Cell Switching Across Different CUs With Low-Latency Mobility
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Solution Overview
Problem
Intra-centralized unit (CU) Layer 1/Layer 2 (L1/L2) triggered mobility (LTM) is limited to mobility between cells within the same Next Generation Node B (gNB) or CU, restricting its application opportunities.
Innovation Solution
A method for cell switching that enables mobility between the same CU or different CUs, involving a network node initiating a request for cell switch configuration, receiving acknowledge messages, and transmitting configurations to a user equipment (UE) for intra-CU or inter-CU LTM, with backup plans for information transfer failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If intra-CU LTM is used for cell switching, then mobility latency is improved, but the applicability is limited to cells within the same CU only
Solution Approach 1:
The patent extends the LTM mechanism originally designed for intra-CU scenarios to support inter-CU cell switching as well. The network node initiates cell switch requests that can target cells belonging to different CUs, and the target CU is notified and prepares the target cell for switching. This makes the LTM mechanism universally applicable to both intra-CU and inter-CU scenarios, resolving the contradiction between low latency and limited applicability.
2Adaptability or versatility
If inter-CU cell switching is enabled, then the applicability scope is improved, but the system complexity increases due to additional coordination between CUs
Solution Approach 1:
The source network node acts as an intermediary that coordinates between the UE and the target CU during inter-CU cell switching. The source node initiates the cell switch request, receives the configuration from the target CU, and manages the overall switching process. This intermediary role simplifies the direct coordination complexity between multiple CUs while enabling inter-CU switching functionality.
Solution Approach 2:
The target CU prepares the target cell configuration in advance by receiving the cell switch request and generating the necessary configuration parameters before the actual switching occurs. This preliminary action allows the switching process to proceed smoothly without last-minute complications, reducing the operational complexity during the actual cell switch event.
3Manufacturing precision
If multiple configuration messages are exchanged during cell switching, then the switching accuracy is improved, but the signaling overhead increases
Solution Approach 1:
The patent combines multiple configuration parameters and cell switch information into integrated message structures. The cell switch request message includes target cell identifiers and switching parameters, while the configuration message contains multiple parameters (e.g., time offset, frequency offset, resource allocation) in a consolidated format. This merging reduces the number of separate signaling messages while maintaining comprehensive configuration accuracy.
Data Source
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AI summary
A method of cell switching and a first network node and a user equipment using the same method are provided. The method includes initiating a request message to request a cell switch related configuration for at least one candidate cell, wherein the at least one candidate cell belongs to a second network node. Receiving a request acknowledge message from the second network node, wherein the request acknowledge message comprises a first configuration for at least one accepted candidate cell. Transmitting a first message to the second network node to update information of the at least one accepted candidate cell. Transmitting a second configuration to a user equipment.