Timing Advance Validation Using SSB Time Drift
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Solution Overview
Problem
Current methods for validating timing advance in uplink transmission in 5G NR systems are inadequate, particularly in scenarios with beam changes, leading to potential misalignment and inefficiencies in small data transmission over pre-configured PUSCH resources.
Innovation Solution
A network-controlled method that allows user equipment (UE) to validate timing advance by estimating the synchronization signal block (SSB) time drift during downlink synchronization, comparing it with a fraction of the cyclic prefix length to determine if the timing advance is valid for small data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RSRP-based timing advance validation is used, then timing alignment can be maintained in stable beam conditions, but validation accuracy deteriorates when beam changes occur
Solution Approach 1:
The patent changes the validation parameter from RSRP (reference signal received power) to SSB time drift (synchronization signal block time drift). This parameter change makes the validation method insensitive to beam changes while remaining effective for detecting timing misalignment. The SSB time drift directly reflects timing advance validity without being influenced by beam-specific power variations.
2Measurement precision
If timing advance validation is performed frequently to ensure accuracy, then timing alignment precision is improved, but transmission delay increases
Solution Approach 1:
The patent performs timing advance validation preliminarily before small data transmission by checking SSB time drift. This preliminary check ensures timing alignment is verified in advance, allowing small data transmission to proceed without additional validation delays. The validation is done once during the synchronization phase, not repeatedly during data transmission.
Data Source
AI summary
In order to perform small data transmission during an RRC_INACTIVE mode, a UE may need to determine whether the stored timing advance (TA) is valid. A TA may be valid if its usage would result in an uplink transmission arriving at a TRP of a base station during a time period during which the base station expects to receive uplink transmission. A UE may determine that a TA is valid based on a received fraction of the length of a cyclic prefix and observed SSB time shift.