Small Data Transmission Routing via Source gNB-CU-UP
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Solution Overview
Problem
Conventional small data transmission (SDT) routing solutions in 5G networks incur excessive unnecessary signaling and involve unnecessary involvement of the target gNB-central unit, leading to overloaded target gNBs and dropped data radio bearers, especially during UE context retrieval and patch switch procedures.
Innovation Solution
The proposed solution optimizes SDT routing by providing a shortcut from the target gNB-DU to the source gNB-CU-UP without anchor relocation, using an additional information element in the Xn retrieve UE context request message to forward SDT packets directly via the source gNB-CU-UP, reducing latency and unnecessary signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional SDT routing is used involving target gNB-CU-UP, then routing flexibility is improved, but signaling overhead increases and target gNB becomes overloaded
Solution Approach 1:
The patent extracts the SDT packet routing function from the target gNB-CU-UP and redirects it directly to the source gNB-CU-UP. This is achieved by having the target gNB-DU forward SDT packets directly to the source gNB-CU-UP using the source gNB's transport layer information, thereby removing the unnecessary involvement of the target gNB-CU-UP in the user plane data path and reducing signaling overhead.
Solution Approach 2:
The source gNB-CU-UP acts as an intermediary that receives both the context information and the SDT packets. The target gNB-DU uses the source gNB-CU-UP as the final destination for SDT packets, eliminating the need for target gNB-CU-UP to handle the data forwarding, thus reducing the load on the target gNB while maintaining routing flexibility.
2Reliability
If anchor relocation is performed for SDT, then connection reliability is improved, but latency increases
Solution Approach 1:
The patent performs preliminary action by obtaining the source gNB-CU-UP's transport layer information during the UE context retrieval phase. This information is stored and ready for immediate use when SDT packets need to be forwarded, eliminating the need for anchor relocation procedures during actual data transmission and thus reducing latency while maintaining connection reliability.
3Adaptability or versatility
If target gNB handles UE context retrieval and patch switch, then mobility management is improved, but network overload occurs
Solution Approach 1:
The patent segments the mobility management functions by separating control plane operations (handled by target gNB-CU-CP) from user plane data forwarding (handled directly by source gNB-CU-UP). This segmentation allows the target gNB to focus on control functions while the source gNB-CU-UP handles data transmission, preventing network overload while maintaining effective mobility management.
Data Source
AI summary
Systems, methods, apparatuses, and computer program products for inter-gNB small data transmission (SDT) routing at a radio access network (RAN). A method may include transmitting an initial request message from a first element in a first network node, to a second element in the first network node to obtain context information. The method may also include receiving, at the first element, a context setup request message based on the context information containing a transport layer information of a third element of a second network node and context information of a user equipment in the second network node. The method may further include processing a data packet according to the received context information. In addition, the method may include forwarding the data packet to the third element of the second network node according to the received transport layer information.