LDPC Group-Wise Interleaving for Lower Bit and Frame Error Rates
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Solution Overview
Problem
Current digital broadcasting systems face challenges in providing high decoding and receiving performance, particularly in supporting various receiving methods for digital broadcasting services, as evident in the limitations of existing bit interleaved coded modulation based on LDPC codes in DVB-NGH standards.
Innovation Solution
A transmitting apparatus and interleaving method that maps bits from a low-density parity-check (LDPC) codeword onto modulation symbols using a specific interleaving scheme, involving a group interleaver and block interleaver, to optimize bit error rates and frame error rates, with the interleaver rearranging bit groups based on density evolution methods and cyclic shift parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bit interleaved coded modulation based on LDPC codes is used in DVB-NGH standards, then basic transmission functionality is achieved, but decoding and receiving performance is insufficient
Solution Approach 1:
The LDPC codeword is divided into multiple bit groups, and these bit groups are further divided into sub-bit groups. This segmentation allows for group-wise interleaving at multiple levels, improving decoding performance by distributing errors more effectively across the codeword while maintaining manageable complexity through structured segmentation.
Solution Approach 2:
Different interleaving patterns are applied to different bit groups based on their position and importance. The interleaver uses position-dependent permutation patterns that adapt to local characteristics of the codeword structure, optimizing error correction performance for specific regions while maintaining overall system functionality.
2Reliability
If bit groups are interleaved to optimize error rates, then decoding performance improves, but the complexity of the interleaving scheme increases
Solution Approach 1:
The interleaving scheme uses dynamic permutation patterns that are determined by mathematical functions of the bit group positions. Rather than using fixed static patterns, the interleaver adapts its permutation behavior based on the position indices, providing optimized error distribution while maintaining a relatively simple implementation through formula-based pattern generation.
Solution Approach 2:
The interleaving parameters such as group size, number of sub-groups, and permutation patterns are optimized based on the specific LDPC code rate and block length. By adjusting these parameters according to the communication conditions and code characteristics, the system achieves optimal error rate performance without requiring a completely different interleaver structure for each scenario.
Data Source
Figure 1A
Figure 1B~1C
Figure 2~3A
AI summary
A transmitting apparatus is provided. The transmitting apparatus includes: an encoder configured to generate a low-density parity check (LDPC) codeword by LDPC encoding of input bits based on a parity check matrix including information word bits and parity bits, the LDPC codeword including a plurality of bit groups each including a plurality of bits; an interleaver configured to interleave the LDPC codeword; and a modulator configured to map the interleaved LDPC codeword onto a modulation symbol, wherein the interleaver is further configured to interleave the LDPC codeword such that a bit included in a predetermined bit group from among the plurality of bit groups constituting the LDPC codeword onto a predetermined bit of the modulation symbol.