Code Block Cluster HARQ for Wireless Transport Blocks
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Solution Overview
Problem
In wireless communication systems, retransmitting entire transport blocks when only a portion is corrupt can decrease system performance due to inefficient error correction and increased ACK/NACK traffic.
Innovation Solution
Implementing code block cluster (CBC) level hybrid automatic repeat request (HARQ) by partitioning transport blocks into CBCs, allowing for granular acknowledgement and retransmission of specific redundancy versions of CBCs, and using control messages to indicate the composition of transport blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If entire transport blocks are retransmitted when corrupt, then reliability is improved, but productivity deteriorates due to inefficient error correction
Solution Approach 1:
The transport block is segmented into multiple code block clusters (CBCs), allowing the system to identify and retransmit only the specific corrupted CBCs rather than the entire transport block. This segmentation enables granular error correction, improving productivity by reducing unnecessary retransmissions while maintaining reliability through targeted retransmission of only the affected segments.
2Reliability
If entire transport blocks are retransmitted, then reliability is improved, but loss of time increases due to increased ACK/NACK traffic
Solution Approach 1:
By segmenting the transport block into multiple CBCs and implementing separate ACK/NACK feedback for each CBC, the system can identify and retransmit only the corrupted segments. This reduces the overall retransmission time compared to retransmitting entire transport blocks, as only the affected portions need to be resent, thereby reducing loss of time while maintaining reliability.
Solution Approach 2:
The system applies partial action by retransmitting only the necessary corrupted CBCs rather than the entire transport block. This partial retransmission approach reduces the time required for error correction while maintaining the reliability needed for accurate data transmission, avoiding the excessive time consumption of full transport block retransmissions.
3Productivity
If granular ACK/NACK per CBC is implemented, then productivity is improved, but device complexity increases
Solution Approach 1:
The transport block is divided into multiple CBCs, each with its own ACK/NACK feedback mechanism. This segmentation enables granular control over retransmissions, improving productivity by allowing selective retransmission of only corrupted CBCs. While this increases device complexity compared to whole-block HARQ, the complexity is justified by the significant gains in retransmission efficiency and system performance.
4Loss of information
If redundancy versions are grouped in segments, then loss of information is reduced, but device complexity increases
Solution Approach 1:
The transport block is segmented into multiple CBCs, with each CBC assigned a specific redundancy version. This segmentation approach reduces information loss by enabling targeted retransmission of only the corrupted CBCs with their appropriate redundancy versions, rather than retransmitting the entire transport block. The complexity increase is managed through systematic organization of CBCs and their associated redundancy versions.
Solution Approach 2:
Different redundancy versions are assigned to different CBCs based on their specific requirements and corruption status. This local quality approach allows the system to optimize error correction for each individual CBC, reducing overall information loss by applying the most appropriate redundancy version to each segment rather than using a uniform approach for the entire transport block.
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. The transport blocks may be partitioned into code block clusters (CBCs), each of which may include one or more code blocks. A receiving device may attempt to decode a transport block and send acknowledgement (ACK) and negative-acknowledgment (NACK) information to the transmitting device based on the whether each CBC was successfully decoded. The transmitting device may retransmit a redundancy version of a CBC for each NACK received. The transmitting device may group CBCs in segments of a transport block according to redundancy version. In some cases, the transmitting device may send a control message in a control channel which indicates the composition of the transport block.