Uplink Power Control for Fast L1/L2 Cell Activation
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Solution Overview
Problem
Existing techniques for activating a deactivated cell to a newly activated cell in wireless communication systems are too slow and time-consuming, leading to potential failures in meeting latency and quality of service requirements due to the need to determine transmission power requirements based on path loss reference signals after a cell activation command.
Innovation Solution
The user equipment (UE) receives path loss reference signals in a deactivated cell prior to activation and uses these measurements to transmit uplink signals based on pre-determined power settings upon receiving the activation command, reducing latency by transmitting earlier than if measurements were taken post-activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE determines transmission power requirements based on path loss reference signals after receiving the cell activation command, then the transmission power can be accurately adapted to current channel conditions, but the cell activation process becomes too slow and fails to meet latency requirements
Solution Approach 1:
The UE performs path loss measurements and determines transmission power requirements in advance, before receiving the cell activation command. Specifically, the UE measures path loss reference signals (PLRS) in the deactivated cell prior to activation and calculates the transmission power that would be needed. When the activation command is received, the UE can immediately transmit uplink signals using the pre-calculated power settings, eliminating the measurement and calculation delay that would otherwise occur after activation.
2Speed
If the UE transmits uplink signals immediately after cell activation without pre-measuring path loss, then the response time is reduced, but the transmission power may be inaccurate leading to quality of service failures
Solution Approach 1:
The UE performs path loss measurements and determines transmission power requirements in advance, before receiving the cell activation command. Specifically, the UE measures path loss reference signals (PLRS) in the deactivated cell prior to activation and calculates the transmission power that would be needed. When the activation command is received, the UE can immediately transmit uplink signals using the pre-calculated power settings, eliminating the measurement and calculation delay that would otherwise occur after activation.
3Reliability
If the UE waits for path loss reference signals to be available in the activated cell before transmitting, then the transmission power measurement is reliable, but the latency requirement cannot be met
Solution Approach 1:
The UE performs path loss measurements and determines transmission power requirements in advance, before receiving the cell activation command. Specifically, the UE measures path loss reference signals (PLRS) in the deactivated cell prior to activation and calculates the transmission power that would be needed. When the activation command is received, the UE can immediately transmit uplink signals using the pre-calculated power settings, eliminating the measurement and calculation delay that would otherwise occur after activation.
Data Source
AI summary
Example implementations include a method, apparatus and computer-readable medium of wireless communication by a user equipment, comprising receiving an indication of a first set of PLRSs in a first cell or an indication of a second set of PLRSs in a second cell, prior to a cell activation indication being received in the second cell, wherein the first cell is a deactivated cell and the second cell is an active cell. The implementations further includes receiving the cell activation indication in the second cell activating the first cell. Additionally, the implementations further includes transmitting an uplink signal in the first cell based on a first transmission power measurement or a second transmission power measurement, in response to receiving the cell activation indication, where the first transmission power measurement is based on the first set of PLRSs and the second transmission power measurement is based on the second set of PLRSs.