LDPC Encoder Structure for 64800-Length 5/15 Codewords
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Solution Overview
Problem
Current terrestrial TV broadcasting systems face co-channel interference issues, leading to white spaces where frequency reuse is not possible, resulting in deteriorated spectrum efficiency, and existing LDPC codes are not optimized for the DVB broadcast standard or specific LDPC encoding methods.
Innovation Solution
A new LDPC codeword of length 64800 with a code rate of 5/15 is developed, utilizing an LDPC encoding technique that includes a systematic part, a first parity part corresponding to a dual diagonal matrix, and a second parity part corresponding to an identity matrix, with a sequence that updates parity bit addresses using a circulant permutation matrix, enabling efficient encoding and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a new LDPC codeword with length 64800 and code rate 5/15 is designed, then error correction performance near the Shannon limit is achieved, but device complexity increases due to larger memory requirements and more complex encoding structures
Solution Approach 1:
The LDPC codeword is segmented into three distinct parts: a systematic part (21600 bits) containing the original information, a first parity part (1440 bits) corresponding to a dual diagonal matrix, and a second parity part (41760 bits) corresponding to an identity matrix. This segmentation allows the encoder to handle different portions of the codeword with specialized structures, achieving near-Shannon-limit performance while managing complexity through modular design
Solution Approach 2:
The patent employs specific parameter configurations including a code rate of 5/15, codeword length of 64800, and a circulant permutation matrix size of 360. These parameter changes optimize the balance between error correction capability and implementation complexity, with the systematic part preserving original data and the two parity parts providing distributed error correction coverage
2Ease of operation
If a systematic part with length 21600 is included in the LDPC codeword, then ease of operation is improved by preserving original information bits, but device complexity increases due to the need for separate parity generation sections
Solution Approach 1:
The encoding section is segmented into distinct functional units: a systematic part that directly preserves the 21600 information bits, a first parity generation unit producing 1440 bits via dual diagonal matrix operations, and a second parity generation unit producing 41760 bits via identity matrix operations. This segmentation enables the systematic part to maintain ease of operation by keeping original information intact while distributing the complexity burden across specialized parity generation sections
3Manufacturing precision
If a circulant permutation matrix with size 360 is used in the encoding process, then manufacturing precision is improved through structured matrix operations, but loss of time increases due to the computational overhead of sequence-based address updates
Solution Approach 1:
The circulant permutation matrix of size 360 introduces a periodic structure to the encoding process, where parity bit addresses are updated using predetermined sequences that repeat every 360 positions. This periodic action ensures manufacturing precision through consistent, structured matrix operations while the predetermined sequences optimize computational efficiency by avoiding redundant calculations within each period
Solution Approach 2:
The patent employs preliminary action by pre-defining the sequences for updating parity bit addresses based on the circulant permutation matrix structure. These sequences are calculated and stored in advance, allowing the encoder to simply follow the predetermined pattern during operation rather than performing complex real-time calculations, thus reducing actual encoding time while maintaining precision
Data Source
AI summary
A low density parity check (LDPC) encoder, an LDPC decoder, and an LDPC encoding method are disclosed. The LDPC encoder includes first memory, second memory, and a processor. The first memory stores an LDPC codeword having a length of 64800 and a code rate of 5/15. The second memory is initialized to 0. The processor generates the LDPC codeword corresponding to information bits by performing accumulation with respect to the second memory using a sequence corresponding to a parity check matrix (PCM).