Capacity-approaching code using repeat-interleave-accumulate construction. Serial concatenation of repetition code with differential encoder (mod-2 accumulator). Used in DVB-RCS satellite standard. Simple construction achieving near-Shannon limit performance with iterative decoding.
| Property | Value |
|---|---|
| Category | Error Correction |
| Sub-category | Concatenated Code |
| Security status | 🎓 Educational Only |
| Complexity | Intermediate |
| Inventor | Dariush Divsalar, Hui Jin, Robert J. McEliece |
| Year | 1998 |
| Origin | 🇺🇸 United States |
| Source | algorithms/ecc/repeat-accumulate-code.js |
Status: 🎓 Educational Only
| Issue | Description | Mitigation |
|---|---|---|
| Not Asymptotically Good | RA codes do not maintain constant rate and minimum distance as block length increases. Subject to upper bounds on minimum distance. | — |
| Decoding Complexity | Iterative belief propagation decoding requires significant computation. Performance depends on interleaver quality and iteration count. | — |
| Error Floor | May exhibit error floor at high SNR due to low-weight codewords. Interleaver design critical for performance. | — |
5 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — RA code all zeros - K=2 q=3 seed=42
| Field | Value |
|---|---|
input |
0000 |
expected |
000000000000 |
Vector 2 — RA code pattern 10 - K=2 q=3 seed=42
| Field | Value |
|---|---|
input |
0100 |
expected |
010100000101 |
Vector 3 — RA code pattern 01 - K=2 q=3 seed=42
| Field | Value |
|---|---|
input |
0001 |
expected |
000101000001 |
Vector 4 — RA code pattern 11 - K=2 q=3 seed=42
| Field | Value |
|---|---|
input |
0101 |
expected |
010001000100 |
Vector 5 — RA code pattern 101 - K=3 q=3 seed=42
| Field | Value |
|---|---|
input |
010001 |
expected |
010100010101000100 |