Conditional PCell Handover Measurement Reporting
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Solution Overview
Problem
In conditional handover scenarios in wireless communication systems, the secondary cell configuration for carrier aggregation (CA) and dual connectivity (DC) may be outdated by the time a wireless device executes the handover, leading to delayed configuration and potential resource wastage, as the source base station provides outdated measurement results to the target base station.
Innovation Solution
A method where a wireless device transmits a handover complete message to the target cell only when the handover condition is met, including measurement results of neighbor cells, allowing the target base station to configure CA and/or DC operations based on up-to-date measurements, thereby reducing delays and optimizing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the source base station provides measurement results to the target base station before handover execution, then the target base station can prepare SCell configuration in advance, but the measurement results become outdated by the time handover is executed
Solution Approach 1:
The source base station performs measurement results acquisition and SCell configuration preparation in advance before handover execution, allowing the target base station to have configuration ready while the wireless device is still connected to the source base station. This preliminary action reduces handover execution time while managing the inherent information staleness through subsequent updates.
Solution Approach 2:
The wireless device performs new measurements after connecting to the target base station and feeds back updated measurement results through a handover complete message. This feedback mechanism ensures the target base station receives current measurement data to update SCell configuration, resolving the information staleness issue caused by early measurement acquisition.
2Loss of information
If the target base station waits for measurement results from the wireless device before configuring CA/DC, then measurement accuracy is improved, but SCell addition is significantly delayed
Solution Approach 1:
The source base station obtains measurement results and prepares SCell configuration before handover execution, so the target base station has configuration ready in advance. This preliminary preparation reduces the time delay for SCell addition while managing measurement accuracy through subsequent feedback updates after connection.
Solution Approach 2:
The system transitions from a static measurement approach (single pre-handover measurement) to a dynamic two-stage measurement process: first measurements before handover for initial configuration preparation, then updated measurements after connection for configuration refinement. This dynamic approach balances speed and accuracy.
3Speed
If the wireless device executes conditional handover immediately when condition is met, then handover speed is improved, but configuration may be outdated leading to handover failure
Solution Approach 1:
The source base station prepares SCell configuration in advance based on pre-handover measurement results, so when the wireless device executes conditional handover immediately upon condition fulfillment, the configuration is already ready rather than waiting for post-connection measurements. This preliminary preparation maintains handover speed while improving reliability.
Solution Approach 2:
After the wireless device connects to the target base station, it performs updated measurements and feeds back results through a handover complete message. The target base station uses this feedback to update SCell configuration, ensuring configuration accuracy and preventing handover failure due to outdated information.
Data Source
AI summary
A method and apparatus for measurement reporting during a conditional PCell handover in a wireless communication system is provided. A wireless device receives, from the source cell, a handover command including a handover condition for a target cell. A wireless device performs measurement on at least one of neighbor cells. A wireless device transmits, to the target cell, a handover complete message based on that the handover condition for the target cell is met, wherein the handover complete message includes results of the measurement on the at least one of the neighbor cells.