Configured Grant Uplink HARQ Feedback for CBG Retransmissions
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Solution Overview
Problem
In wireless communication using configured grants in unlicensed spectrum, multiple listen-before-talk procedures for uplink transmissions reduce channel access efficiency, and HARQ retransmissions with code block group (CBG) based transmissions lead to significant signaling overhead.
Innovation Solution
Implementing a downlink feedback information (DFI) format that includes both transport block (TB) and CBG-based HARQ-ACK bitmaps, allowing efficient HARQ retransmissions without increasing blind decoding complexity, and aligning the DCI format size with legacy formats to support autonomous UL transmissions on multiple serving cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple listen-before-talk procedures are performed for uplink transmissions in unlicensed spectrum, then channel access fairness is improved, but channel access efficiency deteriorates
Solution Approach 1:
The patent performs listen-before-talk procedures in advance before configuring granted uplink transmissions. By completing LBT checks beforehand and securing channel access rights提前, the system avoids multiple LBT procedures during actual data transmission, thereby maintaining fairness while improving efficiency.
2Productivity
If code block group based transmissions are implemented for configured grants, then retransmission efficiency is improved, but signaling overhead increases
Solution Approach 1:
The patent segments the transport block into code block groups for independent HARQ feedback and retransmission. This allows selective retransmission of only failed CBGs rather than entire transport blocks, improving retransmission efficiency while the feedback mechanism is optimized to reduce signaling overhead.
Solution Approach 2:
The patent changes the feedback mechanism parameter by using a unified DCI format with HARQ-ACK bitmaps that can accommodate both TB-based and CBG-based feedback. This parameter change enables efficient CBG-level retransmission control without proportionally increasing signaling overhead through optimized bitmap structures.
3Adaptability or versatility
If downlink feedback information format includes both TB and CBG based HARQ-ACK bitmaps, then retransmission flexibility is improved, but DCI format complexity increases
Solution Approach 1:
The patent designs a universal DCI format that can serve multiple functions: it can provide TB-based HARQ-ACK feedback, CBG-based HARQ-ACK feedback, or both simultaneously through configurable bitmaps. This multi-functionality achieves retransmission flexibility while avoiding the need for multiple separate DCI formats.
Solution Approach 2:
The patent implements dynamic configurability in the DCI format where the interpretation of HARQ-ACK bitmaps can change based on higher-layer configuration and transmission type. The same DCI structure adapts its meaning dynamically whether for TB-based or CBG-based transmissions, managing complexity through flexible interpretation rather than rigid structure.
Data Source
AI summary
The exemplary embodiments relate to determining that code block group (CBG) based transmissions are enabled, transmitting, via an unlicensed spectrum, configured grants comprising one or more CBG based transmissions and one or more transport block (TB) based transmissions and receiving a downlink feedback information (DFI) downlink control information (DCI) format, wherein the DFI DCI format comprises a hybrid automatic repeating request (HARQ) bitmap corresponding to the TB based transmissions and a HARQ bitmap corresponding to the CBG based transmissions. The exemplary embodiments may be implemented in a computer readable storage medium, a user equipment (UE) or an integrated circuit.