Beam-Specific RSRP for NR Timing Advance Validation
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Solution Overview
Problem
Current technologies face challenges in detecting timing advance (TA) changes in fifth generation (5G) new radio (NR), particularly in radio resource control (RRC) inactive mode, due to the reliance on cell-specific reference signal receive power (RSRP) which is less effective in frequency range 2 (FR2) with its challenging signal propagation.
Innovation Solution
The proposed solution involves using a beam-specific RSRP method to validate timing advance in NR RRC inactive mode. This approach measures the RSRP within a configured beam and compares it over time to determine if the TA configuration remains valid, thereby requesting a new TA value when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cell-specific RSRP is used for TA change detection, then the method is simple and compatible with existing LTE systems, but it becomes less effective in FR2 with challenging signal propagation
Solution Approach 1:
The patent applies local quality by transitioning from cell-specific RSRP measurement to beam-specific RSRP measurement. In FR2 with beamforming, different beams have different propagation characteristics. By measuring RSRP on the specific beam level rather than cell level, the system adapts to the local propagation conditions of each beam, improving TA change detection accuracy in challenging FR2 environments.
2Measurement precision
If beam-specific RSRP measurement is implemented, then TA detection accuracy in FR2 is improved, but measurement and processing complexity increases
Solution Approach 1:
The patent segments the cell coverage into multiple beams, each with its own RSRP measurement. Instead of a single cell-level measurement, the system performs measurements on individual beams (e.g., SSB beams). This segmentation allows precise TA change detection per beam while maintaining manageable complexity through standardized beam measurement procedures defined in NR specifications.
Solution Approach 2:
The patent performs preliminary beam RSRP measurements before determining TA validity. By pre-measuring and storing beam-specific RSRP values, the system prepares the necessary data in advance for TA change detection, reducing real-time processing complexity when TA validation is needed.
3Reliability
If TA validation is performed frequently to ensure accuracy, then uplink transmission reliability is improved, but signaling overhead and latency increase
Solution Approach 1:
The patent implements a feedback mechanism where the UE measures beam-specific RSRP, compares it with previously stored values, and determines TA validity based on the comparison result. This feedback loop allows the system to validate TA only when necessary (when RSRP change exceeds threshold), reducing unnecessary validation operations and associated latency while maintaining uplink transmission reliability.
Data Source
AI summary
In some embodiments, a method performed by a wireless device comprises: obtaining a timing advance (TA) value for uplink transmissions; receiving a grant for a radio resource control (RRC) inactive mode uplink transmission; measuring a reference signal associated with each beam of a plurality of beams at a first time; selecting a first beam based on the measured reference signals; measuring a reference signal associated with each beam of a plurality of beams at a second time in preparation for the RRC inactive mode uplink transmission; selecting a second beam for which the measuring was performed at the second time; and when the first selected beam is the same as the second selected beam and the reference signal for the first selected beam is within a threshold value of the reference signal for the second selected beam, transmitting the RRC inactive mode uplink transmission using the obtained TA.