use long preamble for channel estimation and add lms equalizer

grc/ieee802_11_ofdm_equalize_symbols.xml

@@ -5,7 +5,24 @@
 	<key>ieee802_11_ofdm_equalize_symbols</key>
 	<category>IEEE802.11</category>
 	<import>import ieee802_11</import>
-	<make>ieee802_11.ofdm_equalize_symbols($debug)</make>
+	<make>ieee802_11.ofdm_equalize_symbols($algo, $debug)</make>
+	<callback>set_algorithm($algo)</callback>
+
+	<param>
+		<name>Algorithm</name>
+		<key>algo</key>
+		<value>ieee802_11.LINEAR_COMB</value>
+		<type>int</type>
+
+		<option>
+			<name>LMS</name>
+			<key>ieee802_11.LMS</key>
+		</option>
+		<option>
+			<name>linear comb</name>
+			<key>ieee802_11.LINEAR_COMB</key>
+		</option>
+	</param>
 
 	<param>
 		<name>Debug</name>

include/ieee802-11/ofdm_equalize_symbols.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013 Bastian Bloessl <bloessl@ccs-labs.org>
+ * Copyright (C) 2013, 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
@@ -20,6 +20,11 @@
 #include <ieee802-11/api.h>
 #include <gnuradio/block.h>
 
+enum Equalizer {
+	LMS          = 0,
+	LINEAR_COMB  = 1,
+};
+
 namespace gr {
 namespace ieee802_11 {
 
@@ -28,7 +33,8 @@ class IEEE802_11_API ofdm_equalize_symbols : virtual public block
 public:
 
 	typedef boost::shared_ptr<ofdm_equalize_symbols> sptr;
-	static sptr make(bool debug = false);
+	static sptr make(Equalizer algo, bool debug = false);
+	virtual void set_algorithm(Equalizer algo) = 0;
 
 };
 

lib/CMakeLists.txt

@@ -94,6 +94,8 @@ add_dependencies(ieee802_11_generated_sources ieee802_11_generated_includes)
 ########################################################################
 list(APPEND gr_ieee802_11_sources
     ${generated_sources}
+    equalizer/linear_comb.cc
+    equalizer/lms.cc
     chunks_to_symbols_impl.cc
     ether_encap_impl.cc
     ofdm_decode_mac.cc

lib/equalizer/base.h

@@ -0,0 +1,37 @@
+/*
+ * 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/>.
+ */
+
+#ifndef INCLUDED_IEEE802_11_EQUALIZER_BASE_H
+#define INCLUDED_IEEE802_11_EQUALIZER_BASE_H
+
+#include <gnuradio/gr_complex.h>
+
+namespace gr {
+namespace ieee802_11 {
+namespace equalizer {
+
+class base {
+public:
+	virtual ~base() {};
+	virtual void equalize(const gr_complex *in, gr_complex *out, int n) = 0;
+};
+
+} /* namespace channel_estimation */
+} /* namespace ieee802_11 */
+} /* namespace gr */
+
+#endif /* INCLUDED_IEEE802_11_EQUALIZER_BASE_H */

lib/equalizer/linear_comb.cc

@@ -0,0 +1,63 @@
+/*
+ * 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 "linear_comb.h"
+
+using namespace gr::ieee802_11::equalizer;
+
+void linear_comb::equalize(const gr_complex *in, gr_complex *out, int n) {
+	if(n < 2)
+		return;
+
+	double avg_mag = (abs(in[11]) + abs(in[25]) + abs(in[39]) + abs(in[53])) / 4;
+
+	gr_complex p = POLARITY[(n - 2) % 127 ];
+
+	double p1 = arg( p * in[11]);
+	double p2 = arg( p * in[25] * conj(p * in[11])) + p1;
+	double p3 = arg( p * in[39] * conj(p * in[25])) + p2;
+	double p4 = arg(-p * in[53] * conj(p * in[39])) + p3;
+
+	double my = (p1 + p2 + p3 + p4) / 4;
+	double mx = (11.0 + 25 + 39 + 53) / 4;
+
+	double var = (((11.0 * 11.0) + (25.0 * 25.0) + (39.0 * 39.0) + (53.0 * 53.0)) / 4) - (mx * mx);
+	double cov =  (( (p1 * 11) + (p2 * 25) + (p3 * 39) + (p4 * 53) ) / 4) - (mx * my);
+	double beta = cov / var;
+	double alpha = my - beta * mx;
+
+	int c = 0;
+	for(int n = 0; n < 64; n++) {
+		if( (n == 11) || (n == 25) || (n == 32) || (n == 39) || (n == 53) || (n < 6) || ( n > 58)) {
+			continue;
+		} else {
+			out[c] = in[n] * exp(gr_complex(0, -n * beta - alpha)) * gr_complex(1 / avg_mag, 0);
+			c++;
+		}
+	}
+
+}
+
+const gr_complex linear_comb::POLARITY[127] = {
+		 1, 1, 1, 1,-1,-1,-1, 1,-1,-1,-1,-1, 1, 1,-1, 1,
+		-1,-1, 1, 1,-1, 1, 1,-1, 1, 1, 1, 1, 1, 1,-1, 1,
+		 1, 1,-1, 1, 1,-1,-1, 1, 1, 1,-1, 1,-1,-1,-1, 1,
+		-1, 1,-1,-1, 1,-1,-1, 1, 1, 1, 1, 1,-1,-1, 1, 1,
+		-1,-1, 1,-1, 1,-1, 1, 1,-1,-1,-1, 1, 1,-1,-1,-1,
+		-1, 1,-1,-1, 1,-1, 1, 1, 1, 1,-1, 1,-1, 1,-1, 1,
+		-1,-1,-1,-1,-1, 1,-1, 1, 1,-1, 1,-1, 1, 1, 1,-1,
+		-1, 1,-1,-1,-1, 1, 1, 1,-1,-1,-1,-1,-1,-1,-1 };

