Code Block HARQ Feedback Format Selection
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Solution Overview
Problem
In wireless communication systems, the existing methods for hybrid automatic repeat request (HARQ) often result in inefficient data transmission due to the retransmission of entire transport blocks, even when only a portion is corrupt, leading to decreased system performance.
Innovation Solution
Implementing code block (CB) level HARQ, where wireless devices exchange data using transport blocks divided into code blocks, allowing for acknowledgement (ACK) and negative-acknowledgement (NACK) feedback on a CB basis, with formats selected from available options such as uncompressed, compressed, or bundled schemes based on the number of CBs and errors, to efficiently use uplink resources and retransmit only affected CBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If entire transport blocks are retransmitted when corruption is detected, then data integrity is maintained, but system performance decreases due to redundant transmission
Solution Approach 1:
The transport block is segmented into multiple code blocks, each with its own CRC check. This allows the receiver to identify exactly which code blocks are corrupted and request retransmission of only those specific blocks, rather than retransmitting the entire transport block. The segmentation enables granular error handling that improves system performance by eliminating redundant transmissions of correctly received data.
2Productivity
If ACK/NACK feedback is transmitted for each code block, then channel efficiency is improved through selective retransmission, but feedback transmission complexity increases
Solution Approach 1:
Instead of transmitting full ACK/NACK feedback for every code block, the system transmits only partial feedback indicating which specific code blocks require retransmission. The receiver sends back minimal information (identifiers of NACKed code blocks) rather than complete status information, reducing feedback overhead while still enabling selective retransmission of only the necessary code blocks.
3Productivity
If multiple feedback formats are used based on number of CBs and errors, then UL resource efficiency is optimized, but format selection complexity increases
Solution Approach 1:
The feedback transmission format is made dynamic and adaptive based on the number of code blocks in the transport block and the number of errors detected. The system automatically selects from multiple predefined formats (e.g., compact format for few errors, detailed format for many errors) to optimize uplink resource usage. This dynamic adaptation allows efficient resource utilization while managing complexity through standardized format options.
Data Source
AI summary
Methods, systems, and devices are described for wireless communication. Wireless devices may exchange data using Medium Access Control (MAC) layer units known as transport blocks which may include a number of code blocks (CBs). A receiving device may attempt to decode each CB and send acknowledgement (ACK) and negative-acknowledgment (NACK) feedback to the transmitting device based on the whether each CB was successfully decoded. The receiving device may determine a format from two or more available formats for transmitting the ACK/NACK feedback. The format for the ACK/NACK feedback may be determined based at least in part on a number of CBs received and a number of CBs that have a NACK feedback. ACK/NACK feedback may be provided on an individual CB basis, or for bundles of CBs. The transmitting device may perform blind decoding of the received feedback to determine the ACK/NACK format and CBs that have NACK feedback.