Lower-Layer Mobility Handover With Pre-Obtained Timing Advance
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Solution Overview
Problem
Current 3GPP 5G technology lacks discussion on uplink synchronization failure and compliance check mechanisms in lower layer-based mobility cases, which are crucial for seamless handovers in wireless communication systems.
Innovation Solution
A user equipment (UE) is equipped with a processor to receive RRC reconfiguration messages, perform random access procedures to obtain timing advance (TA) values for candidate cells, and switch to a candidate cell upon receiving an indication, with mechanisms for handling synchronization failures and compliance checks, including timer management and message transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs random access procedures to obtain TA values for candidate cells, then the reliability of uplink synchronization is improved, but the processing time and complexity increase
Solution Approach 1:
The UE performs random access procedures to obtain TA values for candidate cells in advance, before the actual handover is triggered. This preliminary action ensures that when handover is needed, the UE already has synchronization parameters ready, reducing the time loss during actual handover execution.
Solution Approach 2:
The patent introduces timer mechanisms and failure handling procedures that prepare the system in advance for potential synchronization failures. By having backup TA values and predefined failure recovery procedures ready beforehand, the system cushions against synchronization issues without causing significant time loss.
2Reliability
If the UE implements compliance check mechanisms for handover, then the reliability of mobility management is improved, but the device complexity increases
Solution Approach 1:
The compliance check mechanism is segmented into distinct functional components: TA value acquisition, timer management, failure detection, and recovery procedures. Each component handles a specific aspect of the compliance check, making the overall complex mechanism more manageable and implementable through modular processing.
Solution Approach 2:
The UE performs compliance checks and obtains TA values before the actual handover execution. This preliminary compliance verification ensures that when handover is triggered, the UE is already compliant with the target cell's requirements, reducing the need for complex real-time decision-making during handover.
3Speed
If the UE switches to a candidate cell upon receiving indication, then the handover speed is improved, but the risk of synchronization failure increases
Solution Approach 1:
The UE obtains TA values and performs compliance checks before the handover indication is received. This preliminary preparation ensures that when the handover indication arrives, the UE can switch cells immediately with already-validated synchronization parameters, achieving both high speed and high reliability.
Solution Approach 2:
The patent implements feedback mechanisms where the UE monitors synchronization status and reports to the network. This continuous feedback allows the system to detect and correct synchronization issues before they cause handover failures, maintaining reliability while enabling fast handover execution.
Data Source
AI summary
Embodiments of the present application relate to methods and apparatuses for an uplink (UL) synchronization failure and compliance check in a lower layer-based mobility case under a 3rd Generation Partnership Project (3GPP) 5G system or the like. According to an embodiment of the present application, a user equipment (UE) includes a transceiver and a processor coupled to the transceiver, and the processor is configured to receive a radio resource control (RRC) reconfiguration message via the transceiver, wherein the RRC reconfiguration message includes first configuration information regarding one or more candidate cells; after receiving the RRC reconfiguration message, get one or more timing advance (TA) values related to the one or more candidate cells by performing one or more random access (RA) procedures or by transmitting one or more reference signals to the one or more candidate cells; and switch from a source cell to a first candidate cell within the one or more candidate cells, upon receiving a first indication associated with the first candidate cell from the source cell.