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use a shortened systematic polar code and CA-SCL decoding
using SPC(64800, 43072): mode 6: 8PSK, 2700 Hz BW and about 10 seconds long mode 7: 8PSK, 2500 Hz BW and about 11 seconds long mode 8: QPSK, 2500 Hz BW and about 16 seconds long mode 9: QPSK, 2250 Hz BW and about 18 seconds long using SPC(64512, 43072): mode 10: 8PSK, 3200 Hz BW and about 9 seconds long mode 11: 8PSK, 2400 Hz BW and about 11 seconds long mode 12: QPSK, 2400 Hz BW and about 16 seconds long mode 13: QPSK, 1600 Hz BW and about 24 seconds long
This commit is contained in:
Ahmet Inan
parent
a3a56bc830
commit
99b6a4e963
7 changed files with 339 additions and 325 deletions
194
encode.cc
194
encode.cc
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@ -18,19 +18,19 @@ Copyright 2021 Ahmet Inan <inan@aicodix.de>
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#include "mls.hh"
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#include "crc.hh"
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#include "psk.hh"
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#include "ldpc_tables.hh"
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#include "ldpc_encoder.hh"
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#include "galois_field.hh"
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#include "polar_tables.hh"
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#include "polar_helper.hh"
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#include "polar_encoder.hh"
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#include "bose_chaudhuri_hocquenghem_encoder.hh"
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template <typename value, typename cmplx, int rate>
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struct Encoder
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{
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typedef int8_t code_type;
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static const int symbol_len = (1280 * rate) / 8000;
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static const int guard_len = symbol_len / 8;
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static const int ldpc_bits = 64800;
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static const int bch_bits = ldpc_bits - 21600;
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static const int data_bits = bch_bits - 10 * 16;
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static const int data_bits = 43040;
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static const int crc_bits = data_bits + 32;
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static const int mls0_len = 127;
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static const int mls0_poly = 0b10001001;
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static const int mls1_len = 255;
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@ -41,20 +41,24 @@ struct Encoder
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DSP::FastFourierTransform<4*symbol_len, cmplx, -1> fwd4;
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DSP::FastFourierTransform<4*symbol_len, cmplx, 1> bwd4;
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CODE::CRC<uint16_t> crc0;
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CODE::BoseChaudhuriHocquenghemEncoder<255, 71> bchenc0;
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CODE::BoseChaudhuriHocquenghemEncoder<65535, 65375> bchenc1;
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CODE::LDPCEncoder<DVB_T2_TABLE_A3> ldpcenc;
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int8_t code[ldpc_bits], bint[ldpc_bits];
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CODE::CRC<uint32_t> crc1;
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CODE::BoseChaudhuriHocquenghemEncoder<255, 71> bchenc;
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CODE::PolarSysEnc<code_type> polarenc;
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code_type code[65536], mesg[44096];
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cmplx fdom[symbol_len], fdom4[4*symbol_len];
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cmplx tdom[symbol_len], tdom4[4*symbol_len];
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cmplx temp[symbol_len];
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cmplx guard[guard_len];
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cmplx papr_min, papr_max;
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const uint32_t *frozen_bits;
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int code_order;
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int oper_mode;
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int mod_bits;
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int cons_cnt;
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int code_cols;
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int code_rows;
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int cons_cols;
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int cons_rows;
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int cons_bits;
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int mesg_bits;
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int code_off;
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int mls0_off;
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int mls1_off;
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@ -126,10 +130,10 @@ struct Encoder
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void pilot_block()
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{
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CODE::MLS seq2(mls2_poly);
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value code_fac = std::sqrt(value(symbol_len) / value(code_cols));
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value code_fac = std::sqrt(value(symbol_len) / value(cons_cols));
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for (int i = 0; i < symbol_len; ++i)
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fdom[i] = 0;
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for (int i = code_off; i < code_off + code_cols; ++i)
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for (int i = code_off; i < code_off + cons_cols; ++i)
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fdom[bin(i)] = code_fac * nrz(seq2());
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symbol();
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}
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@ -155,7 +159,7 @@ struct Encoder
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uint16_t cs = crc0(md << 9);
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for (int i = 0; i < 16; ++i)
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CODE::set_be_bit(data, i+55, (cs>>i)&1);
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bchenc0(data, parity);
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bchenc(data, parity);
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CODE::MLS seq4(mls1_poly);
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value mls1_fac = std::sqrt(value(symbol_len) / value(mls1_len));
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for (int i = 0; i < symbol_len; ++i)
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@ -171,62 +175,111 @@ struct Encoder
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fdom[bin(i+mls1_off)] *= nrz(seq4());
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symbol();
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}
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cmplx mod_map(int8_t *b)
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void shorten()
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{
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int code_bits = 1 << code_order;
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for (int i = 0, j = 0, k = 0; i < code_bits; ++i)
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if ((frozen_bits[i/32] >> (i%32)) & 1 || k++ < crc_bits)
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code[j++] = code[i];
