Base Station Apparatus for Dual Connectivity Master Node Change
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Solution Overview
Problem
Existing Dual Connectivity (DC) procedures in 3GPP Release 12 require the release of a secondary base station (SeNB) during master base station (MeNB) changes, which is inefficient and involves additional signaling and data forwarding steps.
Innovation Solution
A method and apparatus that allow for MeNB changes without SeNB release or addition, using existing X2 interface procedures and messages, by modifying the SeNB addition request message to indicate configuration changes for the secondary cell group (SCG) during handovers, enabling seamless handovers while maintaining connectivity with the SeNB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing DC procedures in 3GPP Release 12 are used for MeNB changes, then the handover can be performed, but the SeNB must be released and re-added which increases signaling overhead and handover time
Solution Approach 1:
The patent applies preliminary action by pre-establishing the SCG configuration at the target MeNB before the actual handover occurs. The target MeNB receives and stores the SCG configuration from the source MeNB in advance, so that when handover is triggered, the SeNB connection is already prepared and can be immediately activated without release and re-addition, thus reducing handover time while ensuring reliable connection establishment
2Reliability
If existing DC procedures in 3GPP Release 12 are used for MeNB changes, then the handover can be performed, but additional signaling steps are required which increases signaling overhead
Solution Approach 1:
The patent merges the SCG configuration transfer process with the existing handover signaling流程. By integrating the SCG configuration information into the handover request and handover confirm messages that are already being exchanged between MeNBs, the patent eliminates the need for separate signaling messages, thereby reducing signaling overhead while ensuring complete and reliable configuration transfer for handover completion
3Reliability
If SeNB release and re-addition is performed during MeNB change, then connectivity can be maintained, but the procedure becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-establishing the SCG configuration at the target MeNB before the actual handover occurs. The target MeNB receives and stores the SCG configuration from the source MeNB in advance, so that when handover is triggered, the SeNB connection is already prepared and can be immediately activated without release and re-addition, thus reducing handover time while ensuring reliable connection establishment
Solution Approach 2:
The patent makes the target MeNB universally capable of handling both MCG and SCG configurations. By enabling the target MeNB to receive, store, and activate the SCG configuration just like the source MeNB, the patent creates a symmetric handover procedure where either MeNB can independently manage the dual connectivity configuration, simplifying the overall procedure and reducing the need for special case handling
Data Source
AI summary
A secondary base station (2) receives an SeNB addition request message (302) from a second master base station (3) while providing a radio terminal (4) with a secondary cell group (SCG) for DC in cooperation with a first master base station (1). If the SeNB addition request message (302) explicitly or implicitly indicates that a master base station in DC for the radio terminal (4) is to be changed from the first master base station (1) to the second master base station (3), the secondary base station (2) considers that the SeNB addition request message (302) requests modification of the SCG that has already been configured. It is thus, for example, possible to contribute to performing a procedure for changing a master base station in Dual Connectivity (DC) by using existing inter-base station interface procedures and inter-base station signaling messages.