Conditional L1/L2 Mobility Using UE-Triggered Cell Switching
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Solution Overview
Problem
Existing 5G wireless communication systems face challenges in managing increased communication traffic and supporting efficient mobility, 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
Implementing terminal-based Layer 1/Layer 2 Triggered Mobility (LTM) by configuring user equipment (UE) with conditional LTM execution conditions, allowing UE to autonomously evaluate and execute mobility based on predefined criteria, reducing network decision delays and enhancing mobility flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If network-based cell switching is used, then centralized control is maintained, but mobility switching is delayed and vulnerable to radio link fluctuations
Solution Approach 1:
The terminal autonomously evaluates execution conditions and determines cell switching without waiting for network-based decisions. The terminal independently monitors reference signals, evaluates conditions (A1-A3 events), and executes switching to candidate cells when conditions are met, enabling self-service mobility that eliminates network decision delays while maintaining reliability through pre-configured candidate cells
Solution Approach 2:
The network pre-configures multiple candidate cells and execution conditions (A1-A3 events) before mobility is needed. The terminal evaluates these pre-prepared conditions in real-time, allowing immediate switching when conditions are satisfied without requiring real-time network decisions, thus performing preliminary preparation to enable rapid response
2Loss of time
If terminal-based autonomous mobility is implemented, then switching delay is reduced, but complexity of mobility management increases
Solution Approach 1:
The mobility management function is segmented between network configuration (providing candidate cells and conditions) and terminal execution (evaluating conditions and switching). This division allows the terminal to handle real-time decisions using simplified logic based on pre-configured parameters, reducing overall system complexity while enabling autonomous operation
Solution Approach 2:
The terminal uses standardized measurement events (A1-A3) with predefined parameters to evaluate mobility conditions. By changing from complex real-time network decisions to evaluating specific parameter thresholds (signal strength, quality metrics), the system reduces computational complexity while maintaining rapid switching capability
3Speed
If conditional LTM configuration is continuously evaluated, then mobility responsiveness is improved, but terminal processing load increases
Solution Approach 1:
The terminal evaluates execution conditions periodically based on measurement events (A1-A3) rather than continuously. The evaluation is triggered by specific conditions (signal quality thresholds, reference signal measurements) occurring at defined intervals or events, maintaining rapid responsiveness while reducing processing load compared to continuous evaluation
Data Source
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AI summary
Provided are a method and apparatus for configuring mobility in a wireless communication system. The method of a terminal may include receiving a conditional layer 1 (L1)/layer 2 (L2) triggered mobility (LTM) configuration, starting an evaluation of an execution condition for conditional LTM based on the received conditional LTM configuration, and stopping the evaluation of the execution condition, wherein the stopping of the evaluation may be performed based on reception of ReconfigurationWith Synch.