NR-U Joint Acknowledgment Codebook for PDSCH Resource Conflicts
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Solution Overview
Problem
In 5G NR-U radio access networks, dynamically scheduled and semi-persistent scheduling PDSCH transmissions can lead to conflicts where uplink acknowledgment resources overlap, causing transmission failures due to shared unlicensed spectrum usage and Listen Before Talk procedures.
Innovation Solution
The user equipment generates a joint acknowledgment codebook by concatenating group and semi-persistent scheduling codebooks, associating acknowledgment information elements for both types of transmissions, and attempts to transmit this codebook in a specified slot, even after initial transmission failures, ensuring successful delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If uplink acknowledgment resources are dynamically scheduled for group-based PDSCH transmissions and semi-persistent scheduling PDSCH transmissions, then resource utilization efficiency is improved, but resource conflicts occur when acknowledgment resources overlap in the same slot
Solution Approach 1:
The patent combines multiple downlink data receptions (both group-based dynamically scheduled PDSCHs and semi-persistent scheduling PDSCHs) into a single joint acknowledgment codebook. Instead of transmitting separate acknowledgments for each PDSCH type, the UE concatenates acknowledgment information elements for all received PDSCHs into one unified codebook structure, which is then transmitted in a single uplink acknowledgment message. This merging approach resolves resource conflicts by consolidating multiple acknowledgment transmissions into one unified transmission opportunity.
2Adaptability or versatility
If Listen Before Talk procedure is performed before uplink acknowledgment transmission in unlicensed spectrum, then spectrum sharing and coexistence are improved, but transmission failures occur when channel access fails
Solution Approach 1:
The patent performs preliminary concatenation of the joint acknowledgment codebook before the actual uplink transmission attempt. The UE prepares the complete codebook structure in advance, incorporating acknowledgment information for all received PDSCHs (both group-based and SPS types). This preliminary action ensures that when channel access is successfully obtained after LBT, the acknowledgment can be transmitted immediately without additional processing delays, maximizing the use of the seized channel opportunity.
Solution Approach 2:
The patent implements a feedback mechanism where the base station monitors uplink acknowledgment transmissions and provides downlink control information to trigger retransmissions when acknowledgments are not successfully received. The UE maintains buffering of acknowledgment information and can perform subsequent transmission attempts based on base station feedback, ensuring reliable delivery despite initial LBT failures or channel conflicts.
Data Source
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AI summary
The downlink data receptions include a set of one or more PDSCH receptions (PDSCH1, PDSCH2) belonging to a same group GO, scheduled by respective associated DCI elements (DCI1, DCI2) that indicate a same first slot (PUCCH1 slot) for a corresponding acknowledgement transmission, and a 'SPS' PDSCH reception (SPS-PDSCH1), for which an acknowledgment transmission is scheduled on the next of a plurality of fixed periodic slots. The UE determines that the first slot for acknowledgment transmission is the same as the next fixed periodic slot for acknowledgment transmission, generates a joint acknowledgment codebook concatenating a group codebook for group GO including an AN element for each dynamically scheduled PDSCH receptions of the group GO and a SPS codebook including an AN element for the 'SPS' PDSCH reception, and attempts to transmit the generated joint acknowledgment codebook on said first slot for acknowledgment transmission.