RedCap Initial Access Using Split SS/PBCH Bandwidth Blocks

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The introduction of Reduced Capability (RedCap) UEs with narrower bandwidths, such as 5 MHz, poses challenges for initial access procedures as they may not be able to contain synchronization signal blocks within their maximum bandwidth, necessitating techniques to support coexistence with both 20 MHz RedCap and Non-RedCap UEs.

Innovation Solution

The method involves receiving and decoding synchronization signals and physical broadcast channels tailored for RedCap UEs, including modified PBCH structures and additional symbols to support decoding, along with configuring bandwidth parts to balance traffic load, and using specific resource sets to ensure compatibility with legacy systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the synchronization signal block (SSB) is contained within the maximum UE bandwidth, then legacy UEs can perform initial access, but RedCap UEs with 5 MHz bandwidth cannot accommodate the SSB which requires larger bandwidth

Engineering Contradiction:

Improvebandwidth adaptabilityVSAvoidinitial access reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The SSB is segmented into two separate blocks: a first SSB with reduced bandwidth (20 PRBs) that fits within the 5 MHz RedCap UE bandwidth, and a second SSB with full bandwidth (80 PRBs) for legacy UEs. Each SSB contains the necessary synchronization signals (PSS, SSS) and broadcast channel (PBCH) elements, allowing RedCap UEs to perform initial access using the first SSB while legacy UEs use the second SSB.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different quality levels of SSB are provided for different UE types. The first SSB is optimized for RedCap UEs with narrower bandwidth requirements, while the second SSB maintains full bandwidth quality for legacy UEs. This local differentiation allows each UE type to receive appropriate signal quality without compromising the other.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the SSB bandwidth is reduced to fit within 5 MHz for RedCap UEs, then RedCap UEs can perform initial access, but the bandwidth is insufficient for legacy UEs and 20 MHz RedCap UEs

Engineering Contradiction:

Improveinitial access procedureVSAvoidbandwidth compatibility

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The system implements a universal initial access mechanism that serves multiple UE types simultaneously. By transmitting both a reduced-bandwidth SSB (first SSB) and a full-bandwidth SSB (second SSB), the system enables RedCap UEs with 5 MHz bandwidth, 20 MHz RedCap UEs, and legacy UEs to all perform initial access using the appropriate SSB for their capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically adapts the SSB bandwidth based on UE capability. RedCap UEs with 5 MHz bandwidth automatically detect and use the first SSB with reduced bandwidth, while other UEs detect and use the second SSB with full bandwidth. This dynamic adaptation occurs without requiring UE configuration or network intervention.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If multiple SSB blocks are transmitted at different frequency locations, then both RedCap and Non-RedCap UEs can find suitable SSBs, but the network complexity and resource overhead increase

Engineering Contradiction:

Improvemulti-UE type supportVSAvoidnetwork configuration complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The network pre-configures multiple SSB blocks with different bandwidth characteristics before UE arrival. The first SSB (reduced bandwidth) and second SSB (full bandwidth) are transmitted at predetermined frequency locations, allowing UEs to autonomously select the appropriate SSB based on their bandwidth capabilities without requiring complex real-time network configuration or UE-specific signaling.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12574873B2Initial access and initial bandwidth part configuration for reduced capability user equipments

Publication Date: 2026.03.10 SAMSUNG ELECTRONICS CO LTD

AI summary

A method for performing an initial access process includes receiving, by a reduced capabilities (RedCap) user equipment (UE), a synchronization signal (SS)/physical broadcast channel (PBCH) block from a network. The SS/PBCH block may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a first set of physical broadcast channels (PBCH), a second set of PBCH, and a third set of PBCH, wherein the third set of PBCH may be a duplicate of the second set of PBCH. The method may further include decoding, by the RedCap UE, the PSS, the SSS, the first set of PBCH, and the third set of PBCH.