Terminal Device Clock Synchronization Using Time-of-Arrival Positioning
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Solution Overview
Problem
Terminal devices in cellular communication systems face challenges in synchronizing their clocks with the network clock, particularly when they are powered up or in idle states, leading to potential drift and the need for frequent resynchronization.
Innovation Solution
The solution involves receiving control messages from access nodes that include clock values and geographical location information, using time-of-arrival positioning to compute a second clock value indicating the reception time, and updating the terminal device's clock to synchronize with the network clock, even in idle states without active network connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If terminal devices continuously synchronize with network clock using active network connection, then clock synchronization accuracy is improved, but power consumption and signaling overhead increase
Solution Approach 1:
The terminal device performs clock synchronization periodically by utilizing idle radio resources to receive control messages from access nodes. Instead of maintaining continuous active connection, the device synchronizes its clock at specific intervals when radio resources are available, reducing power consumption while maintaining acceptable synchronization accuracy.
Solution Approach 2:
The terminal device autonomously computes the second clock value indicating reception time by combining the first clock value from the control message with the time difference derived from geographical locations. This self-service mechanism allows the device to update its clock without requiring continuous network interaction or additional signaling overhead.
2Loss of energy
If terminal devices use time-of-arrival positioning for clock synchronization, then signaling overhead is reduced, but measurement precision requirements increase
Solution Approach 1:
The control message from the access node serves multiple purposes: it provides the first clock value indicating transmission time and simultaneously enables the terminal device to compute the second clock value for synchronization. This multi-functionality reduces signaling overhead by reusing existing control messages rather than transmitting separate synchronization commands.
Solution Approach 2:
The geographical location information acts as an intermediary element that bridges the transmission time and reception time. By using the known geographical locations of both the access node and terminal device, the system can calculate the time difference without requiring direct time-stamping measurements, thereby reducing signaling overhead while maintaining synchronization accuracy.
3Reliability
If terminal devices update clock frequently to maintain synchronization, then clock drift is reduced, but device complexity and processing load increase
Solution Approach 1:
The terminal device performs clock synchronization in advance during idle states when radio resources are available, before significant clock drift occurs. By proactively updating the clock using the computed second clock value, the device maintains synchronization reliability without requiring complex real-time adjustment mechanisms.
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 method reduces signaling overhead, conserves power, and allows for efficient clock synchronization, enabling accurate time-stamping and communication without continuous radio resource allocation, scalable for multiple devices.
Implementation Method 1
The terminal device is configured to compute the second clock value by using time-of-arrival positioning
Data Source
AI summary
This document discloses a solution for synchronizing a terminal device to a network clock. According to an aspect, a method comprises as performed by the terminal device: receiving a control message from at least one access node, the control message comprising a first clock value indicating a transmission time of the control message; determining a geographical location of the terminal device and a geographical location of the at least one access node; computing, on the basis of the geographical locations of the terminal device and the at least one access node and further on the basis of the first clock value transmission time of the control message, a second clock value indicating a reception time of the control message at the terminal device; and updating a clock of the terminal device by using the second clock value.