CU-CP PDCP Version Indication for EN-DC Sequence Alignment
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Solution Overview
Problem
In wireless communication systems supporting evolved universal terrestrial radio access and new radio dual connectivity (EN-DC), there is a mismatch in the setting of the Packet Data Convergence Protocol (PDCP) sequence number between the Central Unit-User Plane (CU-UP) and User Equipment (UE), leading to data loss when a secondary node (SgNB) using New Radio (NR) PDCP allocates a radio resource for a bearer using Long-Term Evolution (LTE) PDCP.
Innovation Solution
The method involves generating indication information indicating whether the PDCP version of a bearer has been changed, and transmitting this information from the Central Unit-Control Plane (CU-CP) to the CU-UP in the secondary node. This information is used to align the PDCP sequence number for downlink and uplink packets, preventing mismatches and data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the secondary node allocates radio resources for LTE bearers using NR PDCP, then dual connectivity functionality is enabled, but PDCP sequence number mismatch occurs between CU-UP and UE
Solution Approach 1:
The invention applies preliminary action by having the CU-CP generate indication information about PDCP version changes before the CU-UP processes packets. This advance notification allows the CU-UP to properly align sequence numbers from the outset, preventing mismatches between CU-UP and UE while maintaining dual connectivity functionality.
Solution Approach 2:
The indication information generated by the CU-CP serves as an intermediary mechanism that bridges the control plane and user plane. This intermediary carries critical version change information from the CU-CP to the CU-UP, enabling the CU-UP to adjust its sequence number allocation accordingly and maintain synchronization with the UE.
2Manufacturing precision
If PDCP version change indication is transmitted from CU-CP to CU-UP, then sequence number alignment is achieved, but signaling overhead increases
Solution Approach 1:
The invention extracts only the essential information needed for sequence number alignment - specifically, the indication of PDCP version changes. By taking out only this critical information rather than transmitting complete configuration details, the solution achieves sequence number alignment while minimizing signaling overhead between CU-CP and CU-UP.
Solution Approach 2:
The indication information changes key parameters (PDCP version indicators) that trigger sequence number realignment in the CU-UP. By monitoring and responding to these parameter changes rather than continuous signaling, the system maintains precise sequence number alignment with minimal overhead, only communicating when actual version changes occur.
Data Source
AI summary
The present disclosure relates to a communication method and system for converging a 4th-Generation (4G) or 5th-Generation (5G) communication system for supporting higher data rates beyond the 4G system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on 5G communication technology and IoT-related technology. A method of a central unit-control plane (CU-CP) included in a secondary node (or secondary gNB (SgNB)) in a wireless communication system supporting evolved universal terrestrial radio access and new radio dual connectivity includes receiving, from a master node (or master eNB (MeNB)), a first message requesting the SgNB to allocate a radio resource for a bearer, and transmitting a second message, including indication information indicating whether a packet data convergence protocol version of the bearer has been changed, to the CU-UP included in the SgNB. The indication information is generated based on the first message.