Bastian Bloessl
105 lines
3.3 KiB
C++
105 lines
3.3 KiB
C++
/*
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* Copyright (C) 2015 Bastian Bloessl <bloessl@ccs-labs.org>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "lms.h"
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#include <cstring>
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#include <iostream>
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using namespace gr::ieee802_11::equalizer;
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void lms::equalize(const gr_complex *in, gr_complex *out, int n) {
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static float freq_offset = 0;
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static float freq_sum = 0;
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static float alpha = 0.9;
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if(n == 0) {
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std::memcpy(carrier, in, 64 * sizeof(gr_complex));
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} else if(n == 1) {
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gr_complex sum =
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(carrier[11] * conj(in[11])) +
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(carrier[25] * conj(in[25])) +
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(carrier[39] * conj(in[39])) +
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(carrier[53] * conj(in[53]));
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freq_offset = arg(sum);
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freq_sum = 0;
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for(int i = 0; i < 64; i++) {
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carrier[i] += in[i];
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carrier[i] *= ref[i] * gr_complex(0.5, 0);
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}
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} else {
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gr_complex p = POLARITY[(n - 2) % 127];
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gr_complex sum =
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(carrier[11] * conj(in[11]) * p) +
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(carrier[25] * conj(in[25]) * p) +
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(carrier[39] * conj(in[39]) * p) +
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(carrier[53] * conj(in[53]) * -p);
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freq_offset = (1 - alpha) * freq_offset + alpha * arg(sum);
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freq_sum += freq_offset;
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//std::cout << "lms: symbol " << n
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// << " p1 " << abs(carrier[11] * conj(in[11]) * p)
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// << " p2 " << abs(carrier[25] * conj(in[25]) * p)
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// << " p3 " << abs(carrier[39] * conj(in[39]) * p)
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// << " p4 " << abs(carrier[53] * conj(in[53]) * -p)
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// << std::endl;
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//std::cout << "lms: symbol " << n
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// << " p1 " << arg(carrier[11] * conj(in[11]) * p)
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// << " p2 " << arg(carrier[25] * conj(in[25]) * p)
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// << " p3 " << arg(carrier[39] * conj(in[39]) * p)
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// << " p4 " << arg(carrier[53] * conj(in[53]) * -p)
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// << std::endl;
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carrier[11] = in[11] * p;
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carrier[25] = in[25] * p;
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carrier[39] = in[39] * p;
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carrier[53] = in[53] * -p;
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int c = 0;
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for(int i = 0; i < 64; i++) {
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if( (i == 11) || (i == 25) || (i == 32) || (i == 39) || (i == 53) || (i < 6) || ( i > 58)) {
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continue;
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} else {
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out[c] = in[i] / carrier[i] * exp(gr_complex(0, freq_sum));
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c++;
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}
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}
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}
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}
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const gr_complex lms::ref[] = {
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0, 0, 0, 0, 0, 0, 1, 1, -1, -1,
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1, 1, -1, 1, -1, 1, 1, 1, 1, 1,
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1, -1, -1, 1, 1, -1, 1, -1, 1, 1,
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1, 1, 0, 1, -1, -1, 1, 1, -1, 1,
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-1, 1, -1, -1, -1, -1, -1, 1, 1, -1,
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-1, 1, -1, 1, -1, 1, 1, 1, 1, 0,
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0, 0, 0, 0
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};
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const gr_complex lms::POLARITY[127] = {
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1, 1, 1, 1,-1,-1,-1, 1,-1,-1,-1,-1, 1, 1,-1, 1,
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-1,-1, 1, 1,-1, 1, 1,-1, 1, 1, 1, 1, 1, 1,-1, 1,
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1, 1,-1, 1, 1,-1,-1, 1, 1, 1,-1, 1,-1,-1,-1, 1,
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-1, 1,-1,-1, 1,-1,-1, 1, 1, 1, 1, 1,-1,-1, 1, 1,
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-1,-1, 1,-1, 1,-1, 1, 1,-1,-1,-1, 1, 1,-1,-1,-1,
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-1, 1,-1,-1, 1,-1, 1, 1, 1, 1,-1, 1,-1, 1,-1, 1,
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-1,-1,-1,-1,-1, 1,-1, 1, 1,-1, 1,-1, 1, 1, 1,-1,
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-1, 1,-1,-1,-1, 1, 1, 1,-1,-1,-1,-1,-1,-1,-1 };
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