Closed Loop Frequency Correction for Non-Terrestrial Networks
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Solution Overview
Problem
Non-terrestrial network (NTN) systems face challenges in determining accurate uplink frequencies due to Doppler effects, leading to frequency errors and inter-carrier interference, which limit throughput and require complex calculations that drain UE power.
Innovation Solution
A closed loop frequency correction scheme where a satellite provides an uplink frequency correction to the UE, allowing it to transmit an uplink signal at an appropriate frequency, reducing interference and improving throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex frequency correction calculations are performed at the UE, then frequency accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent introduces an intermediary frequency correction mechanism where the network side (gNB or satellite) provides frequency correction information to the UE. This intermediary approach allows the UE to achieve accurate frequency correction without performing complex calculations itself, thereby improving frequency accuracy while reducing device complexity and power consumption.
Solution Approach 2:
The patent implements a feedback-based frequency correction scheme where the network side monitors uplink frequency deviations and provides correction commands back to the UE. This closed-loop feedback mechanism enables continuous frequency accuracy improvement without requiring the UE to perform complex open-loop calculations, resolving the contradiction between accuracy and complexity.
2Measurement precision
If complex frequency correction calculations are performed at the UE, then frequency accuracy is improved, but power consumption increases
Solution Approach 1:
The network side acts as an intermediary that performs the computationally intensive frequency correction calculations and communicates the results to the UE. This shifts the power consumption burden from the mobile UE to the network infrastructure, improving frequency accuracy while reducing UE power consumption.
Solution Approach 2:
The network side autonomously performs frequency correction calculations and provides correction commands to UEs without requiring the UEs to perform complex calculations themselves. This self-service approach on the network side eliminates the need for power-intensive processing at the UE, resolving the power consumption issue.
3Device complexity
If uplink frequency is not corrected, then device complexity is reduced, but frequency errors and inter-carrier interference increase
Solution Approach 1:
The patent implements a feedback mechanism where the network side detects uplink frequency deviations and provides correction commands to UEs. This feedback-based approach maintains system simplicity at the UE while effectively eliminating frequency errors and inter-carrier interference through network-side correction.
4Measurement precision
If Doppler compensation is performed without closed-loop correction, then initial frequency accuracy is improved, but residual frequency errors persist
Solution Approach 1:
The patent implements continuous frequency correction through closed-loop feedback, where the network side continuously monitors uplink frequency and provides ongoing correction commands. This continuous correction action maintains frequency accuracy over time, eliminating residual errors that would persist with one-time Doppler compensation alone.
Solution Approach 2:
The closed-loop feedback mechanism continuously refines frequency accuracy by detecting residual errors and providing corrective commands. This feedback process transforms the system from static Doppler compensation to dynamic continuous correction, improving overall reliability and eliminating persistent frequency errors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The scheme enables efficient identification of appropriate uplink frequencies, reducing frequency errors and inter-carrier interference, thereby enhancing communication throughput in NTN systems.
Implementation Method 1
the satellite may determine a correction on the uplink frequency for the UE based on the initial uplink frequency
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. Generally, the described techniques provide for efficiently determining appropriate uplink frequencies for uplink transmissions to a satellite. As described herein, a wireless communications system may support a closed loop frequency correction scheme where a satellite may provide an uplink frequency correction to a user equipment (UE) such that the UE may be able to identify an appropriate uplink frequency for an uplink transmission. In some implementations, the UE may first transmit an uplink signal to the satellite on an initial uplink frequency, and the satellite may determine a corrected uplink frequency for the UE based on the initial uplink frequency. The satellite may then transmit an indication of the corrected uplink frequency to the UE, and the UE may transmit a second uplink signal based on the corrected uplink frequency.