HARQ-ACK Codebook Multiplexing for Priority-Based Retransmission
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Solution Overview
Problem
In communication systems with multiple transmission reception points (TRPs), there is a need for effective methods to synchronize TRPs and share channel state information (CSI) to enable coherent communication.
Innovation Solution
A method for a terminal to receive downlink control information (DCI) with fields indicating HARQ-ACK retransmission and priority, and transmit HARQ-ACK codebooks based on these fields, including multiplexing multiple HARQ-ACK codebooks in a HARQ-ACK bitstream, with priority arrangements, and a base station to generate and transmit DCI to manage these transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple HARQ-ACK codebooks are transmitted separately, then each codebook can be processed independently, but the transmission overhead and complexity increase
Solution Approach 1:
The patent combines multiple HARQ-ACK codebooks (initial transmission codebook and retransmission codebook) into a single multiplexed transmission. The terminal device generates one combined HARQ-ACK codebook that includes both initial and retransmission acknowledgments, reducing the number of separate transmissions and simplifying system complexity while maintaining reliable acknowledgment delivery.
Solution Approach 2:
The unified HARQ-ACK codebook structure serves multiple functions simultaneously: it carries both initial transmission acknowledgments and retransmission acknowledgments, provides priority-based scheduling information, and enables efficient resource utilization by allowing the base station to process all HARQ-ACK information in a single reception event.
2Reliability
If HARQ-ACK retransmission is implemented, then acknowledgment reliability is improved, but the transmission delay increases
Solution Approach 1:
The patent prepares the retransmission HARQ-ACK codebook in advance alongside the initial transmission codebook. Both codebooks are generated and multiplexed together before transmission, so that when retransmission is needed, the acknowledgment information is already prepared and can be sent immediately without additional processing delay.
Solution Approach 2:
The multiplexed HARQ-ACK codebook enables continuous acknowledgment transmission by combining initial and retransmission acknowledgments in a single unified structure. This eliminates gaps between separate transmission events and maintains continuous feedback flow, reducing overall transmission delay while ensuring reliable delivery.
3Adaptability or versatility
If priority fields are added to DCI, then scheduling flexibility is improved, but the control information overhead increases
Solution Approach 1:
The patent uses a compact priority field in the DCI that provides sufficient scheduling flexibility through partial differentiation. Instead of extensive priority levels, the system uses a concise priority indicator that distinguishes between high-priority (e.g., URLLC) and normal-priority (e.g., eMBB) traffic, achieving the necessary adaptability with minimal overhead.
Solution Approach 2:
The priority field in DCI uses optimized parameter encoding to convey scheduling flexibility. By carefully selecting the number of bits and the meaning of each priority level, the system achieves versatile scheduling control while minimizing the information overhead added to the control message.
Data Source
AI summary
A method of a terminal may comprise: receiving, from a base station, DCI including a first field indicating HARQ-ACK retransmission and a second field indicating a priority; identifying first HARQ-ACK information having a priority identical to the priority indicated by the second field; and transmitting, to the base station, a first HARQ-ACK codebook including the first HARQ-ACK information based on the indication of the first field.