convcode.cpp
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#include <itpp/comm/convcode.h>
#include <itpp/base/binary.h>
#include <itpp/base/matfunc.h>
#include <limits>
namespace itpp
{
// ----------------- Protected functions -----------------------------
/*
The weight of the transition from given state with the input given
*/
int Convolutional_Code::weight(const int state, const int input)
{
int i, j, temp, out, w = 0, shiftreg = state;
shiftreg = shiftreg | (input << m);
for (j = 0; j < n; j++) {
out = 0;
temp = shiftreg & gen_pol(j);
for (i = 0; i < K; i++) {
out ^= (temp & 1);
temp = temp >> 1;
}
w += out;
//w += weight_int_table(temp);
}
return w;
}
/*
The weight (of the reverse code) of the transition from given state with
the input given
*/
int Convolutional_Code::weight_reverse(const int state, const int input)
{
int i, j, temp, out, w = 0, shiftreg = state;
shiftreg = shiftreg | (input << m);
for (j = 0; j < n; j++) {
out = 0;
temp = shiftreg & gen_pol_rev(j);
for (i = 0; i < K; i++) {
out ^= (temp & 1);
temp = temp >> 1;
}
w += out;
//w += weight_int_table(temp);
}
return w;
}
/*
The weight of the two paths (input 0 or 1) from given state
*/
void Convolutional_Code::weight(const int state, int &w0, int &w1)
{
int i, j, temp, out, shiftreg = state;
w0 = 0;
w1 = 0;
shiftreg = shiftreg | (1 << m);
for (j = 0; j < n; j++) {
out = 0;
temp = shiftreg & gen_pol(j);
for (i = 0; i < m; i++) {
out ^= (temp & 1);
temp = temp >> 1;
}
w0 += out;
w1 += out ^(temp & 1);
}
}
/*
The weight (of the reverse code) of the two paths (input 0 or 1) from
given state
*/
void Convolutional_Code::weight_reverse(const int state, int &w0, int &w1)
{
int i, j, temp, out, shiftreg = state;
w0 = 0;
w1 = 0;
shiftreg = shiftreg | (1 << m);
for (j = 0; j < n; j++) {
out = 0;
temp = shiftreg & gen_pol_rev(j);
for (i = 0; i < m; i++) {
out ^= (temp & 1);
temp = temp >> 1;
}
w0 += out;
w1 += out ^(temp & 1);
}
}
/*
Output on transition (backwards) with input from state
*/
bvec Convolutional_Code::output_reverse(const int state, const int input)
{
int j, temp, temp_state;
bvec output(n);
temp_state = (state << 1) | input;
for (j = 0; j < n; j++) {
temp = temp_state & gen_pol(j);
output(j) = xor_int_table(temp);
}
return output;
}
/*
Output on transition (backwards) with input from state
*/
void Convolutional_Code::output_reverse(const int state, bvec &zero_output,
bvec &one_output)
{
int j, temp, temp_state;
bin one_bit;
temp_state = (state << 1) | 1;
for (j = 0; j < n; j++) {
temp = temp_state & gen_pol(j);
one_bit = temp & 1;
temp = temp >> 1;
one_output(j) = xor_int_table(temp) ^ one_bit;
zero_output(j) = xor_int_table(temp);
}
}
/*
Output on transition (backwards) with input from state
*/
void Convolutional_Code::output_reverse(const int state, int &zero_output,
int &one_output)
{
int j, temp, temp_state;
bin one_bit;
zero_output = 0, one_output = 0;
temp_state = (state << 1) | 1;
for (j = 0; j < n; j++) {
temp = temp_state & gen_pol(j);
one_bit = temp & 1;
temp = temp >> 1;
one_output = (one_output << 1) | int(xor_int_table(temp) ^ one_bit);
zero_output = (zero_output << 1) | int(xor_int_table(temp));
}
}
/*
Output on transition (backwards) with input from state
*/
void Convolutional_Code::calc_metric_reverse(int state,
const vec &rx_codeword,
double &zero_metric,
double &one_metric)
{
int temp;
bin one_bit;
one_metric = zero_metric = 0;
int temp_state = (state << 1) | 1;
for (int j = 0; j < n; j++) {
temp = temp_state & gen_pol(j);
one_bit = temp & 1;
temp >>= 1;
one_metric += (2 * static_cast<int>(xor_int_table(temp) ^ one_bit) - 1)
* rx_codeword(j);
zero_metric += (2 * static_cast<int>(xor_int_table(temp)) - 1)
* rx_codeword(j);
}
}
// calculates metrics for all codewords (2^n of them) in natural order
void Convolutional_Code::calc_metric(const vec &rx_codeword,
vec &delta_metrics)
{
int no_outputs = pow2i(n), no_loop = pow2i(n - 1), mask = no_outputs - 1,
temp;
delta_metrics.set_size(no_outputs, false);
if (no_outputs <= no_states) {
for (int i = 0; i < no_loop; i++) { // all input possibilities
delta_metrics(i) = 0;
temp = i;
for (int j = n - 1; j >= 0; j--) {
if (temp & 1)
delta_metrics(i) += rx_codeword(j);
else
delta_metrics(i) -= rx_codeword(j);
temp >>= 1;
}
delta_metrics(i ^ mask) = -delta_metrics(i); // the inverse codeword
}
}
else {
double zero_metric, one_metric;
int zero_output, one_output, temp_state;
bin one_bit;
for (int s = 0; s < no_states; s++) { // all states
zero_metric = 0, one_metric = 0;
zero_output = 0, one_output = 0;
temp_state = (s << 1) | 1;
for (int j = 0; j < n; j++) {
temp = temp_state & gen_pol(j);
one_bit = temp & 1;
temp >>= 1;
if (xor_int_table(temp)) {
zero_metric += rx_codeword(j);
}
else {
zero_metric -= rx_codeword(j);
}
if (static_cast<int>(xor_int_table(temp)^one_bit)) {
one_metric += rx_codeword(j);
} else {
one_metric -= rx_codeword(j);
}
one_output = (one_output << 1)
| static_cast<int>(xor_int_table(temp) ^ one_bit);
zero_output = (zero_output << 1)
| static_cast<int>(xor_int_table(temp));
}
delta_metrics(zero_output) = zero_metric;
delta_metrics(one_output) = one_metric;
}
}
}
// MFD codes R=1/2
int Conv_Code_MFD_2[15][2] = {
{0, 0},
{0, 0},
{0, 0},
