences, the system uses impulse signals and measures time of flight directly in the time domain, eliminating the need for carrier frequency synchronization.
2Device complexity
If impulse radio measures TOF without carrier frequency synchronization, then device complexity is reduced, but measurement precision deteriorates due to inability to resolve phases of arrival
Solution Approach 1:
The patent changes the measurement parameter from phase of arrival (which requires carrier frequency synchronization) to time of flight (which can be measured directly from impulse signals). By operating in the time domain rather than the frequency domain, the system achieves high precision TOF measurements without needing to resolve carrier phases.
Solution Approach 2:
The patent uses periodic impulse sequences with known timing relationships to enable precise TOF measurement. By transmitting periodic impulses and measuring the time of flight for each impulse, the system achieves high precision without requiring carrier frequency synchronization, as each impulse provides a clear time reference.
3Measurement precision
If multiple consecutive TOF measurements are used to accumulate total TOF change, then measurement precision is improved, but error accumulation from phase wrapping increases
Solution Approach 1:
The patent introduces an intermediary reference signal with known timing that travels along a reference path with known characteristics. By comparing the measured TOF against this reference, the system can detect and correct phase wrapping errors, enabling reliable accumulation of multiple consecutive TOF measurements without error propagation.
Data Source
AI summary
Disclosed are methods for time-of-flight (TOF) ranging between wireless devices using single-sided two-way ranging (SS-TWR) and double-sided TWR (DS-TWR) exchanges. The SS-TWR method involves performing the exchange between the wireless devices and determining a first path angle, a relative carrier frequency offset of the initiator and responder devices, and response delay of the responder. The method also involves determining a single SS-TWR delay and calculating a TOF delta from the determined information. Finally, the method involves calculating the TOF using the TOF delta with the single SS-TWR delay. The DS-TWR method eliminates the need for the relative carrier frequency estimation. Both methods enable accurate ranging between wireless devices by considering first path angles, and delays delay, which can be used in a variety of applications such as localization and tracking of objects. The method can be implemented on a processor of one or more of the wireless devices.