PDCP Counter Wrap-Around Prevention in Multi-Connectivity Networks
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Solution Overview
Problem
In mobile or wireless telecommunication systems, particularly in dual or multi-connectivity scenarios, there is no proper PDCP procedure for resetting the packet data convergence protocol (PDCP) count value, leading to potential wrap-around issues on bearers mapped on radio link control (RLC) acknowledged mode (AM) where PDCP is not terminated in the Master Node (MN).
Innovation Solution
A process is implemented where the node hosting PDCP detects an impending wrap-around of the PDCP count value and sends a counter check request to the Master Node, including the count value approaching its maximum. The Master Node then initiates the release and re-establishment of the data radio bearer (DRB) to prevent the count wrap-around.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP is not terminated in the Master Node for SCG bearers, then network connectivity and data transmission are maintained, but PDCP count wrap-around occurs leading to packet delivery failures
Solution Approach 1:
The Secondary Node detects impending wrap-around of the PDCP count value before it actually occurs and proactively triggers the counter check procedure to release and re-establish the SCG bearer. This preliminary action prevents the wrap-around from causing packet delivery failures, resolving the contradiction by maintaining reliability without requiring complex real-time monitoring during data transmission.
Solution Approach 2:
The invention implements a feedback mechanism where the Secondary Node monitors the PDCP count value and sends counter check requests to the Master Node when wrap-around is detected. This feedback loop enables the system to detect and respond to the wrap-around condition, ensuring continuous reliable packet delivery while maintaining manageable procedure complexity through standardized signaling.
2Reliability
If the node hosting PDCP silently releases the DRB upon detecting wrap-around, then the wrap-around is prevented, but network throughput and connection continuity are compromised
Solution Approach 1:
Instead of silently releasing the DRB, the invention implements a feedback mechanism where the Secondary Node sends counter check requests to the Master Node to inform it of the impending wrap-around. This allows the Master Node to be aware of the situation and coordinate the bearer re-establishment, preventing throughput loss while maintaining reliability.
Solution Approach 2:
The counter check request message acts as an intermediary communication between the Secondary Node and Master Node. It conveys the wrap-around status without immediately terminating the connection, allowing coordinated handling that preserves network throughput while preventing wrap-around issues.
3Device complexity
If no counter check procedure is implemented, then device complexity is minimized, but PDCP count wrap-around cannot be detected or prevented
Solution Approach 1:
The invention reuses the existing counter check request message structure (defined in TS 36.423 section 9.1.3.14) for the purpose of detecting PDCP count wrap-around. By making this existing message multi-functional, the system achieves reliable wrap-around detection without adding significant complexity, as the message format and basic procedure are already standardized.
Data Source
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AI summary
Systems, methods, apparatuses, and computer program products for informing a multi-connectivity master node of an impending wrap around of packet counter value are provided. One method includes receiving, from a nodehosting packet data convergence protocol (PDCP) for a data radio bearer (DRB), a counter check request including a count value, and determining that the count value is approaching its maximum value. In response to the determining, the method may further include initiating release of the data radio bearer (DRB) and optionally adding a new bearer.