Uplink Power Control for Dual Active Protocol Stack Handover
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Solution Overview
Problem
During dual active protocol stack (DAPS) based handover in wireless communications, user equipment (UE) experiences significant interruption time due to simultaneous uplink transmissions to both source and target cells, as the source cell's transmission power is prioritized over the target cell's, leading to potential power imbalances and increased interruption times.
Innovation Solution
The processing circuitry determines and adjusts transmission powers for uplink transmissions between the source and target cells to ensure that total power remains within thresholds, potentially dropping or re-timing transmissions to prevent overlap and optimize power usage, allowing simultaneous communications without interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the UE maintains connection with both source and target cells during DAPS handover, then the handover interruption time is minimized, but the UE cannot perform simultaneous uplink transmissions to both cells with adequate power
Solution Approach 1:
The patent applies dynamic power adjustment by monitoring the actual power levels of simultaneous uplink transmissions to source and target cells. The UE dynamically modifies transmission parameters based on real-time power conditions, switching between different transmission modes (simultaneous transmission with power adjustment, or time-division multiplexing) to maintain both connectivity and power balance during handover.
Solution Approach 2:
The patent changes transmission parameters including power levels, timing, and multiplexing patterns to resolve power conflicts. By adjusting these parameters dynamically, the system enables simultaneous uplink transmissions to both cells while maintaining power balance, or falls back to time-division multiplexing when necessary to ensure adequate power for both connections.
2Productivity
If the UE performs simultaneous uplink transmissions to source and target cells, then the handover process is continuous, but power imbalance occurs due to source cell priority
Solution Approach 1:
The patent implements feedback mechanisms where the UE monitors the actual power levels of uplink transmissions to both cells. Based on this feedback, the system identifies power imbalance conditions and automatically adjusts transmission parameters or switches to time-division multiplexing patterns to achieve power balance while maintaining handover continuity.
Solution Approach 2:
The system dynamically adapts its transmission strategy based on real-time power conditions. When power imbalance is detected, the UE dynamically modifies transmission parameters or switches between simultaneous transmission modes and time-division multiplexing modes to maintain both connectivity and power balance.
3Power
If the UE uses time-division multiplexing for uplink transmissions, then power balance is achieved, but the handover interruption time increases
Solution Approach 1:
The patent applies dynamic mode switching between simultaneous transmission and time-division multiplexing based on real-time power conditions. When power balance can be achieved through simultaneous transmission with power adjustment, the system uses that mode to minimize interruption. When power imbalance occurs, it switches to time-division multiplexing to ensure power balance, thus dynamically optimizing the trade-off between continuity and power balance.
Data Source
AI summary
Aspects of the disclosure further provide various apparatuses and methods for wireless communications. One apparatus includes processing circuitry that can determine a first transmission power for a first uplink transmission associated with the source cell and a second transmission power for a second uplink transmission associated with the target cell. When the first uplink transmission and the second uplink transmission overlap in time domain and a total power of the first transmission power and the second transmission power is above a first threshold, the processing circuitry reduces the first transmission power for the first uplink transmission to a third transmission power so that a total power of the second transmission power and the third transmission power is equal to or less than the first threshold. The processing circuitry performs the first uplink transmission at the third transmission power and the second uplink transmission at the second transmission power.