Grant-Free HARQ for Uplink Transmissions

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Solution Overview

Problem

Existing wireless communication systems face challenges in implementing Hybrid Automatic Repeat Request (HARQ) for grant-free uplink transmissions, as they lack scheduling grants and explicit resource allocation, making it difficult to perform acknowledgement, retransmission timing, redundancy version determination, and HARQ combining.

Innovation Solution

The implementation of systems and methods that enable HARQ for grant-free uplink transmissions by using preconfigured or semi-statically configured uplink resources, MA signatures, and redundancy versions, allowing for acknowledgement and retransmission management without explicit scheduling grants from the base station.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If grant-free uplink transmissions are implemented without scheduling grants, then resource allocation efficiency and transmission speed are improved, but the ability to perform HARQ operations (acknowledgement, retransmission timing, redundancy version determination) deteriorates

Engineering Contradiction:

Improvetransmission speedVSAvoidHARQ operation capability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-configuring HARQ parameters (process IDs, redundancy versions, timing information) before grant-free transmissions occur. The base station and UE establish HARQ configurations in advance through RRC signaling or system information, enabling HARQ operations to function properly even without dynamic scheduling grants during actual transmission.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements self-service by enabling UEs to autonomously determine HARQ parameters based on pre-configured rules and their own transmission characteristics. The UE can self-select redundancy versions and determine retransmission timing based on stored configurations and channel conditions, reducing dependency on base station scheduling while maintaining HARQ functionality.

Inventive Principle:

Principle #25Self-service

2Device complexity

If explicit scheduling grants are removed for uplink transmissions, then signaling overhead and system complexity are reduced, but the precision of resource allocation and transmission control deteriorates

Engineering Contradiction:

Improvesignaling overheadVSAvoidresource allocation precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting HARQ parameters (redundancy versions, process IDs, timing offsets) based on channel conditions, traffic characteristics, and UE capabilities. The base station can modify these parameters through RRC reconfiguration or MAC CE signaling to optimize performance for different scenarios while maintaining reduced signaling overhead compared to full scheduling grants.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10868640B2HARQ systems and methods for grant-free uplink transmissions

Publication Date: 2020.12.15 HUAWEI TECH CO LTD

AI summary

Systems and methods are disclosed for performing hybrid automatic repeat request (HARQ) for grant-free uplink transmissions. Some of the systems and methods disclosed herein may address problems such as how to perform acknowledgement (ACK) and/or negative acknowledgement (NACK), how to determine and signal retransmission timing, how to determine the transmission/retransmission attempt and the redundancy version (RV), and/or how to perform the HARQ combining.