RedCap Random Access Signaling with Shared PRACH and Distinct RA-RNTIs

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Solution Overview

Problem

Existing wireless communication systems face inefficiencies in performing random access procedures for devices with varying bandwidth capabilities, particularly for reduced capability user equipment (RedCap UE), leading to resource insufficiency and wastage due to separate resource allocation, and challenges in distinguishing RedCap UE from legacy UEs during initial access.

Innovation Solution

A method and apparatus that allow RedCap UE to share random access resources with legacy UEs by using different random access radio network temporary identifiers (RA-RNTIs) and configuring relaxed processing times, enabling efficient resource utilization and identification through distinct RA-RNTI calculations and masking techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If separate random access resources are allocated for RedCap UE and legacy UE, then resource allocation is simplified and identification is easier, but resource utilization efficiency deteriorates and resource wastage increases

Engineering Contradiction:

Improveresource allocation simplicityVSAvoidresource utilization efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent merges the random access resources for RedCap UE and legacy UE into a shared resource pool. Both UE types use the same PRACH resources and preamble sequences, eliminating the need for separate resource allocation while improving resource utilization efficiency and reducing wastage.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent makes the random access resources universal by allowing them to serve multiple UE types (both RedCap UE and legacy UE) simultaneously. The same PRACH resources and preambles are used by different UE types, with differentiation achieved through RA-RNTI calculation rather than separate resource allocation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of operation

If separate random access resources are allocated for RedCap UE and legacy UE, then identification during initial access is easier, but resource wastage increases

Engineering Contradiction:

Improveidentification easeVSAvoidresource wastage

Core Design Contradiction:

Ease of operationVSLoss of substance

Solution Approach 1:

The patent changes the identification parameter from separate resource allocation to RA-RNTI calculation. The RA-RNTI is calculated based on time-frequency resources and a UE-specific parameter (msg1-FrequencyStart), allowing differentiation between RedCap UE and legacy UE while sharing the same physical random access resources, thus avoiding resource wastage.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If PRACH preamble sequences are reused for both UE types, then resource utilization improves, but difficulty in detecting and measuring UE type increases

Engineering Contradiction:

Improveresource utilizationVSAvoidUE type detection difficulty

Core Design Contradiction:

ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces RA-RNTI as an intermediary parameter for UE type detection. Instead of directly detecting UE type from shared PRACH resources, the base station uses the RA-RNTI calculation (which incorporates msg1-FrequencyStart specific to each UE type) to indirectly identify whether the UE is RedCap or legacy, maintaining resource utilization while solving the detection problem.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12369197B2Method for transmitting or receiving signal for wireless communication, and device therefor

Publication Date: 2025.07.22 LG ELECTRONICS INC

AI summary

A base station according to an embodiment of the present invention may determine multiple different RA-RNTIs, and transmit message 2 for a random access response on the basis that: the base station supports not only a random access procedure of a first type terminal having a first maximum terminal bandwidth, but also a random access procedure of a second type terminal having a second maximum terminal bandwidth smaller than the first maximum terminal bandwidth; message 1 including a PRACH preamble has been detected on a PRACH resource shared between the first type terminal and the second type terminal; and at least one of PRACH preamble sequences for the first type terminal is reused for the second type terminal.