5G Random Access Parameters to Prevent RedCap RAR Collisions

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Solution Overview

Problem

The current 5G NR system faces challenges in accommodating reduced capability user equipment (Redcap UE) due to overlapping random access responses (RARs) between Redcap UE and normal NR UE, leading to collisions in the same physical downlink shared channel, which is not addressed by existing technologies.

Innovation Solution

A method for determining unique random access parameters for Redcap UE, including different initial uplink bandwidth parts and RA-RNTI calculations based on frequency division multiplexing and supplementary uplink configurations, to avoid collisions and ensure distinct random access processes for Redcap and normal NR UEs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If low-capability terminals and normal UEs share the same PRACH resources and CORESET #0, then resource utilization is improved, but random access response collisions occur

Engineering Contradiction:

Improveresource utilizationVSAvoidrandom access response collision

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent segments the random access response resources by introducing a terminal type identifier that divides UEs into different types (low-capability and normal). This segmentation allows the network to differentiate and separately handle random access responses for different UE types, preventing collisions while maintaining shared PRACH resources.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by configuring different random access parameters specifically for low-capability terminals compared to normal UEs. The network device determines whether to send RAR to a low-capability terminal based on local conditions (terminal type, capability information) rather than applying a uniform approach to all UEs.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If the same RA-RNTI is used for low-capability terminals and normal UEs, then signaling overhead is reduced, but random access response collision occurs

Engineering Contradiction:

Improvesignaling overheadVSAvoidrandom access response collision

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the RA-RNTI parameter by incorporating a terminal type identifier into the RA-RNTI calculation formula. This parameter change ensures that low-capability terminals and normal UEs receive different RA-RNTI values even when accessing through the same PRACH resources, eliminating collisions while maintaining efficient signaling.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If 5G NR systems use unified random access parameters for all UEs, then system complexity is reduced, but low-capability IoT devices cannot meet delay and rate requirements

Engineering Contradiction:

Improvesystem complexityVSAvoiddelay and rate requirement satisfaction

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces dynamics by making the random access parameter configuration adaptive to terminal type. The network device dynamically determines whether to send random access response based on terminal type identification and capability information, allowing the system to optimize performance for different device types without requiring completely separate systems.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12621865B2Random access parameter processing method and apparatus, and storage medium

Publication Date: 2026.05.05 BEIJING XIAOMI MOBILE SOFTWARE CO LTD

AI summary

A method for processing a random access parameter is performed by a first type user equipment (UE), and includes: determining a first parameter for random access of the first type UE, wherein the first parameter for random access of the first type UE is not completely the same as or completely different from a second parameter for random access of a second type UE, and a type of the first type UE is different from a type of the second type UE.