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}
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cmplx mod_map(code_type *b)
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{
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switch (oper_mode) {
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case 2:
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case 3:
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return PhaseShiftKeying<8, cmplx, int8_t>::map(b);
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case 4:
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case 5:
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return PhaseShiftKeying<4, cmplx, int8_t>::map(b);
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case 6:
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case 7:
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case 10:
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case 11:
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return PhaseShiftKeying<8, cmplx, code_type>::map(b);
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case 8:
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case 9:
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case 12:
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case 13:
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return PhaseShiftKeying<4, cmplx, code_type>::map(b);
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}
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return 0;
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}
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void interleave()
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{
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for (int i = 0; i < cons_cnt; ++i)
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for (int k = 0; k < mod_bits; ++k)
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bint[mod_bits*i+k] = code[cons_cnt*k+i];
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}
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Encoder(DSP::WritePCM<value> *pcm, uint8_t *inp, int freq_off, uint64_t call_sign, int oper_mode) :
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pcm(pcm), crc0(0xA8F4), bchenc0({
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Encoder(DSP::WritePCM<value> *pcm, const uint8_t *inp, int freq_off, uint64_t call_sign, int oper_mode) :
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pcm(pcm), crc0(0xA8F4), crc1(0xD419CC15), bchenc({
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0b100011101, 0b101110111, 0b111110011, 0b101101001,
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0b110111101, 0b111100111, 0b100101011, 0b111010111,
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0b000010011, 0b101100101, 0b110001011, 0b101100011,
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0b100011011, 0b100111111, 0b110001101, 0b100101101,
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0b101011111, 0b111111001, 0b111000011, 0b100111001,
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0b110101001, 0b000011111, 0b110000111, 0b110110001}), bchenc1({
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0b10000000000101101, 0b10000000101110011, 0b10000111110111101,
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0b10101101001010101, 0b10001111100101111, 0b11111011110110101,
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0b11010111101100101, 0b10111001101100111, 0b10000111010100001,
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0b10111010110100111}),
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0b110101001, 0b000011111, 0b110000111, 0b110110001}),
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oper_mode(oper_mode)
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{
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switch (oper_mode) {
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case 2:
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code_cols = 432;
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case 6:
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cons_cols = 432;
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mod_bits = 3;
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code_order = 16;
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cons_bits = 64800;
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mesg_bits = 43808;
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frozen_bits = frozen_64800_43072;
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break;
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case 3:
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code_cols = 400;
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case 7:
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cons_cols = 400;
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mod_bits = 3;
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code_order = 16;
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cons_bits = 64800;
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mesg_bits = 43808;
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frozen_bits = frozen_64800_43072;
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break;
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case 4:
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code_cols = 400;
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case 8:
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cons_cols = 400;
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mod_bits = 2;
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code_order = 16;
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cons_bits = 64800;
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mesg_bits = 43808;
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frozen_bits = frozen_64800_43072;
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break;
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case 5:
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code_cols = 360;
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case 9:
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cons_cols = 360;
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mod_bits = 2;
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code_order = 16;
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cons_bits = 64800;
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mesg_bits = 43808;
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frozen_bits = frozen_64800_43072;
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break;
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case 10:
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cons_cols = 512;
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mod_bits = 3;
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code_order = 16;
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cons_bits = 64512;
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mesg_bits = 44096;
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frozen_bits = frozen_64512_43072;
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break;
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case 11:
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cons_cols = 384;
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mod_bits = 3;
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code_order = 16;
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cons_bits = 64512;
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mesg_bits = 44096;
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frozen_bits = frozen_64512_43072;
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break;
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case 12:
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cons_cols = 384;
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mod_bits = 2;
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code_order = 16;
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cons_bits = 64512;
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mesg_bits = 44096;
