NTN UE Rx-Tx Time Difference Reporting via Slot Offset
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Solution Overview
Problem
Non-terrestrial networks (NTN) face challenges in accurately determining timing-related parameters like round trip time (RTT) due to high propagation delays and large timing advances, which affect communication quality and positioning accuracy, especially with satellites in low Earth orbit moving at high velocities.
Innovation Solution
The proposed solution involves modifying the reporting of UE Rx-Tx time difference by reusing the K_offset parameter to provide an accurate time domain value, allowing for precise provisioning of timing information without increasing overhead, and configuring the UL reporting range to maintain bit usage while enabling fine granularity in slot offset indication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE reports the full UE Rx-Tx time difference value in NTN, then the positioning accuracy is improved, but the number of bits required for reporting increases
Solution Approach 1:
The patent extracts only the necessary portion of the UE Rx-Tx time difference value by reporting the slot offset (difference between indicated UL slot and actual UL slot) rather than the full time difference. This extraction approach provides sufficient positioning accuracy while significantly reducing the number of bits required for reporting in NTN scenarios.
Solution Approach 2:
The patent transforms the continuous time difference measurement into a discrete slot offset indication. By changing from reporting the full UE Rx-Tx time difference value to reporting only the slot offset dimension, the system achieves adequate positioning accuracy with reduced bit requirements, effectively moving from a continuous to a discrete representation.
2Measurement precision
If the UL reporting range is configured to cover large RTT values in NTN, then the accuracy for high RTT scenarios is improved, but the bit usage increases
Solution Approach 1:
The patent applies partial action by reporting only the slot offset portion of the UE Rx-Tx time difference rather than the full value. This partial reporting approach provides sufficient accuracy for positioning while avoiding the excessive bit usage that would result from reporting the complete time difference value, especially in high RTT NTN scenarios.
Solution Approach 2:
The patent changes the reporting parameter from the full UE Rx-Tx time difference value to the slot offset (difference between indicated and actual UL slots). This parameter transformation allows the system to maintain adequate measurement precision for positioning while significantly reducing the bit usage required for reporting, particularly in scenarios with large RTT values.
3Reliability
If the UE applies large timing advance for NTN communication, then the communication quality is improved, but the timing determination accuracy deteriorates
Solution Approach 1:
The patent segments the timing advance compensation into two parts: the indicated UL slot (which accounts for the large timing advance) and the actual UL slot (which contains the residual offset information). By reporting only the difference (slot offset), the system maintains communication quality through large timing advance while preserving timing determination accuracy through the offset indication.
Solution Approach 2:
The patent applies preliminary timing advance compensation through the indicated UL slot assignment, then reports only the residual slot offset. This preliminary action approach allows large timing advance to be applied for NTN communication quality while the residual offset reporting maintains timing determination accuracy without requiring additional bits for the full time difference value.
Data Source
AI summary
There is provided a method performed by a user equipment configured to operate in a non-terrestrial network, the method comprising: acquiring a scheduling offset value for communication between the apparatus and a first network node; determining a time difference between a reception of a downlink message and transmission of an uplink message, wherein the uplink message is transmitted in response to the downlink message; determining a time domain value based on the determined time difference and the acquired scheduling offset; and reporting the time domain value to a second network entity.