LDPC Group Interleaving for Robust Broadcast Symbol Mapping
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Solution Overview
Problem
Current digital broadcasting systems face challenges in providing robust encoding and decoding performance for high-quality digital television and multimedia services, particularly in multi-channel and wideband environments.
Innovation Solution
A transmitter apparatus and signal processing method that employs Low Density Parity Check (LDPC) coding, interleaving, and modulation to efficiently map bits from LDPC codewords onto modulation symbols, utilizing a parity interleaver, group interleaver, and block interleaver to enhance decoding and receiving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional encoding and modulation methods are used in digital broadcasting systems, then the system structure remains simple, but the decoding and receiving performance is insufficient for high-quality digital television and multimedia services
Solution Approach 1:
The patent divides the LDPC codeword into multiple groups (e.g., 360 bits per group) and applies different interleaving operations to different groups. The codeword is segmented into information bits and parity bits, with further segmentation into sub-groups for differential interleaving. This segmentation enables improved decoding performance through diversified bit mapping while maintaining manageable complexity through systematic group processing.
Solution Approach 2:
The patent applies preliminary interleaving operations to the LDPC codeword before modulation. The parity interleaver performs preliminary rearrangement of parity bits, and the group interleaver performs preliminary group-based reordering. These preliminary actions prepare the codeword for more effective modulation mapping, improving receiving performance while the complexity is handled through pre-computed interleaving patterns.
2Reliability
If bit mapping is performed without group-based interleaving, then the modulation process is simple, but the robustness of digital broadcasting services deteriorates
Solution Approach 1:
The patent applies different interleaving strategies to different parts of the LDPC codeword. Information bits and parity bits receive different treatment, and within parity bits, different groups undergo different interleaving operations. This local differentiation improves robustness by ensuring that critical bits are mapped to more reliable modulation positions while maintaining overall system complexity through localized rather than global complexity.
Solution Approach 2:
The patent introduces group-based interleving as an additional dimension of processing beyond simple bit-by-bit mapping. By organizing bits into groups and applying interleaving at the group level, the system adds a dimensional layer of complexity that improves robustness through diversified mapping patterns, while the group structure keeps the overall complexity manageable through repetition of the same interleaving logic across groups.
Data Source
AI summary
A transmitter apparatus and a receiver apparatus are provided. The transmitter apparatus includes: an encoder configured to generate a low density parity check (LDPC) by performing LDPC encoding; an interleaver configured to interleave the LDPC codeword; and a modulator configured to map the interleaved LDPC codeword onto a modulation symbol. The modulator maps a bit included in a predetermined group from among a plurality of groups constituting the LDPC codeword onto a predetermined bit in the modulation symbol.