HARQ-ACK Codebook Determination for NR SPS Reliability
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Solution Overview
Problem
The existing Hybrid Automatic Repeat Request (HARQ) codebook in New Radio (NR) systems has an insufficient number of bits, leading to unnecessary retransmissions of Semi-persistent Scheduling (SPS) Physical Downlink Shared Channel (PDSCH) and reduced spectral efficiency due to postponed HARQ-ACK feedback.
Innovation Solution
The method involves determining a HARQ-ACK codebook by expanding the set of candidate PDSCH reception opportunities and incorporating redundant feedback, using predefined or configured slot timing values and uplink-downlink configuration information to reserve additional bits for HARQ-ACK information, thereby ensuring sufficient codebook bits and avoiding unnecessary retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the HARQ-ACK codebook uses a limited number of bits to save downlink control signaling overhead, then the signaling overhead is reduced, but the codebook bits become insufficient leading to unnecessary SPS PDSCH retransmissions
Solution Approach 1:
The patent determines the set of candidate PDSCH reception opportunities in advance by considering all possible PDSCH reception slots within a time window before actual transmission. This preliminary determination ensures that the HARQ-ACK codebook allocates sufficient bits for all potential PDSCH receptions, preventing insufficient codebook bits and unnecessary retransmissions while maintaining efficient signaling overhead
Solution Approach 2:
The patent establishes a feedback mechanism where the terminal determines HARQ-ACK information based on the predetermined set of candidate PDSCH reception opportunities. The HARQ-ACK codebook is constructed to include bits for all candidate PDSCH receptions, ensuring that feedback is always available even if some PDSCH transmissions occur unexpectedly, thereby improving feedback reliability without significantly increasing signaling overhead
2Device complexity
If the HARQ-ACK feedback is postponed due to insufficient codebook bits, then the codebook structure remains simple, but unnecessary retransmissions occur reducing spectral efficiency
Solution Approach 1:
The patent preliminarily determines the complete set of candidate PDSCH reception opportunities by considering all possible reception slots within a time window and all configured K1 values. This advance determination ensures the HARQ-ACK codebook is properly sized from the outset, eliminating the need for postponement and preventing unnecessary retransmissions, thus maintaining spectral efficiency without complicating the codebook structure
Solution Approach 2:
The patent dynamically adapts the HARQ-ACK codebook size by determining candidate PDSCH reception opportunities based on actual system configuration (number of K1 values, time window size) rather than using a fixed structure. This dynamic approach ensures the codebook is neither too large nor too small, optimizing spectral efficiency while keeping the structure adaptable to different scenarios
3Reliability
If the set of candidate PDSCH reception opportunities is expanded to include all possible slots, then sufficient codebook bits are ensured, but the determination complexity increases
Solution Approach 1:
The patent performs preliminary determination of candidate PDSCH reception opportunities by establishing a time window and identifying all possible reception slots within it, then mapping these to HARQ-ACK feedback opportunities using configured K1 values. This structured preliminary approach ensures comprehensive coverage of all potential PDSCH receptions while organizing the determination process in a systematic manner that manages complexity
Solution Approach 2:
The patent segments the determination process into distinct steps: first determining the time window, then identifying candidate PDSCH reception slots within that window, then mapping to HARQ-ACK feedback opportunities using K1 values, and finally constructing the codebook. This segmentation breaks down the complex determination into manageable stages, reducing overall complexity while ensuring reliability
Data Source
AI summary
A method and a device of determining a Hybrid Automatic Repeat reQuest-Acknowledgement are provided. The method includes: determining a first set of candidate PDSCH reception opportunities according to first information; determining HARQ-ACK information or a HARQ-ACK codebook transmitted on PUCCH resources of a first uplink slot or sub-slot n, according to the first set.