PDCP Version Handling in RRC Re-establishment
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Solution Overview
Problem
Traditional techniques for re-establishing a connection between a UE and a network node in wireless communication systems face latency and disrupted communications due to mismatches in PDCP configurations between different base stations, particularly when transitioning from an NR-capable base station to a legacy LTE base station.
Innovation Solution
The techniques involve re-establishing the PDCP configuration for SRB1 by reverting to LTE PDCP upon connection re-establishment, modifying the UE AS context to ensure compatibility with legacy base stations, and using explicit flags or configurations to specify the PDCP version for SRB1 and SRB2, ensuring seamless communication across different base station types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If NR PDCP configuration is used for SRB1 during connection establishment, then communication efficiency is improved when connecting to NR-capable base stations, but connection re-establishment fails or experiences latency when transitioning to legacy LTE base stations
Solution Approach 1:
The patent implements dynamic PDCP version selection for SRB1 based on base station capability detection. The UE determines whether to use NR PDCP or LTE PDCP configuration by checking the PDCP version indicator in the RRCReconfiguration message from the base station. This dynamic adaptation allows the system to optimize for NR when available while ensuring compatibility with legacy LTE base stations during connection re-establishment.
Solution Approach 2:
The patent changes the PDCP version parameter (NR PDCP vs. LTE PDCP) based on detected base station capabilities. When the UE receives an RRCReconfiguration message with a PDCP version indicator, it adjusts its PDCP configuration accordingly - using NR PDCP for enhanced performance with NR-capable stations, and falling back to LTE PDCP when connecting to legacy base stations or during re-establishment scenarios.
2Productivity
If the UE maintains NR PDCP configuration after connection suspension, then performance is optimized for NR networks, but compatibility issues arise when re-establishing connection with LTE base stations
Solution Approach 1:
The system dynamically adjusts PDCP configuration based on the target base station's capabilities detected during connection re-establishment. The UE monitors the PDCP version indicator in RRC messages and transitions between NR PDCP and LTE PDCP modes as needed, ensuring both optimal performance and broad compatibility across different base station types.
Solution Approach 2:
The UE implements multi-functionality by supporting both NR PDCP and LTE PDCP configurations for SRB1. This universal capability allows the UE to operate efficiently with NR-capable base stations while maintaining seamless compatibility with legacy LTE base stations, achieving broad interoperability across different network generations.
3Ease of operation
If PDCP configuration is not explicitly specified during re-establishment, then procedure simplicity is maintained, but configuration mismatches cause communication disruptions
Solution Approach 1:
The base station provides feedback to the UE about its PDCP version capability through the PDCP version indicator in the RRCReconfiguration message. This feedback mechanism allows the UE to automatically determine the appropriate PDCP configuration without complex manual configuration, maintaining procedure simplicity while ensuring reliable communication by preventing configuration mismatches.
Solution Approach 2:
The PDCP version indicator in the RRCReconfiguration message serves as an intermediary that conveys base station capability information to the UE. This intermediary element enables automatic and reliable PDCP configuration selection during re-establishment, eliminating the need for complex explicit configuration while ensuring communication continuity through proper protocol matching.
Data Source
AI summary
Systems, methods, and apparatus are disclosed for a user equipment. An example method performed by a user equipment includes establishing a connection to a Radio Access Network (RAN) via a first network node. Communications are provided over the connection using Signaling Radio Bearer 1 (SRB1) configured with a New Radio (NR) Packet Data Convergence Protocol (PDCP). After the connection is suspended, the user equipment receives a Radio Resource Control (RRC) connection re-establishment message from a second network node. The connection re-establishment message includes a radioResourceConfigDedicated information element (IE). The user equipment re-establishes the connection to the RAN by applying a Long-Term Evolution (LTE) PDCP configuration to SRB1, performing a radio resource configuration procedure in accordance with the radioResourceConfigDedicated IE, and sending an RRC connection re-establishment complete message to the second network node.