/** Finds the PSS sequence previously defined by a call to srslte_sync_set_N_id_2()
* around the position find_offset in the buffer input.
* Returns 1 if the correlation peak exceeds the threshold set by srslte_sync_set_threshold()
* or 0 otherwise. Returns a negative number on error (if N_id_2 has not been set)
*
* The maximum of the correlation peak is always stored in *peak_position
*/
int srslte_sync_find(srslte_sync_t *q, cf_t *input, uint32_t find_offset, uint32_t *peak_position)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL &&
srslte_N_id_2_isvalid(q->N_id_2) &&
fft_size_isvalid(q->fft_size))
{
int peak_pos;
ret = SRSLTE_SUCCESS;
if (peak_position) {
*peak_position = 0;
}
/* Estimate CFO using CP */
if (q->enable_cfo_corr) {
uint32_t cp_offset = srslte_cp_synch(&q->cp_synch, input, q->nof_symbols, q->nof_symbols, SRSLTE_CP_LEN_NORM(1,q->fft_size));
cf_t cp_corr_max = srslte_cp_synch_corr_output(&q->cp_synch, cp_offset);
float cfo = -carg(cp_corr_max) / M_PI / 2;
/* compute cumulative moving average CFO */
INFO("cp_offset_pos=%d, abs=%f, cfo=%f, mean_cfo=%f, nof_symb=%d\n",
cp_offset, cabs(cp_corr_max), cfo, q->mean_cfo, q->nof_symbols);
if (q->mean_cfo) {
q->mean_cfo = SRSLTE_VEC_EMA(cfo, q->mean_cfo, q->cfo_ema_alpha);
} else {
q->mean_cfo = cfo;
}
/* Correct CFO with the averaged CFO estimation */
srslte_cfo_correct(&q->cfocorr, input, input, -q->mean_cfo / q->fft_size);
}
if (q->find_cfo_i && q->enable_cfo_corr) {
float peak_value;
float max_peak_value = -99;
peak_pos = 0;
srslte_pss_synch_t *pss_obj[3] = {&q->pss_i[0], &q->pss, &q->pss_i[1]};
for (int cfo_i=0;cfo_i<3;cfo_i++) {
srslte_pss_synch_set_N_id_2(pss_obj[cfo_i], q->N_id_2);
int p = srslte_pss_synch_find_pss(pss_obj[cfo_i], &input[find_offset], &peak_value);
if (peak_value > max_peak_value) {
max_peak_value = peak_value;
peak_pos = p;
q->peak_value = peak_value;
q->cfo_i = cfo_i-1;
}
}
if (q->cfo_i != 0) {
srslte_vec_prod_ccc(input, q->cfo_i_corr[q->cfo_i<0?0:1], input, q->frame_size);
INFO("Compensating cfo_i=%d\n", q->cfo_i);
}
} else {
srslte_pss_synch_set_N_id_2(&q->pss, q->N_id_2);
peak_pos = srslte_pss_synch_find_pss(&q->pss, &input[find_offset], &q->peak_value);
if (peak_pos < 0) {
fprintf(stderr, "Error calling finding PSS sequence\n");
return SRSLTE_ERROR;
}
}
q->mean_peak_value = SRSLTE_VEC_EMA(q->peak_value, q->mean_peak_value, MEANPEAK_EMA_ALPHA);
if (peak_position) {
*peak_position = (uint32_t) peak_pos;
}
/* If peak is over threshold, compute CFO and SSS */
if (q->peak_value >= q->threshold) {
// Try to detect SSS
if (q->sss_en) {
// Set an invalid N_id_1 indicating SSS is yet to be detected
q->N_id_1 = 1000;
if (sync_sss(q, input, find_offset + peak_pos, q->cp) < 0) {
DEBUG("No space for SSS processing. Frame starts at %d\n", peak_pos);
}
}
if (q->detect_cp) {
if (peak_pos + find_offset >= 2*(q->fft_size + SRSLTE_CP_LEN_EXT(q->fft_size))) {
srslte_sync_set_cp(q, srslte_sync_detect_cp(q, input, peak_pos + find_offset));
} else {
DEBUG("Not enough room to detect CP length. Peak position: %d\n", peak_pos);
}
}
// Return 1 (peak detected) even if we couldn't estimate CFO and SSS
ret = 1;
} else {
ret = 0;
}
DEBUG("SYNC ret=%d N_id_2=%d find_offset=%d pos=%d peak=%.2f threshold=%.2f sf_idx=%d, CFO=%.3f KHz\n",
ret, q->N_id_2, find_offset, peak_pos, q->peak_value, q->threshold, q->sf_idx, 15*(q->cfo_i+q->mean_cfo));
} else if (srslte_N_id_2_isvalid(q->N_id_2)) {
fprintf(stderr, "Must call srslte_sync_set_N_id_2() first!\n");
}
return ret;
}
/** Finds the PSS sequence previously defined by a call to srslte_sync_set_N_id_2()
* around the position find_offset in the buffer input.
