Uplink Synchronization Timer Management for SDT
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Solution Overview
Problem
The management of uplink synchronization for Small Data Transmission (SDT) procedures in wireless communication systems is not clearly defined, leading to potential data communication latency and network inefficiencies.
Innovation Solution
A base station maintains a single time alignment timer for a UE and transitions this timer accordingly when switching between connected and inactive states, specifically for CG-SDT operations. This involves stopping and restarting timers as necessary during state transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple time alignment timers are maintained for connected and inactive states separately, then timing alignment can be maintained for both states, but device complexity and management overhead increase
Solution Approach 1:
The patent merges the time alignment timer management for connected state and inactive state into a single shared timer mechanism. The base station uses one time alignment timer that is appropriately started or stopped based on the UE's state and SDT configuration, eliminating the need for separate timers for each state while maintaining proper timing alignment for both connected and inactive operations.
2Adaptability or versatility
If time alignment timer is not properly managed during state transitions, then state transitions can proceed freely, but uplink synchronization is lost causing data communication latency
Solution Approach 1:
The patent applies preliminary action by proactively managing the time alignment timer status before and during state transitions. When transitioning from connected to inactive state with SDT configured, the base station ensures the time alignment timer is appropriately maintained or restarted in advance, preventing synchronization loss and avoiding the need for corrective timing procedures that would cause latency.
3Measurement precision
If dedicated SDT-specific timer is implemented, then CG-SDT timing can be precisely controlled, but network resource overhead and configuration complexity increase
Solution Approach 1:
The patent implements a universal time alignment timer that serves multiple functions across different UE states and SDT configurations. The same timer mechanism is used for both connected state timing management and inactive state CG-SDT timing control, eliminating the need for dedicated SDT-specific timers while maintaining precise timing control through appropriate timer starting, stopping, and resetting operations based on current operational context.
Data Source
AI summary
A method, performed by a DU of a distributed base station that includes the DU and a CU, of managing time alignment includes transmitting a timing advance command to a UE, starting or restarting a first time alignment timer that indicates validity of a configured grant configuration when the UE is in an RRC connected state with a RAN, and, after starting or restarting the first time alignment timer, determining to transition the UE from the RRC connected state to an RRC inactive state. The method also includes, in response to the determining, (i) transitioning the UE from the RRC connected state to the RRC inactive state by transmitting a first message to the UE, (ii) stopping the first time alignment timer, and (iii) starting or restarting a second time alignment timer that indicates validity of a CG-SDT configuration when the UE is in the RRC inactive state.