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frozen_bits = frozen_64512_43072;
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break;
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case 13:
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cons_cols = 256;
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mod_bits = 2;
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code_order = 16;
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cons_bits = 64512;
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mesg_bits = 44096;
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frozen_bits = frozen_64512_43072;
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break;
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default:
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return;
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}
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cons_cnt = ldpc_bits / mod_bits;
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code_rows = cons_cnt / code_cols;
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cons_cnt = cons_bits / mod_bits;
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cons_rows = cons_cnt / cons_cols;
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int offset = (freq_off * symbol_len) / rate;
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code_off = offset - code_cols / 2;
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code_off = offset - cons_cols / 2;
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mls0_off = offset - mls0_len + 1;
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mls1_off = offset - mls1_len / 2;
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papr_min = cmplx(1000, 1000), papr_max = cmplx(-1000, -1000);
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@ -234,15 +287,21 @@ struct Encoder
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schmidl_cox();
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meta_data((call_sign << 8) | oper_mode);
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pilot_block();
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bchenc1(inp, inp+data_bits/8, data_bits);
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for (int i = 0; i < bch_bits; ++i)
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code[i] = nrz(CODE::get_le_bit(inp, i));
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ldpcenc(code, code + bch_bits);
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interleave();
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for (int j = 0; j < code_rows; ++j) {
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for (int i = 0; i < code_cols; ++i)
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for (int i = 0; i < data_bits; ++i)
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mesg[i] = nrz(CODE::get_le_bit(inp, i));
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crc1.reset();
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for (int i = 0; i < data_bits / 8; ++i)
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crc1(inp[i]);
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for (int i = 0; i < 32; ++i)
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mesg[i+data_bits] = nrz((crc1()>>i)&1);
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for (int i = crc_bits; i < mesg_bits; ++i)
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mesg[i] = 1;
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polarenc(code, mesg, frozen_bits, code_order);
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shorten();
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for (int j = 0; j < cons_rows; ++j) {
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for (int i = 0; i < cons_cols; ++i)
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fdom[bin(i+code_off)] *=
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mod_map(bint+mod_bits*(code_cols*j+i));
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mod_map(code+mod_bits*(cons_cols*j+i));
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symbol();
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}
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schmidl_cox();
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@ -300,26 +359,36 @@ int main(int argc, char **argv)
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return 1;
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}
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int oper_mode = 2;
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int oper_mode = 6;
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if (argc >= 9)
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oper_mode = std::atoi(argv[8]);
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if (oper_mode < 2 || oper_mode > 5) {
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if (oper_mode < 6 || oper_mode > 13) {
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std::cerr << "Unsupported operation mode." << std::endl;
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return 1;
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}
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int band_width;
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switch (oper_mode) {
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case 2:
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case 6:
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band_width = 2700;
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break;
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case 3:
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case 4:
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case 7:
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case 8:
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band_width = 2500;
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break;
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case 5:
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case 9:
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band_width = 2250;
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break;
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case 10:
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band_width = 3200;
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break;
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case 11:
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case 12:
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band_width = 2400;
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break;
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case 13:
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band_width = 1600;
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break;
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default:
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return 1;
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}
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@ -342,9 +411,8 @@ int main(int argc, char **argv)
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std::cerr << "Couldn't open file \"" << input_name << "\" for reading." << std::endl;
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return 1;
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}
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const int code_len = 64800 / 8;
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const int data_len = code_len - (10 * 16 + 21600) / 8;
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uint8_t *input_data = new uint8_t[code_len];
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const int data_len = 43040 / 8;
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uint8_t *input_data = new uint8_t[data_len];
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for (int i = 0; i < data_len; ++i)
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input_data[i] = input_file.get();
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CODE::Xorshift32 scrambler;
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