PUSCH Repetition Signaling for NR Random Access Coverage

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Solution Overview

Problem

Msg3 and MsgA transmissions on the physical uplink shared channel (PUSCH) are a potential coverage performance bottleneck in NR networks, complicating the random access procedure with increased latency and overhead due to multiple HARQ retransmissions.

Innovation Solution

Implementing repetition and frequency hopping techniques for Msg3 and MsgA transmissions, including dynamic signaling of transmission parameters and power control mechanisms to enhance coverage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Msg3 and MsgA transmissions use repeated PUSCH occasions to improve coverage, then coverage enhancement is achieved, but uplink resources are wasted when repetitions are not needed

Engineering Contradiction:
ImprovecoverageVSAvoiduplink resource waste
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the parameter of PUSCH repetition configuration based on the selected random access preamble. Different preamble groups (e.g., group A and group B) are associated with different repetition factors or PUSCH occasion configurations. This allows the system to adapt the repetition level to the actual channel conditions and device needs, providing coverage enhancement only when necessary and avoiding resource waste when good coverage is already available.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If coverage enhancement is provided for all random access devices, then devices with poor coverage benefit, but devices with good coverage waste uplink resources

Engineering Contradiction:
Improvecoverage for poor coverage devicesVSAvoiduplink resource waste for good coverage devices
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by providing differentiated PUSCH repetition configurations to different devices based on their individual coverage conditions. Devices that select preambles indicating poor coverage receive higher repetition factors, while devices selecting preambles indicating good coverage receive lower or no repetition. This localized adaptation ensures that each device receives appropriate resource allocation based on its specific needs rather than applying a uniform configuration to all devices.

Inventive Principle:
Principle #3Local quality

3Reliability

If Msg3 and MsgA use different PUSCH repetition configurations, then each message can be optimized, but device complexity increases for determining and managing multiple configurations

Engineering Contradiction:
Improvemessage transmission reliabilityVSAvoidcomplexity for managing multiple PUSCH configurations
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-configuring multiple PUSCH repetition configurations and associating them with different random access preamble groups before the actual random access procedure. The network node provides these configurations in advance through system information or RRC signaling. When a device selects a preamble, it can directly determine the corresponding PUSCH repetition configuration without complex real-time calculations, reducing device complexity while still allowing optimized configurations for different messages.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4391675B1Coverage enhancement of msg3 and msga transmissions on physical uplink shared channel
Publication Date: 2026.04.29 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4391675B1 patent drawingFigure 1~2
  • EP4391675B1 patent drawingFigure 3~4
  • EP4391675B1 patent drawingFigure 5~8

AI summary

A communication device operating in a communications network can determine to transmit information using repetition to a network node operating in the communications network during a random access, RA, procedure. The communication device can further determine a subset of preambles based on determining to transmit the information using repetition. Responsive to determining the subset of preambles, the communication device can determine a preamble of the subset of preambles to transmit to the network node to indicate a type of the repetition. The communication device can further transmit the preamble to the network node. The communication device can further transmit the information using the type of repetition to the network node.