Uplink Reference-Signal Path-Loss Tracking for Beam Updates
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Solution Overview
Problem
Current methods for tracking reference signal path losses in uplink transmissions experience a significant mismatch between the application of new spatial relations and path-loss RS indications, leading to incorrect power compensation and degraded UL signal quality due to high-frequency propagation losses and limited UE capabilities in maintaining path-loss RSs.
Innovation Solution
Implement mechanisms for pre-activating candidate path-loss RSs and establishing priority rules to ensure timely and accurate path-loss estimation, allowing UEs to associate and apply calculated path-loss estimates with updated UL transmission beams, thereby reducing latency and improving power compensation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If MAC-CE commands for updating spatial relation and path-loss RS are transmitted through the same PDSCH, then the beam indication is updated, but a long-time mismatch occurs between the updated spatial relation and the updated path-loss RS indication
Solution Approach 1:
The patent introduces a preliminary action by having the UE maintain multiple path-loss RS estimates in advance (current active path-loss RS estimate and at least one candidate path-loss RS estimate) before the spatial relation update is applied. This allows the path-loss estimate to be ready and synchronized when the new spatial relation becomes active, eliminating the mismatch delay.
2Measurement precision
If the UE waits for ACK signal plus 3 ms plus measurement samples before applying new path-loss RS estimates, then measurement accuracy is improved, but the latency increases significantly to approximately 100 ms
Solution Approach 1:
The UE performs path-loss RS measurements and maintains candidate path-loss RS estimates in advance, before the spatial relation update is applied. This preliminary measurement action ensures that accurate path-loss estimates are ready when needed, reducing the update latency while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces dynamic switching between multiple path-loss RS estimates. The UE maintains both current and candidate path-loss RS estimates and can switch between them based on spatial relation updates. This dynamic approach allows the system to adapt quickly to changing spatial relations while maintaining accurate path-loss measurements.
3Device complexity
If incorrect path-loss compensation is applied due to mismatched path-loss RS, then the UL transmission power control becomes inaccurate, but the system continues to operate without additional complexity
Solution Approach 1:
By maintaining multiple path-loss RS estimates in advance and switching to the appropriate candidate estimate when spatial relations are updated, the system ensures accurate path-loss compensation is applied from the start of the new spatial relation, preventing incorrect power control without adding significant complexity.
Data Source
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AI summary
Methods and systems for controlling a transmit power of a wireless communication device are disclosed herein. In one embodiment, a method includes: determining one or more reference signals transmitted by a wireless communication node; maintaining one or more path loss estimates for the one or more reference signals; associating at least one path loss estimate with an uplink (UL) signal; calculating a transmission power of the UL signal according to the at least one path loss estimate; and transmitting the UL signal in accordance with the calculated transmission power.