NR Random Access Fallback After Early Data Transmission Failure

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Solution Overview

Problem

In the NR system, user equipment (UE) experiencing failed early data transmission (EDT) in a random access procedure leads to significant delays and signaling overheads due to continuous attempts, which is not effectively addressed by existing technologies.

Innovation Solution

A method for random access procedure fallback is introduced, allowing UE to fall back from a first random access procedure to a target random access procedure based on specific information, such as the number of attempts or duration, thereby reducing delays and signaling overheads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If UE continuously performs EDT attempts during random access procedure, then data transmission can be maintained in non-connected state, but delay and signaling overheads increase significantly

Engineering Contradiction:

Improvedata transmission efficiencyVSAvoiddelay

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent implements dynamic switching between different random access procedures (2-step RACH and 4-step RACH) based on real-time transmission success. When EDT fails, the system dynamically transitions from 2-step RACH to 4-step RACH, adapting the access procedure to current channel conditions and UE state, thereby reducing delay while maintaining transmission efficiency

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes key parameters of the random access procedure by switching between different RACH types. When EDT failure is detected, parameters such as message structure, timing advance procedures, and resource allocation are changed by transitioning to 4-step RACH, which resolves the contradiction between maintaining productivity and reducing time loss

Inventive Principle:

Principle #35Parameter changes

2Productivity

If UE continuously performs EDT attempts during random access procedure, then data transmission can be maintained in non-connected state, but signaling overheads increase significantly

Engineering Contradiction:

Improvedata transmission efficiencyVSAvoidsignaling overheads

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The system dynamically adjusts signaling behavior based on transmission outcomes. Upon EDT failure, the system transitions to 4-step RACH which reduces redundant signaling exchanges, thereby lowering signaling overheads while maintaining the ability to transmit data efficiently in non-connected state

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent extracts and removes redundant signaling elements from the continuous EDT attempt process. By switching to 4-step RACH after EDT failure, unnecessary repeated signaling messages are eliminated, reducing signaling overheads while preserving essential data transmission functionality

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12432782B2Method for random access procedure fallback, device, and system

Publication Date: 2025.09.30 VIVO MOBILE COMM CO LTD

AI summary

A method for random access procedure fallback, a device, and a system. The method includes: in a case that UE initiates a first random access procedure, falling back from the first random access procedure to a target random access procedure based on first information, where the first information is information about the first random access procedure or information about the target random access procedure. The embodiments of this disclosure are applied to a process in which the UE performs random access procedure fallback.