HARQ-ACK Codebook Retransmission for Overlap-Aware Uplink Feedback
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing HARQ-ACK information transmission due to overlapping transmissions, cancellation, and redundancy, which affect throughput, latency, and resource utilization.
Innovation Solution
Implementing HARQ deferral and retransmission strategies to manage HARQ-ACK information transmission, including determining deferred slots and separate codebooks to avoid redundant signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ deferral is implemented to avoid overlapping with downlink symbols, then transmission reliability is improved, but transmission latency increases due to deferred transmission
Solution Approach 1:
The UE determines in advance whether HARQ deferral is needed by checking if the scheduled transmission overlaps with downlink symbols, and proactively defers the transmission to a later slot, preventing potential conflicts before they occur
Solution Approach 2:
The transmission timing of HARQ-ACK is made dynamic rather than fixed - the UE can transmit in the originally scheduled slot or defer to a later slot based on real-time channel conditions and downlink symbol patterns, optimizing both reliability and latency
2Reliability
If HARQ-ACK codebook retransmission is performed to ensure accurate delivery, then information reliability is improved, but signaling overhead increases
Solution Approach 1:
The UE transmits a HARQ-ACK codebook that includes copies of previously transmitted HARQ-ACK information when retransmission is triggered by downlink control information, ensuring reliable delivery through redundancy
Solution Approach 2:
The system recovers and retransmits only the necessary HARQ-ACK information that needs acknowledgment, rather than transmitting all possible control information, optimizing signaling efficiency
3Productivity
If the number of UEs served by a base station is increased to improve network capacity, then system productivity is improved, but resource utilization efficiency deteriorates due to limited available resources
Solution Approach 1:
The system enables continuous HARQ-ACK transmission opportunities for multiple UEs by utilizing both scheduled slots and deferred transmission slots, ensuring that uplink control information can be transmitted without interruption even as UE density increases
Solution Approach 2:
The patent introduces an additional time dimension for HARQ-ACK transmission by allowing deferral to later slots, creating more transmission opportunities in the time domain to accommodate increased UE density without overwhelming resources in any single slot
4Reliability
If HARQ deferral and codebook retransmission are both implemented, then transmission reliability is improved, but system complexity increases
Solution Approach 1:
The HARQ-ACK transmission process is segmented into distinct phases: initial transmission determination, overlap detection, deferral decision, and retransmission triggering, making the complex process more manageable and implementable
Solution Approach 2:
The system uses feedback mechanisms where downlink control information triggers codebook retransmission, and the UE monitors for such triggers to determine when to retransmit deferred or original HARQ-ACK information, creating a closed-loop control system
Data Source
AI summary
A UE may determine a target slot for HARQ deferral for transmission of first HARQ-ACK information, based on transmission of the first HARQ-ACK information overlapping with a downlink symbol in a first slot, transmit a second HARQ-ACK codebook including a first HARQ-ACK codebook in a second slot for retransmission of the first HARQ-ACK codebook, based on DCI triggering retransmission of the first HARQ-ACK codebook scheduled to be transmitted in the first slot, and transmit uplink control information in the target slot. The uplink control information does not include the first HARQ-ACK information, based on the second HARQ-ACK codebook including the first HARQ-ACK information.