PDCP Count Handling for RRC Connection Resume
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Solution Overview
Problem
When a user equipment (UE) moves to a new base station after suspending a radio resource control (RRC) connection, the lack of synchronization in PDCP COUNT between the UE and the new base station can lead to failure in integrity verification, causing the suspended RRC connection to be left and a new connection to be established instead of resuming the previous one.
Innovation Solution
The use of a predetermined PDCP hyper frame number (HFN) value, set to all bits '1', ensures synchronization between the UE and the base station, allowing successful resumption of the suspended RRC connection even when the UE moves to a different base station, by avoiding the reuse of previous PDCP COUNT values and maintaining connection integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE uses the stored PDCP COUNT value from the suspended connection, then the connection resumption is fast and efficient, but the integrity verification fails when the UE moves to a new base station due to PDCP COUNT desynchronization
Solution Approach 1:
The patent changes the PDCP COUNT parameter by clearing its value to zero before resuming the suspended RRC connection. This parameter modification ensures that the UE and the new base station start with synchronized PDCP COUNT values, enabling successful integrity verification while maintaining efficient connection resumption. The principle is applied in the method where the UE clears the PDCP COUNT value stored in the context before resuming the connection at a new base station.
2Quantity of substance
If the UE maintains the suspended connection context without clearing PDCP COUNT, then memory resources are preserved, but connection integrity cannot be guaranteed when moving between base stations
Solution Approach 1:
The patent selectively modifies only the PDCP COUNT parameter within the suspended connection context by clearing it to zero, while preserving other context information such as security parameters, radio bearer configurations, and cell identifiers. This selective parameter clearing approach balances memory resource preservation with connection integrity guarantee, allowing the UE to resume connections reliably at new base stations without losing essential context data.
3Loss of time
If the PDCP COUNT value is not cleared before resumption, then the connection can be resumed quickly using stored context, but the previous PDCP COUNT values may be reused causing security issues
Solution Approach 1:
The patent clears the PDCP COUNT value to zero before resuming the suspended connection, which prevents reuse of previous PDCP COUNT values and associated security keys. This parameter clearing ensures that new security context is established during connection resumption, maintaining security integrity while keeping the resumption process efficient by only clearing the necessary counter value rather than re-establishing the entire connection.
Solution Approach 2:
The patent performs the PDCP COUNT clearing action before the connection resumption process begins, as part of the context preparation. This preliminary action ensures that when the connection is resumed, the PDCP COUNT is already synchronized and security context is properly initialized, avoiding security issues that would arise from reusing old COUNT values while maintaining fast resumption timing.
Data Source
AI summary
Methods and apparatus, including computer program products, are provided for resuming connections. In some example embodiments, there may be provided a method that includes receiving, at a user equipment, a radio resource control connection resume message; verifying, at the user equipment, an integrity of the received radio resource control connection resume message, wherein the user equipment verifies the integrity based on a predetermined value of a packet data convergence protocol hyper frame number; and resuming, by the user equipment, use of a suspended radio resource control connection, when the integrity verification of the received radio resource connection resume message is passed successfully. Related systems, methods, and articles of manufacture are also described.