Disaggregated Base Station Cell Change With Target Cell Preconfiguration
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Solution Overview
Problem
Existing serving cell change procedures in wireless communication systems involve significant latency and overhead due to complete L2 and L1 resets, particularly in scenarios like carrier aggregation and dual connectivity, necessitating the development of faster mobility techniques.
Innovation Solution
A method involving a centralized unit (CU) of a distributed base station that receives and transmits configurations for a serving cell change from a target distributed unit (DU) to a user equipment (UE), enabling faster transitions by preparing the target cell configuration before the actual switch, thereby reducing latency and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete L2 and L1 resets are performed during serving cell change, then reliability of connection is improved, but latency and overhead increase significantly
Solution Approach 1:
The patent applies preliminary action by performing L2 reset and configuration preparation in advance, before the actual serving cell change occurs. The source DU completes the L2 reset and prepares target cell configurations beforehand, so that when the cell change is triggered, the UE can switch cells without waiting for L2 reset completion, thereby reducing handover latency while maintaining connection reliability
Solution Approach 2:
The patent segments the serving cell change process into distinct phases: L2 reset phase (performed in advance by source DU), configuration preparation phase (target cell configuration prepared beforehand), and actual cell switch phase (triggered by RRC reconfiguration). This segmentation allows the L2 reset to occur independently before the cell change, preventing it from blocking the handover process and reducing overall latency
2Reliability
If traditional RRC-based serving cell change procedure is used, then protocol layer reliability is improved, but procedure complexity and overhead increase
Solution Approach 1:
The patent uses preliminary action by having the source DU prepare and transmit target cell configuration information to the UE in advance through RRC reconfiguration messages. This pre-configuration includes all necessary L1 and L2 parameters for the target cell, so that when the cell change is executed, the UE can immediately apply the pre-prepared configuration without complex real-time negotiations, reducing procedure complexity while maintaining reliability
Solution Approach 2:
The patent introduces the source DU as an intermediary that prepares and manages the target cell configuration on behalf of the target DU. The source DU acts as a mediator by consolidating configuration information from the target DU and delivering it to the UE through existing RRC signaling, thereby simplifying the overall handover procedure and reducing the complexity of direct UE-target DU interactions
Data Source
AI summary
A distributed base station includes a centralized unit (CU), a source distributed unit (DU), and a target DU. The CU receives, from the target DU, a configuration related to a target cell for a serving cell change by a user equipment (UE) currently communicating with the CU via the source DU, the serving cell change to the target cell initiated subsequent to a measurement report from the UE. The CU transmits the configuration to the UE via the source DU.