HARQ Feedback Switching Between CBG and TB Modes
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently processing HARQ ACK/NACK feedback, particularly in scenarios involving code block groups and transport blocks, which affects communication performance.
Innovation Solution
A method for transmitting and receiving HARQ ACK/NACK feedback by terminals and base stations, involving the transmission of feedback for each code block group and transport block based on specific control information, with the ability to multiplex and reconfigure the number of code blocks, even during CBG-based retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CBG-based retransmission is configured for efficient error handling, then retransmission efficiency is improved, but feedback processing complexity increases due to the need to handle both CBG-level and TB-level HARQ ACK/NACK feedback
Solution Approach 1:
The patent implements dynamic switching between CBG-based feedback mode and TB-based feedback mode through a fallback indicator. The terminal can adaptively select the feedback granularity based on the fallback indicator received from the network, allowing the system to transition from fine-grained CBG feedback to coarser TB feedback when needed, thus managing complexity while maintaining retransmission efficiency
Solution Approach 2:
The patent segments the feedback processing into two distinct levels: CBG-level feedback for fine-grained error handling and TB-level feedback for overall transport block status. The fallback indicator mechanism allows selective activation of TB-level feedback when CBG-level feedback becomes too complex, effectively segmenting the complexity management strategy
2Ease of operation
If the number of code blocks in CBG is fixed for simplified processing, then processing simplicity is improved, but adaptability to different transmission scenarios deteriorates
Solution Approach 1:
The patent introduces dynamic reconfiguration of the number of code blocks per CBG through RRC signaling. The network can adjust the parameter numberOfCodeBlocksPerCBG based on transmission conditions, allowing the system to adapt between having fewer larger CBGs or more smaller CBGs, thus balancing processing simplicity with adaptability to different scenarios
Solution Approach 2:
The patent changes the parameter numberOfCodeBlocksPerCBG dynamically through RRC reconfiguration signaling. This parameter change allows the system to adapt the code block structure according to different transmission scenarios, channel conditions, and traffic requirements, maintaining both processing simplicity and versatility
3Measurement precision
If HARQ feedback is transmitted for each CBG to improve retransmission granularity, then retransmission precision is improved, but feedback overhead increases
Solution Approach 1:
The patent implements dynamic control of feedback overhead through the fallback indicator mechanism. When the fallback indicator is activated, the terminal switches to TB-level feedback which reduces the number of feedback bits compared to CBG-level feedback, thus dynamically controlling overhead based on network conditions and retransmission needs
Solution Approach 2:
The patent applies partial CBG-level feedback only when necessary for high precision retransmission, while using TB-level feedback for other cases. The fallback indicator allows the network to control when full CBG-level feedback is needed versus when coarser TB-level feedback suffices, avoiding excessive feedback overhead while maintaining precision when required
Data Source
AI summary
A method for transmitting a HARQ ACK/NACK feedback by a terminal may comprise: a step of transmitting, to a base station, a HARQ ACK/NACK feedback for a first downlink data, on a code block group (CBG) basis; a step of receiving, from the base station, a control channel including a specific control information; and a step of transmitting a HARQ ACK/NACK feedback on a transport block (TB) basis on the basis of the specific control information, for a second downlink data scheduled and received by the control channel, even if a CBG based retransmission is set for the terminal.