Dynamic Feedback Bit Allocation for HARQ Efficiency
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Solution Overview
Problem
In wireless communication systems, particularly in LTE and NR/5G, the existing HARQ mechanism leads to inefficient data retransmissions as it requires retransmitting entire transport blocks even if only a few code blocks fail, resulting in high communication overheads due to the use of 1-bit feedback for error indication.
Innovation Solution
A method where the quantity of feedback bits is dynamically determined based on channel conditions, transmission time units, and control message parameters, allowing for flexible use of 1 bit or multiple bits to indicate successful reception of data, thereby reducing unnecessary retransmissions and optimizing communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If 1-bit feedback is used to indicate successful reception, then feedback overhead is reduced, but communication efficiency deteriorates due to unnecessary retransmission of entire transport blocks
Solution Approach 1:
The transport block is divided into multiple code blocks, and feedback is provided for each code block individually rather than for the entire transport block. This segmentation allows the receiver to indicate which specific code blocks were successfully decoded and which need retransmission, avoiding unnecessary retransmission of correctly received data.
Solution Approach 2:
The feedback mechanism dynamically adapts between 1-bit feedback mode (for entire transport block) and multi-bit feedback mode (for individual code blocks) based on channel conditions and configuration. This dynamic adjustment allows the system to optimize between feedback overhead and communication efficiency depending on the specific transmission scenario.
2Productivity
If multiple bits are used to feed back each code block reception status, then communication efficiency is improved by retransmitting only failed code blocks, but feedback overhead increases drastically
Solution Approach 1:
The system dynamically selects between 1-bit feedback mode and multi-bit feedback mode based on channel conditions, transport block size, and configuration parameters. When channel conditions are good and transport blocks are small, 1-bit feedback is used to minimize overhead. When channel conditions are poor or transport blocks are large, multi-bit feedback is used to improve efficiency by targeting only failed code blocks for retransmission.
Solution Approach 2:
The feedback bit quantity is changed as a parameter based on transmission conditions. The system adjusts the feedback mechanism from fixed 1-bit to variable multi-bit based on code block size, channel quality, and configuration, allowing optimization of the trade-off between feedback overhead and retransmission efficiency.
3Reliability
If the entire transport block is retransmitted when any code block fails, then transmission reliability is maintained, but communication efficiency deteriorates due to redundant data transmission
Solution Approach 1:
By segmenting the transport block into independent code blocks with individual CRC checks, the system enables selective retransmission of only those code blocks that failed decoding. This maintains transmission reliability for failed blocks while avoiding redundant retransmission of successfully received blocks, thereby improving communication efficiency.
Solution Approach 2:
The system uses detailed feedback information from the receiver indicating which specific code blocks were successfully decoded and which need retransmission. This feedback mechanism allows the transmitter to reliably retransmit only the necessary failed code blocks rather than the entire transport block, maintaining reliability while improving efficiency.
Data Source
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AI summary
This application provides a feedback method, including: receiving, by a first device, data sent by a second device; and sending, by the first device to the second device, feedback information indicating whether the data is successfully received, where a quantity of bits of the feedback information is associated with a size of a transmission time unit in a communications system. By using the foregoing method, the quantity of bits of the feedback information is determined based on the size of the transmission time unit. This flexibly implements a compromise between transmission efficiency and feedback overheads in the communications system, thereby improving performance of the entire communications system.