gNB-DU RRC Release Confirmation via Lower Layer Feedback
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Solution Overview
Problem
In the 3GPP specifications for 5G New Radio (NR), there is a risk of resource allocation conflicts and deteriorated communication quality due to the inability of the gNB-CU to confirm whether a UE has normally received an RRCRelease message, as the UE does not always return an RRC message, leading to premature release of resources.
Innovation Solution
The gNB-DU transmits a context release completion message to the gNB-CU only after determining that the RRCRelease message has been successfully received by the UE, using methods such as RLC or MAC layer acknowledgments or radio environment measurements, ensuring that resources are released accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gNB-DU releases UE context and returns UE CONTEXT RELEASE COMPLETE upon receiving UE CONTEXT RELEASE COMMAND, then the resource release process is simplified and faster, but resource allocation conflicts occur when the UE has not actually received the RRCRelease message
Solution Approach 1:
The patent introduces a feedback mechanism where the gNB-DU monitors whether the UE has successfully received and processed the RRCRelease message before releasing UE context. The gNB-DU uses lower layer protocols (RLC, MAC, PHY) to detect UE reception status and only returns UE CONTEXT RELEASE COMPLETE when confirmation is received, ensuring accurate resource release timing.
Solution Approach 2:
The patent implements preliminary verification actions where the gNB-DU checks UE message reception status before executing the resource release. By performing this verification in advance through lower layer protocols, the system prevents premature resource release and avoids allocation conflicts with other UEs.
2Loss of energy
If the UE does not return an RRC message after receiving RRCRelease, then the signaling overhead is reduced, but the gNB-CU cannot confirm whether the UE has normally received the message
Solution Approach 1:
The patent introduces lower layer protocols (RLC, MAC, PHY) as intermediaries to transmit confirmation information from the UE to the gNB-DU. These intermediary layers provide acknowledgment mechanisms that allow the gNB-DU to verify UE message reception without requiring additional RRC layer signaling, thus maintaining low overhead while gaining confirmation capability.
Solution Approach 2:
The patent shifts the confirmation mechanism from the RRC layer to lower layers (RLC, MAC, PHY). By moving the verification function to a different dimensional layer of the protocol stack, the system achieves message reception confirmation without increasing RRC signaling overhead, effectively solving the contradiction through dimensional transition.
3Productivity
If resources are released before confirming UE message receipt, then resource allocation efficiency is improved, but resource allocation conflicts and communication quality deterioration occur
Solution Approach 1:
The patent performs preliminary verification of UE message reception status before executing resource release. The gNB-DU uses lower layer protocols to confirm UE receipt of RRCRelease in advance, ensuring that resources are only released when the UE has successfully processed the message, thereby preventing allocation conflicts while maintaining efficient resource utilization.
Solution Approach 2:
The patent implements a feedback loop where the gNB-DU continuously monitors UE reception status through lower layer protocols and adjusts resource release timing accordingly. This feedback mechanism ensures resources are released at the optimal moment - after UE confirmation but without unnecessary delay - resolving the conflict between allocation efficiency and conflict prevention.
Data Source
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AI summary
When RRC connection release in a radio resource control layer reaches UE (200A), gNB-DU (110) transmits UE CONTEXT RELEASE COMPLETE of the UE (200A) to gNB-CU (120) . The gNB-CU (120) releases a context allocated to the UE (200A) based on the UE CONTEXT RELEASE COMPLETE.