NTN Tx-Rx Transition Gaps for Timing Advance Scheduling
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Solution Overview
Problem
In non-terrestrial network (NTN) communications, the timing advance (TA) can be large, leading to potential collisions between downlink (DL) and uplink (UL) scheduling due to the base station's unawareness of the UE's TA, necessitating enhanced support for transmit-receive (Tx-Rx) transition gaps.
Innovation Solution
Implementing guard periods as Tx-Rx transition gaps around UL transmissions, with pre- and post-UL gaps to account for timing drift, and reporting or updating TA drift rates to align RF conditions, ensuring no DL transmissions occur during these gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timing advance (TA) is used in NTN communications, then uplink transmission timing can be adjusted, but the base station cannot know the TA value completely, leading to potential collisions between downlink and uplink scheduling
Solution Approach 1:
The patent introduces a guard period before the uplink transmission timing that is calculated based on the timing advance value. This preliminary action ensures that the base station completes any downlink transmissions before the UE begins uplink transmission, preventing collisions without requiring the base station to know the exact TA value. The guard period acts as a preventive measure taken in advance.
Solution Approach 2:
The guard period serves as an intermediary time interval between downlink and uplink transmissions. It mediates the scheduling conflict by providing a buffer zone where the base station can finish downlink transmissions and the UE can prepare for uplink transmission, resolving the collision problem caused by incomplete TA information.
2Reliability
If guard periods are introduced to prevent DL-UL collisions, then scheduling reliability improves, but transmission time efficiency decreases due to the additional gap duration
Solution Approach 1:
The patent dynamically adjusts the guard period duration based on the timing advance value and transmission parameters. By changing the parameter of guard period length according to actual conditions, the system maintains sufficient protection against collisions while minimizing the time loss, optimizing the balance between reliability and efficiency.
Data Source
AI summary
Solutions pertaining to enhanced support for transmit-receive (Tx-Rx) gap in non-terrestrial network (NTN) communications are proposed. An apparatus implemented in a UE receives from a non-terrestrial (NT) network node of a network an uplink (UL) grant or a configuration that schedules an UL transmission (Tx). The apparatus performs the UL transmission to the NT network node within a transmit-receive (Tx-Rx) transition gap during which no downlink (DL) Tx from the NT network node is expected. The Tx-Rx transition gap includes an UL Tx duration, a pre-UL Tx gap (Gap_start) before a starting time of the UL Tx duration (t_start), and a post-UL Tx gap (Gap_end) after an ending time of the UL Tx duration (t_end). A starting timing of the Tx-Rx transition gap can be expressed as: t_start−timing advance (TA)−Gap_start. An ending time of the Tx-Rx transition gap can be expressed as: t_end−TA+Gap_end.