// generate short sequence symbols
// _p : subcarrier allocation array
// _M : total number of subcarriers
// _S0 : output symbol (freq)
// _s0 : output symbol (time)
// _M_S0 : total number of enabled subcarriers in S0
void ofdmframe_init_S0(unsigned char * _p,
unsigned int _M,
float complex * _S0,
float complex * _s0,
unsigned int * _M_S0)
{
unsigned int i;
// compute m-sequence length
unsigned int m = liquid_nextpow2(_M);
if (m < 4) m = 4;
else if (m > 8) m = 8;
// generate m-sequence generator object
msequence ms = msequence_create_default(m);
unsigned int s;
unsigned int M_S0 = 0;
// short sequence
for (i=0; i<_M; i++) {
// generate symbol
//s = msequence_generate_symbol(ms,1);
s = msequence_generate_symbol(ms,3) & 0x01;
if (_p[i] == OFDMFRAME_SCTYPE_NULL) {
// NULL subcarrier
_S0[i] = 0.0f;
} else {
if ( (i%2) == 0 ) {
// even subcarrer
_S0[i] = s ? 1.0f : -1.0f;
M_S0++;
} else {
// odd subcarrer (ignore)
_S0[i] = 0.0f;
}
}
}
// destroy objects
msequence_destroy(ms);
// ensure at least one subcarrier was enabled
if (M_S0 == 0) {
fprintf(stderr,"error: ofdmframe_init_S0(), no subcarriers enabled; check allocation\n");
exit(1);
}
// set return value(s)
*_M_S0 = M_S0;
// run inverse fft to get time-domain sequence
fft_run(_M, _S0, _s0, FFT_REVERSE, 0);
// normalize time-domain sequence level
float g = 1.0f / sqrtf(M_S0);
for (i=0; i<_M; i++)
_s0[i] *= g;
}
//
// autotest helper function
//
void validate_crc(crc_scheme _check,
unsigned int _n)
{
unsigned int i;
// generate pseudo-random data
unsigned char data[_n];
msequence ms = msequence_create_default(9);
for (i=0; i<_n; i++)
data[i] = msequence_generate_symbol(ms,8);
msequence_destroy(ms);
// generate key
unsigned int key = crc_generate_key(_check, data, _n);
// contend data/key are valid
CONTEND_EXPRESSION(crc_validate_message(_check, data, _n, key));
//
unsigned char data_corrupt[_n];
unsigned int j;
for (i=0; i<_n; i++) {
for (j=0; j<8; j++) {
// copy original data sequence
memmove(data_corrupt, data, _n*sizeof(unsigned char));
// flip bit j at byte i
data[i] ^= (1 << j);
// contend data/key are invalid
CONTEND_EXPRESSION(crc_validate_message(_check, data, _n, key)==0);
}
}
}
// generate long sequence symbols
// _p : subcarrier allocation array
// _M : total number of subcarriers
// _S1 : output symbol (freq)
// _s1 : output symbol (time)
// _M_S1 : total number of enabled subcarriers in S1
void ofdmframe_init_S1(unsigned char * _p,
unsigned int _M,
float complex * _S1,
float complex * _s1,
unsigned int * _M_S1)
{
unsigned int i;
// compute m-sequence length
unsigned int m = liquid_nextpow2(_M);
if (m < 4) m = 4;
else if (m > 8) m = 8;
// increase m such that the resulting S1 sequence will
// differ significantly from S0 with the same subcarrier
// allocation array
m++;
// generate m-sequence generator object
msequence ms = msequence_create_default(m);
unsigned int s;
unsigned int M_S1 = 0;
// long sequence
for (i=0; i<_M; i++) {
// generate symbol
//s = msequence_generate_symbol(ms,1);
s = msequence_generate_symbol(ms,3) & 0x01;
if (_p[i] == OFDMFRAME_SCTYPE_NULL) {
// NULL subcarrier
_S1[i] = 0.0f;
} else {
_S1[i] = s ? 1.0f : -1.0f;
M_S1++;
}
}
// destroy objects
msequence_destroy(ms);
// ensure at least one subcarrier was enabled
if (M_S1 == 0) {
fprintf(stderr,"error: ofdmframe_init_S1(), no subcarriers enabled; check allocation\n");
exit(1);
}
// set return value(s)
*_M_S1 = M_S1;
// run inverse fft to get time-domain sequence
fft_run(_M, _S1, _s1, FFT_REVERSE, 0);
// normalize time-domain sequence level
float g = 1.0f / sqrtf(M_S1);
for (i=0; i<_M; i++)
_s1[i] *= g;
}
// generate long sequence symbols
// _p : subcarrier allocation array
// _num_subcarriers : total number of subcarriers
