Timing Advance Management for Wireless Mobility
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently handling timing advance for candidate cells, particularly during L1/L2 Triggered Mobility (LTM), which leads to high latency and signaling overhead, especially in scenarios involving frequent Secondary Cell Group (SCG) changes and inter-frequency mobility.
Innovation Solution
The method involves a User Equipment (UE) receiving candidate cell configurations from the network, storing and managing Timing Advance (TA) values for candidate cells, and transmitting reports to the network, while clearing or discarding TA values based on timer expiry, RRC re-establishment, state changes, or storage capacity limits, to optimize TA management and reduce signaling latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RRC-based mobility procedures are used for serving cell changes, then connection reliability is maintained, but signaling latency increases and productivity decreases
Solution Approach 1:
The patent applies preliminary action by pre-configuring candidate cells with their Timing Advance values before the actual mobility event. The UE stores TA values for candidate cells in advance, so when mobility is needed, the TA information is already available and can be immediately applied without waiting for RRC reconfiguration procedures, thus reducing signaling latency while maintaining connection reliability.
Solution Approach 2:
The patent segments the mobility procedure into two parts: L1/L2 triggered mobility for fast cell switching (using pre-stored TA values) and traditional RRC procedures for connection reconfiguration. This segmentation allows the critical time-sensitive cell change to occur rapidly without blocking the slower but reliable RRC connection establishment, thereby reducing overall signaling latency while preserving connection reliability.
2Productivity
If L1/L2 Triggered Mobility is implemented for fast cell changes, then productivity improves, but device complexity increases
Solution Approach 1:
The patent reduces device complexity by having the network perform preliminary actions of configuring and providing TA values for candidate cells before mobility is needed. The UE simply stores these pre-provided TA values and applies them when mobility occurs, rather than performing complex TA calculations or procedures during the mobility event itself, thus improving productivity while limiting complexity increase.
Solution Approach 2:
The patent introduces TA values as intermediary information that mediates between the network's mobility control and the UE's execution. The network provides TA values as pre-configured parameters, and the UE uses these intermediary values to quickly execute cell changes without needing to perform complex autonomous TA determination, thereby improving mobility performance while keeping device complexity manageable.
3Speed
If TA values are stored for multiple candidate cells, then mobility responsiveness improves, but device complexity and memory requirements increase
Solution Approach 1:
The patent applies preliminary action by having the network pre-configure and provide TA values for multiple candidate cells before the UE needs to perform mobility. The UE stores these pre-provided TA values in association with candidate cell identifiers. When mobility is triggered, the UE can immediately retrieve and apply the appropriate TA value without performing complex real-time calculations, thus improving mobility responsiveness while keeping the storage management task simple through network-assisted pre-configuration.
Data Source
AI summary
Methods, systems, and apparatuses are provided for handling timing advance for cells in a wireless communication system, comprising a User Equipment (UE) receiving a configuration indicating at least one candidate cell including a first candidate cell, storing a first Timing Advance (TA) associated with the first candidate cell, and clearing or discarding the first TA associated with the first candidate cell in response to at least one of: expiry of a timer associated with the first TA; performing Radio Resource Control (RRC) re-establishment; the UE entering RRC_IDLE state or RRC_INACTIVE state; a serving cell change; and/or the UE storing a second TA when a list or a set of stored TAs for the at least one candidate cell is full.