add equalizers

2016-05-31 15:36:05 +02:00
parent 5a9846fa67
commit 052d5022b0
12 changed files with 413 additions and 140 deletions
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2015 Bastian Bloessl <bloessl@ccs-labs.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "comb.h"
+
+using namespace gr::ieee802_11::equalizer;
+
+void comb::equalize(gr_complex *in, int n, gr_complex *symbols, uint8_t *bits, boost::shared_ptr<gr::digital::constellation> mod) {
+
+	gr_complex pilot[4];
+
+	if(n < 2) {
+		pilot[0] =  in[11];
+		pilot[1] = -in[25];
+		pilot[2] =  in[39];
+		pilot[3] =  in[53];
+	} else {
+		gr_complex p = POLARITY[(n - 2) % 127];
+		pilot[0] = in[11] *  p;
+		pilot[1] = in[25] *  p;
+		pilot[2] = in[39] *  p;
+		pilot[3] = in[53] * -p;
+	}
+
+	gr_complex avg = (pilot[0] + pilot[1] + pilot[2] + pilot[3]) / gr_complex(4, 0);
+
+	for(int i = 0; i < 64; i++) {
+		gr_complex H;
+		if(i <= 11) {
+			H = gr_complex((11-i) / 11.0, 0) * avg      + gr_complex( i     / 11.0, 0) * pilot[0];
+		} else if(i <= 25) {
+			H = gr_complex((25-i) / 14.0, 0) * pilot[0] + gr_complex((i-11) / 14.0, 0) * pilot[1];
+		} else if(i <= 39) {
+			H = gr_complex((39-i) / 14.0, 0) * pilot[1] + gr_complex((i-25) / 14.0, 0) * pilot[2];
+		} else if(i <= 53) {
+			H = gr_complex((53-i) / 14.0, 0) * pilot[2] + gr_complex((i-39) / 14.0, 0) * pilot[3];
+		} else {
+			H = gr_complex((64-i) / 11.0, 0) * pilot[3] + gr_complex((i-53) / 11.0, 0) * avg;
+		}
+
+		if(n == 0) {
+			d_H[i] = H;
+		} else {
+			d_H[i] = gr_complex(1-alpha, 0) * d_H[i] + gr_complex(alpha, 0) * H;
+		}
+	}
+
+	int c = 0;
+	for(int i = 0; i < 64; i++) {
+		if( (i == 11) || (i == 25) || (i == 32) || (i == 39) || (i == 53) || (i < 6) || ( i > 58)) {
+			continue;
+		} else {
+			symbols[c] = in[i] / d_H[i];
+			bits[c] = mod->decision_maker(&symbols[c]);
+			c++;
+		}
+	}
+}
+
+double
+comb::get_snr() {
+	return 42;
+}