PDCP Configuration Reversion for Seamless NR-LTE Handover
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Solution Overview
Problem
Current wireless communication systems face challenges in seamlessly handover scenarios between New Radio (NR) and Long Term Evolution (LTE) networks, particularly when a user equipment (UE) configured with NR Packet Data Convergence Protocol (PDCP) needs to switch to LTE PDCP due to legacy eNBs not supporting NR PDCP, leading to potential service interruptions.
Innovation Solution
The system enables a wireless device to revert to LTE PDCP configuration for Signaling Radio Bearer 1 (SRB1) during handover to a legacy eNB by determining specific handover commands, applying default LTE configurations, and changing security algorithms, thereby minimizing service disruptions without requiring upgrades to legacy eNBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE configured with NR PDCP performs handover to a legacy eNB, then connectivity is maintained, but service interruptions occur due to PDCP version mismatch
Solution Approach 1:
The UE proactively determines the target eNB's NR PDCP support capability before completing the handover, and prepares the appropriate PDCP configuration in advance. This preliminary assessment allows the UE to switch to LTE PDCP configuration before the handover executes, preventing service interruptions rather than reacting to them afterward.
Solution Approach 2:
The UE dynamically adapts its PDCP configuration based on the target eNB's capabilities. Instead of using a fixed PDCP version, the UE can switch between NR PDCP and LTE PDCP configurations depending on whether the target eNB supports NR PDCP, making the system flexible and adaptable to different network scenarios.
2Loss of time
If legacy eNBs are upgraded to support NR PDCP, then service interruptions are minimized, but deployment costs increase
Solution Approach 1:
The UE is designed with multi-functionality to support both NR PDCP and LTE PDCP configurations. This allows the UE to communicate with both legacy eNBs and modern gNBs using appropriate PDCP versions, eliminating the need for legacy eNB upgrades while maintaining seamless connectivity.
Solution Approach 2:
The invention changes the PDCP version parameter dynamically based on network conditions and target eNB capabilities. Instead of requiring hardware upgrades to change system capabilities, the solution modifies the operational parameter (PDCP version) to match the target network's supported formats.
3Adaptability or versatility
If the UE reverts to LTE PDCP configuration during handover, then compatibility with legacy eNBs is achieved, but configuration complexity increases
Solution Approach 1:
The UE autonomously determines the target eNB's NR PDCP support capability and self-manages the PDCP configuration switching without requiring complex network-side coordination. The UE services itself by making intelligent decisions about which PDCP version to use based on received handover commands and its own capability assessments.
Data Source
AI summary
A wireless device is configured to support connections to one or more serving cells in a first radio access network (RAN), using a first radio access technology (RAT) and to one or more serving cells in a second RAN, using a second RAT that differs from the first RAT. The wireless device receives one or more handover commands as part of a handover of the wireless device to a base station in the first RAN, and determines, based on the one or more handover commands, that the wireless device is to revert from a currently configured Packet Data Convergence Protocol (PDCP) configuration to a PDCP configuration associated with the first RAT. The wireless device then reverts to the PDCP configuration associated with the first RAT, in response to said determining.