PRACH Occasion Grouping for Random Access Coverage

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Solution Overview

Problem

Future radio communication systems face challenges in improving coverage during the random access procedure, which can lead to reduced communication throughput if not adequately addressed.

Innovation Solution

A terminal and base station are designed to enhance coverage by receiving downlink reference signals and determining the occasions of time and frequency for random access channels, incorporating features like beam management and multiple PRACH transmissions to optimize signal delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the random access procedure uses traditional single transmission method, then the system complexity remains low, but the coverage is insufficient and communication throughput is reduced

Engineering Contradiction:
Improvecoverage in random access procedureVSAvoidrandom access procedure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The random access procedure is segmented into multiple transmission occasions grouped by downlink reference signal repetitions. Each group contains multiple PRACH occasions corresponding to multiple DL RS repetitions, allowing the terminal to select appropriate groups based on coverage requirements without overwhelming system complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The network pre-configures multiple groups of PRACH occasions, where each group is associated with a specific number of DL RS repetitions. This preliminary configuration enables terminals to directly select suitable groups based on their coverage needs, avoiding real-time complex decision-making and reducing procedural complexity

Inventive Principle:
Principle #10Preliminary action

2Productivity

If multiple PRACH transmissions are implemented to improve coverage, then the communication throughput increases, but the time resources and system complexity increase

Engineering Contradiction:
Improvecommunication throughputVSAvoidrandom access procedure time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

Multiple PRACH transmissions are organized in periodic groups corresponding to periodic downlink reference signal repetitions. Each group of PRACH occasions is transmitted at regular intervals, enabling throughput improvement through repeated attempts while maintaining predictable time resource usage and allowing parallel processing

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent introduces a grouping dimension that organizes PRACH occasions according to DL RS repetition counts. Instead of sequential single transmissions, multiple PRACH occasions are arranged in parallel groups, utilizing time-frequency resources more efficiently and reducing overall procedure time while improving throughput

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

Data Source

PatentEP4694528A1Terminal, wireless communication method, and base station
Publication Date: 2026.02.11 NTT DOCOMO INC
  • EP4694528A1 patent drawingFigure 1
  • EP4694528A1 patent drawingFigure 2A~2B
  • EP4694528A1 patent drawingFigure 3

AI summary

A terminal according to one aspect of the present disclosure includes a receiving section that receives a downlink reference signal, and a control section that determine a group of a plurality of occasions of time and frequency of a random access channel corresponding to a number of repetitions of the random access channel and the downlink reference signal. According to one aspect of the present disclosure, coverage in a random access procedure can be improved.