Wireless Communication Timing Offset Adjustment for NTN Interference
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Solution Overview
Problem
In wireless communication systems, especially in Non-Terrestrial Networks (NTN) with large delays, UEs have differing understandings of time-domain resources for uplink and sidelink transmissions due to large Timing Advance (TA) values, leading to interference issues, particularly when UEs are in idle states without Timing Advance Commands (TAC).
Innovation Solution
A method is introduced where a first node receives radio signals indicating synchronization timing and information about time offsets, adjusting the transmission slot by a second time offset related to a residual time offset, ensuring synchronization within a specific time window to minimize interference across UEs in both connected and idle states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UEs use large Timing Advance (TA) values for uplink transmission in NTN scenarios, then the uplink transmission can reach the base station, but different UEs have different understandings of time-domain resources leading to interference
Solution Approach 1:
The patent segments the time-domain resource understanding by introducing a reference slot concept within a time window. Instead of using a single large TA value that causes misalignment, the system divides the time window into multiple slots and uses a reference slot as a common reference point for all UEs, thereby segmenting the interference problem into manageable time intervals where synchronization can be maintained.
Solution Approach 2:
The patent introduces a reference slot as an intermediary element that mediates between the base station's downlink timing and UE uplink transmissions. This reference slot serves as a common reference point that all UEs can identify, allowing them to align their uplink transmissions without relying solely on large TA values, thus reducing interference while maintaining transmission reliability.
2Ease of operation
If UEs in idle state synchronize with downlink transmission timing, then they can maintain simple synchronization, but their understanding of time-domain resources configured by base station becomes more different from connected state UEs
Solution Approach 1:
The patent makes the reference slot mechanism universal for both idle and connected state UEs. By defining a reference slot based on downlink synchronization timing that all UEs can identify regardless of their state, the system provides a common time-domain resource understanding framework that works for both idle UEs (who use downlink timing) and connected UEs (who use uplink timing with TA), eliminating the inconsistency between the two states.
3Adaptability or versatility
If base station uses slot occupied by DCI for adjusting uplink transmission, then TA adjustment can be implemented, but UE cannot know actual slot of transmitted uplink radio signal arriving at base station
Solution Approach 1:
The patent applies preliminary action by having the base station indicate the reference slot in advance through DCI before the UE transmits uplink signals. This allows the UE to know beforehand which slot will be used as the reference point for timing alignment, enabling the UE to correctly identify the actual slot of its transmitted signal arriving at the base station while still allowing flexible TA adjustment through the DCI-based reference slot indication.
Data Source
AI summary
An illustrative aspect, performed by a first node, includes receiving a first radio signal, first information and second information; transmits a second radio signal in a first target slot; herein, the first radio signal is used to indicate a synchronization timing of a first time window, and the first information indicates a first slot out of the first time window; the second information indicates a first time offset; the first target slot is advanced by a second time offset compared with the first slot; the second time offset is related to a first residual time offset, a sum of the first residual time offset plus L1 first time length(s) is equal to the first time offset, L1 being a positive integer; the first residual time offset does not exceed the first time length.