{05, 07},
{015, 017},
{023, 035},
{053, 075},
{0133, 0171},
{0247, 0371},
{0561, 0753},
{01167, 01545},
{02335, 03661},
{04335, 05723},
{010533, 017661},
{021675, 027123},
};
// MFD codes R=1/3
int Conv_Code_MFD_3[15][3] = {
{0, 0, 0},
{0, 0, 0},
{0, 0, 0},
{05, 07, 07},
{013, 015, 017},
{025, 033, 037},
{047, 053, 075},
{0133, 0145, 0175},
{0225, 0331, 0367},
{0557, 0663, 0711},
{0117, 01365, 01633},
{02353, 02671, 03175},
{04767, 05723, 06265},
{010533, 010675, 017661},
{021645, 035661, 037133},
};
// MFD codes R=1/4
int Conv_Code_MFD_4[15][4] = {
{0, 0, 0, 0},
{0, 0, 0, 0},
{0, 0, 0, 0},
{05, 07, 07, 07},
{013, 015, 015, 017},
{025, 027, 033, 037},
{053, 067, 071, 075},
{0135, 0135, 0147, 0163},
{0235, 0275, 0313, 0357},
{0463, 0535, 0733, 0745},
{0117, 01365, 01633, 01653},
{02327, 02353, 02671, 03175},
{04767, 05723, 06265, 07455},
{011145, 012477, 015573, 016727},
{021113, 023175, 035527, 035537},
};
// MFD codes R=1/5
int Conv_Code_MFD_5[9][5] = {
{0, 0, 0, 0, 0},
{0, 0, 0, 0, 0},
{0, 0, 0, 0, 0},
{07, 07, 07, 05, 05},
{017, 017, 013, 015, 015},
{037, 027, 033, 025, 035},
{075, 071, 073, 065, 057},
{0175, 0131, 0135, 0135, 0147},
{0257, 0233, 0323, 0271, 0357},
};
// MFD codes R=1/6
int Conv_Code_MFD_6[9][6] = {
{0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0},
{07, 07, 07, 07, 05, 05},
{017, 017, 013, 013, 015, 015},
{037, 035, 027, 033, 025, 035},
{073, 075, 055, 065, 047, 057},
{0173, 0151, 0135, 0135, 0163, 0137},
{0253, 0375, 0331, 0235, 0313, 0357},
};
// MFD codes R=1/7
int Conv_Code_MFD_7[9][7] = {
{0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0},
{07, 07, 07, 07, 05, 05, 05},
{017, 017, 013, 013, 013, 015, 015},
{035, 027, 025, 027, 033, 035, 037},
{053, 075, 065, 075, 047, 067, 057},
{0165, 0145, 0173, 0135, 0135, 0147, 0137},
{0275, 0253, 0375, 0331, 0235, 0313, 0357},
};
// MFD codes R=1/8
int Conv_Code_MFD_8[9][8] = {
{0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0},
{0, 0, 0, 0, 0, 0, 0, 0},
{07, 07, 05, 05, 05, 07, 07, 07},
{017, 017, 013, 013, 013, 015, 015, 017},
{037, 033, 025, 025, 035, 033, 027, 037},
{057, 073, 051, 065, 075, 047, 067, 057},
{0153, 0111, 0165, 0173, 0135, 0135, 0147, 0137},
{0275, 0275, 0253, 0371, 0331, 0235, 0313, 0357},
};
int maxK_Conv_Code_MFD[9] = {0, 0, 14, 14, 14, 8, 8, 8, 8};
void get_MFD_gen_pol(int n, int K, ivec & gen)
{
gen.set_size(n);
switch (n) {
case 2: // Rate 1/2
it_assert(K >= 3 && K <= maxK_Conv_Code_MFD[2], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_MFD_2[K][0];
gen(1) = Conv_Code_MFD_2[K][1];
break;
case 3: // Rate 1/3
it_assert(K >= 3 && K <= maxK_Conv_Code_MFD[3], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_MFD_3[K][0];
gen(1) = Conv_Code_MFD_3[K][1];
gen(2) = Conv_Code_MFD_3[K][2];
break;
case 4: // Rate 1/4
it_assert(K >= 3 && K <= maxK_Conv_Code_MFD[4], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_MFD_4[K][0];
gen(1) = Conv_Code_MFD_4[K][1];
gen(2) = Conv_Code_MFD_4[K][2];
gen(3) = Conv_Code_MFD_4[K][3];
break;
case 5: // Rate 1/5
it_assert(K >= 3 && K <= maxK_Conv_Code_MFD[5], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_MFD_5[K][0];
gen(1) = Conv_Code_MFD_5[K][1];
gen(2) = Conv_Code_MFD_5[K][2];
gen(3) = Conv_Code_MFD_5[K][3];
gen(4) = Conv_Code_MFD_5[K][4];
break;
case 6: // Rate 1/6
it_assert(K >= 3 && K <= maxK_Conv_Code_MFD[6], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_MFD_6[K][0];
gen(1) = Conv_Code_MFD_6[K][1];
gen(2) = Conv_Code_MFD_6[K][2];
gen(3) = Conv_Code_MFD_6[K][3];
gen(4) = Conv_Code_MFD_6[K][4];
gen(5) = Conv_Code_MFD_6[K][5];
break;
case 7: // Rate 1/7
it_assert(K >= 3 && K <= maxK_Conv_Code_MFD[7], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_MFD_7[K][0];
gen(1) = Conv_Code_MFD_7[K][1];
gen(2) = Conv_Code_MFD_7[K][2];
gen(3) = Conv_Code_MFD_7[K][3];
gen(4) = Conv_Code_MFD_7[K][4];
gen(5) = Conv_Code_MFD_7[K][5];
gen(6) = Conv_Code_MFD_7[K][6];
break;
case 8: // Rate 1/8
it_assert(K >= 3 && K <= maxK_Conv_Code_MFD[8], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_MFD_8[K][0];
gen(1) = Conv_Code_MFD_8[K][1];
gen(2) = Conv_Code_MFD_8[K][2];
gen(3) = Conv_Code_MFD_8[K][3];
gen(4) = Conv_Code_MFD_8[K][4];
gen(5) = Conv_Code_MFD_8[K][5];
gen(6) = Conv_Code_MFD_8[K][6];
gen(7) = Conv_Code_MFD_8[K][7];
break;
default: // wrong rate
it_assert(false, "This convolutional code doesn't exist in the tables");
}
}
// ODS codes R=1/2
int Conv_Code_ODS_2[17][2] = {
{0, 0},
{0, 0},
{0, 0},
{05, 07},
{015, 017},
{023, 035},
{053, 075},
{0133, 0171},
{0247, 0371},
{0561, 0753},
{01151, 01753},
{03345, 03613},
{05261, 07173},
{012767, 016461},
{027251, 037363},
{063057, 044735},
{0126723, 0152711},
};
// ODS codes R=1/3
int Conv_Code_ODS_3[14][3] = {
{0, 0, 0},
{0, 0, 0},
{0, 0, 0},
{05, 07, 07},
{013, 015, 017},
{025, 033, 037},
{047, 053, 075},
{0133, 0165, 0171},
{0225, 0331, 0367},
{0575, 0623, 0727},
{01233, 01375, 01671},
{02335, 02531, 03477},
{05745, 06471, 07553},
{013261, 015167, 017451},
};
// ODS codes R=1/4
int Conv_Code_ODS_4[12][4] = {
{0, 0, 0, 0},
{0, 0, 0, 0},
{0, 0, 0, 0},
{05, 05, 07, 07},
{013, 015, 015, 017},
{025, 027, 033, 037},
{051, 055, 067, 077},
{0117, 0127, 0155, 0171},
{0231, 0273, 0327, 0375},