lib/equalizer/linear_comb.h

@@ -0,0 +1,39 @@
+/*
+ * 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/>.
+ */
+
+#ifndef INCLUDED_IEEE802_11_EQUALIZER_LINEAR_COMB_H
+#define INCLUDED_IEEE802_11_EQUALIZER_LINEAR_COMB_H
+
+#include "base.h"
+
+namespace gr {
+namespace ieee802_11 {
+namespace equalizer {
+
+class linear_comb: public base {
+public:
+	virtual void equalize(const gr_complex *in, gr_complex *out, int n);
+private:
+	static const gr_complex POLARITY[127];
+};
+
+} /* namespace channel_estimation */
+} /* namespace ieee802_11 */
+} /* namespace gr */
+
+#endif /* INCLUDED_IEEE802_11_EQUALIZER_LINEAR_COMB_H */
+

lib/equalizer/lms.cc

@@ -0,0 +1,104 @@
+/*
+ * 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 "lms.h"
+#include <cstring>
+#include <iostream>
+
+using namespace gr::ieee802_11::equalizer;
+
+void lms::equalize(const gr_complex *in, gr_complex *out, int n) {
+
+	static float freq_offset = 0;
+	static float freq_sum = 0;
+	static float alpha = 0.9;
+
+	if(n == 0) {
+		std::memcpy(carrier, in, 64 * sizeof(gr_complex));
+	} else if(n == 1) {
+		gr_complex sum =
+			(carrier[11] * conj(in[11])) +
+			(carrier[25] * conj(in[25])) +
+			(carrier[39] * conj(in[39])) +
+			(carrier[53] * conj(in[53]));
+		freq_offset = arg(sum);
+		freq_sum = 0;
+		for(int i = 0; i < 64; i++) {
+			carrier[i] += in[i];
+			carrier[i] *= ref[i] * gr_complex(0.5, 0);
+		}
+	} else {
+
+		gr_complex p = POLARITY[(n - 2) % 127];
+		gr_complex sum =
+			(carrier[11] * conj(in[11]) *  p) +
+			(carrier[25] * conj(in[25]) *  p) +
+			(carrier[39] * conj(in[39]) *  p) +
+			(carrier[53] * conj(in[53]) * -p);
+
+		freq_offset = (1 - alpha) * freq_offset + alpha * arg(sum);
+		freq_sum += freq_offset;
+
+		//std::cout << "lms: symbol " << n
+		//	<< "   p1 " << abs(carrier[11] * conj(in[11]) *  p)
+		//	<< "   p2 " << abs(carrier[25] * conj(in[25]) *  p)
+		//	<< "   p3 " << abs(carrier[39] * conj(in[39]) *  p)
+		//	<< "   p4 " << abs(carrier[53] * conj(in[53]) * -p)
+		//	<< std::endl;
+		//std::cout << "lms: symbol " << n
+		//	<< "   p1 " << arg(carrier[11] * conj(in[11]) *  p)
+		//	<< "   p2 " << arg(carrier[25] * conj(in[25]) *  p)
+		//	<< "   p3 " << arg(carrier[39] * conj(in[39]) *  p)
+		//	<< "   p4 " << arg(carrier[53] * conj(in[53]) * -p)
+		//	<< std::endl;
+
+		carrier[11] = in[11] *  p;
+		carrier[25] = in[25] *  p;
+		carrier[39] = in[39] *  p;
+		carrier[53] = in[53] * -p;
+
+		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 {
+				out[c] = in[i] / carrier[i] * exp(gr_complex(0, freq_sum));
+				c++;
+			}
+		}
+	}
+}
+
+const gr_complex lms::ref[] = {
+	 0,  0,  0,  0,  0,  0,  1,  1, -1, -1,
+	 1,  1, -1,  1, -1,  1,  1,  1,  1,  1,
+	 1, -1, -1,  1,  1, -1,  1, -1,  1,  1,
+	 1,  1,  0,  1, -1, -1,  1,  1, -1,  1,
+	-1,  1, -1, -1, -1, -1, -1,  1,  1, -1,
+	-1,  1, -1,  1, -1,  1,  1,  1,  1,  0,
+	 0,  0,  0,  0
+};
+
+const gr_complex lms::POLARITY[127] = {
+	 1, 1, 1, 1,-1,-1,-1, 1,-1,-1,-1,-1, 1, 1,-1, 1,
+	-1,-1, 1, 1,-1, 1, 1,-1, 1, 1, 1, 1, 1, 1,-1, 1,
+	 1, 1,-1, 1, 1,-1,-1, 1, 1, 1,-1, 1,-1,-1,-1, 1,
+	-1, 1,-1,-1, 1,-1,-1, 1, 1, 1, 1, 1,-1,-1, 1, 1,
+	-1,-1, 1,-1, 1,-1, 1, 1,-1,-1,-1, 1, 1,-1,-1,-1,
+	-1, 1,-1,-1, 1,-1, 1, 1, 1, 1,-1, 1,-1, 1,-1, 1,
+	-1,-1,-1,-1,-1, 1,-1, 1, 1,-1, 1,-1, 1, 1, 1,-1,
+	-1, 1,-1,-1,-1, 1, 1, 1,-1,-1,-1,-1,-1,-1,-1 };

