Fast Mobility Frequency Compensation for Doppler-Shifted Links
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Solution Overview
Problem
Communication systems experience performance deterioration due to the effects of carrier frequency offset (CFO) and Doppler shift (DS), particularly in environments where terminals move at high speeds, affecting downlink (DL) and uplink (UL) performance.
Innovation Solution
A method involving frequency offset estimation and compensation techniques, including time-varying characteristic feedback, is employed to mitigate the impact of CFO and DS on DL and UL performance by adjusting transmissions based on estimated frequency offsets and Doppler shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency offset estimation and compensation techniques are employed, then reception quality is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by estimating frequency offset and Doppler shift before downlink reception, and performing compensation in advance. The terminal estimates frequency offset from uplink transmissions, calculates Doppler shift based on time-varying characteristics, and compensates downlink signals before reception, thereby improving reception quality while managing complexity through proactive rather than reactive processing
Solution Approach 2:
The patent implements feedback mechanisms where the terminal feeds back time-varying characteristic information to the base station, and the base station uses this feedback to adjust Doppler shift compensation parameters. This closed-loop feedback system enables continuous optimization of frequency offset and Doppler compensation, improving reception quality adaptively
2Reliability
If Doppler shift compensation is performed in real-time, then communication reliability is improved, but processing time increases
Solution Approach 1:
The patent performs Doppler shift estimation and compensation preparation in advance based on uplink transmissions and time-varying characteristic analysis. By estimating Doppler shift before downlink reception and preparing compensation parameters beforehand, the system ensures reliable compensation without adding significant processing delay during actual reception
Solution Approach 2:
The patent employs dynamic Doppler shift compensation by continuously updating compensation parameters based on real-time feedback about time-varying characteristics. The base station adjusts Doppler shift compensation dynamically according to terminal mobility conditions, maintaining high communication reliability while adapting processing to actual needs rather than using fixed static compensation
3Measurement precision
If time-varying characteristic feedback is implemented, then frequency offset accuracy is improved, but information processing load increases
Solution Approach 1:
The patent extracts only the essential time-varying characteristic information needed for Doppler shift estimation from uplink transmissions. Instead of processing all uplink signal parameters, the system selectively extracts frequency offset and time-varying characteristics relevant to Doppler compensation, reducing information processing load while maintaining frequency offset accuracy
Solution Approach 2:
The patent applies local quality by focusing processing resources on specific aspects of the signal that contain frequency offset and Doppler information. Rather than uniformly processing all signal components, the system concentrates analysis on portions of the uplink transmission that provide the most valuable information for frequency offset estimation, optimizing the trade-off between accuracy and processing load
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 proposed method effectively removes CFO and DS, improving the performance of high-speed mobility in communication systems by compensating for frequency offsets and shifts, thereby enhancing reception quality.
Implementation Method 1
estimating a first frequency offset based on a first downlink transmission received from a base station... The first FO may be estimated as a sum of a carrier frequency offset (CFO) in the first DL transmission and a Doppler shift (DS) in the first DL transmission
Data Source
AI summary
Disclosed are a method and an apparatus for supporting high-speed mobility in a communication. A method of a terminal may comprise: estimating a first frequency offset based on a downlink transmission received from a base station; estimating first time-varying characteristic information based on the downlink transmission; and transmitting, to the base station, a first uplink transmission including time-varying characteristic feedback information based on the first time-varying characteristic information and a configured time-varying characteristic information feedback condition.