PDCCH Transmission in RACH Procedure for RedCap Devices

Solution Overview

Problem

Current 5G NR wireless networks face challenges in managing reduced capability (RedCap) UEs due to RAR message multiplexing limitations, leading to increased initial access latency and RAR blocking probability, especially in scenarios with a large number of RedCap devices.

Innovation Solution

The solution involves dividing component carrier bandwidth into sub-bands and transmitting the physical random access channel (PRACH) resource and Type1-PDCCH CSS sets on different sub-bands, allowing RedCap UEs to monitor PDCCH candidates in Type1-PDCCH CSS sets configured by the random access search space, thereby optimizing RAR message handling and reducing latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If RAR messages are multiplexed in the same bandwidth, then resource utilization is improved, but RAR blocking probability increases and initial access latency increases for RedCap devices

Engineering Contradiction:

Improveresource utilizationVSAvoidRAR blocking probability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent divides the component carrier bandwidth into multiple sub-bands and associates different Type1-PDCCH CSS sets with different PRACH resources in different sub-bands. This segmentation allows RAR messages to be transmitted in different frequency sub-bands, reducing collision and blocking probability while maintaining efficient resource utilization.

Inventive Principle:

Principle #1Segmentation

2Productivity

If RAR messages are multiplexed in the same bandwidth, then resource utilization is improved, but initial access latency increases for RedCap devices

Engineering Contradiction:

Improveresource utilizationVSAvoidinitial access latency

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent divides the component carrier bandwidth into multiple sub-bands and associates different Type1-PDCCH CSS sets with different PRACH resources in different sub-bands. This segmentation allows RAR messages to be transmitted in different frequency sub-bands, reducing collision and blocking probability while maintaining efficient resource utilization.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If PRACH and Type1-PDCCH CSS set are transmitted on the same sub-band, then device complexity is reduced, but RAR blocking probability increases for RedCap devices

Engineering Contradiction:

Improvedevice complexityVSAvoidRAR blocking probability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent divides the component carrier bandwidth into multiple sub-bands and associates different Type1-PDCCH CSS sets with different PRACH resources in different sub-bands. This segmentation allows RAR messages to be transmitted in different frequency sub-bands, reducing collision and blocking probability while maintaining efficient resource utilization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent configures different Type1-PDCCH CSS sets with different frequency locations (sub-bands) to match different PRACH resources. This local differentiation in frequency domain provides specialized resources for different RedCap devices, reducing blocking probability while maintaining manageable device complexity through standardized configuration procedures.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12095682B2PDCCH transmission in RACH procedure for reduced capability devices

Publication Date: 2024.09.17 APPLE INC

AI summary

A base station configures a Physical Downlink Control Channel (PDCCH) for transmission to one or more user equipments (UEs). The base station divides a component carrier (CC) bandwidth into a plurality of sub-bands, transmits a physical random access channel (PRACH) resource on at least one of the sub-bands and transmits a Type1-PDCCH CSS (Physical Downlink Control Channel Common Search Space) set on at least one of the sub-bands, wherein the Type1-PDCCH CSS set corresponds to the PRACH resource.