Multi-PRACH Transmission Within Narrow Uplink Bands for RedCap UEs

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Solution Overview

Problem

Current communication systems lack feasible methods for multi-physical random access channel (PRACH) transmissions with limited bandwidth, particularly for reduced capability (RedCap) UEs and in scenarios involving cross-division duplex (XDD), leading to inefficient PRACH detection and coverage issues.

Innovation Solution

The proposed solution involves configuring a narrower first uplink band for multi-PRACH transmissions, adjusting frequency and time-domain ROs, and utilizing multi-PRACH transmission patterns to enhance PRACH detection performance for UEs with varying bandwidth capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a separate initial UL BWP is configured for RedCap UEs within their maximum BW, then RedCap UEs can perform PRACH transmission, but the PRACH detection performance deteriorates due to limited bandwidth

Engineering Contradiction:

Improvesupport for RedCap UEs with limited bandwidthVSAvoidPRACH detection performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments the PRACH transmission into multiple transmissions across different RACH occasions, allowing the UE to transmit multiple preambles sequentially. This segmentation enables the gNB to accumulate energy from multiple transmissions to improve detection reliability, effectively resolving the contradiction between limited UE bandwidth and reliable PRACH detection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges multiple PRACH transmissions from the same UE across different RACH occasions into a single detection process at the gNB. By combining the energy from multiple transmissions through energy accumulation, the system achieves reliable detection despite the UE's limited bandwidth constraints.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If multiple PRACH transmissions are performed over multiple RACH occasions, then PRACH detection reliability improves, but the time required for random access increases

Engineering Contradiction:

ImprovePRACH detection reliabilityVSAvoidrandom access time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by configuring the UE with multiple preambles and multiple RACH occasions in advance. The UE can prepare and transmit multiple preambles across different occasions, allowing the gNB to detect and respond more efficiently, thereby reducing the overall time loss while maintaining high reliability.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If the initial UL BWP is narrowed for RedCap UEs, then device complexity is reduced, but the frequency resources available for PRACH transmission are limited

Engineering Contradiction:

ImproveUE bandwidth configuration complexityVSAvoidfrequency resources for PRACH

Core Design Contradiction:

Device complexityVSArea of stationary object

Solution Approach 1:

The patent transitions from a single-frequency-resource approach to a multi-dimensional approach by utilizing multiple RACH occasions in the time domain. This allows the system to compensate for the limited frequency resources in RedCap UEs by spreading transmissions across multiple time occasions, effectively increasing the total available resources without increasing device complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS20250274986A1Communication apparatuses and communication methods for multi-prach transmissions with limited bandwidth

Publication Date: 2025.08.28 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

The present disclosure provides communication apparatuses and communication methods for multi-PRACH transmissions with limited bandwidth. The communication apparatuses include a communication apparatus comprising: circuitry which, in operation, determines a first uplink (UL) band associated with the communication apparatus, the first UL band being narrower than a second UL band; and a transmitter, which in operation, transmits a multi-PRACH transmission in the first UL band.