Two-Root Preamble Design for Non-Terrestrial Network Delay

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Solution Overview

Problem

Non-terrestrial wireless communication systems face inefficiencies due to large round-trip delays and frequency shifts caused by long distances and Doppler effects, which existing preamble designs are unable to accommodate effectively, leading to inaccurate message reception and transmission inefficiencies.

Innovation Solution

A two-root preamble design is implemented, using Zadoff-Chu sequences and orthogonal frequency division multiplexing, which allows for the detection of round-trip delay and frequency shift, enabling pre-compensation of subsequent transmissions and improving communication reliability in non-terrestrial networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a traditional single-root preamble design is used, then the system is simple to implement, but it cannot accurately detect large round-trip delays and frequency shifts in non-terrestrial networks

Engineering Contradiction:

Improvedetection accuracy of round-trip delay and frequency shiftVSAvoidpreamble design complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The preamble sequence is segmented into multiple segments, each generated using a different root sequence. This segmentation allows the receiver to detect round-trip delay and frequency shift by analyzing the correlation properties of different segments, thereby improving measurement precision without requiring a completely complex new design paradigm

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the parameters of the preamble design by using multiple root sequences with different properties. Each root sequence provides different correlation characteristics, allowing the system to detect large delays and frequency shifts that would be undetectable with a single root sequence, thus improving detection accuracy

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the round-trip delay and frequency shift are not compensated, then the transmission process is simple, but the message reception accuracy deteriorates due to large delays and Doppler effects

Engineering Contradiction:

Improvemessage reception accuracyVSAvoidprocessing complexity for delay and frequency shift detection

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The receiver detects the round-trip delay and frequency shift from the received preamble and provides feedback information back to the transmitter. This feedback enables the transmitter to adjust subsequent transmissions to compensate for the detected impairments, thereby improving message reception accuracy through a closed-loop system

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection of round-trip delay and frequency shift using the preamble before actual message transmission begins. This preliminary action allows the system to pre-compensate for detected impairments in subsequent transmissions, improving reliability without adding complexity to the message transmission process itself

Inventive Principle:

Principle #10Preliminary action

3Productivity

If existing preamble designs are used in non-terrestrial networks, then the system architecture remains simple, but transmission efficiency deteriorates due to inaccurate message reception

Engineering Contradiction:

Improvetransmission efficiencyVSAvoidmessage reception errors

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The invention replaces the traditional mechanical approach of simple repetition or scaling of single-root preambles with a signal processing approach using multiple root sequences with specific correlation properties. This substitution enables accurate detection of transmission impairments, reducing message reception errors and improving transmission efficiency

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 two-root preamble design enhances communication efficiency and reliability by accurately detecting and compensating for delays and frequency shifts, thereby reducing latency and improving message transmission quality in non-terrestrial networks.

Implementation Method 1

there may be a long round-trip delay (RTD) and frequency shift in message transmissions between the UE and the base station due to the Doppler shift effect

Methodology Applied

Scientific EffectDoppler effect: Doppler Effect

Data Source

PatentUS11490426B2Two-root preamble design for delay and frequency shift

Publication Date: 2022.11.01 QUALCOMM INC

AI summary

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may communicate with a base station by initiating a random access procedure with a two-root preamble. The UE may receive, from the base station, control signaling that indicates a set of root preamble sequences. The UE may transmit, to the base station, a preamble signal that is generated based on a first root preamble sequence and a second root preamble sequence of the set of root preamble sequences. The UE may then monitor for a preamble response based on the preamble signal. In some cases, the base station may be a base station in a terrestrial network. In other cases, the base station may be a satellite in a non-terrestrial network (NTN).