LDPC Parity Permutation and Puncturing for Reliable Broadcast Decoding
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Solution Overview
Problem
Current signal transmission methods for digital broadcasting lack efficient mechanisms for improving decoding performance at the receiver, particularly in high-definition digital television and portable broadcasting scenarios, where existing methods do not adequately support various receiving schemes and user demands for enhanced performance.
Innovation Solution
A transmitter system that includes a Low Density Parity Check (LDPC) encoder, a parity permutator, a puncturer, and an additional parity generator, which encodes input bits, interleaves and punctures parity bits using specific patterns to generate additional parity bits, improving decoding performance by optimizing the transmission of LDPC codewords through QPSK modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LDPC encoding is performed to generate parity bits for current frame transmission, then transmission reliability is improved, but bandwidth efficiency deteriorates due to the large number of parity bits required
Solution Approach 1:
The patent applies puncturing to discard (remove) certain parity bits from the current frame transmission, and then recovers them by generating additional parity bits from previous frames. Specifically, the puncturer removes selected parity bits to reduce current bandwidth usage, while the additional parity generator creates replacement parity bits using historical data, achieving both bandwidth efficiency and decoding reliability.
Solution Approach 2:
The patent generates additional parity bits in advance (in previous frames) before they are needed for decoding. By pre-generating and storing parity bits from prior frames, the system prepares recovery data beforehand, enabling efficient reconstruction of punctured bits without requiring retransmission or increasing current frame overhead.
2Measurement precision
If all parity bits are transmitted in the current frame, then decoding accuracy is improved, but transmission time increases
Solution Approach 1:
The system discards transmission of certain parity bits in the current frame by applying puncturing, then recovers the discarded information by utilizing additional parity bits generated from previous frames. This approach maintains decoding accuracy while reducing the time required to transmit all necessary parity data.
Solution Approach 2:
The patent creates additional parity bits as copies or equivalents of the punctured parity bits by using the same LDPC encoding process on previous frame data. These copied parity relationships allow the receiver to reconstruct missing information without waiting for retransmission, thereby reducing transmission time while preserving decoding accuracy.
3Quantity of substance
If puncturing is applied to reduce parity bit transmission, then bandwidth efficiency is improved, but decoding reliability deteriorates
Solution Approach 1:
The additional parity bits act as an intermediary between the punctured parity bits and the decoding process. Instead of directly using punctured bits (which would reduce reliability), the system introduces additional parity bits generated from previous frames as intermediate elements that preserve the necessary redundancy information, thereby maintaining decoding reliability while achieving bandwidth efficiency through puncturing.
Solution Approach 2:
The patent changes the parameter of parity bit availability by generating additional parity bits with different temporal characteristics (from previous frames instead of current frame). This parameter change allows the system to maintain the required redundancy level for reliable decoding while using puncturing to reduce current frame bandwidth consumption.
4Quantity of substance
If additional parity bits are generated from previous frames, then current frame bandwidth is reduced, but system complexity increases
Solution Approach 1:
The LDPC encoder performs a dual function: it generates parity bits for the current frame and simultaneously generates additional parity bits for previous frames. By making the encoder universal and multi-functional, the system reduces current frame bandwidth requirements without adding separate dedicated hardware or processing stages, thereby limiting the increase in system complexity.
Solution Approach 2:
The system uses its own historical data (previous frames) to generate the additional parity bits needed for puncturing. Instead of requiring external sources or complex recovery mechanisms, the system serves itself by utilizing its own past transmissions as the basis for generating recovery parity bits, thereby reducing bandwidth requirements without proportionally increasing system complexity.
Data Source
AI summary
A transmitter is provided. The transmitter includes: a Low Density Parity Check (LDPC) encoder configured to encode input bits to generate an LDPC codeword including the input bits and parity bits to be transmitted in a current frame; a parity permutator configured to interleave the parity bits and group-wise interleave a plurality of parity bit groups configuring the interleaved parity bits based on a group-wise interleaving pattern including a first pattern and a second pattern to perform parity permutation; a puncturer configured to puncture at least some of the group-wise interleaved parity bit groups; and an additional parity generator configured to select at least some of the punctured parity bit groups to generate additional parity bits to be transmitted in a previous frame of the current frame, based on the first pattern and the second pattern.