RAR Message Format Type Indication for 2-Step RACH

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Solution Overview

Problem

The 2-step RACH procedure in communications technologies lacks definitive content in the RAR message, making it difficult for terminals to differentiate between different response cases, resulting in increased latency and processing complexity.

Innovation Solution

Incorporating indication information in the RAR message that indicates the format type, allowing terminals to perform corresponding random access operations based on this information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the 2-step RACH procedure is introduced to reduce latency, then the random access speed is improved, but the terminal cannot differentiate between different response cases due to indefinite content in the RAR message

Engineering Contradiction:

Improverandom access speedVSAvoidresponse differentiation capability

Core Design Contradiction:

SpeedVSLoss of information

Solution Approach 1:

The RAR message is segmented into different format types (first format and second format) with distinct structures. The first format includes a RAPID field for random access preamble identification, while the second format includes an UL grant field for uplink resource allocation. This segmentation allows terminals to differentiate between response cases based on the message format, resolving the information loss problem while maintaining the fast 2-step RACH procedure.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the RAR message content is kept flexible to accommodate different response cases, then the adaptability is improved, but the terminal processing complexity increases

Engineering Contradiction:

Improveresponse message adaptabilityVSAvoidterminal processing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Different RAR message formats are distinguished by their structural characteristics, analogous to color coding. The first format is identified by the presence of a RAPID field, while the second format is identified by the presence of an UL grant field. This structural differentiation allows terminals to quickly identify the message type and process accordingly, reducing processing complexity while maintaining adaptability to different response cases.

Inventive Principle:

Principle #32Color changes

3Ease of operation

If the RAR message structure is simplified to reduce processing complexity, then the ease of operation is improved, but the ability to convey different response types is reduced

Engineering Contradiction:

Improvemessage processing easeVSAvoidresponse type differentiation

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The RAR message structure is made dynamic by allowing it to switch between two predefined formats based on the response type. The network device selects the appropriate format (first or second) depending on whether the response requires preamble identification or uplink resource allocation. This dynamic structure maintains simplicity for the terminal while preserving the ability to convey different response types effectively.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20250063605A1Random access method, random access response method, terminal, and network device

Publication Date: 2025.02.20 VIVO MOBILE COMM CO LTD

AI summary

A network device, including: a memory, a processor and a computer program which is stored in the memory and executable on the processor, where the computer program, when executed by the processor, causes the network device to perform: receiving a random access message from a terminal; sending a RAR message to the terminal, where the RAR message includes indication information, and the indication information indicates a format type of the RAR message.