HARQ DCI Format Segmentation for Unlicensed Band Access
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Solution Overview
Problem
In wireless communications, the unlicensed band experiences interference and quality of service issues due to competitive WLAN installations, making it challenging to support hybrid automatic repeat request (HARQ) operations, especially when multiple users are present and mobility is required.
Innovation Solution
A method and device that receive downlink control information with a carrier indicator field to determine the format of the control information, allowing for efficient uplink data transmission by using either a first DCI format for licensed cells or a second DCI format for unlicensed cells, which includes specific resource allocation fields, thereby simplifying HARQ operations across both licensed and unlicensed bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single DCI format is used for both licensed and unlicensed cells, then device complexity is reduced, but resource allocation efficiency deteriorates in unlicensed bands
Solution Approach 1:
The patent segments DCI formats into two distinct types: first DCI format for licensed cells and second DCI format for unlicensed cells. This segmentation allows each format to be optimized for its specific band characteristics, with the second DCI format including LBT-related fields and adjusted resource allocation fields suitable for unlicensed spectrum operations, thereby resolving the contradiction between device complexity and resource allocation efficiency.
Solution Approach 2:
The patent applies local quality by configuring different DCI format structures according to the specific requirements of each cell type. The second DCI format for unlicensed cells includes locally adapted fields such as LBT failure indication and adjusted resource allocation parameters, allowing each part of the system to have the specific properties needed for its operational context while maintaining overall system coherence.
2Productivity
If carrier aggregation is used to combine licensed and unlicensed bands, then throughput is increased, but interference from unlicensed band contention increases
Solution Approach 1:
The patent implements preliminary action by performing Clear Channel Assessment (CCA) and Listen-Before-Talk (LBT) procedures before transmitting data in unlicensed bands. The base station conducts these preliminary channel access procedures to ensure the channel is clear before scheduling uplink transmissions, thereby reducing interference from unlicensed band contention while maintaining the throughput benefits of carrier aggregation.
Solution Approach 2:
The patent uses the first DCI format as an intermediary mechanism that provides fallback scheduling information for unlicensed cells when LBT fails or channel conditions are poor. This intermediary DCI format allows the system to maintain throughput by scheduling retransmissions or alternative transmissions on licensed bands when unlicensed band access is blocked, thus mediating between the throughput goal and interference avoidance.
3Stability of the object's composition
If legacy DCI format is used for unlicensed cells, then control information consistency is maintained, but HARQ operation reliability deteriorates
Solution Approach 1:
The patent applies local quality by introducing a second DCI format specifically tailored for unlicensed cells that includes LBT-related fields and adjusted resource allocation parameters. This format maintains consistency with legacy DCI structures where applicable but adds local adaptations for unlicensed band operations, ensuring both control information consistency and HARQ operation reliability in the challenging unlicensed environment.
Solution Approach 2:
The patent implements parameter changes by modifying the DCI format structure for unlicensed cells, including adding LBT failure indication fields, adjusting resource allocation field sizes and positions, and incorporating LBT-related parameters. These parameter changes enable the control information to accurately reflect unlicensed band conditions, thereby improving HARQ operation reliability while maintaining overall structural consistency with legacy formats.
Data Source
AI summary
A method and device for supporting a hybrid automatic repeat request (HARQ) in an unlicensed band is provided. A user equipment receives first downlink control information (DCI) including uplink scheduling information. The first DCI further includes a carrier indicator field (CIF) indicating a cell to be scheduled. If the type of the cell indicated by the CIF is a licensed cell, the format of the DCI is determined as a first DCI format including a first resource allocation (RA) field used for the uplink scheduling information. If the type of the cell indicated by the CIF is an unlicensed cell, the format of the DCI is determined as a second DCI format including a second RA field used for the uplink scheduling information.