Turbo Decoder CRC Flow With Selective Soft Combining
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Solution Overview
Problem
Conventional LTE uplink data processing methods are inefficient due to excessive re-transmissions and unnecessary computational load on the baseband processor, as they perform CRC checks on all code blocks regardless of failures and consume time and air interface resources.
Innovation Solution
A method involving selective CRC checks on code blocks, followed by soft combining of failed blocks with their corresponding originally transmitted blocks, reducing re-transmissions and computational load by only processing blocks that fail initial CRC checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CRC check is performed on all code blocks unconditionally, then reliability of error detection is improved, but computational load and processing time increase
Solution Approach 1:
The patent segments the code blocks into two groups: those that failed initial CRC checks and those that passed. Only the failed blocks undergo soft combining and re-evaluation, while passed blocks are accepted directly. This segmentation reduces the scope of subsequent processing to only the necessary subset of blocks.
Solution Approach 2:
Instead of performing full CRC verification on all code blocks, the patent applies partial action by only re-evaluating blocks that initially failed. The soft combining operation is performed selectively on failed blocks combined with their corresponding retransmitted blocks, avoiding unnecessary processing of already-valid blocks.
2Reliability
If all code blocks are retransmitted upon any CRC failure, then reliability of data integrity is improved, but loss of time and air interface resources increases
Solution Approach 1:
The patent extracts only the failed code blocks from the complete set of transmitted blocks for retransmission. Instead of retransmitting all blocks when any failure occurs, the system identifies and isolates only the specific blocks that failed CRC checks, retrieves their corresponding soft bits from previous transmissions, and performs targeted soft combining only on these extracted failed blocks.
Solution Approach 2:
The patent applies local quality by treating failed code blocks differently from successful ones. Failed blocks receive additional processing through soft combining with their corresponding retransmitted blocks, while blocks that passed initial CRC checks are accepted without further processing. This localized treatment optimizes resource usage by applying enhanced verification only where needed.
3Reliability
If soft combine procedure is performed on all retransmitted blocks, then reliability of decoding is improved, but computational load increases
Solution Approach 1:
The patent segments retransmitted blocks into those corresponding to failed original blocks and those corresponding to successful blocks. Soft combining is applied only to the segment of blocks that initially failed CRC checks, while blocks corresponding to originally successful transmissions are processed separately without soft combining, reducing overall computational complexity.
Data Source
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AI summary
Disclosed is a method for processing code blocks as implemented by a baseband processor. The method involves performing a cyclic redundancy check on decoded and deinterleaved code blocks until one fails its CRC check. On first failure the baseband processor requests a retransmission of the code blocks and resumes CRC checks on the retransmitted code blocks, beginning at the code block that had failed. In the event of subsequent failures, the baseband processor performs a soft combine on the failed retransmitted block with its original transmitted counterpart. Only if the soft combined code block fails does the baseband processor request another retransmission. In this case, subsequent CRC failures result in soft combines of three corresponding code words, making the process more robust. The method reduces the number of retransmissions as well as the computing resources needed for processing incoming code blocks.