Partial Retransmission of Code Block Groups in Wireless Systems
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Solution Overview
Problem
Conventional wireless communication systems, such as LTE, require the entire transport block to be retransmitted even if only one code block fails, leading to inefficient data transmission and resource wastage.
Innovation Solution
A method and apparatus that allow for partial retransmission of code blocks or code block groups, where a base station transmits information about the number of code block groups in a transport block and control information, enabling efficient communication by retransmitting only the necessary data, thereby reducing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire transport block is retransmitted when a decoding failure occurs, then reliability is improved, but resource usage increases and transmission efficiency deteriorates
Solution Approach 1:
The transport block is divided into multiple code block groups (CBGs), each with its own CRC check. This segmentation allows the system to identify and retransmit only the specific CBGs that failed decoding, rather than retransmitting the entire transport block. The base station transmits a CBG transmission indicator to specify which CBGs require retransmission, enabling selective retransmission at the CBG level.
2Reliability
If the entire transport block is retransmitted when a decoding failure occurs, then reliability is improved, but transmission time increases
Solution Approach 1:
By segmenting the transport block into multiple CBGs with individual CRC checks, the system can identify only the failed CBGs for retransmission. This reduces the amount of data that needs to be retransmitted, thereby reducing retransmission time and improving overall transmission efficiency while maintaining decoding reliability.
3Reliability
If the entire transport block is retransmitted, then decoding reliability is improved, but data transmission efficiency deteriorates
Solution Approach 1:
The transport block is segmented into multiple CBGs, each with independent CRC verification. This allows the receiver to identify exactly which CBGs failed decoding and request retransmission of only those specific groups. The base station uses the CBG transmission indicator to efficiently retransmit only the necessary CBGs, improving data transmission efficiency by avoiding redundant retransmission of successfully decoded data.
4Loss of energy
If code block groups are used for selective retransmission, then resource usage is improved, but system complexity increases
Solution Approach 1:
The system divides the transport block into CBGs with individual CRC checks, adding segmentation logic to the transmitter and receiver. The base station maintains a CBG transmission indicator to track and manage which CBGs require retransmission. This segmentation approach, while adding some complexity, enables efficient selective retransmission that significantly reduces resource usage compared to full transport block retransmission.
Data Source
AI summary
A communication method and system are provided for converging a 5G communication system for supporting higher data rates beyond a 4G system with an IoT technology. A method, by a base station, for performing retransmission with respect to a code block requiring the retransmission among transport blocks, includes transmitting, to a terminal, first information related to a number of code block groups (CBGs) included in a transport block (TB); determining the CBGs for the TB based on a number of code blocks (CBs) included in the TB and the first information; and transmitting, to the terminal, the determined CBGs and control information including second information related to transmission of the TB.