{0473, 0513, 0671, 0765},
{01173, 01325, 01467, 01751},
{02565, 02747, 03311, 03723},
};
int maxK_Conv_Code_ODS[5] = {0, 0, 16, 13, 11};
void get_ODS_gen_pol(int n, int K, ivec & gen)
{
gen.set_size(n);
switch (n) {
case 2: // Rate 1/2
it_assert(K >= 3 && K <= maxK_Conv_Code_ODS[2], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_ODS_2[K][0];
gen(1) = Conv_Code_ODS_2[K][1];
break;
case 3: // Rate 1/3
it_assert(K >= 3 && K <= maxK_Conv_Code_ODS[3], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_ODS_3[K][0];
gen(1) = Conv_Code_ODS_3[K][1];
gen(2) = Conv_Code_ODS_3[K][2];
break;
case 4: // Rate 1/4
it_assert(K >= 3 && K <= maxK_Conv_Code_ODS[4], "This convolutional code doesn't exist in the tables");
gen(0) = Conv_Code_ODS_4[K][0];
gen(1) = Conv_Code_ODS_4[K][1];
gen(2) = Conv_Code_ODS_4[K][2];
gen(3) = Conv_Code_ODS_4[K][3];
break;
default: // wrong rate
it_assert(false, "This convolutional code doesn't exist in the tables");
}
}
// --------------- Public functions -------------------------
void Convolutional_Code::set_code(const CONVOLUTIONAL_CODE_TYPE type_of_code,
int inverse_rate, int constraint_length)
{
ivec gen;
if (type_of_code == MFD)
get_MFD_gen_pol(inverse_rate, constraint_length, gen);
else if (type_of_code == ODS)
get_ODS_gen_pol(inverse_rate, constraint_length, gen);
else
it_assert(false, "This convolutional code doesn't exist in the tables");
set_generator_polynomials(gen, constraint_length);
}
/*
Set generator polynomials. Given in Proakis integer form
*/
void Convolutional_Code::set_generator_polynomials(const ivec &gen,
int constraint_length)
{
it_error_if(constraint_length <= 0, "Convolutional_Code::set_generator_polynomials(): Constraint length out of range");
gen_pol = gen;
n = gen.size();
it_error_if(n <= 0, "Convolutional_Code::set_generator_polynomials(): Invalid code rate");
// Generate table look-up of weight of integers of size K bits
if (constraint_length != K) {
K = constraint_length;
xor_int_table.set_size(pow2i(K), false);
for (int i = 0; i < pow2i(K); i++) {
xor_int_table(i) = (weight_int(K, i) & 1);
}
}
trunc_length = 5 * K;
m = K - 1;
no_states = pow2i(m);
gen_pol_rev.set_size(n, false);
rate = 1.0 / n;
for (int i = 0; i < n; i++) {
gen_pol_rev(i) = reverse_int(K, gen_pol(i));
}
int zero_output, one_output;
output_reverse_int.set_size(no_states, 2, false);
for (int i = 0; i < no_states; i++) {
output_reverse(i, zero_output, one_output);
output_reverse_int(i, 0) = zero_output;
output_reverse_int(i, 1) = one_output;
}
// initialise memory structures
visited_state.set_size(no_states);
visited_state = false;
visited_state(start_state) = true; // mark start state
sum_metric.set_size(no_states);
sum_metric.clear();
trunc_ptr = 0;
trunc_state = 0;
}
// Reset encoder and decoder states
void Convolutional_Code::reset()
{
init_encoder();
visited_state = false;
visited_state(start_state) = true; // mark start state
sum_metric.clear();
trunc_ptr = 0;
trunc_state = 0;
}
/*
Encode a binary vector of inputs using specified method
*/
void Convolutional_Code::encode(const bvec &input, bvec &output)
{
switch (cc_method) {
case Trunc:
encode_trunc(input, output);
break;
case Tailbite:
encode_tailbite(input, output);
break;
case Tail:
default:
encode_tail(input, output);
break;
};
}
/*
Encode a binary vector of inputs starting from state set by the
set_state function
*/
void Convolutional_Code::encode_trunc(const bvec &input, bvec &output)
{
int temp;
output.set_size(input.size() * n, false);
for (int i = 0; i < input.size(); i++) {
encoder_state |= static_cast<int>(input(i)) << m;
for (int j = 0; j < n; j++) {
temp = encoder_state & gen_pol(j);
output(i * n + j) = xor_int_table(temp);
}
encoder_state >>= 1;
}
}
/*
Encode a binary vector of inputs starting from zero state and also adds
a tail of K-1 zeros to force the encoder into the zero state. Well
suited for packet transmission.
*/
void Convolutional_Code::encode_tail(const bvec &input, bvec &output)
{
int temp;
output.set_size((input.size() + m) * n, false);
// always start from state 0
encoder_state = 0;
for (int i = 0; i < input.size(); i++) {
encoder_state |= static_cast<int>(input(i)) << m;
for (int j = 0; j < n; j++) {
temp = encoder_state & gen_pol(j);
output(i * n + j) = xor_int_table(temp);
}
encoder_state >>= 1;
}
// add tail of m = K-1 zeros
for (int i = input.size(); i < input.size() + m; i++) {
for (int j = 0; j < n; j++) {
temp = encoder_state & gen_pol(j);
output(i * n + j) = xor_int_table(temp);
}
encoder_state >>= 1;
}
}
/*
Encode a binary vector of inputs starting using tail biting
*/
void Convolutional_Code::encode_tailbite(const bvec &input, bvec &output)
{
int temp;
output.set_size(input.size() * n, false);
// Set the start state equal to the end state:
encoder_state = 0;
bvec last_bits = input.right(m);
for (int i = 0; i < m; i++) {
encoder_state |= static_cast<int>(last_bits(i)) << m;
encoder_state >>= 1;
}
for (int i = 0; i < input.size(); i++) {
encoder_state |= static_cast<int>(input(i)) << m;
for (int j = 0; j < n; j++) {
temp = encoder_state & gen_pol(j);
output(i * n + j) = xor_int_table(temp);
}
encoder_state >>= 1;
}
}
/*
Encode a binary bit starting from the internal encoder state.
