LDPC Interleaving Scheme for Puncturing Without Short Tanner Cycles
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Solution Overview
Problem
The use of puncturing schemes in communication systems to support various coding rates for LDPC codes leads to performance degradation due to changes in the cycle structure of the Tanner graph, necessitating a method to prevent this degradation.
Innovation Solution
An encoding apparatus and method that employs an interleaving scheme to generate LDPC codes, ensuring no short-length cycles exist in the Tanner graph when the codes are punctured, thereby maintaining performance by using a check node-merged Tanner graph for decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a puncturing scheme is used to support various coding rates, then coding rate flexibility is improved, but LDPC code performance degrades due to short-length cycles in the Tanner graph
Solution Approach 1:
The patent applies preliminary action by pre-designing the interleaver structure before puncturing occurs. The interleaver is configured in advance to ensure that when puncturing is applied, the resulting Tanner graph will not contain short-length cycles. This proactive design prevents performance degradation before it can occur, rather than attempting to fix the issue after puncturing.
Solution Approach 2:
The patent changes the parameters of the interleaver structure to achieve the desired cycle properties in the punctured Tanner graph. By adjusting the interleaver configuration parameters, the system maintains freedom from short cycles even after puncturing, thus preserving LDPC code performance across different coding rates.
2Adaptability or versatility
If puncturing rate is increased to achieve higher coding rates, then coding rate flexibility is improved, but convergence rate of decoding decreases
Solution Approach 1:
The interleaver is pre-configured to anticipate the effects of puncturing on decoding convergence. By designing the interleaver structure in advance to prevent short cycles, the patent ensures that the decoding process maintains its convergence rate even when high puncturing rates are applied to achieve higher coding rates.
3Adaptability or versatility
If puncturing is applied to support various coding rates, then system adaptability is improved, but computational complexity increases
Solution Approach 1:
The patent changes the interleaver parameters to create a structure that is optimized for punctured codes. This parameter adjustment allows the system to handle various coding rates through puncturing while maintaining manageable computational complexity during decoding, as the pre-designed interleaver prevents problematic cycle structures that would increase complexity.
Data Source
AI summary
A Low Density Parity Check (LDPC) code encoding apparatus for a communication system is provided. The encoding apparatus receives information bits, and generates an LDPC code by encoding the information bits using an interleaving scheme. The interleaving scheme is generated such that when the LDPC code is punctured, there is no short-length cycle in a Tanner graph of the punctured LDPC code.