add ofdm_utils

lib/CMakeLists.txt

@@ -28,6 +28,7 @@ list(APPEND gr_ieee802_11_sources
     ofdm_parse_mac.cc
     ofdm_sync_long.cc
     ofdm_sync_short.cc
+    ofdm_utils.cc
 )
 
 list(APPEND gr_ieee802_11_libs

lib/ofdm_utils.cc

@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2013 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 "ofdm_utils.h"
+
+#include <boost/crc.hpp>
+#include <cassert>
+#include <cstring>
+#include <iostream>
+#include <math.h>
+
+
+ofdm_param::ofdm_param(ENCODING e) {
+	encoding = e;
+
+	switch(e) {
+		case BPSK_1_2:
+			n_bpsc = 1;
+			n_cbps = 48;
+			n_dbps = 24;
+			rate_field = 0x0D; // 0b00001101
+			break;
+
+		case BPSK_3_4:
+			n_bpsc = 1;
+			n_cbps = 48;
+			n_dbps = 36;
+			rate_field = 0x0F; // 0b00001111
+			break;
+
+		case QPSK_1_2:
+			n_bpsc = 2;
+			n_cbps = 96;
+			n_dbps = 48;
+			rate_field = 0x05; // 0b00000101
+			break;
+
+		case QPSK_3_4:
+			n_bpsc = 2;
+			n_cbps = 96;
+			n_dbps = 72;
+			rate_field = 0x07; // 0b00000111
+			break;
+
+		case QAM16_1_2:
+			n_bpsc = 4;
+			n_cbps = 192;
+			n_dbps = 96;
+			rate_field = 0x09; // 0b00001001
+			break;
+
+		case QAM16_3_4:
+			n_bpsc = 4;
+			n_cbps = 192;
+			n_dbps = 144;
+			rate_field = 0x0B; // 0b00001011
+			break;
+
+		case QAM64_2_3:
+			n_bpsc = 6;
+			n_cbps = 288;
+			n_dbps = 192;
+			rate_field = 0x01; // 0b00000001
+			break;
+
+		case QAM64_3_4:
+			n_bpsc = 6;
+			n_cbps = 288;
+			n_dbps = 216;
+			rate_field = 0x03; // 0b00000011
+			break;
+		defaut:
+			assert(false);
+			break;
+	}
+}
+
+void
+ofdm_param::print_out() {
+	std::cout << "OFDM Parameters:" << std::endl;
+	std::cout << "endcoding :" << encoding << std::endl;
+	std::cout << "rate_field :" << (int)rate_field << std::endl;
+	std::cout << "n_bpsc :" << n_bpsc << std::endl;
+	std::cout << "n_cbps :" << n_cbps << std::endl;
+	std::cout << "n_dbps :" << n_dbps << std::endl;
+}
+
+tx_param::tx_param(ofdm_param &ofdm, int psdu_length) {
+
+	psdu_size = psdu_length;
+
+	// number of symbols (17-11)
+	n_sym = (int) ceil((16 + 8 * psdu_size + 6) / (double) ofdm.n_dbps);
+
+	// number of bits of the data field (17-12)
+	n_data = n_sym * ofdm.n_dbps;
+
+	// number of padding bits (17-13)
+	n_pad = n_data - (16 + 8 * psdu_size + 6);
+
+	n_encoded_bits = n_sym * ofdm.n_cbps;
+}
+void
+tx_param::print_out() {
+	std::cout << "TX Parameters:" << std::endl;
+	std::cout << "psdu_size: " << psdu_size << std::endl;
+	std::cout << "n_sym: " << n_sym << std::endl;
+	std::cout << "n_data: " << n_data << std::endl;
+	std::cout << "n_pad: " << n_pad << std::endl;
+}
+

lib/ofdm_utils.h

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2013 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_OFDM_UTILS_H
+#define INCLUDED_IEEE802_11_OFDM_UTILS_H
+
+#include <ieee802-11/api.h>
+
+/**
+ * Define structure for the MAC header of a data frame.
+ * Values as stored as MSB, but standard mandates LSB
+ * representation. Bit utils functions can help changing
+ * endiannes
+ */
+struct MAC_DATAFRAME_HEADER {
+    char frame_control[2];  //protocol version, type, subtype, to_ds, from_ds, ...
+    char duration[2];       //duration field
+    char address1[6];       //address 1 indicating BSSID: 6 bytes MAC address
+    char address2[6];       //address 2 indicating receiver
+    char address3[6];       //address 3 indicating sender
+    char sequence[2];       //sequence number plus fragment number
+};
+
+enum ENCODING {
+	BPSK_1_2  = 0,
+	BPSK_3_4  = 1,
+	QPSK_1_2  = 2,
+	QPSK_3_4  = 3,
+	QAM16_1_2 = 4,
+	QAM16_3_4 = 5,
+	QAM64_2_3 = 6,
+	QAM64_3_4 = 7,
+};
+
+/**
+ * OFDM parameters
+ */
+class ofdm_param {
+public:
+	ofdm_param(ENCODING e);
+
+	// data rate
+	ENCODING encoding;
+	// rate field of the SIGNAL header
+	char     rate_field;
+	// number of coded bits per sub carrier
+	int      n_bpsc;
+	// number of coded bits per OFDM symbol
+	int      n_cbps;
+	// number of data bits per OFDM symbol
+	int      n_dbps;
+
+	void print_out();
+};
+
+/**
+ * packet specific parameters
+ */
+class tx_param {
+public:
+	tx_param(ofdm_param &ofdm, int psdu_length);
+	// PSDU size in bytes
+	int psdu_size;
+	// number of OFDM symbols (17-11)
+	int n_sym;
+	// number of data bits in the DATA field, including service and padding (17-12)
+	int n_data;
+	// number of padding bits in the DATA field (17-13)
+	int n_pad;
+	int n_encoded_bits;
+
+	void print_out();
+};
+
+#endif /* INCLUDED_IEEE802_11_OFDM_UTILS_H */