HARQ-ACK Codebook Overlap Elimination in 5G NR
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Solution Overview
Problem
In 3GPP 5G new radio (NR) systems, the semi-static HARQ-ACK feedback results in high overhead due to redundant transmission of HARQ-ACK feedback for overlapped slots within multiple downlink association sets, leading to inefficient retransmission and increased payload.
Innovation Solution
The proposed solution involves determining overlapping slots between different downlink slot sets and including HARQ-ACK feedback for each overlapped slot in either the first or second HARQ-ACK codebook, reducing redundant transmission and synchronizing codebook sizes between the base unit and remote unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If semi-static HARQ-ACK codebook determination is used with multiple downlink association sets, then comprehensive coverage of downlink transmissions is improved, but HARQ-ACK feedback overhead increases due to redundant transmissions for overlapped slots
Solution Approach 1:
The patent extracts and identifies the overlapped slots between multiple downlink association sets, then removes the redundant HARQ-ACK feedback transmissions for these slots. By determining which slots are overlapped and excluding them from one of the codebooks, the solution eliminates unnecessary feedback overhead while preserving the reliability benefits of multiple association sets.
Solution Approach 2:
The patent introduces dynamic determination of downlink slot sets based on the specific configuration of multiple downlink association sets. Instead of using fixed static codebooks, the system dynamically identifies overlapped slots and adjusts the HARQ-ACK codebook composition accordingly, allowing adaptive optimization of feedback overhead based on actual network conditions and configurations.
2Loss of information
If HARQ-ACK feedback for all slots is included in multiple codebooks, then feedback completeness is improved, but retransmission efficiency decreases due to redundant acknowledgements
Solution Approach 1:
The patent extracts the redundant HARQ-ACK feedback elements corresponding to overlapped slots and removes them from one of the multiple codebooks. This ensures that each slot's feedback is transmitted exactly once, maintaining feedback completeness for all slots while eliminating redundant acknowledgements that would otherwise reduce retransmission efficiency.
3Measurement precision
If separate HARQ-ACK codebooks are transmitted for each downlink association set, then association accuracy is improved, but payload size increases due to lack of synchronization
Solution Approach 1:
The patent merges the determination processes of multiple downlink association sets by identifying and coordinating the overlapped slots between them. By synchronizing the codebook generation to exclude redundant overlapped slot feedback, the solution maintains precise association accuracy for each set while combining the feedback transmissions to reduce overall payload size.
Solution Approach 2:
The patent introduces dynamic synchronization mechanisms that adjust the HARQ-ACK codebook composition based on the specific overlap patterns between downlink association sets. This dynamic coordination allows each association set to maintain its accuracy while adapting the payload content to eliminate redundancies, optimizing the trade-off between association precision and payload efficiency.
Data Source
AI summary
The present application relates to method and apparatus for downlink slot set determination. One embodiment of the present disclosure provides an apparatus comprising: a receiver that receives a first number of downlink transmissions indicating a first slot for transmitting corresponding HARQ-ACK feedback and receives a second number of downlink transmissions indicating a second slot for transmitting corresponding HARQ-ACK feedback; a processor that determines a first downlink slot set for the HARQ-ACK feedback transmitted in the first slot and a second downlink slot set for the HARQ-ACK feedback transmitted in the second slot, and determines the first downlink slot set and the second downlink slot set have at least one overlapped slot; and a transmitter that transmits a first HARQ-ACK codebook in the first slot for the first downlink slot set and a second HARQ-ACK codebook in the second slot for the second downlink slot set, wherein HARQ-ACK feedback for each of the at least one overlapped slot is included in either the first HARQ-ACK codebook or the second HARQ-ACK codebook.