Active Cell Configuration for 5G NR Inter-Cell Mobility Latency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In 5G New Radio (NR) cellular communication networks, the denser deployment of narrower beams and more frequent cell switching result in increased latency and interruption during inter-cell mobility, especially in Frequency Range 2 (FR2) where higher mobility failure rates lead to longer interruptions.
Innovation Solution
A method is proposed to configure a set of active cells among neighboring cells, allowing for fast cell switching and reducing latency and interruption during inter-cell mobility. This is achieved by the network configuring the active set based on UE measurement reports or network deployment information, and the UE maintaining synchronization and configuration with the active cells before receiving a cell-switch command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional handover procedure is used in 5G NR with narrower beams and denser deployment, then cell switching can be performed, but latency and interruption time increase significantly (e.g., ~75 ms per cell change)
Solution Approach 1:
The patent applies preliminary action by configuring an active set of candidate target cells in advance before handover is needed. The UE performs pre-synchronization and maintains measurements on these pre-configured cells, so when handover is triggered, the UE can quickly switch to a ready cell without performing full synchronization procedures, thereby reducing handover interruption time from ~75 ms to significantly lower values.
2Reliability
If frequent cell switching is performed to maintain connection in dense deployment, then mobility robustness improves, but overall interruption time increases and mobility failure rate increases (e.g., 10% in FR2)
Solution Approach 1:
The network pre-configures an active set of candidate target cells based on UE measurement reports or network deployment information. The UE performs pre-synchronization and maintains measurements on these cells in advance. When mobility is needed, the UE can quickly switch to a pre-prepared cell from the active set, reducing the frequency and duration of interruptions while maintaining mobility robustness even in challenging FR2 conditions.
3Reliability
If full synchronization procedure is performed during handover to target cell, then connection reliability is ensured, but handover latency increases
Solution Approach 1:
The patent performs pre-synchronization to candidate target cells in advance during the active set configuration phase. The UE acquires downlink timing and frequency information for target cells before handover is triggered. When handover occurs, the UE can apply pre-acquired synchronization parameters directly, maintaining connection reliability while significantly reducing handover latency by avoiding repeated full synchronization procedures.
Data Source
AI summary
A method of configuring a set of active cells among neighboring cells to reduce latency and interruption for inter-cell mobility is proposed. The set of active cells is an active set of cells among which UE can do fast cell switching. The set of active cells is configured by the network based on UE measurement report or network deployment information. UE maintains the configuration and can perform pre-synchronization to the configured active cells in downlink (DL) only or in both DL and uplink (UL). UE maintains the DL/UL synchronization with the active cells, and applies configuration once UE is indicated to switch to an active cell as the target cell. Because UE maintains the configuration and DL/UL timing of the target cell before receiving the cell-switch command, the mobility latency and interruption time for inter-cell mobility is reduced.