Multi-Cell HARQ-ACK Codebook Feedback for NR PDSCH Scheduling
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Solution Overview
Problem
In the new radio (NR) system, the challenge lies in performing Hybrid Automatic Repeat Request-Acknowledgement (HARQ-ACK) information feedback for Physical Downlink Shared Channel (PDSCH) scheduled by Downlink Control Information (DCI) supporting multi-cell scheduling, as existing methods are inadequate for this scenario.
Innovation Solution
A mechanism is provided for HARQ-ACK feedback by monitoring N DCIs, each supporting scheduling of PDSCH transmissions on at least two cells, and sending a HARQ-ACK codebook to feed back HARQ-ACK information sequentially based on counter-downlink assignment indexes (C-DAIs) or cell indexes, facilitating correct determination of PDSCH transmission and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If one DCI supports scheduling of PDSCH transmissions on at least two cells, then scheduling flexibility and resource utilization efficiency are improved, but the complexity of HARQ-ACK information feedback increases
Solution Approach 1:
The patent segments the HARQ-ACK feedback process by introducing separate C-DAI and T-DAI fields in DCI formats. C-DAI segments the downlink assignments across cells in a monitoring occasion, while T-DAI provides total counting information. This segmentation allows the terminal to accurately determine the number of PDSCHs and their corresponding cells without overwhelming complexity, resolving the contradiction between multi-cell scheduling flexibility and feedback complexity.
Solution Approach 2:
The patent introduces DAI (Downlink Assignment Index) as an intermediary mechanism between the network device's multi-cell scheduling decisions and the terminal's HARQ-ACK feedback. The DAI fields (C-DAI and T-DAI) act as mediators that carry scheduling information from the DCI to the terminal, enabling the terminal to correctly interpret and feedback HARQ-ACK information for multiple cells without directly processing complex multi-cell scheduling logic.
2Productivity
If HARQ-ACK information is fed back for PDSCH on multiple cells scheduled by one DCI, then resource utilization efficiency is improved, but the difficulty of determining correctness of PDSCH transmission increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring DAI fields in the DCI before PDSCH transmission. The C-DAI and T-DAI values are predetermined based on the scheduling decisions, allowing the terminal to proactively determine the expected number of PDSCHs and their cell distributions before generating HARQ-ACK feedback. This preliminary information preparation simplifies the subsequent correctness determination process.
Solution Approach 2:
The patent implements a structured feedback mechanism where the terminal uses the received C-DAI and T-DAI values to verify the number and positioning of PDSCHs. The terminal compares the actual received PDSCH count against the T-DAI indication, and uses C-DAI to map each PDSCH to its corresponding cell and HARQ-ACK bit position. This feedback verification process ensures accurate determination of PDSCH transmission correctness across multiple cells.
Data Source
AI summary
A communication method and a communication apparatus are provided. The communication method includes the following. N downlink control information (DCIs) are monitored, where the N DCIs each support scheduling of physical downlink shared channel (PDSCH) transmissions on at least two cells, and N is a positive integer and N≥1. A hybrid automatic repeat request-acknowledgement (HARQ-ACK) codebook is sent, where the HARQ-ACK codebook is used for feeding back HARQ-ACK information of a PDSCH on at least one cell scheduled by each of the N DCIs.