Single-Bit CBG Feedback for Punctured Resource Retransmission
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing single bit acknowledgment (ACK)/negative acknowledgment (NACK) feedback for codeblock group (CBG) based transmissions, particularly in scenarios where resources are punctured for dynamic sharing between Ultra-Reliable and Low-Latency Communications (URLLC) and Enhanced Mobile Broadband (eMBB) services, leading to inefficiencies in retransmissions and decoding errors.
Innovation Solution
The implementation of a method and apparatus that support single bit ACK/NACK feedback for CBG transmissions, allowing for retransmissions of specific CBGs based on feedback, with a base station transmitting CBGs on partially punctured resources and a user equipment (UE) decoding and responding with ACK/NACK to trigger retransmissions, while providing a CBG confirmation list to manage affected CBGs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resources are punctured for dynamic sharing between URLLC and eMBB services, then resource utilization efficiency is improved, but decoding errors increase and reliability deteriorates
Solution Approach 1:
The transport block is segmented into multiple codeblock groups (CBGs), allowing selective retransmission of only the failed CBGs affected by puncturing rather than retransmitting the entire block. This segmentation enables targeted error recovery while maintaining overall transmission efficiency.
Solution Approach 2:
Different quality of service (QoS) requirements are applied to different CBGs based on their service type (URLLC vs eMBB). URLLC CBGs receive higher priority and more robust handling, while eMBB CBGs can tolerate higher error rates. This local differentiation allows the system to optimize reliability where needed while maintaining resource efficiency elsewhere.
2Loss of time
If selective retransmission of CBGs is implemented, then latency is reduced and efficiency is improved, but feedback complexity increases
Solution Approach 1:
Instead of providing full granular feedback for every individual CBG (which would be excessively complex), the system uses a simplified feedback mechanism that provides partial information - sufficient to enable selective retransmission of failed CBGs while avoiding the overhead of complete CBG-level acknowledgment for each individual group.
Solution Approach 2:
The system implements an enhanced feedback mechanism where the UE provides acknowledgment information that enables the gNB to identify which specific CBGs failed decoding. This feedback is more sophisticated than traditional ACK/NACK but less complex than full CBG-level individual feedback, striking an optimal balance between information completeness and signaling overhead.
3Measurement precision
If CBG confirmation information is transmitted, then decoding accuracy is improved, but overhead increases
Solution Approach 1:
The gNB transmits CBG confirmation information in advance, before the actual retransmission occurs. This preliminary indication allows the UE to prepare for selective decoding and combine received signals more effectively, improving decoding accuracy while the overhead is paid only once rather than repeatedly with each retransmission.
Data Source
AI summary
Various features related to a single bit ACK/NACK feedback for CBG based transmissions in a communication system are described. In an aspect, a base station may transmit, to a UE, a set of CBGs of a TB including a first subset of CBGs and a second subset of CBGs, the first subset of CBGs being transmitted on at least partially punctured resources. The base station may receive an ACK/NACK from the UE based on the transmitted set of CBGs, and retransmit to the UE one of the full set of CBGs or the first subset of CBGs based the received ACK/NACK. In an aspect, a UE may decode the set of CBGs received from the base station, transmit ACK/NACK feedback based on a result of the decoding, and receive, based on the transmitted ACK/NACK feedback, a retransmission of either the full set of CBGs, or the first subset of CBGs.