PRACH Repetition Grouping for Low-Latency Random Access

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Solution Overview

Problem

Existing wireless communication systems, particularly 5G NR, face challenges in improving the latency and reliability of random access procedures due to limited PRACH resources and coverage issues.

Innovation Solution

The implementation of PRACH resource grouping, where a user equipment (UE) receives indications for additional PRACH resources, allowing for non-overlapping random access repetition groups, thereby enhancing PRACH repetitions and improving reliability and reducing latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional PRACH resources are configured for random access repetitions, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improverandom access reliabilityVSAvoidPRACH resource management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments PRACH resources into distinct sets (first set and second set) with different configurations. The UE can be configured with multiple PRACH resource sets, each containing multiple random access occasions, and selectively activate appropriate sets based on coverage requirements and repetition numbers, thereby managing complexity through structured division while improving reliability through resource diversity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic PRACH resource allocation where the network can activate or deactivate specific PRACH resource sets through RRC signaling based on UE coverage conditions. This dynamic adaptation allows the system to optimize between reliability and complexity by activating additional resources only when needed rather than maintaining them permanently

Inventive Principle:

Principle #15Dynamics

2Reliability

If PRACH repetitions are increased to improve coverage, then reliability is improved, but latency increases

Engineering Contradiction:

Improvecoverage reliabilityVSAvoidrandom access latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent pre-configures multiple PRACH resource sets with different repetition numbers and time/frequency configurations before the random access procedure begins. When a UE needs to perform random access, it can immediately select from pre-configured options rather than negotiating parameters during the procedure, reducing latency while maintaining the ability to provide enhanced coverage through appropriate repetition selection

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent enables changing key PRACH parameters (repetition number, frequency resources, time resources) based on UE coverage conditions. The network can configure different PRACH resource sets with varying repetition numbers and activate the appropriate set based on measured RSRP or other coverage indicators, allowing optimization between coverage reliability and access latency through parameter adaptation

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If multiple PRACH resource sets are configured, then adaptability is improved, but device complexity increases

Engineering Contradiction:

ImprovePRACH configuration adaptabilityVSAvoidresource configuration complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a universal PRACH resource set structure where each PRACH resource set contains multiple random access occasions with consistent internal configuration. This universal structure allows the same framework to serve different purposes (different repetition numbers, different frequency resources) while maintaining manageable complexity through standardized organization and activation mechanisms

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20260046932A1Prach adaptation for prach repetition

Publication Date: 2026.02.12 QUALCOMM INC

AI summary

A method for wireless communication at a user equipment (UE) and related apparatus are provided. In the method, the UE receives from a network entity a first indication of a first set of random access resources for a first number of random access repetitions. The UE further receives an activation indication for a second set of random access resources different from the first set of random access resources; and transmits a second number of random access repetitions in random access resources from a random access repetition group based on at least the second set of random access resources.