static
void assert_ivec(const ivec &expected, const ivec &actual)
{
ASSERT_EQ(expected.length(), actual.length());
for (int n = 0; n < expected.length(); ++n)
{
ASSERT_EQ(expected[n], actual[n]);
}
}
void cofdm_map::set_data(ivec x)
{
cvec qv;
bvec ce;
int K = x.length();
int i;
ce.set_length(K); ce.ones();
#if (DEBUG_LEVEL == 3)
cout << "***** cofdm_map::set_data *****" << endl;
cout << "K=" << K << endl;
cout << "ce=" << ce << endl;
cout << "x=" << x << endl;
cout << "data_carriers=" << data_carriers << endl;
#endif
if( K == data_carriers.length() ) {
qv = qammod.process(ce,x);
#if (DEBUG_LEVEL == 3)
cout << "qv=" << qv << endl;
#endif
for (i=0; i<K; i++) {
y0(data_carriers(i))=qv(i);
}
}
else {
throw sci_exception("cofdm_map::set_data - x.size() <> data_carriers.size()=", data_carriers.length());
}
#if (DEBUG_LEVEL == 3)
cout << "y0(piltos) y0(zeros) migh have rubbish" << endl;
cout << "y0=" << y0 << endl;
cout << "+++++ cofdm_map::set_data +++++" << endl;
#endif
}
void gfx::set(int qvalue, const ivec &invalues)
{
// it_assert0(qvalue>0, "gfx::set, out of range");
degree=invalues.length()-1;
coeffs.set_size(degree+1);
for (int i=0;i<degree+1;i++)
coeffs[i].set(qvalue,invalues[i]);
q=qvalue;
}
cvec qam_mod::process(bvec ce, ivec x)
{
cvec y;
int N;
ivec iv;
cvec cv;
#if (DEBUG_LEVEL==3)
cout << "***** qam_mod::process *****" << endl;
cout << "ce=" << ce << endl;
cout << "x=" << x << endl;
sleep(1000);
#endif
iv.set_length(1);
cv.set_length(1);
N=ce.length();
y.set_length(N);
if (x.length()!=N) {
throw sci_exception("qam_mod::process - ce.size <> x.size", x.length() );
}
for (int i=0; i<N; i++) {
if ( bool(ce[i])) {
iv[0] = x[i];
cv = modulate(iv);
y0 = scale * cv[0];
}
y[i]=y0;
}
#if (DEBUG_LEVEL==3)
cout << "y=" << y << endl;
cout << "+++++ qam_mod::process +++++" << endl;
sleep(1000);
#endif
return (y);
}
bmat int2bin::process(bvec ce, ivec x)
{
bmat y;
int N;
#if (DEBUG_LEVEL==3)
cout << "***** int2bin::process *****" << endl;
cout << "ce=" << ce << endl;
cout << "x=" << x << endl;
sleep(1000);
#endif
N=ce.length();
if (x.length()!=N) {
throw sci_exception("int2bin::process - ce.size <> x.rows()", x.length() );
}
y.set_size(N,symbol_size);
for (int i=0; i<N; i++) {
if ( bool(ce[i])) {
y0 = dec2bin(symbol_size, x[i]);
if (! msb_first) {
y0 = reverse(y0);
}
}
y.set_row(i,y0);
}
#if (DEBUG_LEVEL==3)
cout << "y=" << y << endl;
cout << "+++++ int2bin::process +++++" << endl;
sleep(1000);
#endif
return (y);
}
void cofdm_sel::set_sel_carriers(ivec cindx)
{
if( cindx.length() < NFFT ) {
if (itpp::min(cindx) >= 0) {
if (itpp::max(cindx) < NFFT) {
sel_carriers = cindx;
}
else {
throw sci_exception("cofdm_sel::set_sel_carriers - max(cindx) > NFFT=", NFFT);
}
}
else {
throw sci_exception("cofdm_sel::set_sel_carriers - min(cindx) < 0 ");
