Base Station Doppler Compensation for High-Speed Rail Throughput
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Solution Overview
Problem
In high-speed railway mobile communications networks, the Doppler frequency shift causes low average downlink throughput for user equipment (UE) due to limited frequency compensation capabilities, resulting in poor demodulation performance and throughput improvement.
Innovation Solution
An access network device determines a downlink frequency shift based on an uplink signal and adjusts the transmit frequency to compensate for the Doppler effect, sending the downlink signal to the UE at a corresponding receive frequency, thereby minimizing frequency shifts and improving demodulation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UE performs frequency compensation based on estimated Doppler frequency shift, then demodulation performance improves, but average downlink throughput cannot be improved further due to limited compensation capability
Solution Approach 1:
Instead of having the UE estimate and compensate for Doppler frequency shift, the base station performs frequency compensation by determining the downlink frequency shift based on uplink signal characteristics and adjusting the transmit frequency accordingly. This inversion of the compensation role from UE to base station enables more accurate frequency alignment and significantly improves average downlink throughput while maintaining demodulation performance.
2Productivity
If base station sends downlink signal at adjusted frequency to compensate Doppler effect, then frequency shift is minimized and throughput improves, but terminal device must adapt to frequency adjustment
Solution Approach 1:
The base station determines the downlink frequency shift in advance based on uplink signal characteristics before transmitting the downlink signal. By performing this frequency adjustment preparation beforehand, the base station can send the downlink signal at the pre-calculated adjusted frequency, minimizing frequency shifts without requiring complex real-time coordination during data transmission.
3Productivity
If UE estimates Doppler frequency shift using CRS and performs compensation, then some throughput improvement is achieved, but expected demodulation performance cannot be obtained
Solution Approach 1:
The base station acts as an intermediary by determining the downlink frequency shift based on uplink signal characteristics rather than relying on UE's autonomous estimation. The base station uses the uplink signal as a reference to calculate the frequency shift and applies compensation through adjusted transmit frequency, providing more accurate frequency alignment than UE-based estimation and achieving both improved throughput and demodulation performance.
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
This approach enhances the average downlink throughput of the UE by ensuring the downlink signal is received and demodulated without significant frequency shifts, improving overall communication efficiency.
Implementation Method 1
When UE moves at a high speed, a Doppler frequency shift phenomenon occurs in a high-speed railway mobile communications network
Data Source
AI summary
Embodiments of the present invention relate to the communications field and disclose a data transmission device, method, and system, so as to better improve an average downlink throughput of UE. A specific solution is: A determining unit determines a downlink frequency shift according to a received uplink signal sent by a terminal device, and determines a second transmit frequency according to the downlink frequency shift and a first transmit frequency; and a sending unit sends a downlink signal to the terminal device according to the second transmit frequency determined by the determining unit, so that the terminal device receives the downlink signal according to a receive frequency corresponding to the first transmit frequency, where the downlink signal includes at least one of a DMRS or downlink data. The present invention is applied in a data transmission process.