lib/equalizer/lms.h

@@ -0,0 +1,42 @@
+/*
+ * 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/>.
+ */
+
+#ifndef INCLUDED_IEEE802_11_EQUALIZER_LMS_H
+#define INCLUDED_IEEE802_11_EQUALIZER_LMS_H
+
+#include "base.h"
+#include <vector>
+
+namespace gr {
+namespace ieee802_11 {
+namespace equalizer {
+
+class lms: public base {
+public:
+	virtual void equalize(const gr_complex *in, gr_complex *out, int n);
+private:
+	gr_complex carrier[64];
+	static const gr_complex ref[64];
+	static const gr_complex POLARITY[127];
+};
+
+} /* namespace channel_estimation */
+} /* namespace ieee802_11 */
+} /* namespace gr */
+
+#endif /* INCLUDED_IEEE802_11_EQUALIZER_LMS_H */
+

lib/ofdm_equalize_symbols.cc

@@ -17,6 +17,9 @@
 #include <ieee802-11/ofdm_equalize_symbols.h>
 
 #include "utils.h"
+#include "equalizer/base.h"
+#include "equalizer/linear_comb.h"
+#include "equalizer/lms.h"
 #include <gnuradio/io_signature.h>
 
 using namespace gr::ieee802_11;
@@ -25,12 +28,14 @@ using namespace gr::ieee802_11;
 class ofdm_equalize_symbols_impl : public ofdm_equalize_symbols {
 
 public:
-ofdm_equalize_symbols_impl(bool debug) : block("ofdm_equalize_symbols",
+ofdm_equalize_symbols_impl(Equalizer algo, bool debug) : block("ofdm_equalize_symbols",
 			gr::io_signature::make(1, 1, 64 * sizeof(gr_complex)),
 			gr::io_signature::make(1, 1, 48 * sizeof(gr_complex))),
-			d_debug(debug) {
+			d_debug(debug), d_equalizer(NULL) {
 
 	set_relative_rate(1);
+	set_tag_propagation_policy(block::TPP_DONT);
+	set_algorithm(algo);
 }
 
 ~ofdm_equalize_symbols_impl(){
@@ -40,87 +45,76 @@ int general_work (int noutput_items, gr_vector_int& ninput_items,
 		gr_vector_const_void_star& input_items,
 		gr_vector_void_star& output_items) {
 
+	gr::thread::scoped_lock lock(d_mutex);
+
 	const gr_complex *in = (const gr_complex*)input_items[0];
 	gr_complex *out = (gr_complex*)output_items[0];
 
-	int noutput = noutput_items;
 	int i = 0;
-
+	int o = 0;
-	std::vector<gr::tag_t> tags;
-	const uint64_t nread = nitems_read(0);
 
 	dout << "SYMBOLS: input " << ninput_items[0] << "  output " << noutput_items << std::endl;
 
-	while((i < ninput_items[0]) && (i < noutput)) {
+	while((i < ninput_items[0]) && (o < noutput_items)) {
 
-		get_tags_in_range(tags, 0, nread + i, nread + i + 1,
+		get_tags_in_window(tags, 0, i, i + 1, pmt::string_to_symbol("ofdm_start"));
-			pmt::string_to_symbol("ofdm_start"));
 
