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replaced reserved tones with pilot tones

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This commit is contained in:
Ahmet Inan 2025-07-10 17:45:07 +02:00
commit 04beed4a4c
3 changed files with 16 additions and 61 deletions
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51
encode.cc
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@ -48,7 +48,7 @@ struct Encoder : public Common
{
return 1 - 2 * bit;
}
void clipping_and_filtering(value scale, bool limit)
void clipping_and_filtering(value scale)
{
for (int i = 0; i < symbol_len; ++i) {
value pwr = norm(tdom[i]);
@ -58,39 +58,17 @@ struct Encoder : public Common
fwd(fdom, tdom);
for (int i = 0; i < symbol_len; ++i) {
int j = bin(i + tone_off);
if (i >= tone_count) {
if (i >= tone_count)
fdom[j] = 0;
} else if (i % block_length == pilot_off) {
else if (i % block_length == pilot_off)
fdom[j] = temp[i];
} else if (i % block_length == reserved_off) {
fdom[j] = 0;
} else {
else
fdom[j] *= 1 / (scale * symbol_len);
cmplx err = fdom[j] - temp[i];
value mag = abs(err);
value lim = 0.5 * mod_distance();
if (limit && mag > lim)
fdom[j] -= ((mag - lim) / mag) * err;
}
}
bwd(tdom, fdom);
for (int i = 0; i < symbol_len; ++i)
tdom[i] *= scale;
}
void tone_reservation()
{
for (int n = 0; n < 10; ++n) {
int peak = 0;
for (int i = 1; i < symbol_len; ++i)
if (norm(tdom[peak]) < norm(tdom[i]))
peak = i;
cmplx orig = tdom[peak];
if (norm(orig) <= value(1))
break;
for (int i = 0; i < symbol_len; ++i)
tdom[i] -= orig * kern[bin(i-peak)];
}
}
void symbol(int symbol_number)
{
for (int i = 0; differential && symbol_number > 0 && i < tone_count; ++i)
@ -105,7 +83,7 @@ struct Encoder : public Common
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)
else
temp[i] *= nrz(seq());
}
for (int i = 0; i < symbol_len; ++i)
@ -117,10 +95,8 @@ struct Encoder : public Common
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();
}
if (papr_reduction)
clipping_and_filtering(scale);
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()));
@ -243,15 +219,6 @@ struct Encoder : public Common
dest[i] = src[seq()];
}
}
void tone_reservation_kernel()
{
value mag(0.001);
for (int i = 0; i < symbol_len; ++i)
fdom[i] = 0;
for (int i = 0; i < reserved_tones; ++i)
fdom[bin(i*block_length+tone_off+reserved_off)] = mag;
bwd(kern, fdom);
}
void guard_interval_weights()
{
for (int i = 0; i < guard_len / 4; ++i)
@ -298,12 +265,9 @@ struct Encoder : public Common
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;
for (int i = 0; i < tone_count; ++i) {
if (i % block_length == pilot_off) {
tone[i] = nrz(seq1());
} else if (i % block_length == reserved_off) {
tone[i] = 0;
} else {
int bits = mod_bits;
if (oper_mode >= 7 && oper_mode <= 9 && k % 32 == 30)
@ -314,7 +278,6 @@ struct Encoder : public Common
k += bits;
}
}
tone_reservation_kernel();
symbol(j);
}
std::cerr << std::endl;