Inter-DU Lower Layer Mobility With Parallel Reception to Cut Ping-Pongs
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Solution Overview
Problem
Existing 5G networks experience significant user-plane interruptions and ping-pong effects during inter-DU lower layer mobility due to high handover probabilities and reduced cell coverage from mm-wave frequencies, which are not effectively addressed by current standards.
Innovation Solution
Implementing a mechanism at the gNB-CU-CP for autonomous configuration by the gNB-DU, including early detection of lower-layer mobility and early data transmission to the target DU, and creating a mapping table at the CU-UP to identify UE configuration, allowing for simultaneous data transmission from both source and target cells to minimize interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard handover procedures are used in inter-DU lower layer mobility, then cell change operations can be performed, but user-plane interruptions occur and ping-pong effects increase due to high handover probabilities
Solution Approach 1:
The source DU performs early detection of lower-layer mobility conditions and triggers early data transmission to the target DU before the actual handover is complete. This preliminary action allows the target DU to prepare reception buffers and configure resources in advance, minimizing user-plane interruptions when the handover executes.
Solution Approach 2:
The patent maintains continuous data transmission by keeping the source cell connection active during the handover transition. Data continues to flow from the source DU while parallel data paths are established to the target DU, ensuring uninterrupted user-plane service throughout the mobility operation.
2Adaptability or versatility
If frequent handovers are performed to maintain connectivity in mm-wave networks, then coverage is maintained, but ping-pong effects increase and network stability deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the source DU continuously monitors lower-layer mobility conditions and provides this information to the gNB-CU-CP. This feedback loop enables intelligent handover decision-making, allowing the network to recognize when handovers are unnecessary and avoid triggering ping-pong effects, thus maintaining network stability while preserving coverage adaptability.
3Productivity
If autonomous configuration by gNB-DU is implemented, then configuration speed increases, but coordination with gNB-CU-CP becomes more complex
Solution Approach 1:
The gNB-CU-CP performs preliminary configuration of the target DU and prepares handover parameters in advance, then transfers this pre-configured information to the source DU. This preliminary action reduces the coordination complexity during actual handover execution, as the source DU can autonomously apply pre-prepared configurations rather than negotiating each parameter in real-time.
Data Source
AI summary
In accordance with example embodiments of the invention there is at least a method and apparatus to perform establishing, by a user equipment configured to support parallel reception of data from two cells belonging to different network nodes of a radio access network a connection towards a serving cell supported by a first network node supporting at least one of distributed unit functionality or the layer 2 protocol of the radio access network, and receiving data from the serving; transmitting a layer 1 measurement report including an indication of a second cell supported by a second network node and related measurement information towards the serving to enable the first network node to monitor lower layer mobility conditions, wherein the second network node supports at least one of distributed unit functionality or the layer 2 protocol of the radio access network; and receiving a layer 2 message including instructions for a cell change to the second cell, wherein the layer 2 message further comprises instructions to execute parallel reception from both the serving and the second cell at least during the cell change, and to retain at least one configuration for at least one of data transmission or reception with the serving after success of the cell change to the second cell.