Random Access Channel Repetition Under Poor Channel Conditions

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Solution Overview

Problem

Existing wireless communication systems face challenges in ensuring reliable and efficient random access channel transmissions, particularly for UEs in poor channel conditions, leading to increased error rates and dropped communications.

Innovation Solution

Implementing random access channel repetition by using specific parameters for initial transmissions, allowing UEs to request and utilize repetition for RRC connection requests, thereby improving communication reliability and reducing error rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If random access channel repetition is implemented for UEs in poor channel conditions, then communication reliability is improved, but device complexity and protocol overhead increase

Engineering Contradiction:

Improvecommunication reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by introducing a repetition factor parameter that controls the number of times the random access message is repeated. This parameter can be dynamically adjusted based on channel conditions, allowing the system to improve reliability when needed while maintaining simplicity under normal conditions. The base station configures the repetition factor and the UE applies it during random access procedures, providing adaptive reliability enhancement without permanent system complexity.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If random access channel repetition is used to improve decoding success, then error rates are reduced, but transmission time and latency increase

Engineering Contradiction:

Improvedecoding success rateVSAvoidtransmission time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent implements partial action by applying repetition only to specific random access messages that require enhanced reliability, rather than all messages. The base station determines which messages should be repeated based on UE identity, message type, or channel conditions. This selective repetition reduces the overall time penalty compared to universal repetition, while still providing the reliability benefits for critical messages.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If repetition parameters are configured for random access messages, then communication reliability in challenging conditions is improved, but signaling overhead increases

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent achieves universality by using existing random access configuration parameters to serve multiple functions. The repetition factor is configured as part of the standard random access parameters, allowing it to be conveyed through existing signaling mechanisms without requiring dedicated overhead. The same configuration framework that handles timing, frequency, and power parameters also handles repetition, reducing additional signaling requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP4381882B1Random access channel repetition

Publication Date: 2025.10.29 QUALCOMM INC

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AI summary

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive first information indicating a first set of parameters associated with repetition of a second random access message (RAM) associated with a random access channel (RACH) procedure. The UE may transmit, using the first set of parameters, an initial RAM in association with the RACH procedure. Numerous other aspects are described.