User Terminal Random Access Preambles for Multiple Numerologies

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Solution Overview

Problem

Future radio communication systems face challenges in accommodating multiple user terminals with different numerologies, particularly in setting a suitable configuration for random access preambles to support various services such as eMBB, massive MTC, and URLLC, as existing LTE systems do not adequately address how to set random access preambles for diverse numerology requirements.

Innovation Solution

The solution involves defining random access preambles that support multiple subcarrier spacings, allowing user terminals to transmit preambles with predetermined subcarrier spacing suitable for their specific communication environments, including configurations with cyclic prefixes, guard times, and repetition numbers, and applying analog beam forming or symbol combining to enhance signal-to-noise ratio (SNR).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single random access preamble configuration is used in LTE systems, then the system is simple to operate, but it cannot accommodate multiple user terminals with different numerology requirements

Engineering Contradiction:
Improveaccommodation of multiple numerologiesVSAvoidrandom access preamble configuration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent defines multiple random access preamble formats (Format A, B, C, D) that can serve different numerology requirements within a single system. Each format is designed with specific properties (cyclic prefix length, guard time, subcarrier spacing) to accommodate different service types and numerologies, making the random access mechanism universal across diverse communication scenarios

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent systematically varies key parameters of random access preambles including subcarrier spacing (15kHz, 30kHz, 60kHz), cyclic prefix lengths (4.6875μs, 16.67μs, 66.67μs), and guard time configurations across different formats. These parameter changes enable adaptation to different numerologies while maintaining a structured configuration framework

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If random access preambles are configured for each specific numerology, then adaptability to different services is improved, but the complexity of managing multiple configurations increases

Engineering Contradiction:
Improveservice-specific configurationVSAvoidpreamble configuration management
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent segments the random access preamble space into distinct formats (A, B, C, D) with clearly defined characteristics. Each format is optimized for specific numerology ranges and service types, allowing the system to select appropriate formats based on service requirements without managing a single complex configuration. The segmentation provides clear boundaries and selection criteria for different scenarios

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic format selection mechanisms where the appropriate random access preamble format is chosen based on real-time conditions such as numerology, service type, and channel characteristics. This dynamic adaptation allows the system to optimize performance for each specific scenario while maintaining a manageable set of predefined formats

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If existing LTE random access procedures are used, then backward compatibility is maintained, but they fail to support future services with diverse delay and bandwidth requirements

Engineering Contradiction:
Improvesupport for future servicesVSAvoidrandom access procedure performance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent performs preliminary actions by pre-defining multiple random access preamble formats with optimized parameters for different future services and numerologies. These formats are prepared in advance with specific configurations for eMBB, massive MTC, and URLLC scenarios, enabling the system to immediately support diverse future services without ad-hoc configuration when those services are deployed

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3487254B1User terminal and radio communication method
Publication Date: 2025.09.03 NTT DOCOMO INC
  • EP3487254B1 patent drawingFigure 1
  • EP3487254B1 patent drawingFigure 2
  • EP3487254B1 patent drawingFigure 3A~3B

AI summary

To suitably perform a random access procedure (e.g. , random access preamble transmission) in future radio communication systems, a user terminal for communicating with a cell where predetermined numerology is applied has a control section that controls a random access procedure in the cell, and a transmission section that transmits a random access preamble with a predetermined subcarrier spacing applied among random access preambles for supporting a plurality of subcarrier spacings.