NTN Uplink Synchronization Re-Acquisition Before Signal Loss
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Solution Overview
Problem
In non-terrestrial wireless communications networks, such as those using satellites or airborne vehicles, the challenge of maintaining uplink synchronization is significant due to rapid changes in satellite positions and user equipment (UE) mobility, leading to inefficiencies in resource utilization and potential data transmission interruptions.
Innovation Solution
A method where the UE proactively indicates an imminent loss of uplink synchronization to the network, allowing it to receive updated information for re-acquiring synchronization, thereby preventing synchronization loss and optimizing resource use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the UE waits until synchronization is lost before re-acquiring it, then the device complexity is reduced, but the productivity decreases due to transmission interruptions
Solution Approach 1:
The network proactively provides updated ephemeris information to the UE before the current ephemeris data expires, enabling the UE to re-acquire uplink synchronization in advance. This preliminary action prevents synchronization loss and ensures continuous data transmission without interrupting the UE's normal operation.
2Reliability
If the network provides frequent ephemeris updates, then the reliability of uplink synchronization is improved, but the loss of energy increases due to additional transmissions
Solution Approach 1:
The network monitors the UE's ephemeris validity status and autonomously determines when to provide updates. By detecting when the UE's current ephemeris data is approaching expiration, the network proactively supplies fresh ephemeris information, eliminating the need for the UE to continuously request updates or monitor timing independently, thus reducing the UE's energy consumption.
3Measurement precision
If the UE continuously monitors for synchronization status, then the measurement precision of synchronization timing is improved, but the use of energy by the moving object increases
Solution Approach 1:
The network provides feedback to the UE regarding the validity status of the UE's ephemeris data. This feedback mechanism allows the UE to passively receive synchronization status information without actively monitoring timing parameters, thereby maintaining synchronization timing accuracy while significantly reducing the energy required for continuous monitoring.
Data Source
AI summary
A method of operating a communications device for transmitting signals to and/or receiving signals from a non-terrestrial network apparatus of a wireless communications network is provided. The method comprises determining that the communications device will lose uplink synchronisation with the wireless communications network at a first time, transmitting, to the non-terrestrial network apparatus before the first time, an indication that the communications device will lose uplink synchronisation with the wireless communications network, receiving, from the non-terrestrial network apparatus before the first time and in response to the transmitted indication, a signal comprising information for use by the communications device in re-acquiring uplink synchronisation with the wireless communications network until at least a second time, the second time being later than the first time, and re-acquiring, based at least in part on the received information, uplink synchronisation with the wireless communications network until the second time.