Partial Retransmission via Code Block Groups in 5G Wireless Systems
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Solution Overview
Problem
In conventional wireless communication systems, particularly LTE, data is transmitted in units of transport blocks (TBs), and if any code block (CB) decoding fails, the entire TB is retransmitted, leading to inefficient resource usage.
Innovation Solution
The method allows for retransmission in units of CBs, with a CB index inserted to notify the order, enabling efficient communication by configuring different frequency bandwidths for downlink or uplink, reducing unnecessary data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If entire transport block is retransmitted when any code block decoding fails, then reliability is improved, but resource efficiency deteriorates
Solution Approach 1:
The transport block is segmented into multiple code blocks, and the patent enables selective retransmission at the code block level rather than retransmitting the entire transport block. This segmentation allows only the failed code blocks to be retransmitted, improving resource efficiency while maintaining reliability.
Solution Approach 2:
The patent extracts and identifies specific failed code blocks through CRC checking, and separates them from successfully decoded code blocks. Only the extracted failed code blocks are retransmitted, avoiding unnecessary retransmission of successful data and reducing resource consumption.
2Loss of energy
If selective code block retransmission is implemented, then resource efficiency is improved, but system complexity increases
Solution Approach 1:
The patent introduces a CB group indicator as an intermediary mechanism to manage selective retransmission. This indicator efficiently identifies which code block groups need retransmission without requiring complex individual code block tracking, thus reducing system complexity while maintaining resource efficiency.
Solution Approach 2:
The patent changes the retransmission granularity parameter from transport block level to code block level, and introduces CB group indicators to manage this finer granularity. This parameter change enables selective retransmission while using compact indicator structures to control the increased complexity.
3Productivity
If code block level retransmission is used, then data transmission efficiency is improved, but control information overhead increases
Solution Approach 1:
The patent merges adjacent code blocks into code block groups and uses a single CB group indicator to represent multiple code blocks. This merging reduces the number of individual indicators needed, thereby reducing control information overhead while maintaining the ability to selectively retransmit specific code blocks.
Solution Approach 2:
The patent changes the control information structure by introducing CB group indicators with compact encoding schemes. This parameter change in the control information representation reduces the overhead associated with indicating which code blocks need retransmission, while still enabling fine-grained selective retransmission.
Data Source
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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.