Selective Timing Advance Reporting for NTN Inactive-State Resume
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In non-terrestrial networks (NTNs), user equipment (UE) experiences propagation delays when transitioning from an inactive state to a connected state or performing small data transmission (SDT), leading to inefficient and resource-wasting TA reporting strategies, as the network is unaware of the exact UE location and path changes during the inactive state.
Innovation Solution
The UE selectively transmits a timing advance (TA) report based on a predetermined rule that considers the difference in UE-specific TA before and after the inactive state, RAN-provided indications, and cell changes, optimizing TA reporting to avoid unnecessary overhead and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE transmits TA report every time when transitioning from inactive state to connected state, then the RAN can accurately estimate round-trip-delay for scheduling UL transmissions, but this causes increased signaling overhead and resource waste when the UE path has not changed significantly
Solution Approach 1:
The patent changes the parameter of TA reporting from a fixed mandatory action to a conditional action based on comparing TA values. The UE evaluates whether the path change exceeds a threshold before reporting, dynamically adjusting the reporting behavior based on the actual change in propagation conditions.
Solution Approach 2:
The patent implements a feedback mechanism where the RAN provides TA threshold information to the UE, and the UE uses this feedback to determine whether reporting is necessary. The UE compares its current TA with the threshold and only reports when the difference exceeds the threshold, creating a closed-loop control system.
2Reliability
If the RAN schedules UL transmissions assuming the UE is at the edge of the cell, then the scheduling is conservative and ensures coverage, but this significantly delays UL transmission when the UE is actually closer to the satellite
Solution Approach 1:
The patent applies partial action by having the UE report TA information selectively rather than always. When the UE is close to the satellite and TA has changed significantly, the UE reports to enable optimized scheduling. When the UE position is stable and TA change is minimal, the RAN uses conservative scheduling assuming edge-of-cell position, avoiding unnecessary reporting overhead.
3Productivity
If the UE reports TA information frequently, then the RAN can optimize scheduling for fast-moving UEs, but this increases latency for UEs in inactive state performing connection resume or SDT procedures
Solution Approach 1:
The patent makes the TA reporting behavior dynamic rather than static. The UE adapts its reporting behavior based on its mobility state and the magnitude of TA change. Fast-moving UEs with significant TA changes will trigger reports, while stationary or slow-moving UEs will not report, optimizing the balance between scheduling accuracy and procedure latency.
Data Source
AI summary
Methods and wireless communication devices operating as user equipment (UE) in radio access networks using satellites selectively transmit timing advance information when resuming connection while in an inactive state or when performing a small data transmission (SDT) procedure. A method performed by a UE includes while in an inactive state after being connected to a radio access network (RAN) via a non-terrestrial network (NTN), determining to resume a connection with the RAN, and selectively, based on evaluating a predetermined rule related to a full timing advance, TA, change, transmitting a timing advance (TA) report during a procedure for resuming the connection.