To initialize the encoder state use set_start_state() and init_encoder()
*/
void Convolutional_Code::encode_bit(const bin &input, bvec &output)
{
int temp;
output.set_size(n, false);
encoder_state |= static_cast<int>(input) << m;
for (int j = 0; j < n; j++) {
temp = encoder_state & gen_pol(j);
output(j) = xor_int_table(temp);
}
encoder_state >>= 1;
}
// --------------- Hard-decision decoding is not implemented -----------------
void Convolutional_Code::decode(const bvec &, bvec &)
{
it_error("Convolutional_Code::decode(): Hard-decision decoding not implemented");
}
bvec Convolutional_Code::decode(const bvec &)
{
it_error("Convolutional_Code::decode(): Hard-decision decoding not implemented");
return bvec();
}
/*
Decode a block of encoded data using specified method
*/
void Convolutional_Code::decode(const vec &received_signal, bvec &output)
{
switch (cc_method) {
case Trunc:
decode_trunc(received_signal, output);
break;
case Tailbite:
decode_tailbite(received_signal, output);
break;
case Tail:
default:
decode_tail(received_signal, output);
break;
};
}
/*
Decode a block of encoded data where encode_tail has been used.
Thus is assumes a decoder start state of zero and that a tail of
K-1 zeros has been added. No memory truncation.
*/
void Convolutional_Code::decode_tail(const vec &received_signal, bvec &output)
{
int block_length = received_signal.size() / n; // no input symbols
it_error_if(block_length - m <= 0,
"Convolutional_Code::decode_tail(): Input sequence to short");
int S0, S1;
vec temp_sum_metric(no_states), temp_rec(n), delta_metrics;
Array<bool> temp_visited_state(no_states);
double temp_metric_zero, temp_metric_one;
path_memory.set_size(no_states, block_length, false);
output.set_size(block_length - m, false); // no tail in the output
// clear visited states
visited_state = false;
temp_visited_state = visited_state;
visited_state(0) = true; // starts in the zero state
// clear accumulated metrics
sum_metric.clear();
// evolve up to m where not all states visited
for (int l = 0; l < m; l++) { // all transitions including the tail
temp_rec = received_signal.mid(l * n, n);
// calculate all metrics for all codewords at the same time
calc_metric(temp_rec, delta_metrics);
for (int s = 0; s < no_states; s++) { // all states
// S0 and S1 are the states that expanded end at state s
previous_state(s, S0, S1);
if (visited_state(S0)) { // expand trellis if state S0 is visited
temp_metric_zero = sum_metric(S0)
+ delta_metrics(output_reverse_int(s, 0));
temp_visited_state(s) = true;
}
else {
temp_metric_zero = std::numeric_limits<double>::max();
}
if (visited_state(S1)) { // expand trellis if state S0 is visited
temp_metric_one = sum_metric(S1)
+ delta_metrics(output_reverse_int(s, 1));
temp_visited_state(s) = true;
}
else {
temp_metric_one = std::numeric_limits<double>::max();
}
if (temp_metric_zero < temp_metric_one) { // path zero survives
temp_sum_metric(s) = temp_metric_zero;
path_memory(s, l) = 0;
}
else { // path one survives
temp_sum_metric(s) = temp_metric_one;
path_memory(s, l) = 1;
}
} // all states, s
sum_metric = temp_sum_metric;
visited_state = temp_visited_state;
} // all transitions, l
// evolve from m and to the end of the block
for (int l = m; l < block_length; l++) { // all transitions except the tail
temp_rec = received_signal.mid(l * n, n);
// calculate all metrics for all codewords at the same time
calc_metric(temp_rec, delta_metrics);
for (int s = 0; s < no_states; s++) { // all states
// S0 and S1 are the states that expanded end at state s
previous_state(s, S0, S1);
temp_metric_zero = sum_metric(S0)
+ delta_metrics(output_reverse_int(s, 0));
temp_metric_one = sum_metric(S1)
+ delta_metrics(output_reverse_int(s, 1));
if (temp_metric_zero < temp_metric_one) { // path zero survives
temp_sum_metric(s) = temp_metric_zero;
path_memory(s, l) = 0;
}
else { // path one survives
temp_sum_metric(s) = temp_metric_one;
path_memory(s, l) = 1;
}
} // all states, s
sum_metric = temp_sum_metric;
} // all transitions, l
// minimum metric is the zeroth state due to the tail
int min_metric_state = 0;
// trace back to remove tail of zeros
for (int l = block_length - 1; l > block_length - 1 - m; l--) {
// previous state calculation
min_metric_state = previous_state(min_metric_state,
path_memory(min_metric_state, l));
}
// trace back to calculate output sequence
for (int l = block_length - 1 - m; l >= 0; l--) {
output(l) = get_input(min_metric_state);
// previous state calculation
min_metric_state = previous_state(min_metric_state,
path_memory(min_metric_state, l));
}
}
/*
Decode a block of encoded data where encode_tailbite has been used.
