User Equipment Timing Alignment for Non-Terrestrial Networks
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Solution Overview
Problem
Current wireless communication systems, particularly 5G NR, face challenges in timing alignment for Non-Terrestrial Networks (NTN), which affect the accuracy and reliability of data transmission due to satellite ephemeris information and timing advance variability.
Innovation Solution
A method for User Equipment (UE) to receive satellite ephemeris information and Timing Advance (TA) configurations from a Base Station (BS), calculating a UE-specific TA, and adjusting transmission timing based on total TA, scheduling offset, and TA variables to optimize timing alignment for NTN communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If satellite ephemeris information and Timing Advance configurations are used for timing alignment in NTN, then timing alignment accuracy is improved, but system complexity increases due to multiple TA variables and calculations
Solution Approach 1:
The total Timing Advance is segmented into multiple independent components: common TA (affecting all UEs), UE-specific TA (specific to each UE), and TA offset (adjustment parameter). This segmentation allows each component to be calculated and managed separately, improving timing alignment accuracy while organizing system complexity into manageable segments through the formula: total_TA = common_TA + UE-specific_TA + TA_offset
Solution Approach 2:
The system performs preliminary calculations of satellite ephemeris information and pre-determines TA parameters before actual uplink transmission. The common TA and UE-specific TA are calculated in advance based on satellite position data, and the RA response window is pre-configured with timing adjustments, ensuring accurate timing alignment is ready before transmission occurs
2Reliability
If multiple TA parameters (common TA, UE-specific TA, TA offset) are calculated and applied, then timing alignment reliability is improved, but processing time increases
Solution Approach 1:
The base station calculates common TA and UE-specific TA parameters in advance based on satellite ephemeris information before the random access procedure. The RA response window timing is also pre-determined with built-in offsets, so that when the UE transmits the random access preamble, the timing alignment is already optimized, reducing real-time processing requirements
Solution Approach 2:
The TA calculation is divided into independent segments: common TA calculated from satellite ephemeris, UE-specific TA determined by base station, and TA offset applied to RA response timing. Each segment can be computed separately and in parallel, improving reliability through comprehensive timing control while minimizing total processing time through efficient division of calculations
3Manufacturing precision
If the RA response window timing is adjusted based on total TA and scheduling offset, then data transmission accuracy is improved, but device complexity increases
Solution Approach 1:
The base station acts as an intermediary by calculating the total TA and determining the appropriate timing offset for the RA response window. Instead of requiring the UE to perform complex TA calculations, the base station processes the satellite ephemeris information and TA parameters, then provides simplified timing instructions to the UE, improving transmission accuracy while reducing UE complexity
Solution Approach 2:
The base station pre-calculates the RA response window timing offset based on total TA before the UE needs to transmit. This preliminary determination of timing parameters simplifies the UE's task to merely applying the provided offset rather than performing complex calculations, thereby improving data transmission accuracy without significantly increasing UE device complexity
Data Source
AI summary
A method and a user equipment (UE) for timing alignment is provided. The method comprises receiving, from a Base Station (BS), a first configuration indicating at least one of a scheduling offset, a common Timing Advance (TA), and satellite ephemeris information; receiving, from the BS, a second configuration indicating a TA offset for a TA variable; determining a UE-specific TA based on the satellite ephemeris information; determining a total TA based on at least one of the TA variable, the TA offset for the TA variable, the common TA, and the UE-specific TA; and starting, from a transmission by the UE, a time window after an additional time based on the total TA and the scheduling offset.