PDSCH Control Feedback for Fast eURLLC Uplink Retransmission

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Solution Overview

Problem

Existing methods for retransmitting uplink data in Enhanced Ultra Reliable Low Latency Communication (eURLLC) services fail to meet the stringent delay requirement of 0.5 ms due to inefficient scheduling by the base station.

Innovation Solution

The method involves sending control information, such as ACK or NACK, to the terminal in the time slot n+k of the PDSCH to facilitate timely retransmission of uplink data, ensuring the delay requirement is met by configuring k through target PDCCH formats or RRC signaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the base station schedules the terminal to perform retransmission, then the uplink data can be retransmitted, but the transmission delay increases and cannot meet the eURLLC requirement of 0.5 ms

Engineering Contradiction:
Improvetransmission reliabilityVSAvoidtransmission delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

Instead of the base station scheduling the terminal for retransmission (downlink control), the terminal autonomously performs retransmission based on pre-configured uplink resources and feedback information (uplink autonomous action). This inversion of control direction eliminates scheduling delay and meets the 0.5 ms eURLLC requirement.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The terminal is pre-configured with uplink resources and retransmission parameters before needing retransmission. When feedback indicates failure, the terminal can immediately use the pre-prepared resources without waiting for base station scheduling, thus reducing delay while ensuring reliability.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If the control information is sent in later time slots, then the terminal has more time to process, but the retransmission delay increases

Engineering Contradiction:
Improveterminal processing timeVSAvoidretransmission delay
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent changes the timing parameter by sending control information in the same time slot n or earlier time slots rather than later slots. The terminal processes the feedback information using pre-configured resources, eliminating the need for additional processing time in later slots while achieving faster retransmission.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the base station uses traditional scheduling methods, then resource allocation can be optimized, but the retransmission process cannot meet the stringent delay requirements of eURLLC

Engineering Contradiction:
Improveresource allocation efficiencyVSAvoidretransmission delay
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The terminal autonomously performs retransmission using pre-configured resources and feedback information without requiring base station scheduling intervention. This self-service mechanism eliminates the scheduling overhead while ensuring efficient resource utilization for urgent eURLLC traffic.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3955498B1Control information transmission method, retransmission method and apparatus, terminal, and storage medium
Publication Date: 2025.09.17 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP3955498B1 patent drawingFigure 1
  • EP3955498B1 patent drawingFigure 2
  • EP3955498B1 patent drawingFigure 3

AI summary

Provided are a control information transmission method and apparatus, and a device and a storage medium, wherein same belong to the field of communications. The method comprises: receiving, on a time slot n of a PUSCH, uplink data sent by a terminal, and sending, at a specified frequency-domain position on a time slot n+k of a PDSCH, control information to the terminal, wherein both n and k are integers. According to the present application, the terminal can learn feedback information of uplink data in the shortest possible time and retransmit the uplink data when the feedback information is NACK, such that the timeliness of a retransmission process is ensured, and a delay requirement of an eURLLC service can be met.