RRC Reconfiguration for DAPS Handover Failure Notification
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Solution Overview
Problem
Existing LTE and NR technologies face challenges in efficiently controlling mobility, particularly in minimizing user data interruption during handover between cells, and improving handover robustness.
Innovation Solution
A terminal apparatus and base station apparatus configuration that includes a receiver for RRC reconfiguration messages and a processing unit to perform configuration changes. In case of a DAPS handover, the processing unit reconfigures RLC state variables, resumes suspended Signaling Radio Bearers, and notifies the base station of handover failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If DAPS handover configuration is applied to minimize user data interruption during cell handover, then data interruption is reduced, but the complexity of mobility control processing increases
Solution Approach 1:
The patent applies preliminary action by configuring the terminal apparatus to perform DAPS handover procedures in advance. The processing unit is pre-configured to handle RRC reconfiguration messages, manage RLC state variables, and execute handover failure notifications before actual handover events occur, thereby minimizing data interruption while managing complexity through pre-established protocols
Solution Approach 2:
The patent implements feedback mechanisms where the terminal apparatus monitors handover status and provides feedback to the base station. The processing unit detects handover failure conditions and notifies the base station accordingly, enabling dynamic adjustment of mobility control parameters to balance data interruption minimization with processing complexity management
2Reliability
If handover robustness is improved through enhanced DAPS handover procedures, then handover reliability increases, but the processing time for mobility control increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting handover parameters based on network conditions. The processing unit modifies DAPS handover configurations, RLC state variable settings, and timing parameters to optimize the balance between handover robustness and processing time, adapting protocols to current network state rather than using fixed parameters
3Reliability
If RLC state variables are reconfigured during DAPS handover to handle failure cases, then handover failure detection improves, but the complexity of state management increases
Solution Approach 1:
The patent applies segmentation by dividing the RLC state management into distinct, manageable components. The processing unit handles different RLC state variables separately, configuring and monitoring them independently during DAPS handover. This segmentation enables comprehensive failure detection while reducing overall state management complexity through modular handling of each state parameter
Data Source
AI summary
A terminal apparatus for communicating with a base station apparatus is provided. The terminal apparatus includes a receiver configured to receive a Radio Resource Control (RRC) reconfiguration message including a parameter related to a first configuration from the base station apparatus, and a processing unit configured to perform configuration in accordance with the RRC reconfiguration message received. In a case that a first timer of an RRC protocol expires, a radio link failure of a source primary cell is not detected, and configuration related to Dual Active Protocol Stack (DAPS) handover is performed for the terminal apparatus, the processing unit reconfigures all of state variables configured for a Radio Link Control (RLC) entity of a Signaling Radio Bearer (SRB) in the source primary cell to respective initial values, resumes the SRB suspended in the source primary cell, and transmits an RRC message for notifying the base station apparatus that the DAPS handover has failed.