*/
void Convolutional_Code::decode_tailbite(const vec &received_signal,
bvec &output)
{
int block_length = received_signal.size() / n; // no input symbols
it_error_if(block_length <= 0,
"Convolutional_Code::decode_tailbite(): Input sequence to short");
int S0, S1;
vec temp_sum_metric(no_states), temp_rec(n), delta_metrics;
Array<bool> temp_visited_state(no_states);
double temp_metric_zero, temp_metric_one;
double best_metric = std::numeric_limits<double>::max();
bvec best_output(block_length), temp_output(block_length);
path_memory.set_size(no_states, block_length, false);
output.set_size(block_length, false);
// Try all start states ss
for (int ss = 0; ss < no_states; ss++) {
//Clear the visited_state vector:
visited_state = false;
temp_visited_state = visited_state;
visited_state(ss) = true; // starts in the state s
// clear accumulated metrics
sum_metric.zeros();
for (int l = 0; l < block_length; l++) { // all transitions
temp_rec = received_signal.mid(l * n, n);
// calculate all metrics for all codewords at the same time
calc_metric(temp_rec, delta_metrics);
for (int s = 0; s < no_states; s++) { // all states
// S0 and S1 are the states that expanded end at state s
previous_state(s, S0, S1);
if (visited_state(S0)) { // expand trellis if state S0 is visited
temp_metric_zero = sum_metric(S0)
+ delta_metrics(output_reverse_int(s, 0));
temp_visited_state(s) = true;
}
else {
temp_metric_zero = std::numeric_limits<double>::max();
}
if (visited_state(S1)) { // expand trellis if state S0 is visited
temp_metric_one = sum_metric(S1)
+ delta_metrics(output_reverse_int(s, 1));
temp_visited_state(s) = true;
}
else {
temp_metric_one = std::numeric_limits<double>::max();
}
if (temp_metric_zero < temp_metric_one) { // path zero survives
temp_sum_metric(s) = temp_metric_zero;
path_memory(s, l) = 0;
}
else { // path one survives
temp_sum_metric(s) = temp_metric_one;
path_memory(s, l) = 1;
}
} // all states, s
sum_metric = temp_sum_metric;
visited_state = temp_visited_state;
} // all transitions, l
// minimum metric is the ss state due to the tailbite
int min_metric_state = ss;
// trace back to calculate output sequence
for (int l = block_length - 1; l >= 0; l--) {
temp_output(l) = get_input(min_metric_state);
// previous state calculation
min_metric_state = previous_state(min_metric_state,
path_memory(min_metric_state, l));
}
if (sum_metric(ss) < best_metric) {
best_metric = sum_metric(ss);
best_output = temp_output;
}
} // all start states ss
output = best_output;
}
/*
Viterbi decoding using truncation of memory (default = 5*K)
*/
void Convolutional_Code::decode_trunc(const vec &received_signal,
bvec &output)
{
int block_length = received_signal.size() / n; // no input symbols
it_error_if(block_length <= 0,
"Convolutional_Code::decode_trunc(): Input sequence to short");
int S0, S1;
vec temp_sum_metric(no_states), temp_rec(n), delta_metrics;
Array<bool> temp_visited_state(no_states);
double temp_metric_zero, temp_metric_one;
path_memory.set_size(no_states, trunc_length, false);
output.set_size(0);
// copy visited states
temp_visited_state = visited_state;
for (int i = 0; i < block_length; i++) {
// update path memory pointer
trunc_ptr = (trunc_ptr + 1) % trunc_length;
temp_rec = received_signal.mid(i * n, n);
// calculate all metrics for all codewords at the same time
calc_metric(temp_rec, delta_metrics);
for (int s = 0; s < no_states; s++) { // all states
// the states that expanded end at state s
previous_state(s, S0, S1);
if (visited_state(S0)) { // expand trellis if state S0 is visited
temp_metric_zero = sum_metric(S0)
+ delta_metrics(output_reverse_int(s, 0));
temp_visited_state(s) = true;
}
else {
temp_metric_zero = std::numeric_limits<double>::max();
}
if (visited_state(S1)) { // expand trellis if state S0 is visited
temp_metric_one = sum_metric(S1)
+ delta_metrics(output_reverse_int(s, 1));
temp_visited_state(s) = true;
}
else {
temp_metric_one = std::numeric_limits<double>::max();
}
if (temp_metric_zero < temp_metric_one) { // path zero survives
temp_sum_metric(s) = temp_metric_zero;
path_memory(s, trunc_ptr) = 0;
}
else { // path one survives
temp_sum_metric(s) = temp_metric_one;
path_memory(s, trunc_ptr) = 1;
}
} // all states, s
sum_metric = temp_sum_metric;
visited_state = temp_visited_state;
// find minimum metric
int min_metric_state = min_index(sum_metric);
// normalise accumulated metrics
sum_metric -= sum_metric(min_metric_state);
// check if we had enough metrics to generate output
if (trunc_state >= trunc_length) {
// trace back to calculate the output symbol
for (int j = trunc_length; j > 0; j--) {
// previous state calculation
min_metric_state =
previous_state(min_metric_state,
path_memory(min_metric_state,
(trunc_ptr + j) % trunc_length));
}
output.ins(output.size(), get_input(min_metric_state));
}
else { // if not increment trunc_state counter
trunc_state++;
}
} // end for (int i = 0; i < block_length; l++)
}
/*
Calculate the inverse sequence
Assumes that encode_tail is used in the encoding process. Returns false
if there is an error in the coded sequence (not a valid codeword). Do
not check that the tail forces the encoder into the zeroth state.
*/
bool Convolutional_Code::inverse_tail(const bvec coded_sequence, bvec &input)
{
int state = 0, zero_state, one_state, zero_temp, one_temp, i, j;
bvec zero_output(n), one_output(n);
int block_length = coded_sequence.size() / n - m; // no input symbols
it_error_if(block_length <= 0, "The input sequence is to short");
input.set_length(block_length, false); // not include the tail in the output
for (i = 0; i < block_length; i++) {
zero_state = state;
one_state = state | (1 << m);
for (j = 0; j < n; j++) {
zero_temp = zero_state & gen_pol(j);
one_temp = one_state & gen_pol(j);
zero_output(j) = xor_int_table(zero_temp);
one_output(j) = xor_int_table(one_temp);
}
if (coded_sequence.mid(i*n, n) == zero_output) {
input(i) = bin(0);
state = zero_state >> 1;
}
else if (coded_sequence.mid(i*n, n) == one_output) {
input(i) = bin(1);
state = one_state >> 1;
}
else
return false;
}
return true;
}
/*
Check if catastrophic. Returns true if catastrophic
*/
bool Convolutional_Code::catastrophic(void)
{
int start, S, W0, W1, S0, S1;
bvec visited(1 << m);
for (start = 1; start < no_states; start++) {
visited.zeros();
S = start;
visited(S) = 1;
node1:
S0 = next_state(S, 0);
S1 = next_state(S, 1);
weight(S, W0, W1);
if (S1 < start) goto node0;
if (W1 > 0) goto node0;
if (visited(S1) == bin(1))
return true;
S = S1; // goto node1
visited(S) = 1;
goto node1;
node0:
if (S0 < start) continue; // goto end;
if (W0 > 0) continue; // goto end;
if (visited(S0) == bin(1))
return true;
S = S0;
visited(S) = 1;
goto node1;
//end:
//void;
}
return false;
}
/*
Calculate distance profile. If reverse = true calculate for the reverse code instead.
