Zadoff-Chu Sequence Length Determination for Wireless Reference Signals

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Solution Overview

Problem

In wireless communication systems, existing methods for generating reference signals fail to ensure orthogonality among signals from different user equipment, leading to high cross-correlation and interference, particularly in scenarios with varying system bandwidths and subcarrier allocations.

Innovation Solution

A method where the length of the Zadoff-Chu sequence is determined based on the system bandwidth's resource block quantity or subcarrier quantity, ensuring that reference signal sequences have a higher cross-correlation, thereby reducing mutual interference among different communications devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If reference signals are generated using traditional methods with cyclic shift for different UEs, then orthogonality is maintained through cyclic shift processing, but cross-correlation between partially overlapping reference signals remains relatively high and system requirements cannot be met

Engineering Contradiction:
Improveorthogonality of reference signalsVSAvoidcross-correlation interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fundamental parameter of reference signal generation by using Zadoff-Chu sequences with different root indices instead of cyclic shift processing. This parameter change achieves both orthogonality and low cross-correlation simultaneously, resolving the technical contradiction between maintaining orthogonality and reducing interference.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent extracts and eliminates the cyclic shift processing step from the reference signal generation method. By removing this ineffective component that only maintains orthogonality but fails to reduce cross-correlation, the system achieves better performance using Zadoff-Chu sequences alone.

Inventive Principle:
Principle #2Taking out (Extraction)

2Object-affected harmful factors

If Zadoff-Chu sequences with different root indices are used for reference signals, then cross-correlation is reduced and orthogonality is improved, but sequence length must be optimized based on system bandwidth to prevent performance deterioration

Engineering Contradiction:
Improvecross-correlation interferenceVSAvoidsequence length optimization
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent introduces dynamic adaptation by making the Zadoff-Chu sequence length dependent on system bandwidth. This dynamic parameter adjustment ensures optimal performance across different bandwidth configurations while maintaining low cross-correlation properties of Zadoff-Chu sequences.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the sequence length parameter based on system bandwidth requirements. By dynamically adjusting this parameter, the system achieves both low cross-correlation and optimal performance for different bandwidth scenarios, resolving the contradiction between interference reduction and performance precision.

Inventive Principle:
Principle #35Parameter changes

3Object-generated harmful factors

If reference signal sequences are made orthogonal through cyclic shift, then mutual interference is reduced to some extent, but the generation method is unrelated to mapped locations and cannot achieve sufficient orthogonality

Engineering Contradiction:
Improvemutual interferenceVSAvoidorthogonality achievement
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent fundamentally changes the generation parameter from cyclic shift amount to Zadoff-Chu root index. This parameter change enables both interference reduction and reliable orthogonality achievement simultaneously, as different root indices provide inherent orthogonality without requiring cyclic shift processing.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3579469B1Wireless communication method and device
Publication Date: 2021.10.20 HUAWEI TECH CO LTD
  • EP3579469B1 patent drawingFigure 1~2
  • EP3579469B1 patent drawingFigure 3
  • EP3579469B1 patent drawingFigure 4

AI summary

This application provides a wireless communication method. The method includes: determining a length of a ZC sequence based on a resource block quantity or a subcarrier quantity corresponding to a system bandwidth; and determining a reference signal sequence based on the length of the ZC sequence and a resource block quantity or a subcarrier quantity corresponding to an allocated user bandwidth, where the reference signal sequence is included in an uplink reference signal, and the allocated user bandwidth is a part of the system bandwidth. According to the wireless communication method provided in this application, when different communications devices use a same system bandwidth for communication, reference signal sequences used by the different communications devices correspond to a same ZC sequence length. The ZC sequence length is exclusively designed for a resource block quantity or a carrier quantity of the system bandwidth, and generation of the reference signal sequences is related to mapped locations of the reference signal sequences. Therefore, according to the wireless communication method provided in this application, reference signal sequences used by different communications devices have a relatively high cross correlation.