diff --git a/grc/ieee802_11_decode_mac.xml b/grc/ieee802_11_decode_mac.xml
index 28b950d..c89b5a3 100644
--- a/grc/ieee802_11_decode_mac.xml
+++ b/grc/ieee802_11_decode_mac.xml
@@ -41,9 +41,8 @@
 
 	<sink>
 		<name>in</name>
-		<type>complex</type>
+		<type>byte</type>
 		<vlen>48</vlen>
-		<nports>1</nports>
 	</sink>
 
 	<source>
diff --git a/lib/decode_mac.cc b/lib/decode_mac.cc
index 9d23f4e..448378e 100644
--- a/lib/decode_mac.cc
+++ b/lib/decode_mac.cc
@@ -17,58 +17,35 @@
 #include <ieee802-11/decode_mac.h>
 
 #include "utils.h"
+#include "viterbi_decoder.h"
 
 #include <boost/crc.hpp>
 #include <gnuradio/io_signature.h>
-#include <itpp/itcomm.h>
-#include <iomanip>
 
 using namespace gr::ieee802_11;
-using namespace itpp;
 
 class decode_mac_impl : public decode_mac {
 
 public:
-decode_mac_impl(bool log, bool debug) : block("decode_mac",
-			gr::io_signature::make(1, 1, 48 * sizeof(gr_complex)),
+decode_mac_impl(bool log, bool debug) :
+	block("decode_mac",
+			gr::io_signature::make(1, 1, 48),
 			gr::io_signature::make(0, 0, 0)),
-			d_log(log),
-			d_debug(debug),
-			d_ofdm(BPSK_1_2),
-			d_frame(d_ofdm, 0),
-			d_frame_complete(true) {
+	d_log(log),
+	d_debug(debug),
+	d_snr(0),
+	d_ofdm(BPSK_1_2),
+	d_frame(d_ofdm, 0),
+	d_frame_complete(true) {
 
 	message_port_register_out(pmt::mp("out"));
-
-	// bpsk
-	int bpsk_bits[] = {0, 1};
-	bpsk.set(cvec(BPSK_D, 2), ivec(bpsk_bits, 2));
-
-	// qpsk
-	int qpsk_bits[] = {0, 1, 2, 3};
-	qpsk.set(cvec(QPSK_D, 4), ivec(qpsk_bits, 4));
-
-	// qam16
-	int qam16_bits[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
-	qam16.set(cvec(QAM16_D, 16), ivec(qam16_bits, 16));
-
-	// qam64
-	int qam64_bits[] = {
-		 0,  1,  2,  3,  4,  5,  6,  7,  8,  9,
-		10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
-		20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
-		30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
-		40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
-		50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
-		60, 61, 62, 63};
-	qam64.set(cvec(QAM64_D, 64), ivec(qam64_bits, 64));
 }
 
 int general_work (int noutput_items, gr_vector_int& ninput_items,
 		gr_vector_const_void_star& input_items,
 		gr_vector_void_star& output_items) {
 
-	const gr_complex *in = (const gr_complex*)input_items[0];
+	const uint8_t *in = (const uint8_t*)input_items[0];
 
 	int i = 0;
 
@@ -90,14 +67,15 @@ int general_work (int noutput_items, gr_vector_int& ninput_items,
 			d_frame_complete = false;
 
 			pmt::pmt_t tuple = tags[0].value;
-			int len_data = pmt::to_uint64(pmt::car(tuple));
-			int encoding = pmt::to_uint64(pmt::cdr(tuple));
+			int len_data = pmt::to_uint64(pmt::tuple_ref(tuple, 0));
+			int encoding = pmt::to_uint64(pmt::tuple_ref(tuple, 1));
+			d_snr = pmt::to_double(pmt::tuple_ref(tuple, 2));
 
 			ofdm_param ofdm = ofdm_param((Encoding)encoding);
 			frame_param frame = frame_param(ofdm, len_data);
 
