NR mmWave Frequency Offset Tracking via Doppler Reuse

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Solution Overview

Problem

In 5G New Radio (NR) systems, frequent beam switching due to motion and environmental changes leads to high computational overhead in estimating Doppler shift and frequency offset for each beam, degrading latency and increasing computational cost, especially in high-mobility scenarios.

Innovation Solution

The system estimates Doppler shift for multiple UE beams based on sensor data and the estimated Doppler shift of a serving beam, minimizing the frequency of computation by using reference signals transmitted by the base station, and determining velocity from Doppler shift values, allowing for beam switching without independent computation for each beam.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Doppler shift and frequency offset are estimated independently for each beam, then measurement precision is improved, but computational overhead and processing time increase significantly

Engineering Contradiction:

Improvefrequency offset estimation accuracyVSAvoidcomputational overhead

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines Doppler shift estimation and frequency offset estimation into a unified process. Instead of independently estimating these parameters for each beam, the system performs joint estimation that leverages correlations between beams, thereby reducing computational complexity while maintaining estimation accuracy.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system performs preliminary Doppler shift estimation using reference signals before beam switching occurs. This preliminary estimation is then reused and adjusted for subsequent beams, avoiding the need to perform complete independent estimation for each beam and reducing overall computational overhead.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If Doppler shift estimation is performed frequently for each beam switch, then reliability of frequency tracking is improved, but latency increases

Engineering Contradiction:

Improvefrequency tracking accuracyVSAvoidprocessing latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system implements periodic Doppler shift estimation at specific intervals rather than continuously for every beam switch. Reference signals are transmitted periodically, and estimations are updated at these periodic intervals, maintaining tracking reliability while reducing processing latency compared to continuous estimation.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent uses copying of Doppler shift estimates from previously processed beams to current beams. Instead of performing independent estimation for each beam, the system copies and adapts estimates from reference beams, significantly reducing processing time while maintaining acceptable accuracy through subsequent refinement.

Inventive Principle:

Principle #26Copying

3Adaptability or versatility

If independent frequency offset estimation is performed for multiple beams, then adaptability to different beam conditions is improved, but computational cost increases

Engineering Contradiction:

Improvebeam-specific frequency trackingVSAvoidcomputational energy consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent implements a universal Doppler shift estimation mechanism that serves multiple beams simultaneously. A single estimation process processes reference signals to generate Doppler shift estimates that are then applied and adapted across multiple beams, providing beam-specific tracking capability while reducing overall computational energy consumption compared to completely independent estimation for each beam.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 reduces computational overhead and latency by reusing Doppler shift estimates across beams, improving communication efficiency and reducing the need for frequent recalculations during beam switching, especially in high-mobility scenarios.

Implementation Method 1

The Doppler shift specifies the variations in the frequency of the transmitted signal at the receiver device, caused due to movement of the source/receiver device with respect to the receiver/source device

Methodology Applied

Scientific EffectDoppler shift: Doppler Effect

Data Source

PatentUS12021661B2Methods for frequency offset tracking in NR mmwave for efficient beam management

Publication Date: 2024.06.25 SAMSUNG ELECTRONICS CO LTD

AI summary

Methods and systems for tracking frequency offset in NR are provided. A user equipment (UE) can compute the frequency offset comprising of crystal frequency drift and Doppler shift. Drift in frequencies generated by crystal oscillators in the UE and a base station are detected and nullified. Doppler shift of a serving beam is estimated using either data collected by sensors in the UE or reference signals received from the base station. Values of Doppler shift for a plurality of beams are estimated using the Doppler shift of the serving beam and sensor data, wherein the serving beam and the plurality of beams correspond to a same transmitter beam or different transmitter beams, wherein the type of QCL of the beams is either A, B, or C.