*/
void Convolutional_Code::distance_profile(ivec &dist_prof, int dmax, bool reverse)
{
int max_stack_size = 50000;
ivec S_stack(max_stack_size), W_stack(max_stack_size), t_stack(max_stack_size);
int stack_pos = -1, t, S, W, W0, w0, w1;
dist_prof.set_size(K, false);
dist_prof.zeros();
dist_prof += dmax; // just select a big number!
if (reverse)
W = weight_reverse(0, 1);
else
W = weight(0, 1);
S = next_state(0, 1); // first state 0 and one as input, S = 1<<(m-1);
t = 0;
dist_prof(0) = W;
node1:
if (reverse)
weight_reverse(S, w0, w1);
else
weight(S, w0, w1);
if (t < m) {
W0 = W + w0;
if (W0 < dist_prof(m)) { // store node0 (S, W0, and t+1)
stack_pos++;
if (stack_pos >= max_stack_size) {
max_stack_size = 2 * max_stack_size;
S_stack.set_size(max_stack_size, true);
W_stack.set_size(max_stack_size, true);
t_stack.set_size(max_stack_size, true);
}
S_stack(stack_pos) = next_state(S, 0); //S>>1;
W_stack(stack_pos) = W0;
t_stack(stack_pos) = t + 1;
}
}
else goto stack;
W += w1;
if (W > dist_prof(m))
goto stack;
t++;
S = next_state(S, 1); //S = (S>>1)|(1<<(m-1));
if (W < dist_prof(t))
dist_prof(t) = W;
if (t == m) goto stack;
goto node1;
stack:
if (stack_pos >= 0) {
// get root node from stack
S = S_stack(stack_pos);
W = W_stack(stack_pos);
t = t_stack(stack_pos);
stack_pos--;
if (W < dist_prof(t))
dist_prof(t) = W;
if (t == m) goto stack;
goto node1;
}
}
/*
Calculate spectrum
Calculates both the weight spectrum (Ad) and the information weight spectrum (Cd) and
returns it as ivec:s in the 0:th and 1:st component of spectrum, respectively. Suitable
for calculating many terms in the spectra (uses an breadth first algorithm). It is assumed
that the code is non-catastrophic or else it is a possibility for an eternal loop.
dmax = an upper bound on the free distance
no_terms = no_terms including the dmax term that should be calculated
*/
void Convolutional_Code::calculate_spectrum(Array<ivec> &spectrum, int dmax, int no_terms)
{
imat Ad_states(no_states, dmax + no_terms), Cd_states(no_states, dmax + no_terms);
imat Ad_temp(no_states, dmax + no_terms), Cd_temp(no_states, dmax + no_terms);
ivec mindist(no_states), mindist_temp(1 << m);
spectrum.set_size(2);
spectrum(0).set_size(dmax + no_terms, false);
spectrum(1).set_size(dmax + no_terms, false);
spectrum(0).zeros();
spectrum(1).zeros();
Ad_states.zeros();
Cd_states.zeros();
mindist.zeros();
int wmax = dmax + no_terms;
ivec visited_states(no_states), visited_states_temp(no_states);
bool proceede;
int d, w0, w1, s, s0, s1;
visited_states.zeros(); // 0 = false
s = next_state(0, 1); // Start in state from 0 with an one input.
visited_states(s) = 1; // 1 = true. Start in state 2^(m-1).
w1 = weight(0, 1);
Ad_states(s, w1) = 1;
Cd_states(s, w1) = 1;
mindist(s) = w1;
proceede = true;
while (proceede) {
proceede = false;
Ad_temp.zeros();
Cd_temp.zeros();
mindist_temp.zeros();
visited_states_temp.zeros(); //false
for (s = 1; s < no_states; s++) {
if ((mindist(s) > 0) && (mindist(s) < wmax)) {
proceede = true;
weight(s, w0, w1);
s0 = next_state(s, 0);
for (d = mindist(s); d < (wmax - w0); d++) {
Ad_temp(s0, d + w0) += Ad_states(s, d);
Cd_temp(s0, d + w0) += Cd_states(s, d);
visited_states_temp(s0) = 1; //true
}
s1 = next_state(s, 1);
for (d = mindist(s); d < (wmax - w1); d++) {
Ad_temp(s1, d + w1) += Ad_states(s, d);
Cd_temp(s1, d + w1) += Cd_states(s, d) + Ad_states(s, d);
visited_states_temp(s1) = 1; //true
}
if (mindist_temp(s0) > 0) { mindist_temp(s0) = (mindist(s) + w0) < mindist_temp(s0) ? mindist(s) + w0 : mindist_temp(s0); }
else { mindist_temp(s0) = mindist(s) + w0; }
if (mindist_temp(s1) > 0) { mindist_temp(s1) = (mindist(s) + w1) < mindist_temp(s1) ? mindist(s) + w1 : mindist_temp(s1); }
else { mindist_temp(s1) = mindist(s) + w1; }
}
}
Ad_states = Ad_temp;
Cd_states = Cd_temp;
spectrum(0) += Ad_temp.get_row(0);
spectrum(1) += Cd_temp.get_row(0);
visited_states = visited_states_temp;
mindist = elem_mult(mindist_temp, visited_states);
}
}
/*
Cederwall's fast algorithm
See IT No. 6, pp. 1146-1159, Nov. 1989 for details.
Calculates both the weight spectrum (Ad) and the information weight spectrum (Cd) and
returns it as ivec:s in the 0:th and 1:st component of spectrum, respectively. The FAST algorithm
is good for calculating only a few terms in the spectrum. If many terms are desired, use calc_spectrum instead.
The algorithm returns -1 if the code tested is worse that the input dfree and Cdfree.
It returns 0 if the code MAY be catastrophic (assuming that test_catastrophic is true),
and returns 1 if everything went right.
\arg \c dfree the free distance of the code (or an upper bound)
\arg \c no_terms including the dfree term that should be calculated
\ar \c Cdfree is the best value of information weight spectrum found so far
*/
int Convolutional_Code::fast(Array<ivec> &spectrum, const int dfree, const int no_terms, const int Cdfree, const bool test_catastrophic)
{
int cat_treshold = 7 * K; // just a big number, but not to big!
int i;
ivec dist_prof(K), dist_prof_rev(K);
distance_profile(dist_prof, dfree);
distance_profile(dist_prof_rev, dfree, true); // for the reverse code
int dist_prof_rev0 = dist_prof_rev(0);
bool reverse = false; // false = use dist_prof
// is the reverse distance profile better?
for (i = 0; i < K; i++) {
if (dist_prof_rev(i) > dist_prof(i)) {
reverse = true;
dist_prof_rev0 = dist_prof(0);
dist_prof = dist_prof_rev;
break;
}
else if (dist_prof_rev(i) < dist_prof(i)) {
break;
}
}
int d = dfree + no_terms - 1;
int max_stack_size = 50000;
ivec S_stack(max_stack_size), W_stack(max_stack_size), b_stack(max_stack_size), c_stack(max_stack_size);
int stack_pos = -1;
// F1.
int mf = 1, b = 1;
spectrum.set_size(2);
spectrum(0).set_size(dfree + no_terms, false); // ad
spectrum(1).set_size(dfree + no_terms, false); // cd
spectrum(0).zeros();
spectrum(1).zeros();
int S, S0, S1, W0, W1, w0, w1, c = 0;
S = next_state(0, 1); //first state zero and one as input
int W = d - dist_prof_rev0;
F2:
S0 = next_state(S, 0);
S1 = next_state(S, 1);
if (reverse) {
weight(S, w0, w1);
}
else {
weight_reverse(S, w0, w1);
}
W0 = W - w0;
W1 = W - w1;
if (mf < m) goto F6;
//F3:
if (W0 >= 0) {
spectrum(0)(d - W0)++;
spectrum(1)(d - W0) += b;
// The code is worse than the best found.