-			// sanity check, more than MAX_SYM may indicate garbage
-			if(frame.n_sym <= MAX_SYM && frame.n_encoded_bits <= MAX_BITS) {
+			// check for maximum frame size
+			if(frame.n_sym <= MAX_SYM && frame.psdu_size <= MAX_FRAME_SIZE) {
 				d_ofdm = ofdm;
 				d_frame = frame;
 				copied = 0;
@@ -111,7 +89,7 @@ int general_work (int noutput_items, gr_vector_int& ninput_items,
 
 		if(copied < d_frame.n_sym) {
 			dout << "copy one symbol, copied " << copied << " out of " << d_frame.n_sym << std::endl;
-			std::memcpy(sym + (copied * 48), in, 48 * sizeof(gr_complex));
+			std::memcpy(d_rx_symbols + (copied * 48), in, 48);
 			copied++;
 
 			if(copied == d_frame.n_sym) {
@@ -133,10 +111,16 @@ int general_work (int noutput_items, gr_vector_int& ninput_items,
 }
 
 void decode() {
-	demodulate();
+
+	for(int i = 0; i < d_frame.n_sym * 48; i++) {
+		for(int k = 0; k < d_ofdm.n_bpsc; k++) {
+			d_rx_bits[i*d_ofdm.n_bpsc + k] = !!(d_rx_symbols[i] & (1 << k));
+		}
+	}
+
 	deinterleave();
-	decode_conv();
-	descramble();
+	uint8_t *decoded = d_decoder.decode(&d_ofdm, &d_frame, d_deinterleaved_bits);
+	descramble(decoded);
 	print_output();
 
 	// skip service field
@@ -155,44 +139,10 @@ void decode() {
 	pmt::pmt_t enc = pmt::from_uint64(d_ofdm.encoding);
 	pmt::pmt_t dict = pmt::make_dict();
 	dict = pmt::dict_add(dict, pmt::mp("encoding"), enc);
+	dict = pmt::dict_add(dict, pmt::mp("snr"), pmt::from_double(d_snr));
 	message_port_pub(pmt::mp("out"), pmt::cons(dict, blob));
 }
 
-void demodulate() {
-
-	cvec symbols;
-	symbols.set_length(d_frame.n_sym * 48);
-	for(int i = 0; i < d_frame.n_sym * 48; i++) {
-		symbols[i] = std::complex<double>(sym[i]);
-	}
-
-	switch(d_ofdm.encoding) {
-	case BPSK_1_2:
-	case BPSK_3_4:
-
-		bits = to_vec(bpsk.demodulate_bits(symbols));
-		break;
-
-	case QPSK_1_2:
-	case QPSK_3_4:
-
-		bits = to_vec(qpsk.demodulate_bits(symbols));
-		break;
-
-	case QAM16_1_2:
-	case QAM16_3_4:
-		bits = to_vec(qam16.demodulate_bits(symbols));
-		break;
-	case QAM64_2_3:
-	case QAM64_3_4:
-		bits = to_vec(qam64.demodulate_bits(symbols));
-		break;
-	}
-
-	// I hate the guy who wrote itpp
-	bits = bits * (-2) + 1;
-}
-
 void deinterleave() {
 
 	int n_cbps = d_ofdm.n_cbps;
@@ -208,93 +158,50 @@ void deinterleave() {
 		second[i] = 16 * i - (n_cbps - 1) * int(floor(16.0 * i / n_cbps));
 	}
 
+	int count = 0;
 	for(int i = 0; i < d_frame.n_sym; i++) {
 		for(int k = 0; k < n_cbps; k++) {
-			deinter[i * n_cbps + second[first[k]]] = bits[i * n_cbps + k];
+			d_deinterleaved_bits[i * n_cbps + second[first[k]]] = d_rx_bits[i * n_cbps + k];
 		}
 	}
 }
 
-void decode_conv() {
-	Punctured_Convolutional_Code code;
-	ivec generator(2);
-	generator(0)=0133;
-	generator(1)=0171;
-	code.set_generator_polynomials(generator, 7);
 
-	bmat puncture_matrix;
-	switch(d_ofdm.encoding) {
-	case BPSK_1_2:
-	case QPSK_1_2:
-	case QAM16_1_2:
-		puncture_matrix = "1 1; 1 1";
-		break;
-	case BPSK_3_4:
-	case QPSK_3_4:
-	case QAM16_3_4:
-	case QAM64_3_4:
-		puncture_matrix = "1 1 0; 1 0 1;";
-		break;
-	case QAM64_2_3:
-		puncture_matrix = "1 1 1 1 1 1; 1 0 1 0 1 0;";
-		break;
-	}
-	code.set_puncture_matrix(puncture_matrix);
-	code.set_truncation_length(30);
+void descramble (uint8_t *decoded_bits) {
 
-	dout << "coding rate " << code.get_rate() << std::endl;
-	dout << d_frame.n_encoded_bits << std::endl;
-
-	vec rx_signal(deinter, d_frame.n_encoded_bits);
-
-	code.reset();
-	decoded_bits.set_length(d_frame.n_encoded_bits);
-	code.decode_tail(rx_signal, decoded_bits);
-
-	//dout << "length decoded " << decoded_bits.size() << std::endl;
-	//std::cout << decoded_bits << std::endl;
-}
-
-void descramble () {
 	int state = 0;
+	std::memset(out_bytes, 0, d_frame.n_data_bits/8 + 1);
+
 	for(int i = 0; i < 7; i++) {
-		if(decoded_bits(i)) {
+		if(decoded_bits[i]) {
 			state |= 1 << (6 - i);
 		}
 	}
+	out_bytes[0] = state;
 
 	int feedback;
+	int bit;
 
