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319 lines
9 KiB
C++
319 lines
9 KiB
C++
/*
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Regression Test for the Low-density parity-check Encoder and Decoder
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Table entries below copied from:
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https://www.etsi.org/deliver/etsi_en/302700_302799/302755/01.04.01_60/en_302755v010401p.pdf
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Copyright 2018 Ahmet Inan <inan@aicodix.de>
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*/
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#include <iostream>
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#include <random>
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#include <cmath>
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#include <cassert>
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#include <chrono>
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#include <algorithm>
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#include <functional>
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#include "ldpc_encoder.hh"
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#if 0
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#include "ldpc_decoder.hh"
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#else
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#include "ldpc_decoder2.hh"
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#endif
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struct DVB_T2_TABLE_A1
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{
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static const int M = 360;
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static const int N = 64800;
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static const int K = 32400;
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static const int LINKS_MIN_CN = 6;
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static const int LINKS_MAX_CN = 7;
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static const int LINKS_TOTAL = 226799;
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static const int DEG_MAX = 8;
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static constexpr int DEG[] = {
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8, 3, 0
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};
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static constexpr int LEN[] = {
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36, 54, 0
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};
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static constexpr int POS[] = {
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54, 9318, 14392, 27561, 26909, 10219, 2534, 8597,
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55, 7263, 4635, 2530, 28130, 3033, 23830, 3651,
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56, 24731, 23583, 26036, 17299, 5750, 792, 9169,
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57, 5811, 26154, 18653, 11551, 15447, 13685, 16264,
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58, 12610, 11347, 28768, 2792, 3174, 29371, 12997,
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59, 16789, 16018, 21449, 6165, 21202, 15850, 3186,
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60, 31016, 21449, 17618, 6213, 12166, 8334, 18212,
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61, 22836, 14213, 11327, 5896, 718, 11727, 9308,
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62, 2091, 24941, 29966, 23634, 9013, 15587, 5444,
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63, 22207, 3983, 16904, 28534, 21415, 27524, 25912,
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64, 25687, 4501, 22193, 14665, 14798, 16158, 5491,
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65, 4520, 17094, 23397, 4264, 22370, 16941, 21526,
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66, 10490, 6182, 32370, 9597, 30841, 25954, 2762,
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67, 22120, 22865, 29870, 15147, 13668, 14955, 19235,
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68, 6689, 18408, 18346, 9918, 25746, 5443, 20645,
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69, 29982, 12529, 13858, 4746, 30370, 10023, 24828,
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70, 1262, 28032, 29888, 13063, 24033, 21951, 7863,
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71, 6594, 29642, 31451, 14831, 9509, 9335, 31552,
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72, 1358, 6454, 16633, 20354, 24598, 624, 5265,
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73, 19529, 295, 18011, 3080, 13364, 8032, 15323,
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74, 11981, 1510, 7960, 21462, 9129, 11370, 25741,
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75, 9276, 29656, 4543, 30699, 20646, 21921, 28050,
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76, 15975, 25634, 5520, 31119, 13715, 21949, 19605,
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77, 18688, 4608, 31755, 30165, 13103, 10706, 29224,
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78, 21514, 23117, 12245, 26035, 31656, 25631, 30699,
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79, 9674, 24966, 31285, 29908, 17042, 24588, 31857,
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80, 21856, 27777, 29919, 27000, 14897, 11409, 7122,
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81, 29773, 23310, 263, 4877, 28622, 20545, 22092,
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82, 15605, 5651, 21864, 3967, 14419, 22757, 15896,
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83, 30145, 1759, 10139, 29223, 26086, 10556, 5098,
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84, 18815, 16575, 2936, 24457, 26738, 6030, 505,
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85, 30326, 22298, 27562, 20131, 26390, 6247, 24791,
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86, 928, 29246, 21246, 12400, 15311, 32309, 18608,
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87, 20314, 6025, 26689, 16302, 2296, 3244, 19613,
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88, 6237, 11943, 22851, 15642, 23857, 15112, 20947,
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89, 26403, 25168, 19038, 18384, 8882, 12719, 7093,
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0, 14567, 24965,
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1, 3908, 100,
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2, 10279, 240,
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3, 24102, 764,
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4, 12383, 4173,
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5, 13861, 15918,
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6, 21327, 1046,
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7, 5288, 14579,
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8, 28158, 8069,
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9, 16583, 11098,
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10, 16681, 28363,
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11, 13980, 24725,
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12, 32169, 17989,
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13, 10907, 2767,
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14, 21557, 3818,
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15, 26676, 12422,
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16, 7676, 8754,
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17, 14905, 20232,
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18, 15719, 24646,
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19, 31942, 8589,
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20, 19978, 27197,
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21, 27060, 15071,
