CU-UP Relocation Using L1/L2 Triggered Mobility
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Solution Overview
Problem
Current mobile telephone networks experience longer latency and interruption times due to layer 3 (L3) triggered mobility, which requires resets at lower layers (L1 and L2) during user equipment (UE) relocation between centralized unit user planes (CU-UPs) in cellular networks, leading to inefficiencies.
Innovation Solution
Implementing layer 1/layer 2 (L1/L2) triggered mobility (LTM) for intra-base station centralized unit user plane (CU-UP) relocation, involving preparation of a target CU-UP and DU, data forwarding, and security key management to minimize latency and overhead during UE relocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If layer 3 (L3) triggered mobility is used for UE relocation between CU-UPs, then mobility management is achieved, but latency and interruption time increase due to required resets at lower layers (L1 and L2)
Solution Approach 1:
The patent segments the base station into separate functional units: Centralized Unit Control Plane (CU-CP), Centralized Unit User Plane (CU-UP), and Distributed Unit (DU). This segmentation allows the CU-CP to manage mobility at Layer 3 while the CU-UP and DU maintain persistent Layer 1 and Layer 2 connections, enabling independent optimization of each function and avoiding the need for lower layer resets during mobility events.
Solution Approach 2:
The CU-CP acts as an intermediary between the UE and the target CU-UP/DU during mobility events. It coordinates the relocation process by managing the transition of UE context while maintaining persistent lower layer connections, thereby mediating the mobility management function without requiring resets at L1 and L2.
2Productivity
If layer 3 (L3) triggered mobility with lower layer resets is implemented, then UE relocation between CU-UPs is achieved, but network efficiency decreases due to overhead and service interruption
Solution Approach 1:
The patent establishes persistent Layer 1 and Layer 2 connections between the CU-UP and DU before mobility events occur. This preliminary setup of pre-configured connections allows for rapid UE relocation without requiring time-consuming resets, thereby maintaining service continuity and improving network efficiency during mobility events.
Solution Approach 2:
The patent maintains continuous Layer 1 and Layer 2 connections during UE relocation between CU-UPs. By keeping these lower layer connections persistent and avoiding resets, the system ensures uninterrupted data flow and service continuity, thereby maintaining high network efficiency and reliability throughout the mobility process.
Data Source
AI summary
In general, the current subject matter relates to layer 1/layer 2 (L1/L2) triggered mobility (LTM) for intra-base station centralized unit user plane (CU-UP) relocation. In some implementations, a target distributed unit (DU) of a base station to serve a user equipment (UE) can be determined to be served by a target CU-UP of the base station. A serving CU-UP of the base station can serve a serving DU of the base station that is currently serving the UE. Using a centralized unit control plane (CU-CP) of the base station, the target CU-UP can be prepared for layer 1/layer 2 triggered mobility (LTM), and, using the CU-CP, the target DU can be prepared for LTM.