Frequency Offset Compensation in Non-Terrestrial Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In satellite communication systems, the large Doppler shifts caused by the motion of satellites result in frequency offsets that compromise the orthogonality of subcarriers, leading to severe inter-carrier interference and impairing communication.
Innovation Solution
The proposed solution involves adjusting the transmit frequency for LTE and NR UE to compensate for Doppler shifts in satellite networks. This is achieved through open-loop and closed-loop approaches, considering both cases where the wireless device estimates the frequency offset and where the network node provides an estimation and frequency adjustment indication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If satellite motion is considered for frequency transmission, then communication coverage is improved, but Doppler shifts cause frequency offsets that worsen subcarrier orthogonality
Solution Approach 1:
The patent applies preliminary action by having the wireless device estimate the Doppler shift and apply frequency offset compensation before transmitting uplink signals. The device calculates the expected frequency offset based on satellite motion parameters and pre-adjusts its transmit frequency, thereby preventing the orthogonality degradation that would otherwise occur during communication.
Solution Approach 2:
The patent implements feedback through a two-step process: first, the wireless device estimates the Doppler shift and applies initial frequency compensation; second, the network node provides feedback regarding the accuracy of this estimation, allowing the device to refine its frequency offset calculation and maintain subcarrier orthogonality despite satellite motion.
2Reliability
If frequency offset compensation is applied to maintain subcarrier orthogonality, then communication quality is improved, but system complexity increases due to additional estimation and adjustment mechanisms
Solution Approach 1:
The patent applies self-service by enabling the wireless device to autonomously estimate the Doppler shift and apply frequency offset compensation without requiring complex network-side processing. The device uses its own receiver to measure frequency offsets and independently adjusts its transmitter, thereby maintaining communication quality while minimizing additional system complexity.
Solution Approach 2:
The patent utilizes parameter changes by having the wireless device dynamically adjust its transmit frequency based on estimated Doppler shift values. The device modifies frequency parameters in real-time according to satellite motion conditions, maintaining communication reliability through adaptive parameter adjustment rather than complex structural changes.
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
By compensating for Doppler shifts, the proposed methods ensure the orthogonality of subcarriers, maintaining communication feasibility and reducing inter-carrier interference in non-terrestrial networks.
Implementation Method 1
the large Doppler shifts caused by the motion of satellites result in frequency offsets that compromise the orthogonality of subcarriers
Data Source
AI summary
Methods and apparatus for obtaining a frequency offset corresponding to a Doppler shift of transmission and/or reception frequencies between a wireless device and a network node. In one embodiment a method is performed by a wireless device for operating in a non-terrestrial network, NTN, the NTN having at least one network node and a communication satellite, wherein the at least one network node is one of a terrestrial base station and a satellite base station or satellite gateway, the method includes obtaining a frequency offset corresponding to a Doppler shift of transmission and/or reception frequencies between the wireless device and the network node and applying the frequency offset to an uplink