if (((d - W0) < dfree) || (((d - W0) == dfree) && (spectrum(1)(d - W0) > Cdfree)))
return -1;
}
F4:
if ((W1 < dist_prof(m - 1)) || (W < dist_prof(m))) goto F5;
// select node 1
if (test_catastrophic && W == W1) {
c++;
if (c > cat_treshold)
return 0;
}
else {
c = 0;
W = W1;
}
S = S1;
mf = 1;
b++;
goto F2;
F5:
//if (stack_pos == -1) return n_values;
if (stack_pos == -1) goto end;
// get node from stack
S = S_stack(stack_pos);
W = W_stack(stack_pos);
b = b_stack(stack_pos);
c = c_stack(stack_pos);
stack_pos--;
mf = 1;
goto F2;
F6:
if (W0 < dist_prof(m - mf - 1)) goto F4;
//F7:
if ((W1 >= dist_prof(m - 1)) && (W >= dist_prof(m))) {
// save node 1
if (test_catastrophic && stack_pos > 10000)
return 0;
stack_pos++;
if (stack_pos >= max_stack_size) {
max_stack_size = 2 * max_stack_size;
S_stack.set_size(max_stack_size, true);
W_stack.set_size(max_stack_size, true);
b_stack.set_size(max_stack_size, true);
c_stack.set_size(max_stack_size, true);
}
S_stack(stack_pos) = S1;
W_stack(stack_pos) = W1;
b_stack(stack_pos) = b + 1; // because gone to node 1
c_stack(stack_pos) = c; // because gone to node 1
}
// select node 0
S = S0;
if (test_catastrophic && W == W0) {
c++;
if (c > cat_treshold)
return 0;
}
else {
c = 0;
W = W0;
}
mf++;
goto F2;
end:
return 1;
}
//----------- These functions should be moved into some other place -------
int reverse_int(int length, int in)
{
int i, j, out = 0;
for (i = 0; i < (length >> 1); i++) {
out = out | ((in & (1 << i)) << (length - 1 - (i << 1)));
}
for (j = 0; j < (length - i); j++) {
out = out | ((in & (1 << (j + i))) >> ((j << 1) - (length & 1) + 1));
//out = out | ( (in & (1<<j+i)) >> ((j<<1)-(length&1)+1) ); old version with preecedence problems in MSC
}
return out;
}
int weight_int(int length, int in)
{
int i, w = 0;
for (i = 0; i < length; i++) {
w += (in & (1 << i)) >> i;
}
return w;
}
int compare_spectra(ivec v1, ivec v2)
{
it_assert_debug(v1.size() == v2.size(), "compare_spectra: wrong sizes");
for (int i = 0; i < v1.size(); i++) {
if (v1(i) < v2(i)) {
return 1;
}
else if (v1(i) > v2(i)) {
return 0;
}
}
return -1;
}
int compare_spectra(ivec v1, ivec v2, vec weight_profile)
{
double t1 = 0, t2 = 0;
for (int i = 0; i < v1.size(); i++) {
t1 += (double)v1(i) * weight_profile(i);
t2 += (double)v2(i) * weight_profile(i);
}
if (t1 < t2) return 1;
else if (t1 > t2) return 0;
else return -1;
}
} // namespace itpp
it_error_if
#define it_error_if(t, s)
Abort if t is true.
Definition: itassert.h:117
convcode.h
Definition of a binary convolutional encoder class.
matfunc.h
Various functions on vectors and matrices - header file.
itpp::Convolutional_Code::inverse_tail
bool inverse_tail(const bvec coded_sequence, bvec &input)
Calculate the inverse sequence.
Definition: convcode.cpp:1053
itpp::Convolutional_Code::weight
int weight(const int state, const int input)
The weight of the transition from given state with the input given.
Definition: convcode.cpp:42
itpp::Convolutional_Code::K
int K
Constraint length.
Definition: convcode.h:413
itpp::reverse_int
int reverse_int(int length, int in)
Definition: convcode.cpp:1442
itpp::Array< bool >
itpp::reverse
Vec< T > reverse(const Vec< T > &in)
Reverse the input vector.
Definition: matfunc.h:777
itpp::Convolutional_Code::trunc_length
int trunc_length
The decoder truncation length.
Definition: convcode.h:427
itpp::Array::mid
Array< T > mid(int pos, int n) const
Get n elements of the array starting from pos.
Definition: array.h:377
itpp::Convolutional_Code::decode
virtual void decode(const bvec &coded_bits, bvec &decoded_bits)
Decode a bvec of coded data.
Definition: convcode.cpp:735
itpp::Convolutional_Code::visited_state
Array< bool > visited_state
Visited states.
Definition: convcode.h:439
itpp::Convolutional_Code::weight_reverse
int weight_reverse(const int state, const int input)
The weight (of the reverse code) of the transition from given state with the input given...
Definition: convcode.cpp:64
itpp::Convolutional_Code::output_reverse_int
imat output_reverse_int
output in int format for a given state and input
Definition: convcode.h:433
itpp::elem_mult
Mat< Num_T > elem_mult(const Mat< Num_T > &m1, const Mat< Num_T > &m2)
Element wise multiplication of two matrices.
Definition: mat.h:1582
binary.h
Binary class definition.
itpp::Convolutional_Code::fast
int fast(Array< ivec > &spectrum, const int dfree, const int no_terms, const int Cdfree=1000000, const bool test_catastrophic=false)
Cederwall's fast algorithm.
Definition: convcode.cpp:1299
itpp::Convolutional_Code::calculate_spectrum
void calculate_spectrum(Array< ivec > &spectrum, int dmax, int no_terms)
Calculate spectrum.
Definition: convcode.cpp:1217
itpp::weight_int
int weight_int(int length, int in)
Definition: convcode.cpp:1460
itpp::Convolutional_Code::xor_int_table
bvec xor_int_table
Auxilary table used by the codec.
Definition: convcode.h:431
itpp::Convolutional_Code::set_generator_polynomials
void set_generator_polynomials(const ivec &gen, int constraint_length)
Set generator polynomials. Given in Proakis integer form.
Definition: convcode.cpp:555
itpp::Convolutional_Code::next_state
int next_state(const int instate, const int input)
Next state from instate given the input.
Definition: convcode.h:374
itpp::Convolutional_Code::encode_bit
void encode_bit(const bin &input, bvec &output)
Encode a binary bit starting from the internal encoder state.