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22, 6071, 26649,
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23, 10393, 11176,
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24, 9597, 13370,
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25, 7081, 17677,
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26, 1433, 19513,
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27, 26925, 9014,
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28, 19202, 8900,
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29, 18152, 30647,
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30, 20803, 1737,
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31, 11804, 25221,
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32, 31683, 17783,
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33, 29694, 9345,
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34, 12280, 26611,
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35, 6526, 26122,
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36, 26165, 11241,
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37, 7666, 26962,
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38, 16290, 8480,
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39, 11774, 10120,
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40, 30051, 30426,
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41, 1335, 15424,
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42, 6865, 17742,
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43, 31779, 12489,
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44, 32120, 21001,
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45, 14508, 6996,
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46, 979, 25024,
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47, 4554, 21896,
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48, 7989, 21777,
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49, 4972, 20661,
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50, 6612, 2730,
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51, 12742, 4418,
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52, 29194, 595,
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53, 19267, 20113,
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};
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};
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struct DVB_T2_TABLE_B7
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{
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static const int M = 360;
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static const int N = 16200;
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static const int K = 13320;
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static const int LINKS_MIN_CN = 15;
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static const int LINKS_MAX_CN = 19;
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static const int LINKS_TOTAL = 49319;
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static const int DEG_MAX = 13;
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static constexpr int DEG[] = {
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13, 3, 0
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};
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static constexpr int LEN[] = {
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1, 36, 0
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};
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static constexpr int POS[] = {
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3, 2409, 499, 1481, 908, 559, 716, 1270, 333, 2508, 2264, 1702, 2805,
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4, 2447, 1926,
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5, 414, 1224,
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6, 2114, 842,
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7, 212, 573,
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0, 2383, 2112,
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1, 2286, 2348,
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2, 545, 819,
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3, 1264, 143,
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4, 1701, 2258,
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5, 964, 166,
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6, 114, 2413,
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7, 2243, 81,
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0, 1245, 1581,
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1, 775, 169,
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2, 1696, 1104,
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3, 1914, 2831,
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4, 532, 1450,
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5, 91, 974,
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6, 497, 2228,
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7, 2326, 1579,
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0, 2482, 256,
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1, 1117, 1261,
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2, 1257, 1658,
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3, 1478, 1225,
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4, 2511, 980,
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5, 2320, 2675,
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6, 435, 1278,
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7, 228, 503,
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0, 1885, 2369,
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1, 57, 483,
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2, 838, 1050,
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3, 1231, 1990,
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4, 1738, 68,
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5, 2392, 951,
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6, 163, 645,
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7, 2644, 1704,
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};
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};
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constexpr int DVB_T2_TABLE_A1::DEG[];
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constexpr int DVB_T2_TABLE_A1::LEN[];
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constexpr int DVB_T2_TABLE_A1::POS[];
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constexpr int DVB_T2_TABLE_B7::DEG[];
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constexpr int DVB_T2_TABLE_B7::LEN[];
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constexpr int DVB_T2_TABLE_B7::POS[];
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#if 0
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typedef DVB_T2_TABLE_A1 TABLE;
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static const float QEF_SNR = -1.8;
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static const int BCH_T = 12;
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#else
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typedef DVB_T2_TABLE_B7 TABLE;
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static const float QEF_SNR = 2.5;
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static const int BCH_T = 12;
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#endif
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int main()
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{
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const int TRIALS = 25;
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const int FACTOR = 2;
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const int BETA = 1;
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const int CODE_LEN = TABLE::N;
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const int DATA_LEN = TABLE::K;
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CODE::LDPCEncoder<TABLE> encode;
