Dynamic PRACH Scheduling via RB Assignment Messages

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Solution Overview

Problem

Current PRACH scheduling mechanisms in LTE networks are inflexible, leading to delays and conflicts due to pre-configured static subframes, which reduces dynamic subframe sharing between uplink and downlink communications and incurs long waiting times for PRACH transmissions.

Innovation Solution

Implementing a resource scheduling mechanism at the network node to generate and transmit scheduling messages with RB assignment information for PRACH, allowing on-demand scheduled PRACH transmissions, reducing the need for pre-configured static subframes and minimizing conflicts by scheduling each UE's transmission individually.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PRACH subframes are pre-configured via RRC messages, then UEs can transmit PRACH messages on dedicated resources, but the number of static UL subframes increases, reducing flexibility for dynamic subframe sharing between UL and DL

Engineering Contradiction:

ImprovePRACH transmission reliabilityVSAvoidsubframe sharing flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent makes the PRACH subframe configuration dynamic by allowing the network node to flexibly configure which subframes are available for PRACH transmission through scheduling messages, rather than using fixed RRC-configured subframes. This enables dynamic adjustment of UL/DL subframe sharing while maintaining reliable PRACH transmission.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If fewer PRACH subframes are configured, then more subframes are available for dynamic UL/DL sharing, but UEs experience longer waiting times and conflicts occur when multiple UEs need to transmit PRACH simultaneously

Engineering Contradiction:

Improvesubframe sharing flexibilityVSAvoidPRACH transmission delay

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent implements a self-service mechanism where each UE independently monitors scheduling messages from the network node to determine when to transmit PRACH. This allows UEs to self-adjust their transmission timing based on network conditions, reducing conflicts and delays while maintaining flexibility in subframe usage.

Inventive Principle:

Principle #25Self-service

3Device complexity

If RRC-configured PRACH resources are shared by all UEs, then resource allocation is simplified, but conflicts occur when multiple UEs simultaneously need to transmit PRACH messages

Engineering Contradiction:

Improveresource configuration complexityVSAvoidPRACH transmission success rate

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces a feedback mechanism where the network node monitors PRACH transmission requests and sends scheduling messages to UEs, granting PRACH transmission permissions on a per-UE basis. This feedback loop prevents conflicts by coordinating transmissions while maintaining manageable configuration complexity through centralized control.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11297658B2PRACH scheduling method, scheduled PRACH transmission method, network node and user equipment

Publication Date: 2022.04.05 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The present disclosure provides a PRACH scheduling method at a network node, comprising: generating a scheduling message which includes at least resource block RB assignment information for physical random access channel PRACH, the RB assignment information for PRACH indicating uplink resource for a user equipment UE to transmit a PRACH message; and transmitting the scheduling message on a downlink channel to the UE. The present disclosure also provides a corresponding network node, a scheduled PRACH transmission method at a UE, and a corresponding UE.