C/U-Plane Split Handover Signaling Reduction
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Solution Overview
Problem
In the C/U-plane split scenario of LTE networks, the path switch delay occurs when user equipment (UE) moves between cells, particularly due to unnecessary signaling and processing requirements during handovers between macro and small cells, leading to inefficiencies in data bearer switching.
Innovation Solution
A radio communication system is designed with enhanced mobility management, where the macro base station maintains configuration information for data bearers established in small cells, allowing direct switching and minimizing signaling between cells, thereby reducing path switch delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a normal S1 handover procedure is applied to UE movement in the C/U-plane split scenario, then the handover can be completed with standard protocols, but wasted signaling occurs which increases path switch delay
Solution Approach 1:
The patent extracts and removes the unnecessary C-plane signaling from the handover procedure. Since the C-plane is anchored at the source eNB in the C/U-plane split scenario, the patent eliminates the need for C-plane path switch signaling during handover, keeping only the U-plane path switch signaling. This extraction of redundant signaling directly reduces path switch delay while maintaining reliable handover completion.
Solution Approach 2:
The patent segments the handover procedure into separate C-plane and U-plane components. By treating the control plane and user plane independently, the patent allows the C-plane to remain anchored at the source eNB while only the U-plane undergoes path switching. This segmentation enables selective optimization of signaling paths, reducing overall handover delay.
2Area of stationary object
If the first LPN cell is sparsely deployed so that it does not overlap other LPN cells, then the UE changes the SCell from the first LPN cell to the MeNB cell, but this creates a mobility scenario that requires special considerations and increases complexity
Solution Approach 1:
The patent creates a universal handover mechanism that works for both sparse and dense LPN deployments. By establishing that the source eNB retains C-plane anchoring regardless of deployment density, the patent provides a multi-functional solution that handles different mobility scenarios (UE moving from LPN to eNB, UE moving between LPNs, UE moving within eNB coverage) through a consistent protocol framework, reducing the need for scenario-specific complexity.
3Adaptability or versatility
If the first LPN cell and a second LPN cell are closely deployed so that they partially overlap, then the UE can switch between LPN cells, but this creates a mobility scenario with path switch delay similar to the sparse deployment case
Solution Approach 1:
The patent performs preliminary actions by pre-establishing the C-plane anchoring at the source eNB before the handover occurs. This preliminary configuration allows the target LPN to prepare for U-plane data reception without requiring C-plane path switching. The source eNB maintains the C-plane connection in advance, so when handover occurs, only the U-plane path needs to be switched, reducing delay.
Data Source
AI summary
A first base station (1) is configured to send, to a second base station (2), first configuration information that is necessary to establish a data bearer and a data radio bearer in the second base station (2) for a C/U-plane split scenario (S105). Further, the first base station (1) is configured to keep the first configuration information in the first base station (1) even after the data bearer and the data radio bearer are established in the second base station (2) (S109). It is thus, for example, possible to contribute to a reduction in a path switch delay when a UE moves between cells in the C/U-plane split scenario.