* Returns 1 if the correlation peak exceeds the threshold set by srslte_sync_set_threshold()
* or 0 otherwise. Returns a negative number on error (if N_id_2 has not been set)
*
* The maximum of the correlation peak is always stored in *peak_position
*/
int srslte_sync_find(srslte_sync_t *q, cf_t *input, uint32_t find_offset, uint32_t *peak_position)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL &&
srslte_N_id_2_isvalid(q->N_id_2) &&
fft_size_isvalid(q->fft_size))
{
int peak_pos;
ret = SRSLTE_SUCCESS;
if (peak_position) {
*peak_position = 0;
}
srslte_pss_synch_set_N_id_2(&q->pss, q->N_id_2);
peak_pos = srslte_pss_synch_find_pss(&q->pss, &input[find_offset], &q->peak_value);
if (peak_pos < 0) {
fprintf(stderr, "Error calling finding PSS sequence\n");
return SRSLTE_ERROR;
}
q->mean_peak_value = SRSLTE_VEC_EMA(q->peak_value, q->mean_peak_value, MEANPEAK_EMA_ALPHA);
if (peak_position) {
*peak_position = (uint32_t) peak_pos;
}
/* If peak is over threshold, compute CFO and SSS */
if (q->peak_value >= q->threshold) {
// Make sure we have enough space to estimate CFO
if (peak_pos + find_offset >= q->fft_size) {
float cfo = srslte_pss_synch_cfo_compute(&q->pss, &input[find_offset+peak_pos-q->fft_size]);
/* compute cumulative moving average CFO */
q->mean_cfo = SRSLTE_VEC_EMA(cfo, q->mean_cfo, CFO_EMA_ALPHA);
} else {
DEBUG("No space for CFO computation. Frame starts at \n",peak_pos);
}
/* Correct CFO with the averaged CFO estimation */
if (q->correct_cfo) {
srslte_cfo_correct(&q->cfocorr, input, input, -q->mean_cfo / q->fft_size);
}
// Try to detect SSS
if (q->sss_en) {
// Set an invalid N_id_1 indicating SSS is yet to be detected
q->N_id_1 = 1000;
if (sync_sss(q, input, find_offset + peak_pos, q->cp) < 0) {
DEBUG("No space for SSS processing. Frame starts at %d\n", peak_pos);
}
}
if (q->detect_cp) {
if (peak_pos + find_offset >= 2*(q->fft_size + SRSLTE_CP_LEN_EXT(q->fft_size))) {
q->cp = srslte_sync_detect_cp(q, input, peak_pos + find_offset);
} else {
DEBUG("Not enough room to detect CP length. Peak position: %d\n", peak_pos);
}
}
// Return 1 (peak detected) even if we couldn't estimate CFO and SSS
ret = 1;
} else {
ret = 0;
}
DEBUG("SYNC ret=%d N_id_2=%d find_offset=%d pos=%d peak=%.2f threshold=%.2f sf_idx=%d, CFO=%.3f KHz\n",
ret, q->N_id_2, find_offset, peak_pos, q->peak_value, q->threshold, q->sf_idx, 15*q->mean_cfo);
} else if (srslte_N_id_2_isvalid(q->N_id_2)) {
fprintf(stderr, "Must call srslte_sync_set_N_id_2() first!\n");
}
return ret;
}
int main(int argc, char **argv) {
cf_t *buffer;
int frame_cnt, n;
void *uhd;
srslte_pss_synch_t pss;
srslte_cfo_t cfocorr, cfocorr64;
srslte_sss_synch_t sss;
int32_t flen;
int peak_idx, last_peak;
float peak_value;
float mean_peak;
uint32_t nof_det, nof_nodet, nof_nopeak, nof_nopeakdet;
cf_t ce[SRSLTE_PSS_LEN];
parse_args(argc, argv);
if (N_id_2_sync == -1) {
N_id_2_sync = cell_id%3;
}
uint32_t N_id_2 = cell_id%3;
uint32_t N_id_1 = cell_id/3;
#ifndef DISABLE_GRAPHICS
if (!disable_plots)
init_plots();
#endif
float srate = 15000.0*fft_size;
flen = srate*5/1000;
printf("Opening UHD device...\n");
if (cuhd_open(uhd_args, &uhd)) {
fprintf(stderr, "Error opening uhd\n");
exit(-1);
}
if (srate < 10e6) {
cuhd_set_master_clock_rate(uhd, 4*srate);
} else {
cuhd_set_master_clock_rate(uhd, srate);
}
printf("Set RX rate: %.2f MHz\n", cuhd_set_rx_srate(uhd, srate) / 1000000);
printf("Set RX gain: %.1f dB\n", cuhd_set_rx_gain(uhd, uhd_gain));