}
}
else {
throw sci_exception("cofdm_sel::set_sel_carriers - bad cindx.size() > NFFT=", NFFT);
}
}
void cofdm_map::set_pilots_carriers(ivec pcindx)
{
if( pcindx.length() < NFFT ) {
if (itpp::min(pcindx) >= 0) {
if (itpp::max(pcindx) < NFFT) {
pilots_carriers = pcindx;
}
else {
throw sci_exception("cofdm_map::set_pilots_carriers - max(pcindx) > NFFT=", NFFT);
}
}
else {
throw sci_exception("cofdm_map::set_pilots_carriers - min(dcindx) < 0 ");
}
}
else {
throw sci_exception("cofdm_map::set_pilots_carriers - bad pcindx.size() > NFFT=", NFFT);
}
}
void cofdm_map::set_zero_carriers(ivec zcindx)
{
if( zcindx.length() < NFFT ) {
if (itpp::min(zcindx) >= 0) {
if (itpp::max(zcindx) < NFFT) {
zero_carriers = zcindx;
}
else {
throw sci_exception("cofdm_map::set_zero_carriers - max(zcindx) > NFFT=", NFFT);
}
}
else {
throw sci_exception("cofdm_map::set_zero_carriers - min(zcindx) < 0 ");
}
}
else {
throw sci_exception("cofdm_map::set_zero_carriers - bad zcindx.size() > NFFT=", NFFT);
}
}
void cofdm_map::set_data_carriers(ivec dcindx)
{
if( dcindx.length() < NFFT ) {
if (itpp::min(dcindx) >= 0) {
if (itpp::max(dcindx) < NFFT) {
data_carriers = dcindx;
}
else {
throw sci_exception("cofdm_map::set_data_carriers - max(dcindx) > NFFT=", NFFT);
}
}
else {
throw sci_exception("cofdm_map::set_data_carriers - min(dcindx) < 0 ");
}
}
else {
throw sci_exception("cofdm_map::set_data_carriers - bad dcindx.size() > NFFT=", NFFT);
}
}
bool Reed_Solomon::decode(const bvec &coded_bits, const ivec &erasure_positions, bvec &decoded_message, bvec &cw_isvalid)
{
bool decoderfailure, no_dec_failure;
int j, i, kk, l, L, foundzeros, iterations = floor_i(static_cast<double>(coded_bits.length()) / (n * m));
bvec mbit(m * k);
decoded_message.set_size(iterations * k * m, false);
cw_isvalid.set_length(iterations);
GFX rx(q, n - 1), cx(q, n - 1), mx(q, k - 1), ex(q, n - 1), S(q, 2 * t), Xi(q, 2 * t), Gamma(q), Lambda(q),
Psiprime(q), OldLambda(q), T(q), Omega(q);
GFX dummy(q), One(q, (char*)"0"), Omegatemp(q);
GF delta(q), tempsum(q), rtemp(q), temp(q), Xk(q), Xkinv(q);
ivec errorpos;
if ( erasure_positions.length() ) {
it_assert(max(erasure_positions) < iterations*n, "Reed_Solomon::decode: erasure position is invalid.");
}
no_dec_failure = true;
for (i = 0; i < iterations; i++) {
decoderfailure = false;
//Fix the received polynomial r(x)
for (j = 0; j < n; j++) {
rtemp.set(q, coded_bits.mid(i * n * m + j * m, m));
rx[j] = rtemp;
}
// Fix the Erasure polynomial Gamma(x)
// and replace erased coordinates with zeros
rtemp.set(q, -1);
ivec alphapow = - ones_i(2);
Gamma = One;
for (j = 0; j < erasure_positions.length(); j++) {
rx[erasure_positions(j)] = rtemp;
alphapow(1) = erasure_positions(j);
Gamma *= (One - GFX(q, alphapow));
}
//Fix the syndrome polynomial S(x).