+		// new WiFi frame
 		if(tags.size()) {
-			index = 0;
+			d_nsym = 0;
 		}
 
-		gr_complex p = POLARITY[index];
+		// first data symbol (= signal field)
-		index++;
+		if(d_nsym == 2) {
-		index %= 127;
+			add_item_tag(0, nitems_written(0) + o,
+				pmt::string_to_symbol("ofdm_start"),
+				pmt::PMT_T,
+				pmt::string_to_symbol(name()));
+		}
 
-		// FIXME: think about this... average over amplitude or power
+		d_equalizer->equalize(in + (i * 64), out + (o * 48), d_nsym);
-		double avg_mag = (abs(in[11]) + abs(in[25]) + abs(in[39]) + abs(in[53])) / 4;
 
-
+		if(d_nsym > 1) {
-		double p1 = arg( p * in[11]);
-		double p2 = arg( p * in[25] * conj(p * in[11])) + p1;
-		double p3 = arg( p * in[39] * conj(p * in[25])) + p2;
-		double p4 = arg(-p * in[53] * conj(p * in[39])) + p3;
-
-		double my = (p1 + p2 + p3 + p4) / 4;
-		double mx = (11.0 + 25 + 39 + 53) / 4;
-
-		double var = (((11.0 * 11.0) + (25.0 * 25.0) + (39.0 * 39.0) + (53.0 * 53.0)) / 4) - (mx * mx);
-		double cov =  (( (p1 * 11) + (p2 * 25) + (p3 * 39) + (p4 * 53) ) / 4) - (mx * my);
-		double beta = cov / var;
-		double alpha = my - beta * mx;
-
-		int o = 0;
-		for(int n = 0; n < 64; n++) {
-			if( (n == 11) || (n == 25) || (n == 32) || (n == 39) || (n == 53) || (n < 6) || ( n > 58)) {
-				continue;
-			} else {
-				// FIXME: think about this... square or not
-				out[o] = in[n] * exp(gr_complex(0, -n * beta - alpha)) * gr_complex(1 / avg_mag, 0);
 			o++;
 		}
-		}
-
 		i++;
-		in += 64;
+		d_nsym++;
-		out += 48;
 	}
 
-	dout << "SYMBOLS: produced / consumed " << i << std::endl;
+	dout << "SYMBOLS: consumed " << i << "  produced " << o << std::endl;
 
 	consume(0, i);
-	return i;
+	return o;
+}
+
+void set_algorithm(Equalizer algo) {
+	gr::thread::scoped_lock lock(d_mutex);
+	delete d_equalizer;
+
+	switch(algo) {
+	case LMS:
+		dout << "LMS" << std::endl;
+		d_equalizer = new equalizer::lms();
+		break;
+
+	case LINEAR_COMB:
+		dout << "Linear Comb" << std::endl;
+		d_equalizer = new equalizer::linear_comb();
+		break;
+	}
 }
 
 private:
-	int          index;
+	int          d_nsym;
 	const bool   d_debug;
-	static const gr_complex POLARITY[127];
+	equalizer::base *d_equalizer;
+	std::vector<gr::tag_t> tags;
+	gr::thread::mutex d_mutex;
 };
 
-const gr_complex ofdm_equalize_symbols_impl::POLARITY[127] = {
-		 1, 1, 1, 1,-1,-1,-1, 1,-1,-1,-1,-1, 1, 1,-1, 1,
-		-1,-1, 1, 1,-1, 1, 1,-1, 1, 1, 1, 1, 1, 1,-1, 1,
-		 1, 1,-1, 1, 1,-1,-1, 1, 1, 1,-1, 1,-1,-1,-1, 1,
-		-1, 1,-1,-1, 1,-1,-1, 1, 1, 1, 1, 1,-1,-1, 1, 1,
-		-1,-1, 1,-1, 1,-1, 1, 1,-1,-1,-1, 1, 1,-1,-1,-1,
-		-1, 1,-1,-1, 1,-1, 1, 1, 1, 1,-1, 1,-1, 1,-1, 1,
-		-1,-1,-1,-1,-1, 1,-1, 1, 1,-1, 1,-1, 1, 1, 1,-1,
-		-1, 1,-1,-1,-1, 1, 1, 1,-1,-1,-1,-1,-1,-1,-1 };
 
 ofdm_equalize_symbols::sptr
-ofdm_equalize_symbols::make(bool debug) {
+ofdm_equalize_symbols::make(Equalizer algo, bool debug) {
-	return gnuradio::get_initial_sptr(new ofdm_equalize_symbols_impl(debug));
+	return gnuradio::get_initial_sptr(new ofdm_equalize_symbols_impl(algo, debug));
 }