Uplink Receiver Doppler Compensation for High-Speed OFDM Signals

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Solution Overview

Problem

Conventional wireless network receivers struggle to decode Physical Uplink Shared Channel (PUSCH) and Physical Uplink Control Channel (PUCCH) due to high phase deviation caused by doppler shift in high-speed environments, such as in bullet trains traveling at speeds over 350 kph.

Innovation Solution

A method and apparatus for calculating and compensating doppler shift by correlating Orthogonal Frequency Division Multiplexing (OFDM) symbols of DM-RS, performing phase corrections through Inverse Discrete Fourier Transform (IDFT), and demodulating PUSCH and PUCCH signals to mitigate phase deviations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional wireless network receivers are used in high-speed environments, then device complexity is reduced, but signal decoding reliability deteriorates due to high phase deviation from doppler shift

Engineering Contradiction:

Improvesignal decoding reliabilityVSAvoidreceiver complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The receiver performs preliminary doppler shift estimation by correlating DM-RS symbols before main signal decoding. This preliminary action calculates phase differences between DM-RS symbols to determine doppler shift, enabling subsequent compensation of channel estimates and data symbols to prevent phase deviation issues during decoding

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

DM-RS (Demodulation Reference Signal) symbols serve as an intermediary to measure and characterize the doppler shift effect. The receiver uses these reference symbols as mediators to estimate phase differences, calculate doppler shift values, and subsequently compensate the main data symbols without directly measuring the corrupted data signals

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If doppler shift compensation is implemented, then signal reception quality improves, but processing time increases due to additional correlation and phase correction steps

Engineering Contradiction:

Improvesignal reception qualityVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The receiver applies partial compensation by focusing doppler shift correction primarily on DM-RS symbols and critical channel estimates rather than uniformly processing all signal components. This selective approach compensates for the most critical phase deviations while minimizing additional processing overhead

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system changes the phase parameter of received symbols based on calculated doppler shift values. By dynamically adjusting phase parameters of channel estimates and data symbols using the estimated doppler shift, the receiver corrects phase deviation without requiring complete signal reprocessing

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If phase correction is performed on PUSCH signals, then decoding accuracy improves, but measurement precision requirements increase for phase deviation detection

Engineering Contradiction:

Improvephase deviation measurement precisionVSAvoiddecoding accuracy

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The receiver implements feedback by measuring phase deviation on PUSCH signals after initial doppler shift compensation and using this measured information to perform additional phase correction. The measured phase deviation is fed back into the correction process to refine the final decoded signal, improving accuracy through iterative refinement

Inventive Principle:

Principle #23Feedback

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

Enables effective decoding of PUSCH and PUCCH signals in high-speed environments by accurately compensating for doppler-induced phase shifts, thereby improving signal reception in mobile devices traveling at high velocities.

Implementation Method 1

determine a doppler shift where the doppler shift is proportional to the phase difference across the DM-RS symbols in the channel

Methodology Applied

Scientific EffectDoppler shift: Doppler Effect

Implementation Method 2

performing a first level of phase correction on the PUSCH received by the receiver by correcting the phase on output samples of an Inverse Discrete Fourier transform (IDFT) from the doppler shift received from Layer 2

Methodology Applied

Scientific EffectPhase correction:

Data Source

PatentUS12500707B2Network side receiver for receiving high velocity transmitted signals

Publication Date: 2025.12.16 RAKUTEN SYMPHONY INC

AI summary

Techniques are provided for receiving PUSCH and PUCCH transmitted by a high speed transmitter. The techniques include calculating a phase difference of OFDM symbols of the PUCCH from OFDM symbols of a first DM-RS and OFDM symbols of a second DM-RS of the PUCCH, correlating the OFDM symbols of the first DM-RS and second DM-RS. Determine a doppler shift and report it to L2. Compensate channel estimates and data symbols with the doppler shift. Equalize and demodulate the PUCCH. Perform a first level of phase correction on the PUSCH by correcting the phase on output samples of an IDFT from the doppler shift received from L2. Measure a phase deviation on the output of the first level of phase correction, accumulate the measured phase deviation and the doppler shift received from L2, to derive an accumulated phase correction, and report the accumulated phase correction to L2. Demodulate the PUSCH.