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experimenting with selected mapping

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This commit is contained in:
Ahmet Inan 2025-07-10 16:51:55 +02:00
commit 4838e75415
2 changed files with 46 additions and 37 deletions
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4
decode.cc
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@ -300,6 +300,10 @@ struct Decoder : Common
for (int i = pilot_off; i < tone_count; i += block_length)
chan[i] = DSP::lerp(chan[i], tone[i], value(0.5));
}
CODE::MLS seq(0x163, meta_data);
for (int i = 0; i < tone_count; ++i)
if (i % block_length != pilot_off && i % block_length != reserved_off)
demod[i] *= nrz(seq());
value sp = 0, np = 0;
for (int i = 0, l = k; i < tone_count; ++i) {
if (i % block_length == reserved_off)

79
encode.cc
View file

@ -37,9 +37,8 @@ struct Encoder : public Common
cmplx kern[symbol_len];
cmplx guard[guard_len];
cmplx tone[tone_count];
cmplx prev[tone_count];
cmplx temp[tone_count];
value weight[guard_len];
value papr_min, papr_max;
static int bin(int carrier)
{
@ -62,12 +61,12 @@ struct Encoder : public Common
if (i >= tone_count) {
fdom[j] = 0;
} else if (i % block_length == pilot_off) {
fdom[j] = tone[i];
fdom[j] = temp[i];
} else if (i % block_length == reserved_off) {
fdom[j] = 0;
} else {
fdom[j] *= 1 / (scale * symbol_len);
cmplx err = fdom[j] - tone[i];
cmplx err = fdom[j] - temp[i];
value mag = abs(err);
value lim = 0.5 * mod_distance();
if (limit && mag > lim)
@ -94,33 +93,39 @@ struct Encoder : public Common
}
void symbol(int symbol_number)
{
if (symbol_number >= 0) {
hadamard_encoder(meta, symbol_number ? symbol_number : oper_mode);
for (int i = 0; i < pilot_tones; ++i)
tone[block_length*i+pilot_off] *= meta[i];
}
for (int i = 0; differential && i < tone_count; ++i)
if (symbol_number < 0)
prev[i] = 1;
else if (i % block_length != reserved_off)
prev[i] = tone[i] *= prev[i];
for (int i = 0; i < symbol_len; ++i)
fdom[i] = 0;
for (int i = 0; i < tone_count; ++i)
fdom[bin(i+tone_off)] = tone[i];
bwd(tdom, fdom);
value scale = value(0.5) / std::sqrt(value(tone_count));
for (int i = 0; i < symbol_len; ++i)
tdom[i] *= scale;
bool papr_reduction = symbol_number >= 0;
if (papr_reduction) {
clipping_and_filtering(scale, true);
tone_reservation();
}
auto clamp = [](value v){ return v < value(-1) ? value(-1) : v > value(1) ? value(1) : v; };
for (int i = 0; i < symbol_len; ++i)
tdom[i] = cmplx(clamp(tdom[i].real()), clamp(tdom[i].imag()));
if (papr_reduction) {
for (int i = 0; differential && symbol_number > 0 && i < tone_count; ++i)
tone[i] *= temp[i];
for (int trial = 63; trial >= 0; --trial) {
for (int i = 0; i < tone_count; ++i)
temp[i] = tone[i];
if (symbol_number >= 0) {
int meta_data = symbol_number ? trial : oper_mode;
hadamard_encoder(meta, meta_data);
CODE::MLS seq(0x163, meta_data);
for (int i = 0, m = 0; i < tone_count; ++i)
if (i % block_length == pilot_off)
temp[i] *= meta[m++];
else if (i % block_length != reserved_off)
temp[i] *= nrz(seq());
}
for (int i = 0; i < symbol_len; ++i)
fdom[i] = 0;
for (int i = 0; i < tone_count; ++i)
fdom[bin(i+tone_off)] = temp[i];
bwd(tdom, fdom);
value scale = value(0.5) / std::sqrt(value(tone_count));
for (int i = 0; i < symbol_len; ++i)
tdom[i] *= scale;
bool papr_reduction = symbol_number >= 0;
if (papr_reduction) {
clipping_and_filtering(scale, true);
tone_reservation();
}
auto clamp = [](value v){ return v < value(-1) ? value(-1) : v > value(1) ? value(1) : v; };
for (int i = 0; i < symbol_len; ++i)
tdom[i] = cmplx(clamp(tdom[i].real()), clamp(tdom[i].imag()));
if (!papr_reduction)
break;
value peak = 0, mean = 0;
for (int i = 0; i < symbol_len; ++i) {
value power(norm(tdom[i]));
@ -128,10 +133,10 @@ struct Encoder : public Common
mean += power;
}
mean /= symbol_len;
if (mean > 0) {
value papr(peak / mean);
papr_min = std::min(papr_min, papr);
papr_max = std::max(papr_max, papr);
value papr(peak / mean);
if (symbol_number == 0 || papr < 5 || trial == 0) {
std::cerr << " " << DSP::decibel(papr);
break;
}
}
if (symbol_number != -1) {
@ -264,7 +269,6 @@ struct Encoder : public Common
int offset = (freq_off * symbol_len) / rate;
tone_off = offset - tone_count / 2;
guard_interval_weights();
papr_min = 1000, papr_max = -1000;
leading_noise();
for (int input_index = 0; input_index < input_count; ++input_index) {
const char *input_name = input_names[input_index];
@ -291,6 +295,7 @@ struct Encoder : public Common
polar_encoder(code, mesg, frozen_bits, code_order);
shuffle(perm, code);
CODE::MLS seq1(mls1_poly);
std::cerr << "PAPR (dB):";
for (int j = 0, k = 0; j < symbol_count; ++j) {
pilot_off = (block_skew * j + first_pilot) % block_length;
reserved_off = (block_skew * j + first_reserved) % block_length;
@ -312,9 +317,9 @@ struct Encoder : public Common
tone_reservation_kernel();
symbol(j);
}
std::cerr << std::endl;
}
finish();
std::cerr << "PAPR: " << DSP::decibel(papr_min) << " .. " << DSP::decibel(papr_max) << " dB" << std::endl;
}
};