Packet Coding for Selective Retransmission in LTE
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Solution Overview
Problem
In LTE systems, retransmission of data is inefficient due to the need to retransmit entire Transmission Blocks (TBs) even if only some Code Blocks (CBs) are incorrectly received, leading to excessive resource usage and high feedback overhead.
Innovation Solution
The method involves dividing TBs into multiple CB sets, performing packet coding on selected CB sets to generate check CB sets, and sending only the necessary check bits during retransmission, reducing the retransmission data volume and improving efficiency without increasing feedback information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the entire TB is retransmitted when at least one CB is incorrectly received, then the simplicity of the feedback mechanism is maintained, but the retransmission resource usage increases significantly
Solution Approach 1:
The patent divides the TB into multiple CB sets and applies separate CRC checks to each CB set. This segmentation allows the system to identify which specific CB sets contain errors, enabling selective retransmission of only the erroneous CB sets rather than retransmitting the entire TB, thus reducing retransmission resource usage while maintaining feedback mechanism simplicity
Solution Approach 2:
The patent implements CB set-level ACK/NACK feedback where the receiver feeds back acknowledgment status for each CB set individually. This feedback mechanism enables the transmitter to identify which CB sets require retransmission, allowing for efficient selective retransmission of only the erroneous portions while maintaining system simplicity
2Productivity
If CB-based ACK/NACK feedback is implemented to enable selective retransmission, then retransmission efficiency improves, but the feedback signaling overhead increases excessively
Solution Approach 1:
The patent segments the feedback information into CB set-level ACK/NACK signals rather than individual CB-level feedback. This segmentation reduces the total number of feedback bits required while still enabling identification of erroneous portions for selective retransmission, thus improving retransmission efficiency without excessive feedback overhead
Solution Approach 2:
The patent applies partial feedback by providing ACK/NACK information at the CB set level rather than full CB-level feedback. This partial feedback approach provides sufficient information for selective retransmission of erroneous CB sets while avoiding the excessive overhead of complete CB-level acknowledgment, achieving a balanced solution
3Loss of energy
If packet coding is performed on CB sets to generate check CB sets, then the retransmission data volume is reduced, but the encoding complexity increases
Solution Approach 1:
The patent divides the TB into multiple CB sets and performs packet coding on each CB set separately to generate check CB sets. This segmentation approach reduces the encoding complexity compared to coding the entire TB, while still achieving significant reduction in retransmission data volume through selective retransmission of only erroneous portions
Solution Approach 2:
The patent applies packet coding locally to each CB set rather than globally to the entire TB. This local application of coding reduces the computational complexity and memory requirements while maintaining the benefit of reduced retransmission data volume, as each CB set is encoded independently with its own check CB set
Data Source
AI summary
A data transmission method and device are provided. The method includes: a first transmission node sends data signal(s) for first transmission to a second transmission node, wherein the data signal(s) including data of at least one Transmission Block (TB), the TB including K Code Blocks (CBs), and the K CBs being divided into P CB sets; the first transmission node performs packet coding on M CB sets in the P CB sets to obtain S check CB sets; and the first transmission node generates data signal(s) for retransmission and sends the data signal(s) to the second transmission node, the data signal(s) for retransmission at least including Q bits in the check CB sets when a preset condition is met. The embodiments of the present disclosure may effectively reduce resources for retransmission under the condition of not increasing an amount of feedback information.