User Equipment Timing Alignment for RRC-Inactive CG-SDT
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Solution Overview
Problem
Existing wireless communication systems, particularly 5G NR, face inefficiencies in handling small data transmissions in the RRC_INACTIVE state, leading to unnecessary power consumption and signaling overhead due to frequent state transitions for small data packets.
Innovation Solution
Implementing Configured Grant-based Small Data Transmission (CG-SDT) procedures to enable data transmission in the RRC_INACTIVE state without transitioning to RRC_CONNECTED, using either Random Access (RA)-based or CG-based methods, with timing alignment mechanisms to manage Timing Advance (TA) values and timers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transitions to RRC_CONNECTED state for small data transmission, then reliable data transmission is achieved, but power consumption and signaling overhead increase
Solution Approach 1:
The patent segments the data transmission process by introducing Configured Grant-based Small Data Transmission (CG-SDT) as a separate, simplified procedure that operates independently from the full RRC connection establishment. This allows small data packets to be transmitted using pre-configured resources without requiring complete RRC_CONNECTED state transition, thereby reducing power consumption while maintaining transmission reliability for small data volumes.
Solution Approach 2:
The patent applies preliminary action by pre-configuring grant resources and timing advance parameters while the UE is in RRC_INACTIVE state. The network预先 allocates uplink resources and timing alignment information, so when small data needs to be transmitted, the UE can immediately use these pre-configured resources without performing full random access and RRC connection setup procedures, thus reducing power consumption and latency.
2Productivity
If the UE maintains Timing Advance value during RRC_INACTIVE state, then uplink timing alignment is preserved for CG-SDT, but timing accuracy may degrade over time
Solution Approach 1:
The patent implements dynamic timing management by introducing a timing alignment timer that can expire and trigger timing updates. The UE maintains the Timing Advance value during RRC_INACTIVE state for CG-SDT operations, but when the timer expires or upon receiving specific network commands, the UE performs timing updates through random access procedures. This dynamic approach balances the need for continuous timing alignment with the power savings of maintaining the current TA value during active transmission periods.
Solution Approach 2:
The patent applies self-service by enabling the UE to autonomously manage its timing alignment state using pre-configured parameters and local timer management. The UE can determine when timing updates are needed based on local timer expiration or received commands, and can perform self-correction of timing using stored TA values, reducing the need for continuous network intervention and minimizing signaling overhead.
3Measurement precision
If the UE performs random access procedure to update TA value, then timing alignment accuracy is improved, but signaling overhead and latency increase
Solution Approach 1:
The patent applies partial action by implementing selective random access procedures that are triggered only when timing alignment accuracy becomes insufficient or when specific network conditions require updates. Instead of performing random access continuously or periodically, the UE updates TA values only when necessary (e.g., when timing alignment timer expires or upon receiving specific commands), thereby reducing unnecessary signaling overhead and latency while maintaining adequate timing accuracy for CG-SDT operations.
Data Source
AI summary
A method and a user equipment (UE) for timing alignment is provided. The method includes maintaining a Timing Advance (TA) value as a first TA value; receiving, from a Base Station (BS), a TA command during a Random Access (RA) procedure; applying the TA command to set the TA value to a second TA value included in the TA command in a case that a first timing alignment timer is not running; determining whether a contention resolution for the RA procedure is successful; and when the contention resolution is not successful, setting the TA value to the first TA value in a case that a Configured Grant-based Small Data Transmission (CG-SDT) procedure is ongoing.