gNB Lower Layer Mobility for Low-Latency 5G Cell Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 5G NR handover methods, known as Layer 3 Mobility, result in significant signaling overhead and latency due to the use of layer 3 messages for handover preparation and execution, which can be inefficient and time-consuming.
Innovation Solution
Implementing Lower Layer Triggered Mobility (LTM) in Next Generation Base Stations (gNB) by utilizing L1 measurements and internal network decisions to configure UEs with candidate cells, enabling early synchronization and minimizing layer resets, thus reducing latency and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Layer 3 Mobility handover methods are used, then handover preparation and execution can be performed with comprehensive measurements and control, but signaling overhead and latency increase significantly
Solution Approach 1:
The patent applies preliminary action by performing handover preparation in advance through RRC Reconfiguration message that includes target cell configuration and execution conditions. The UE prepares the handover by configuring measurement criteria and target cell parameters before actual handover execution, so that when handover is triggered, the UE can quickly execute the switch without delays from real-time negotiation.
Solution Approach 2:
The patent extracts the handover execution decision from the UE and places it in the gNB through the RRC Reconfiguration message. Instead of the UE autonomously deciding handover based on measurements, the gNB sends the complete handover command with target cell configuration, removing the need for extensive Layer 3 measurement reporting and decision-making at UE side, thereby reducing signaling overhead and latency.
2Reliability
If Layer 3 Mobility handover methods are used, then comprehensive handover control can be achieved, but signaling overhead increases
Solution Approach 1:
The patent uses preliminary action by including complete target cell configuration in the RRC Reconfiguration message sent beforehand. This pre-configuration approach eliminates the need for multiple back-and-forth signaling exchanges during actual handover execution, as all necessary parameters (frequency, bandwidth, physical cell ID, etc.) are already provided to the UE in advance.
Solution Approach 2:
The patent applies copying by providing the UE with a copy of the target cell configuration parameters through the RRC Reconfiguration message. Instead of requiring the UE to request and receive individual parameters during handover execution, the complete target cell configuration is copied and transmitted to the UE in advance, significantly reducing signaling overhead while maintaining handover control accuracy.
Data Source
AI summary
The present disclosure describes a system and a method (1200) for implementing LTM when performing a cell switch procedure of a UE (122) from source cell (118) to target cell (120). The method comprises identifying a target cell for LTM for the UE (122) based on LTM measurements received from the UE and thereafter performing admission control on the target cell. The method further comprises generating, LTM configuration, when the admission control is successful. The method further comprises transmitting the generated LTM configuration to the UE in a RRC reconfiguration message. The method further comprises facilitating early synchronization of the UE (122) in the target cell (120) based on an F1AP message received from a target DU (204). The method further comprises performing an LTM cell switch completion upon receiving an indication from the target DU (204) indicating that an access to the target cell (120) is successful or not.