One-Shot HARQ-ACK Feedback for Smaller URLLC Codebooks
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently configuring hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback, particularly in ultra-reliable low-latency communication (URLLC), leading to large HARQ-ACK codebooks that impact performance and increase latency, especially on unlicensed frequency carriers.
Innovation Solution
Configuring one-shot HARQ-ACK feedback modes by receiving RRC parameters, MAC control elements, and DCI to trigger HARQ-ACK codebooks, and transmitting feedback only for activated serving cells or HARQ processes meeting specific conditions, thereby reducing codebook size and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional HARQ-ACK feedback configuration is used for PDSCH transmission, then all configured HARQ processes are included in the codebook, but the HARQ-ACK codebook becomes large and impacts performance
Solution Approach 1:
The patent extracts only the necessary HARQ processes from the complete codebook based on activation status. Specifically, it identifies and includes only HARQ processes associated with activated serving cells in the HARQ-ACK codebook, while excluding those from deactivated cells. This selective extraction reduces codebook size while maintaining feedback reliability for active transmissions.
Solution Approach 2:
The patent introduces dynamic adjustment of the HARQ-ACK codebook based on MAC CE commands that activate or deactivate serving cells. The codebook size and content dynamically change according to the current activation state, allowing the system to adapt between including all HARQ processes (when needed) and excluding inactive ones (to reduce overhead).
2Reliability
If HARQ-ACK codebook includes all configured HARQ processes, then comprehensive feedback is provided, but transmission latency increases
Solution Approach 1:
The patent removes unnecessary HARQ process feedback from the codebook by checking activation status. Only HARQ processes that are currently active and may have pending acknowledgments are included. This extraction of essential feedback elements reduces the time required to prepare and transmit the HARQ-ACK codebook while ensuring all relevant acknowledgments are provided.
3Reliability
If one-shot HARQ-ACK feedback is triggered for all serving cells, then complete feedback is achieved, but payload size increases
Solution Approach 1:
The patent applies extraction by filtering the list of serving cells to include only those with activation status before generating one-shot HARQ-ACK feedback. The MAC CE activation/deactivation commands are processed to identify which serving cells should be included in the feedback payload, thereby reducing payload size while maintaining coverage for all active cells.
Data Source
AI summary
The present disclosure describes methods, system, and devices for configuring hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback for physical downlink shared channel (PDSCH) transmission. The method includes receiving, by a user equipment (UE), a radio resource control (RRC) parameter to configure a one-shot HARQ-ACK feedback mode; receiving, by the UE, a medium access control (MAC) control element (CE) indicating a list of activated serving cells; receiving, by the UE, a downlink control information (DCI) comprising an one-shot request field with a positive value, the DCI triggering a one-shot HARQ-ACK codebook; and transmitting, by the UE, a one-shot HARQ-ACK feedback for the list of activated serving cells.