Definition: convcode.cpp:719
it_assert
#define it_assert(t, s)
Abort if t is not true.
Definition: itassert.h:94
itpp::length
int length(const Vec< T > &v)
Length of vector.
Definition: matfunc.h:51
itpp::Convolutional_Code::decode_tailbite
virtual void decode_tailbite(const vec &received_signal, bvec &output)
Decode a block of encoded data where encode_tailbite has been used.
Definition: convcode.cpp:879
itpp::Convolutional_Code::encode_trunc
void encode_trunc(const bvec &input, bvec &output)
Encode a binary vector starting from the previous encoder state.
Definition: convcode.cpp:642
itpp::Convolutional_Code::no_states
int no_states
Number of states.
Definition: convcode.h:417
it_assert_debug
#define it_assert_debug(t, s)
Abort if t is not true and NDEBUG is not defined.
Definition: itassert.h:107
itpp::Convolutional_Code::reverse_int
ITPP_EXPORT int reverse_int(int length, int in)
Reverses the bitrepresentation of in (of size length) and converts to an integer. ...
Definition: convcode.cpp:1442
itpp::Array::set_size
void set_size(int n, bool copy=false)
Resizing an Array<T>.
Definition: array.h:257
itpp::Convolutional_Code::calc_metric
void calc_metric(const vec &rx_codeword, vec &delta_metrics)
Calculate delta metrics for all possible codewords.
Definition: convcode.cpp:213
itpp::Convolutional_Code::trunc_state
int trunc_state
Truncated memory fill state.
Definition: convcode.h:445
itpp::Convolutional_Code::m
int m
Memory of the encoder.
Definition: convcode.h:415
itpp::CONVOLUTIONAL_CODE_TYPE
CONVOLUTIONAL_CODE_TYPE
Type of Convolutional Code.
Definition: convcode.h:47
itpp::Convolutional_Code::encode_tailbite
void encode_tailbite(const bvec &input, bvec &output)
Encode an input binary vector using tailbiting.
Definition: convcode.cpp:692
itpp::Convolutional_Code::gen_pol_rev
ivec gen_pol_rev
Generator polynomials for the reverse code.
Definition: convcode.h:421
itpp::max
T max(const Vec< T > &v)
Maximum value of vector.
Definition: min_max.h:45
itpp::pow2i
int pow2i(int x)
Calculate two to the power of x (2^x); x is integer.
Definition: log_exp.h:53
itpp::Convolutional_Code::weight_int
ITPP_EXPORT int weight_int(int length, int in)
Calculate the Hamming weight of the binary representation of in of size length.
Definition: convcode.cpp:1460
itpp::Convolutional_Code::encoder_state
int encoder_state
The current encoder state.
Definition: convcode.h:423
itpp::spectrum
vec spectrum(const vec &v, int nfft, int noverlap)
Power spectrum calculation.
Definition: sigfun.cpp:267
itpp
itpp namespace
Definition: itmex.h:36
itpp::Convolutional_Code::encode
virtual void encode(const bvec &input, bvec &output)
Encode an input binary vector using specified method (Tail by default)
Definition: convcode.cpp:622
itpp::Convolutional_Code::decode_trunc
virtual void decode_trunc(const vec &received_signal, bvec &output)
Viterbi decoding using truncation of memory (default = 5*K)
Definition: convcode.cpp:965
itpp::Convolutional_Code::set_code
void set_code(const CONVOLUTIONAL_CODE_TYPE type_of_code, int inverse_rate, int constraint_length)
Set the code according to built-in tables.
Definition: convcode.cpp:537
itpp::Convolutional_Code::distance_profile
void distance_profile(ivec &dist_prof, int dmax=100000, bool reverse=false)
Calculate distance profile. If reverse = true calculate for the reverse code instead.
Definition: convcode.cpp:1133
itpp::Convolutional_Code::reset
void reset()
Reset encoder and decoder states.
Definition: convcode.cpp:605
itpp::min_index
int min_index(const Vec< T > &in)
Return the postion of the minimum element in the vector.
Definition: min_max.h:234
itpp::Convolutional_Code::rate
double rate
The rate of the code.
Definition: convcode.h:429
itpp::Convolutional_Code::n
int n
Number of generators.
Definition: convcode.h:411
itpp::Convolutional_Code::start_state
int start_state
The encoder start state.
Definition: convcode.h:425
itpp::Convolutional_Code::trunc_ptr
int trunc_ptr
Truncated path memory pointer.
Definition: convcode.h:443
itpp::bin
Binary arithmetic (boolean) class.
Definition: binary.h:56
it_error
#define it_error(s)
Abort unconditionally.
Definition: itassert.h:126
itpp::Convolutional_Code::previous_state
int previous_state(const int state, const int input)
The previous state from state given the input.
Definition: convcode.h:378
itpp::Convolutional_Code::init_encoder
void init_encoder()
Initialise internal encoder state with start state. Has no effect on Tail and Tailbite methods...
Definition: convcode.h:293
itpp::Convolutional_Code::output_reverse
bvec output_reverse(const int state, const int input)
Output on transition (backwards) with input from state.
Definition: convcode.cpp:132
itpp::Convolutional_Code::catastrophic
bool catastrophic(void)
Check if catastrophic. Returns true if catastrophic.
Definition: convcode.cpp:1090
itpp::Convolutional_Code::cc_method
CONVOLUTIONAL_CODE_METHOD cc_method
encoding and decoding method
Definition: convcode.h:435
itpp::Convolutional_Code::get_input
int get_input(const int state)
Returns the input that results in state, that is the MSB of state.
Definition: convcode.h:408
itpp::compare_spectra
int compare_spectra(ivec v1, ivec v2)
Definition: convcode.cpp:1472
itpp::Convolutional_Code::calc_metric_reverse
void calc_metric_reverse(const int state, const vec &rx_codeword, double &zero_metric, double &one_metric)
Calculate delta metrics for 0 and 1 input branches reaching state.
Definition: convcode.cpp:190
itpp::Convolutional_Code::encode_tail
void encode_tail(const bvec &input, bvec &output)
Encoding that starts and ends in the zero state.
Definition: convcode.cpp:662
itpp::Convolutional_Code::gen_pol
ivec gen_pol
Generator polynomials.
Definition: convcode.h:419
itpp::Convolutional_Code::decode_tail
virtual void decode_tail(const vec &received_signal, bvec &output)
Decode a block of encoded data where encode_tail has been used.
Definition: convcode.cpp:771
itpp::Convolutional_Code::sum_metric
vec sum_metric
Metrics accumulator.
Definition: convcode.h:441
itpp::Convolutional_Code::path_memory
imat path_memory
Path memory (trellis)
Definition: convcode.h:437

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