Dual-Loop Frequency Pre-Compensation for NTN Uplink Stability
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Solution Overview
Problem
Existing wireless communication systems in non-terrestrial networks (NTN) face challenges in efficiently adjusting frequency compensation due to changes in user equipment (UE) location and velocity, leading to suboptimal uplink signal transmission.
Innovation Solution
Implementing a dual-loop frequency control mechanism that includes closed-loop and open-loop frequency pre-compensation, adjusted based on UE location and velocity updates, and network node control adjustments based on GNSS location updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency pre-compensation is adjusted dynamically based on UE location and velocity updates, then uplink signal quality is improved, but system complexity increases due to dual-loop control mechanisms
Solution Approach 1:
The frequency control system is segmented into two independent loops: open-loop frequency pre-compensation based on UE location and velocity, and closed-loop frequency adjustment based on network node feedback. This segmentation allows each loop to handle specific aspects of frequency control, improving overall system reliability while maintaining manageable complexity through modular design
Solution Approach 2:
The open-loop frequency pre-compensation performs preliminary frequency adjustment based on predicted UE location and velocity before actual transmission occurs. This preliminary action reduces the burden on the closed-loop control and minimizes frequency errors proactively, improving uplink signal quality without requiring complex real-time adjustments
2Measurement precision
If closed-loop frequency pre-compensation is used to correct frequency errors, then frequency accuracy is improved, but transmission delay increases due to feedback loop
Solution Approach 1:
The system merges open-loop frequency pre-compensation and closed-loop frequency adjustment into a unified dual-loop control mechanism. The open-loop component provides immediate frequency correction based on UE motion parameters, while the closed-loop component refines accuracy through feedback. This combination achieves high frequency accuracy without relying solely on delayed closed-loop feedback
Solution Approach 2:
The closed-loop control implements feedback from the network node to the UE, where the network node measures frequency errors in received uplink signals and sends correction commands back to the UE. This feedback mechanism continuously improves frequency accuracy despite the presence of transmission delay, as the system adapts to accumulated errors over time
3Stability of the object's composition
If dual-loop frequency control is implemented, then frequency stability is improved, but processing overhead increases
Solution Approach 1:
Processing tasks are segmented between UE and network node: the UE performs open-loop frequency pre-compensation calculations based on location/velocity updates, while the network node handles closed-loop frequency error measurement and correction command generation. This segmentation distributes processing overhead, maintaining frequency stability without concentrating all processing complexity in one device
Solution Approach 2:
The UE performs self-service frequency pre-compensation using its own location and velocity information in the open-loop control. This self-service approach reduces the processing burden on the network node and minimizes overall system overhead, as the UE autonomously handles preliminary frequency adjustments without requiring extensive network processing
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine, after an update to a location or a velocity of the UE, a closed-loop frequency pre-compensation and an open-loop frequency pre-compensation. The UE may transmit, after the update to the location or the velocity of the UE, an uplink signal using a frequency pre-compensation that is based at least in part on the closed-loop frequency pre-compensation and the open-loop frequency pre-compensation. Numerous other aspects are described.