Outer Coding for Unequal Code Blocks in LTE Retransmission
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Solution Overview
Problem
Conventional outer codes in LTE wireless communication systems are inefficient for retransmissions when the number of failed code blocks is high, as they transmit redundancy bits for all code blocks, including those that were successfully decoded, leading to bandwidth wastage and suboptimal error correction.
Innovation Solution
The method involves generating outer code blocks with varying information bit sizes, where code blocks of unequal lengths are padded to a common size for encoding, allowing for more flexible and efficient retransmissions by transmitting only the necessary redundancy bits for failed blocks, and decoding using a combination of correctly received code blocks and outer code information bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional outer codes transmit redundancy bits for all code blocks in retransmission, then error correction capability is maintained, but bandwidth efficiency deteriorates due to transmission of redundant data for successfully decoded blocks
Solution Approach 1:
The invention segments the retransmission data by identifying and separating successfully decoded code blocks from failed ones. The outer code is then applied only to the failed code blocks, creating a segmented retransmission that excludes redundant data for successfully decoded blocks, thereby improving bandwidth efficiency while maintaining error correction capability for failed blocks
Solution Approach 2:
The invention extracts and removes successfully decoded code blocks from the retransmission set. By taking out the redundant successfully decoded blocks before applying outer coding, the system transmits only the necessary redundancy bits for failed blocks, resolving the contradiction between maintaining error correction capability and improving bandwidth efficiency
2Reliability
If outer codes are applied to all code blocks regardless of decoding status, then comprehensive error protection is achieved, but retransmission overhead increases
Solution Approach 1:
The invention applies partial action by restricting outer code application only to failed code blocks rather than all code blocks. This partial application of outer coding provides sufficient error protection for the failed blocks that need it, while avoiding the excessive overhead of protecting already successfully decoded blocks
3Adaptability or versatility
If code blocks of unequal lengths are handled with conventional outer codes, then flexibility in transport block structure is achieved, but coding complexity increases due to padding and alignment requirements
Solution Approach 1:
The invention applies local quality by handling each code block according to its specific characteristics. Successfully decoded blocks are identified and excluded from retransmission, while failed blocks receive targeted outer code protection. This localized approach to different code blocks maintains structural flexibility while managing coding complexity through selective processing
Data Source
AI summary
Methods are disclosed herein for generating and using outer codes based on non-equal length code blocks. In one embodiment, the outer code has a length equal to the length of the longest code block. This can be achieved by padding shorter code blocks such that they are also of equal length to the longest code block. The padding may be a standardized pseudo-random pattern or a standardized repeating pattern. In another embodiment, the outer code has a length shorter than the length of the longest code block. If a code block is received in error it may be recovered by using one or more of: the first outer code block, information bits of other code blocks and the parity bits of the failed code block.