-	for(int i = 7; i < decoded_bits.size(); i++) {
+	for(int i = 7; i < d_frame.n_data_bits; i++) {
 		feedback = ((!!(state & 64))) ^ (!!(state & 8));
-		out_bits[i] = feedback ^ (int)decoded_bits(i);
+		bit = feedback ^ (decoded_bits[i] & 0x1);
+		out_bytes[i/8] |= bit << (i%8);
 		state = ((state << 1) & 0x7e) | feedback;
 	}
-
-	for(int i = 0; i < decoded_bits.size(); i++) {
-		int bit = i % 8;
-		int byte = i / 8;
-		if(bit == 0) {
-			out_bytes[byte] = 0;
-		}
-
-		if(out_bits[i]) {
-			out_bytes[byte] |= (1 << bit);
-		}
-	}
 }
 
 void print_output() {
 
 	dout << std::endl;
-	for(int i = 0; i < decoded_bits.size() / 8; i++) {
+	dout << "psdu size" << d_frame.n_data_bits / 8 << std::endl;
+	for(int i = 0; i < d_frame.psdu_size+2; i++) {
 		dout << std::setfill('0') << std::setw(2) << std::hex << ((unsigned int)out_bytes[i] & 0xFF) << std::dec << " ";
 		if(i % 16 == 15) {
 			dout << std::endl;
 		}
 	}
 	dout << std::endl;
-	for(int i = 0; i < decoded_bits.size() / 8; i++) {
+	for(int i = 0; i < d_frame.n_data_bits / 8; i++) {
 		if((out_bytes[i] > 31) && (out_bytes[i] < 127)) {
 			dout << ((char) out_bytes[i]);
 		} else {
@@ -305,28 +212,24 @@ void print_output() {
 }
 
 private:
-	gr_complex sym[1000 * 48 * 100];
-	vec bits;
-	double deinter[1000 * 48];
-	char out_bits[40000];
-	char out_bytes[40000];
-	bvec decoded_bits;
-
 	bool d_debug;
 	bool d_log;
+
 	frame_param d_frame;
 	ofdm_param d_ofdm;
+	double d_snr;
+	viterbi_decoder d_decoder;
+
+	uint8_t d_rx_symbols[48 * MAX_SYM];
+	uint8_t d_rx_bits[MAX_ENCODED_BITS];
+	uint8_t d_deinterleaved_bits[MAX_ENCODED_BITS];
+	uint8_t out_bytes[MAX_FRAME_SIZE];
+
 	int copied;
 	bool d_frame_complete;
-
-	Modulator<std::complex<double> > bpsk;
-	Modulator<std::complex<double> > qpsk;
-	Modulator<std::complex<double> > qam16;
-	Modulator<std::complex<double> > qam64;
 };
 
 decode_mac::sptr
 decode_mac::make(bool log, bool debug) {
 	return gnuradio::get_initial_sptr(new decode_mac_impl(log, debug));
 }
-
diff --git a/lib/mac.cc b/lib/mac.cc
index 22359de..4cea55a 100644
--- a/lib/mac.cc
+++ b/lib/mac.cc
@@ -66,8 +66,9 @@ mac_impl(std::vector<uint8_t> src_mac, std::vector<uint8_t> dst_mac, std::vector
 
 void phy_in (pmt::pmt_t msg) {
 	// this must be a pair
-	if (!pmt::is_blob(pmt::cdr(msg)))
+	if (!pmt::is_blob(pmt::cdr(msg))) {
 		throw std::runtime_error("PMT must be blob");
+	}
 
 	// strip MAC header
 	// TODO: check for frame type to determine header size
@@ -85,12 +86,7 @@ void app_in (pmt::pmt_t msg) {
 	const char   *msdu;
 	std::string  str;
 
-	if(pmt::is_eof_object(msg)) {
-		message_port_pub(pmt::mp("phy out"), pmt::PMT_EOF);
-		detail().get()->set_done(true);
-		return;
-
-	} else if(pmt::is_symbol(msg)) {
+	if(pmt::is_symbol(msg)) {
 
 		str = pmt::symbol_to_string(msg);
 		msg_len = str.length();
@@ -103,10 +99,10 @@ void app_in (pmt::pmt_t msg) {
 
