Conditional L1/L2 Mobility Switching With Early Cell Synchronization
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Solution Overview
Problem
Existing 5G wireless communication systems face challenges in managing increased communication traffic and supporting seamless mobility between cells, particularly in scenarios requiring ultra-reliability and low latency, such as vehicle-to-everything (V2X) and factory automation, due to network-based cell switching that is vulnerable to radio link fluctuations.
Innovation Solution
The implementation of L1/L2 Triggered Mobility (LTM) for terminals, allowing conditional execution based on predefined conditions and early synchronization with candidate cells, enabling UE-based mobility management through RRC signaling and MAC entity control, including CSI reports and time alignment timers for efficient cell switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If network-based cell switching is used, then mobility management is simplified, but reliability deteriorates due to vulnerability to radio link fluctuations
Solution Approach 1:
The patent inverts the traditional network-based cell switching approach by enabling the terminal to autonomously perform cell switching decisions. Instead of the network controlling handover, the terminal evaluates execution conditions (A1-A6 events) and autonomously switches cells, thereby improving reliability by eliminating network processing delays and vulnerability to radio link fluctuations while maintaining mobility management efficiency.
Solution Approach 2:
The terminal performs self-service by autonomously evaluating execution conditions and performing cell switching without network intervention. The terminal monitors its own radio link quality, evaluates events (A1-A6), and executes handover decisions independently, improving reliability while reducing the complexity of network-based control mechanisms.
2Reliability
If conditional LTM with early synchronization is implemented, then reliability improves through terminal-based decision making, but device complexity increases due to additional evaluation and synchronization procedures
Solution Approach 1:
The patent applies preliminary action by performing early synchronization with candidate cells before actual handover execution. The terminal pre-establishes synchronization with potential target cells, so when execution conditions are met, the switching can occur rapidly and reliably without the need for extensive real-time synchronization procedures, thereby managing complexity while improving reliability.
Solution Approach 2:
The patent changes the operational parameters of the terminal by introducing execution condition thresholds (events A1-A6) that define when cell switching should occur. By parameterizing the decision-making process with specific signal quality thresholds and event conditions, the terminal's complexity is structured and manageable while achieving high reliability through consistent, rule-based autonomous decisions.
3Reliability
If autonomous terminal-based mobility management is used, then reliability improves, but processing time increases due to terminal evaluation overhead
Solution Approach 1:
The patent reduces latency by performing preliminary actions including early synchronization with candidate cells and pre-evaluation of execution conditions. The terminal maintains readiness for handover by pre-establishing synchronization, so when conditions are met, the actual switching occurs rapidly without extensive real-time processing delays.
Solution Approach 2:
The patent enables the terminal to skip traditional network-based handover procedures by directly executing cell switching when execution conditions are satisfied. The terminal can rush through the handover process by autonomously making decisions and performing switching without waiting for network confirmation, thereby reducing latency while maintaining reliability through pre-defined execution conditions.
Data Source
AI summary
Provided are a method and apparatus for controlling mobility in a wireless communication system. The method of the terminal may include receiving a conditional layer 1 (L1)/layer 2 (L2) triggered mobility (LTM) configuration, after receiving the conditional LTM configuration, performing an evaluation of an execution condition for conditional LTM and an early synchronization to a candidate cell, and executing the conditional LTM based on the performed evaluation of the execution condition and the performed early synchronization.