S.clear();
for (j = 1; j <= 2 * t; j++) {
S[j] = rx(GF(q, b + j - 1));
}
// calculate the modified syndrome polynomial Xi(x) = Gamma * (1+S) - 1
Xi = Gamma * (One + S) - One;
// Apply Berlekam-Massey algorithm
if (Xi.get_true_degree() >= 1) { //Errors in the received word
// Iterate to find Lambda(x), which hold all error locations
kk = 0;
Lambda = One;
L = 0;
T = GFX(q, (char*)"-1 0");
while (kk < 2 * t) {
kk = kk + 1;
tempsum = GF(q, -1);
for (l = 1; l <= L; l++) {
tempsum += Lambda[l] * Xi[kk - l];
}
delta = Xi[kk] - tempsum;
if (delta != GF(q, -1)) {
OldLambda = Lambda;
Lambda -= delta * T;
if (2 * L < kk) {
L = kk - L;
T = OldLambda / delta;
}
}
T = GFX(q, (char*)"-1 0") * T;
}
// Find the zeros to Lambda(x)
errorpos.set_size(Lambda.get_true_degree());
foundzeros = 0;
for (j = q - 2; j >= 0; j--) {
if (Lambda(GF(q, j)) == GF(q, -1)) {
errorpos(foundzeros) = (n - j) % n;
foundzeros += 1;
if (foundzeros >= Lambda.get_true_degree()) {
break;
}
}
}
if (foundzeros != Lambda.get_true_degree()) {
decoderfailure = true;
}
else { // Forney algorithm...
//Compute Omega(x) using the key equation for RS-decoding
Omega.set_degree(2 * t);
Omegatemp = Lambda * (One + Xi);
for (j = 0; j <= 2 * t; j++) {
Omega[j] = Omegatemp[j];
}
//Find the error/erasure magnitude polynomial by treating them the same
Psiprime = formal_derivate(Lambda*Gamma);
errorpos = concat(errorpos, erasure_positions);
ex.clear();
for (j = 0; j < errorpos.length(); j++) {
Xk = GF(q, errorpos(j));
Xkinv = GF(q, 0) / Xk;
// we calculate ex = - error polynomial, in order to avoid the
// subtraction when recunstructing the corrected codeword
ex[errorpos(j)] = (Xk * Omega(Xkinv)) / Psiprime(Xkinv);
if (b != 1) { // non-narrow-sense code needs corrected error magnitudes
int correction_exp = ( errorpos(j)*(1-b) ) % n;
ex[errorpos(j)] *= GF(q, correction_exp + ( (correction_exp < 0) ? n : 0 ));
}
}
//Reconstruct the corrected codeword.
// instead of subtracting the error/erasures, we calculated
// the negative error with 'ex' above
cx = rx + ex;
//Code word validation
S.clear();
for (j = 1; j <= 2 * t; j++) {
S[j] = cx(GF(q, b + j - 1));
}
if (S.get_true_degree() >= 1) {
decoderfailure = true;
}
}
}
else {
cx = rx;
decoderfailure = false;
}
//Find the message polynomial
mbit.clear();
if (decoderfailure == false) {
if (cx.get_true_degree() >= 1) { // A nonzero codeword was transmitted
if (systematic) {
for (j = 0; j < k; j++) {
mx[j] = cx[j];
}
}
else {
mx = divgfx(cx, g);
}
for (j = 0; j <= mx.get_true_degree(); j++) {
mbit.replace_mid(j * m, mx[j].get_vectorspace());
}
}
}
else { //Decoder failure.
// for a systematic code it is better to extract the undecoded message
// from the received code word, i.e. obtaining a bit error
// prob. p_b << 1/2, than setting all-zero (p_b = 1/2)
if (systematic) {
mbit = coded_bits.mid(i * n * m, k * m);
}
else {
mbit = zeros_b(k);
}
no_dec_failure = false;
}
decoded_message.replace_mid(i * m * k, mbit);
cw_isvalid(i) = (!decoderfailure);
}
return no_dec_failure;
}
/*
Return the mean value of the elements in the vector
*/
double mean(const ivec& v)
{
return (double)sum(v)/v.length();
}
