NR-to-E-UTRA Handover Using Radio Bearer Configuration Transfer
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Solution Overview
Problem
5G NR base stations do not include radio bearer configurations in Handover Preparation Information messages for handovers to E-UTRA base stations, leading to service interruptions due to incomplete RB configurations.
Innovation Solution
Incorporate the existing 5G NR RB configuration into LTE Handover Preparation Information messages to enable E-UTRA base stations to properly configure RBs, ensuring seamless handovers and continuous service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the source 5G NR base station does not include RB configuration in Handover Preparation Information message, then the message format remains simple and compatible with existing protocols, but the target E-UTRA base station cannot configure RBs properly causing service interruption
Solution Approach 1:
The patent extracts the necessary RB configuration information from the complex 5G NR configuration and includes only the essential elements (drb-Identity, pdp-Type, QoS parameters) in the Handover Preparation Information message. This selective extraction maintains message simplicity while providing sufficient information for the target E-UTRA base station to configure RBs properly, resolving the contradiction between message simplicity and service continuity.
Solution Approach 2:
The patent makes the Handover Preparation Information message universal by including RB configuration information that can be used by both 5G NR and E-UTRA base stations. The message structure is designed to carry configuration parameters that are applicable across different radio access technologies, enabling the target E-UTRA base station to properly configure RBs while maintaining compatibility with existing protocols.
2Ease of manufacture
If the target E-UTRA base station configures a new DRB without receiving RB configuration, then it can establish communication with the UE, but service interruption occurs due to DRB change
Solution Approach 1:
The patent applies preliminary action by including the RB configuration information in the Handover Preparation Information message before the handover occurs. The target E-UTRA base station receives and processes this configuration information in advance, allowing it to configure RBs properly before the UE switches to its coverage. This prevents service interruption by ensuring the DRB configuration remains consistent across the handover.
3Reliability
If complete RB configuration is transferred to enable seamless handover, then service continuity is maintained, but the information transfer requires more complex message structures
Solution Approach 1:
The patent extracts only the essential RB configuration parameters (drb-Identity, pdp-Type, QoS characteristics, tunnel endpoint identifiers) needed for handover from the complete 5G NR RB configuration. By selecting and transferring only these critical elements, the message structure remains relatively simple while providing sufficient information for the target E-UTRA base station to maintain service continuity, thus resolving the contradiction between information completeness and message complexity.
Data Source
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AI summary
This document describes methods, devices, systems, and means for the transfer of radio bearer (RB) configurations from a Fifth Generation (5G) New Radio (NR) base station (121) to an Evolved Universal Terrestrial Radio Access (E-UTRA) base station (122). The 5G NR base station (121) configures an RB configuration to configure an RB for communication of Protocol Data Units between the 5G NR base station (121) and a user equipment (111). The 5G NR base station (121) determines to hand over the user equipment (111) to an Evolved Universal Terrestrial Radio Access (E‑UTRA) base station and sends a Handover Request message for the user equipment (111) to the E-UTRA base station (122). The 5G NR base station (121) receives a Handover Request Acknowledge message from the E-UTRA base station (122) and transmits a 5G NR Radio Resource Control (RRC) message including an E-UTRA RRC message to the user equipment (111).