RACH Resource Allocation in NR Initial Access

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Solution Overview

Problem

Details about signaling of allocation and frequency position of random access channel (RACH) resources for transmitting an uplink signal for initial access in New Radio (NR) systems have not been determined, limiting flexible scheduling of channels and increasing initial access occasions.

Innovation Solution

A RACH resource allocation scheme where the base station allocates RACH resources in the frequency direction and indicates their positions to user equipment, allowing for flexible selection and use of these resources, potentially outside the initial active BWP, to ensure availability and compatibility with user equipment capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If RACH resources are allocated within the initial active BWP, then compatibility with UE capabilities is ensured, but flexibility in resource allocation is limited

Engineering Contradiction:
ImproveRACH resource allocation flexibilityVSAvoidUE capability compatibility
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent extends RACH resource allocation from the time domain only to include both time and frequency dimensions. By allocating RACH resources in the frequency direction outside the initial active BWP and indicating their positions to UEs, the system achieves flexible scheduling while maintaining UE compatibility through proper signaling.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If RACH resource allocation signaling is not defined, then system complexity is reduced, but initial access efficiency deteriorates

Engineering Contradiction:
ImproveInitial access efficiencyVSAvoidAllocation signaling complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The base station performs preliminary allocation of RACH resources in the frequency direction and indicates their positions to UEs before the UEs attempt initial access. This advance preparation enables efficient random access procedures while managing signaling complexity through structured allocation patterns.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3691367B1RACH resource allocation
Publication Date: 2024.11.13 NTT DOCOMO INC
  • EP3691367B1 patent drawingFigure 1~2
  • EP3691367B1 patent drawingFigure 3
  • EP3691367B1 patent drawingFigure 4~5

AI summary

A RACH resource allocation scheme is disclosed. One aspect of the present invention relates to a base station including a RACH resource allocation unit that allocates a RACH band that includes random access channel (RACH) resource to which respective indexes are assigned in a frequency direction, and a random access (RA) processing unit that indicates a frequency position of the RACH resources to user equipment.