 	} else {
 		throw std::invalid_argument("MAC expects PDUs or strings");
-                return;
+		return;
 	}
 
-	if(msg_len > 1500) {
+	if(msg_len >= MAX_FRAME_SIZE - 32) {
 		throw std::invalid_argument("Frame too large (> 1500)");
 	}
 
diff --git a/lib/mapper.cc b/lib/mapper.cc
index dc5c4b3..73b1c42 100644
--- a/lib/mapper.cc
+++ b/lib/mapper.cc
@@ -66,12 +66,11 @@ int general_work(int noutput, gr_vector_int& ninput_items,
 		"   length: " << d_symbols_len << std::endl;
 
 	while(!d_symbols_offset) {
-		pmt::pmt_t msg(delete_head_blocking(pmt::intern("in")));
+		pmt::pmt_t msg(delete_head_nowait(pmt::intern("in")));
 
-                if(pmt::is_eof_object(msg)) {
-			dout << "MAPPER: exiting" << std::endl;
-                        return -1;
-                }
+		if(!msg.get()) {
+			return 0;
+		}
 
 		if(pmt::is_pair(msg)) {
 			dout << "MAPPER: received new message" << std::endl;
@@ -88,16 +87,15 @@ int general_work(int noutput, gr_vector_int& ninput_items,
 			}
 
 			//alloc memory for modulation steps
-			char *data_bits        = (char*)calloc(frame.n_data, sizeof(char));
-			char *scrambled_data   = (char*)calloc(frame.n_data, sizeof(char));
-			char *encoded_data     = (char*)calloc(frame.n_data * 2, sizeof(char));
+			char *data_bits        = (char*)calloc(frame.n_data_bits, sizeof(char));
+			char *scrambled_data   = (char*)calloc(frame.n_data_bits, sizeof(char));
+			char *encoded_data     = (char*)calloc(frame.n_data_bits * 2, sizeof(char));
 			char *punctured_data   = (char*)calloc(frame.n_encoded_bits, sizeof(char));
 			char *interleaved_data = (char*)calloc(frame.n_encoded_bits, sizeof(char));
 			char *symbols          = (char*)calloc((frame.n_encoded_bits / d_ofdm.n_bpsc), sizeof(char));
 
 			//generate the WIFI data field, adding service field and pad bits
 			generate_bits(psdu, data_bits, frame);
-			//print_hex_array(data_bits, frame.n_data);
 
 			// scrambling
 			static uint8_t scrambler = 1;
@@ -106,13 +104,10 @@ int general_work(int noutput, gr_vector_int& ninput_items,
 				scrambler = 1;
 			}
 
-			//print_hex_array(scrambled_data, frame.n_data);
 			// reset tail bits
 			reset_tail_bits(scrambled_data, frame);
-			//print_hex_array(scrambled_data, frame.n_data);
 			// encoding
 			convolutional_encoding(scrambled_data, encoded_data, frame);
-			//print_hex_array(encoded_data, frame.n_data * 2);
 			// puncturing
 			puncturing(encoded_data, punctured_data, frame, d_ofdm);
 			//std::cout << "punctured" << std::endl;
@@ -120,7 +115,7 @@ int general_work(int noutput, gr_vector_int& ninput_items,
 			interleave(punctured_data, interleaved_data, frame, d_ofdm);
 			//std::cout << "interleaved" << std::endl;
 
-                        // one byte per symbol
+			// one byte per symbol
 			split_symbols(interleaved_data, symbols, frame, d_ofdm);
 
 			d_symbols_len = frame.n_sym * 48;
diff --git a/lib/signal_field_impl.cc b/lib/signal_field_impl.cc
index 92270dc..78d4c6b 100644
--- a/lib/signal_field_impl.cc
+++ b/lib/signal_field_impl.cc
@@ -88,14 +88,11 @@ void signal_field_impl::generate_signal_field(char *out, frame_param &frame, ofd
 	}
 
 	ofdm_param signal_ofdm(BPSK_1_2);
-	frame_param signal_param(signal_ofdm, 3);
-	signal_param.n_data = 24;
-	signal_param.n_sym = 1;
+	frame_param signal_param(signal_ofdm, 0);
 
 	// convolutional encoding (scrambling is not needed)
 	convolutional_encoding(signal_header, encoded_signal_header, signal_param);
 	// interleaving
-	//interleave(encoded_signal_header, interleaved_signal_header, signal_param, signal_ofdm);
 	interleave(encoded_signal_header, out, signal_param, signal_ofdm);
 
 	free(signal_header);