// _S1 : output symbol
// _M_S1 : total number of enabled subcarriers in S1
void ofdmoqamframe_init_S1(unsigned char * _p,
unsigned int _num_subcarriers,
float complex * _S1,
unsigned int * _M_S1)
{
unsigned int i;
// compute m-sequence length
unsigned int m = liquid_nextpow2(_num_subcarriers);
if (m < 4) m = 4;
else if (m > 8) m = 8;
// increase m such that the resulting S1 sequence will
// differ significantly from S0 with the same subcarrier
// allocation array
m++;
// generate m-sequence generator object
msequence ms = msequence_create_default(m);
unsigned int s;
unsigned int M_S1 = 0;
// long sequence
for (i=0; i<_num_subcarriers; i++) {
// generate symbol
//s = msequence_generate_symbol(ms,1);
s = msequence_generate_symbol(ms,3) & 0x01;
if (_p[i] == OFDMOQAMFRAME_SCTYPE_NULL) {
// NULL subcarrier
_S1[i] = 0.0f;
} else {
_S1[i] = s ? 1.0f : -1.0f;
M_S1++;
// rotate by pi/2 on odd subcarriers
_S1[i] *= (i%2)==0 ? 1.0f : _Complex_I;
}
}
// destroy objects
msequence_destroy(ms);
// ensure at least one subcarrier was enabled
if (M_S1 == 0) {
fprintf(stderr,"error: ofdmoqamframe_init_S1(), no subcarriers enabled; check allocation\n");
exit(1);
}
// set return value(s)
*_M_S1 = M_S1;
}
// generate short sequence symbols
// _p : subcarrier allocation array
// _num_subcarriers : total number of subcarriers
// _S0 : output symbol
// _M_S0 : total number of enabled subcarriers in S0
void ofdmoqamframe_init_S0(unsigned char * _p,
unsigned int _num_subcarriers,
float complex * _S0,
unsigned int * _M_S0)
{
unsigned int i;
// compute m-sequence length
unsigned int m = liquid_nextpow2(_num_subcarriers);
if (m < 4) m = 4;
else if (m > 8) m = 8;
// generate m-sequence generator object
msequence ms = msequence_create_default(m);
unsigned int s;
unsigned int M_S0 = 0;
// short sequence
for (i=0; i<_num_subcarriers; i++) {
// generate symbol
//s = msequence_generate_symbol(ms,1);
s = msequence_generate_symbol(ms,3) & 0x01;
if (_p[i] == OFDMOQAMFRAME_SCTYPE_NULL) {
// NULL subcarrier
_S0[i] = 0.0f;
} else {
if ( (i%2) == 0 ) {
// even subcarrer
_S0[i] = s ? 1.0f : -1.0f;
M_S0++;
} else {
// odd subcarrer (ignore)
_S0[i] = 0.0f;
}
}
}
// destroy objects
msequence_destroy(ms);
// ensure at least one subcarrier was enabled
if (M_S0 == 0) {
fprintf(stderr,"error: ofdmoqamframe_init_S0(), no subcarriers enabled; check allocation\n");
exit(1);
}
// set return value(s)
*_M_S0 = M_S0;
}
// Helper function to keep code base small
void symsync_crcf_bench(struct rusage * _start,
struct rusage * _finish,
unsigned long int * _num_iterations,
unsigned int _k,
unsigned int _m)
{
unsigned long int i;
unsigned int npfb = 16; // number of filters in bank
unsigned int k = _k; // samples/symbol
unsigned int m = _m; // filter delay [symbols]
float beta = 0.3f; // filter excess bandwidth factor
// create symbol synchronizer
symsync_crcf q = symsync_crcf_create_rnyquist(LIQUID_RNYQUIST_RRC,
k, m, beta, npfb);
//
unsigned int num_samples = 64;
*_num_iterations /= num_samples;
unsigned int num_written;
float complex x[num_samples];
float complex y[num_samples];
// generate pseudo-random data
msequence ms = msequence_create_default(6);
for (i=0; i<num_samples; i++)
x[i] = ((float)msequence_generate_symbol(ms, 6) - 31.5) / 24.0f;
msequence_destroy(ms);
// start trials
getrusage(RUSAGE_SELF, _start);
for (i=0; i<(*_num_iterations); i++) {
symsync_crcf_execute(q, x, num_samples, y, &num_written);
symsync_crcf_execute(q, x, num_samples, y, &num_written);
symsync_crcf_execute(q, x, num_samples, y, &num_written);
symsync_crcf_execute(q, x, num_samples, y, &num_written);
}
getrusage(RUSAGE_SELF, _finish);
*_num_iterations *= 4 * num_samples;
symsync_crcf_destroy(q);
}
