LDPC

Nonbinary LDPC codes encoding and decoding implementation

What is included:

1. Regular Nonbinary LDPC code builder. It gets code length N, redundancy r, Galois field exponent m, column degree Dc and row degree Dr as input. As a result, a check matrix of (n, ≤ (r-k)) regular (Dr, Dc) LDPC code over GF(2^m) it built as the block matrix consisting of random permutation-and-multiplication matrices with fixed dimensions and uniformly distributed nonzero elements. This matrix is further stored in the specification file in following format:

2. First row contains space-separated length, redundancy and field exponent

3. Second row contains space-separated letter 'R' meaning 'Regular', row and column degrees

4. Next r rows contain space-separated indices of nonzero elements along with their values in the corresponding rows of code check matrix

5. LDPC encoder. It extracts check matrix from specification file and gets a generator matrix from it. This matrix is further used for code encoding.

6. Log-domain sum-product decoding algorithm (see H. Wymeersch, H. Steendam, and M. Moeneclaey "Log-domain decoding of LDPC codes over GF(q)").