Power Reservation for Carrier Aggregation Signaling
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Solution Overview
Problem
In wireless communication systems, carrier aggregation with differing transmission time intervals (TTIs) leads to transient power and phase effects, reducing throughput due to the need for frequent power adjustments during shortened TTIs (sTTIs), especially in intra-band carrier aggregation where power changes on one carrier affect another.
Innovation Solution
A method where user equipment (UE) reserves power for expected increases during TTIs and selects a calibration point at the beginning of the TTI based on this reserved power, allowing digital back-off from a calibrated power to achieve desired transmit power without using transient periods, thus minimizing disruptions across overlapping TTIs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE uses different transmit powers for uplink transmissions in each sTTI, then the transmit power can be optimized for each short transmission interval, but transient effects (power and phase) occur on overlapping TTI transmissions on the first carrier
Solution Approach 1:
The UE performs preliminary power calibration at the beginning of the TTI on the first carrier before overlapping sTTI transmissions occur. This preliminary calibration establishes a stable power baseline that prevents transient effects during subsequent sTTI power adjustments, allowing throughput optimization without compromising transmission stability
Solution Approach 2:
The UE applies preliminary power reservation and calibration to counteract expected power transients before they occur. By anticipating and compensating for power changes in advance through calibration point selection, the system prevents transient effects from disrupting overlapping TTI transmissions while still allowing dynamic power adjustment for throughput optimization
2Productivity
If the UE performs frequent power adjustments during sTTIs, then the transmit power can be optimized for each short transmission interval, but the need for transient periods reduces throughput
Solution Approach 1:
The UE performs a single preliminary power calibration at the TTI boundary before overlapping sTTI transmissions, eliminating the need for frequent transient periods during sTTI operations. This preliminary action establishes power stability that allows continuous transmission without time losses from repeated calibration events
Solution Approach 2:
By establishing power calibration at the beginning of the TTI, the UE maintains continuous transmission during overlapping sTTIs without interruption for transient periods. The useful action of data transmission continues uninterrupted while power adjustments are handled through the preliminary calibration, maximizing throughput without time loss
3Measurement precision
If the UE selects calibration points dynamically during sTTIs, then the transmit power can be precisely controlled, but the complexity of power management increases
Solution Approach 1:
The UE performs preliminary calibration point selection at the TTI boundary based on expected power requirements, rather than dynamically selecting calibration points during each sTTI. This preliminary selection maintains precise power control while significantly reducing the complexity of real-time power management during overlapping transmissions
Solution Approach 2:
The UE performs power calibration with sufficient advance timing at the TTI boundary to cover all expected sTTI power requirements within the overlapping period. This partial calibration approach provides adequate precision for all subsequent sTTI transmissions without requiring complex dynamic recalibration, simplifying power management while maintaining control accuracy
Data Source
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AI summary
Methods, systems, and devices for wireless communication are described. In some cases, a user equipment (UE) may be scheduled to transmit uplink signals on different carriers during transmission time intervals (TTIs) that have different durations. As such, a TTI on a first carrier (e.g., a reference carrier) may overlap with multiple shortened TTIs (sTTIs) on a second carrier (e.g., a non-reference carrier). Using the techniques described herein, the UE may select a calibration point (or a gain index) for uplink transmissions at the beginning of the TTI on the reference carrier based on an amount of power reserved for expected power increases during the TTI. As such, when the UE has to update its transmit power for an uplink transmission during an sTTI on the second carrier, the UE may apply a digital back-off from a power associated with the calibration point.