UWB Anchor Device Clock Synchronization for TDoA Localization
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Solution Overview
Problem
Current radio frequency ranging systems for localization in communication networks face challenges such as increased channel usage with the number of anchor devices, limited channel capacity in dense environments, and the need for precise clock calibration in anchor device synchronization, particularly in TDoA methods.
Innovation Solution
A method for synchronizing anchor devices using ultra-wide band communication, where a master anchor device transmits a message indicative of its master clock to slave anchor devices, allowing them to synchronize their clocks, and subsequently performing Time Difference of Arrival (TDoA) calculations for mobile device localization with reduced channel usage and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If double-sided ranging procedure is used for localization, then measurement precision is improved, but channel usage increases linearly with the number of anchor devices and mobile devices
Solution Approach 1:
The patent inverts the traditional ranging approach by using TDoA where mobile devices send signals to anchor devices instead of anchor devices sending signals to mobile devices. This inversion allows multiple mobile devices to be localized simultaneously using the same communication channels, as anchor devices receive and process signals from multiple mobile devices without requiring separate dedicated channels for each device pair.
Solution Approach 2:
The patent makes the anchor devices perform multiple functions: they serve as both receivers for mobile device signals and as synchronized timing references for TDoA calculations. The same anchor device infrastructure supports both signal reception and timing synchronization functions, reducing the need for separate dedicated channels and devices.
2Device complexity
If TDoA method is used for localization, then channel usage is reduced, but anchor device synchronization requires exact calibration of clocks in the pico-second region
Solution Approach 1:
The patent introduces a master anchor device as an intermediary that provides centralized timing synchronization to all other anchor devices. The master anchor device acts as a reference clock source, and other anchor devices synchronize their clocks to it, eliminating the need for complex pairwise calibration between all anchor devices while maintaining pico-second level synchronization accuracy.
Solution Approach 2:
The patent implements continuous calibration updates where anchor devices monitor and adjust their clock synchronization based on received timing signals. The system provides feedback mechanisms that allow anchor devices to detect and correct timing drift, maintaining synchronization accuracy without requiring manual recalibration.
3Adaptability or versatility
If multiple mobile devices send messages to anchor devices for localization, then localization coverage is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic localization updates where mobile devices transmit signals only at scheduled intervals rather than continuously. This periodic action allows the system to maintain localization coverage for multiple mobile devices while significantly reducing energy consumption compared to continuous transmission, as mobile devices can enter low-power states between transmission periods.
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 enables efficient and robust synchronization of anchor devices with picosecond resolution, allowing for accurate TDoA-based localization while managing multiple mobile devices and reducing energy consumption, and is applicable in dense environments.
Implementation Method 1
transmitting a first message (e.g. a signal, a packet, a frame) to the first anchor device and to the second anchor device using a first ultra-wide band (UWB, IR-UWB) communication
Implementation Method 2
calculating a first offset between the master time stamp and a first time stamp provided, when receiving the first message at the first anchor device (in particular under consideration of the time of flight between the master anchor device and the first anchor device)
Data Source
AI summary
A method is described synchronization in a communication system which comprises a master anchor device, a first anchor device, and a second anchor device. The method comprises: i) transmitting, by the master anchor device, a first message to the first anchor device and to the second anchor device using a first ultra-wide band (UWB) communication, wherein the first message is indicative of a master clock of the master anchor device receiving, by the first anchor device, the first message, and synchronizing a first clock of the first anchor device based on the master clock, and iii) receiving, by the second anchor device, the first message, and synchronizing a second clock of the second anchor device based on the master clock. Furthermore, a communication system and a use of UWB communication is described.