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CODE::LDPCDecoder<TABLE, BETA> decode;
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std::random_device rd;
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std::default_random_engine generator(rd());
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typedef std::uniform_int_distribution<int> uniform;
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typedef std::normal_distribution<float> normal;
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int8_t *code = new int8_t[CODE_LEN];
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int8_t *orig = new int8_t[CODE_LEN];
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int8_t *noisy = new int8_t[CODE_LEN];
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float *symb = new float[CODE_LEN];
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float min_SNR = 20, min_mbs = 1000, max_mbs = 0;
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for (float SNR = -5; SNR <= 15; SNR += 0.1) {
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//float mean_signal = 0;
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float sigma_signal = 1;
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float mean_noise = 0;
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float sigma_noise = std::sqrt(sigma_signal * sigma_signal / (2 * std::pow(10, SNR / 10)));
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auto data = std::bind(uniform(0, 1), generator);
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auto awgn = std::bind(normal(mean_noise, sigma_noise), generator);
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for (int i = 0; i < DATA_LEN; ++i)
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code[i] = 1 - 2 * data();
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encode(code, code + DATA_LEN);
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for (int i = 0; i < CODE_LEN; ++i)
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orig[i] = code[i];
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for (int i = 0; i < CODE_LEN; ++i)
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symb[i] = code[i];
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for (int i = 0; i < CODE_LEN; ++i)
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symb[i] += awgn();
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// $LLR=log(\frac{p(x=+1|y)}{p(x=-1|y)})$
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// $p(x|\mu,\sigma)=\frac{1}{\sqrt{2\pi}\sigma}}e^{-\frac{(x-\mu)^2}{2\sigma^2}}$
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float DIST = 2; // BPSK
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float fact = DIST * FACTOR / (sigma_noise * sigma_noise);
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for (int i = 0; i < CODE_LEN; ++i)
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code[i] = std::min<float>(std::max<float>(std::nearbyint(fact * symb[i]), -128), 127);
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for (int i = 0; i < CODE_LEN; ++i)
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noisy[i] = code[i];
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auto start = std::chrono::system_clock::now();
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int count = decode(code, code + DATA_LEN, TRIALS);
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auto end = std::chrono::system_clock::now();
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auto usec = std::chrono::duration_cast<std::chrono::microseconds>(end - start);
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float mbs = (float)DATA_LEN / usec.count();
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int iters = count < 0 ? TRIALS : TRIALS - count;
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int awgn_errors = 0;
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for (int i = 0; i < CODE_LEN; ++i)
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awgn_errors += noisy[i] * orig[i] < 0;
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int quantization_erasures = 0;
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for (int i = 0; i < CODE_LEN; ++i)
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quantization_erasures += !noisy[i];
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int uncorrected_errors = 0;
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for (int i = 0; i < CODE_LEN; ++i)
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uncorrected_errors += code[i] * orig[i] <= 0;
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int decoder_errors = 0;
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for (int i = 0; i < CODE_LEN; ++i)
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decoder_errors += code[i] * orig[i] <= 0 && orig[i] * noisy[i] > 0;
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float bit_error_rate = (float)uncorrected_errors / (float)(CODE_LEN);
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if (uncorrected_errors <= BCH_T)
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min_SNR = std::min(min_SNR, SNR);
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min_mbs = std::min(min_mbs, mbs);
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max_mbs = std::max(max_mbs, mbs);
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if (0) {
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std::cerr << SNR << " Es/N0 => AWGN with standard deviation of " << sigma_noise << " and mean " << mean_noise << std::endl;
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std::cerr << awgn_errors << " errors caused by AWGN." << std::endl;
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std::cerr << quantization_erasures << " erasures caused by quantization." << std::endl;
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std::cerr << decoder_errors << " errors caused by decoder." << std::endl;
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std::cerr << uncorrected_errors << " errors uncorrected." << std::endl;
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std::cerr << bit_error_rate << " bit error rate." << std::endl;
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if (count < 0) {
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std::cerr << "decoder failed at converging to a code word!" << std::endl;
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} else {
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std::cerr << iters << " iterations were needed." << std::endl;
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}
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std::cerr << usec.count() << " microseconds to decode." << std::endl;
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std::cerr << mbs << " megabit per second." << std::endl;
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} else {
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std::cout << SNR << " " << bit_error_rate << " " << iters << " " << mbs << std::endl;
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}
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}
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delete[] code;
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delete[] orig;
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delete[] noisy;
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delete[] symb;
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std::cerr << "QEF at: " << min_SNR << " SNR, speed min: " << min_mbs << " Mb/s and speed max: " << max_mbs << " Mb/s." << std::endl;
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assert(min_SNR < QEF_SNR);
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std::cerr << "Low-density parity-check code regression test passed!" << std::endl;
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return 0;
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}
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