PDCP Re-Establishment for Faster LTE-NR Carrier Aggregation
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Solution Overview
Problem
In next-generation mobile communication systems, the transition from an inactive state to a connected state for carrier aggregation in terminals is delayed due to the need for bearer changes and PDCP version changes during operations like handover or sequence number changes, particularly in dual connectivity between LTE and NR.
Innovation Solution
A method and device for terminal to perform carrier aggregation activation without delay by implementing PDCP re-establishment operations, including first and second PDCP re-establishment procedures to transition from LTE PDCP to NR PDCP, adjusting state variables and processing PDCP PDUs to ensure seamless header interpretation and data delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP re-establishment operations are performed during handover or sequence number changes in dual connectivity between LTE and NR, then bearer change and PDCP version change are achieved, but transition delay from inactive state to connected state occurs
Solution Approach 1:
The patent applies preliminary action by performing PDCP re-establishment operations in advance during handover or sequence number changes while the terminal is in connected state. This prepares the PDCP layer for future inactive-to-connected state transitions, so that when the terminal actually transitions states, the carrier aggregation can be activated immediately without waiting for PDCP re-establishment, thus reducing transition delay while ensuring bearer change reliability
2Adaptability or versatility
If PDCP version change from LTE PDCP to NR PDCP is implemented, then adaptability to dual connectivity is improved, but connection setup time increases
Solution Approach 1:
The patent implements preliminary action by completing the PDCP version change from LTE PDCP to NR PDCP during handover or sequence number changes before the terminal enters inactive state. This preliminary version change ensures dual connectivity adaptability is established in advance, so that when the terminal transitions from inactive to connected state, no additional PDCP version change is needed, thus reducing connection setup time while maintaining adaptability
3Reliability
If carrier aggregation activation is performed after traditional state transition procedures, then protocol compliance is maintained, but data transfer rate is reduced due to delay
Solution Approach 1:
The patent applies preliminary action by preparing all necessary PDCP re-establishment operations and version changes during handover or sequence number changes before the terminal enters inactive state. This allows the terminal to immediately activate carrier aggregation upon transitioning from inactive to connected state without waiting for protocol procedures, thus achieving both protocol compliance and high data transfer rates with minimal delay
Data Source
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AI summary
Disclosed are a communication technique for merging IoT technology with a 5G communication system for supporting a data transmission rate higher than that of a 4G system and a system therefor. The present disclosure can be applied to intelligent services (for example, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail, security, and safety related services, and the like) on the basis of 5G communication technology and IoT-related technology. The present invention relates to operations of a terminal and a base station in a mobile communication system. The present invention provides a method by which a terminal re-establishes a PDCP in a wireless communication system, the method comprising the steps of: receiving a message including PDCP re-establishment information on a DRB from a base station in which an RRC connection is set up; checking whether the PDCP reestablishment information includes configuration information of an SDAP layer; and determining whether to perform a PDCP re-establishment procedure for changing the DRB operating as a PDCP of a first system into a PDCP of a second system on the basis of the checking result.