Group HARQ Feedback Using CBG and TB Acknowledgment Levels
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Solution Overview
Problem
Wireless communication systems face challenges in providing efficient acknowledgment feedback for downlink transmissions, particularly in scenarios where transmissions may not be correctly received due to hidden interfering nodes or occupied medium, leading to incomplete or absent ACK feedback.
Innovation Solution
Implementing group-based acknowledgment feedback techniques that allow user equipment (UE) to transmit hybrid automatic repeat request (HARQ) feedback for multiple downlink transmissions, with options for code-block-group (CBG) or transport block (TB) level feedback, determined by parameters in downlink control information (DCI), and utilizing uplink DCI for timing and DAI values to manage feedback codebooks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If group-based acknowledgment feedback is implemented to provide feedback for multiple downlink transmissions, then feedback efficiency is improved, but feedback accuracy may deteriorate due to potential loss of individual transmission acknowledgments
Solution Approach 1:
The feedback is segmented into different groups (first group for CBG-level feedback, second group for TB-level feedback) allowing selective reporting based on transmission conditions. This segmentation enables the system to maintain high efficiency by grouping transmissions while preserving accuracy by allowing individual CBG or TB acknowledgment when needed.
Solution Approach 2:
The feedback mechanism dynamically adapts between CBG-level and TB-level acknowledgment based on transmission conditions and configuration. The system can switch between different feedback granularities (fine-grained CBG or coarse-grained TB) to optimize the balance between feedback efficiency and accuracy according to channel conditions and traffic requirements.
2Measurement precision
If CBG level feedback is provided for multiple CBGs associated with each transport block, then feedback precision is improved, but system complexity increases
Solution Approach 1:
Different levels of feedback precision are applied locally to different transmission groups. The first group of downlink transmissions receives CBG-level feedback for high precision, while the second group uses TB-level feedback for lower complexity. This local differentiation allows the system to achieve high precision where needed without uniformly increasing complexity across all transmissions.
Solution Approach 2:
The feedback granularity parameter is changed based on transmission characteristics and configuration. The system can adjust the feedback level (CBG vs TB) as a configurable parameter, allowing optimization of the precision-complexity tradeoff by selecting appropriate feedback granularity for different traffic types and channel conditions.
3Adaptability or versatility
If multiple groups of downlink transmissions are configured with different feedback levels, then adaptability is improved, but control complexity increases
Solution Approach 1:
The feedback system is designed with multi-functionality to handle both CBG-level and TB-level feedback within a unified framework. The same uplink transmission resources can carry different types of feedback for different groups, and the base station can interpret and process both feedback types through a single control mechanism, reducing the need for separate specialized systems.
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described that support group-based acknowledgment feedback techniques. Two or more different groups of downlink transmissions may each have an associated transport block (TB) level or code block group (CBG) level group-based acknowledgment feedback, and a base station may transmit downlink control information to a UE that indicates one or more parameters that are used to determine which downlink transmissions are to be reported in the group-based feedback at a TB level, CBG level, or combinations thereof. Based on the parameters in the downlink control information, the UE may determine the feedback to be reported, and a timing for when to transmit the feedback to the base station.