UE-Initiated PRACH Grant Requests for Sparse Uplink Access

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Solution Overview

Problem

Existing wireless communication systems, particularly in 5G NR, face challenges with UE transmissions that are infrequent, leading to significant delays and signaling overhead due to contention-based random access procedures, which can result in collisions and inefficiencies.

Innovation Solution

Implementing UE-initiated grant requests through dedicated resources for physical random-access channels, separate from contention-based and contention-free random access procedures, to facilitate timely and efficient data transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If contention-based random access procedure is used for UE uplink transmission, then resource allocation is achieved, but signaling overhead and transmission delays increase significantly

Engineering Contradiction:

Improveresource allocation efficiencyVSAvoidtransmission delay

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent segments the random access channel into two distinct sets of resources: first resources for UE-initiated grant requests and second resources for traditional contention-based random access. This segmentation allows UEs to use dedicated resources for grant requests, avoiding the time-consuming contention-based procedure while maintaining efficient resource allocation through the separate CBRA/CFRA mechanisms.

Inventive Principle:

Principle #1Segmentation

2Productivity

If contention-based random access procedure is used, then resource allocation is achieved, but signaling overhead increases

Engineering Contradiction:

Improveresource allocationVSAvoidsignaling overhead

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent divides the PRACH resources into first resources for UE-initiated grant requests and second resources for traditional contention-based access. By segmenting the resource allocation process, the system reduces signaling overhead for grant requests while maintaining the necessary resource allocation functionality through the dedicated first resources.

Inventive Principle:

Principle #1Segmentation

3Reliability

If traditional random access procedure is used for infrequent UE transmissions, then resource acquisition is achieved, but transmission efficiency decreases

Engineering Contradiction:

Improveresource acquisitionVSAvoidtransmission efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent enables UEs to autonomously initiate grant requests using dedicated first resources, eliminating the need for network-initiated procedures. This self-service mechanism allows infrequently transmitting UEs to efficiently acquire resources without waiting for network scheduling or undergoing lengthy contention-based procedures, thereby improving transmission efficiency while maintaining reliable resource acquisition.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20260032737A1User equipment (UE) initiated grant request

Publication Date: 2026.01.29 QUALCOMM INC

AI summary

Aspects are directed to a user equipment (UE) configured to perform a UE-initiated physical random-access channel (PRACH). For example, if the UE only performs sparce uplink communications, then certain communication parameters (e.g., timing advance) may change due to mobility, air interface conditions, and the like. Thus, instead of performing a contention-based random access (CBRA) procedure every time the UE has data to transmit, the UE may reduce signaling overhead and delays associated with the CBRA by performing a UE-initiated PRACH process.