printf("Set RX freq: %.2f MHz\n", cuhd_set_rx_freq(uhd, uhd_freq) / 1000000);
cuhd_rx_wait_lo_locked(uhd);
buffer = malloc(sizeof(cf_t) * flen * 2);
if (!buffer) {
perror("malloc");
exit(-1);
}
if (srslte_pss_synch_init_fft(&pss, flen, fft_size)) {
fprintf(stderr, "Error initiating PSS\n");
exit(-1);
}
if (srslte_pss_synch_set_N_id_2(&pss, N_id_2_sync)) {
fprintf(stderr, "Error setting N_id_2=%d\n",N_id_2_sync);
exit(-1);
}
srslte_cfo_init(&cfocorr, flen);
srslte_cfo_init(&cfocorr64, flen);
if (srslte_sss_synch_init(&sss, fft_size)) {
fprintf(stderr, "Error initializing SSS object\n");
return SRSLTE_ERROR;
}
srslte_sss_synch_set_N_id_2(&sss, N_id_2);
printf("N_id_2: %d\n", N_id_2);
cuhd_start_rx_stream(uhd);
printf("Frame length %d samples\n", flen);
printf("PSS detection threshold: %.2f\n", threshold);
nof_det = nof_nodet = nof_nopeak = nof_nopeakdet = 0;
frame_cnt = 0;
last_peak = 0;
mean_peak = 0;
int peak_offset = 0;
float cfo;
float mean_cfo = 0;
uint32_t m0, m1;
uint32_t sss_error1 = 0, sss_error2 = 0, sss_error3 = 0;
uint32_t cp_is_norm = 0;
srslte_sync_t ssync;
bzero(&ssync, sizeof(srslte_sync_t));
ssync.fft_size = fft_size;
while(frame_cnt < nof_frames || nof_frames == -1) {
n = cuhd_recv(uhd, buffer, flen - peak_offset, 1);
if (n < 0) {
fprintf(stderr, "Error receiving samples\n");
exit(-1);
}
peak_idx = srslte_pss_synch_find_pss(&pss, buffer, &peak_value);
if (peak_idx < 0) {
fprintf(stderr, "Error finding PSS peak\n");
exit(-1);
}
mean_peak = SRSLTE_VEC_CMA(peak_value, mean_peak, frame_cnt);
if (peak_value >= threshold) {
nof_det++;
if (peak_idx >= fft_size) {
// Estimate CFO
cfo = srslte_pss_synch_cfo_compute(&pss, &buffer[peak_idx-fft_size]);
mean_cfo = SRSLTE_VEC_CMA(cfo, mean_cfo, frame_cnt);
// Correct CFO
srslte_cfo_correct(&cfocorr, buffer, buffer, -mean_cfo / fft_size);
// Estimate channel
if (srslte_pss_synch_chest(&pss, &buffer[peak_idx-fft_size], ce)) {
fprintf(stderr, "Error computing channel estimation\n");
exit(-1);
}
// Find SSS
int sss_idx = peak_idx-2*fft_size-(SRSLTE_CP_ISNORM(cp)?SRSLTE_CP_LEN(fft_size, SRSLTE_CP_NORM_LEN):SRSLTE_CP_LEN(fft_size, SRSLTE_CP_EXT_LEN));
if (sss_idx >= 0 && sss_idx < flen-fft_size) {
srslte_sss_synch_m0m1_partial(&sss, &buffer[sss_idx], 3, NULL, &m0, &m0_value, &m1, &m1_value);
if (srslte_sss_synch_N_id_1(&sss, m0, m1) != N_id_1) {
sss_error2++;
}
INFO("Partial N_id_1: %d\n", srslte_sss_synch_N_id_1(&sss, m0, m1));
srslte_sss_synch_m0m1_diff(&sss, &buffer[sss_idx], &m0, &m0_value, &m1, &m1_value);
if (srslte_sss_synch_N_id_1(&sss, m0, m1) != N_id_1) {
sss_error3++;
}
INFO("Diff N_id_1: %d\n", srslte_sss_synch_N_id_1(&sss, m0, m1));
srslte_sss_synch_m0m1_partial(&sss, &buffer[sss_idx], 1, NULL, &m0, &m0_value, &m1, &m1_value);
if (srslte_sss_synch_N_id_1(&sss, m0, m1) != N_id_1) {
sss_error1++;
}
INFO("Full N_id_1: %d\n", srslte_sss_synch_N_id_1(&sss, m0, m1));
}
// Estimate CP
if (peak_idx > 2*(fft_size + SRSLTE_CP_LEN_EXT(fft_size))) {
srslte_cp_t cp = srslte_sync_detect_cp(&ssync, buffer, peak_idx);
if (SRSLTE_CP_ISNORM(cp)) {
cp_is_norm++;
}
}
} else {
INFO("No space for CFO computation. Frame starts at \n",peak_idx);
}
if(srslte_sss_synch_subframe(m0,m1) == 0)
{
#ifndef DISABLE_GRAPHICS
if (!disable_plots)
do_plots_sss(sss.corr_output_m0, sss.corr_output_m1);
#endif
}
} else {
nof_nodet++;
}
if (frame_cnt > 100) {
if (abs(last_peak-peak_idx) > 4) {
if (peak_value >= threshold) {
nof_nopeakdet++;
}
nof_nopeak++;
}
}
frame_cnt++;
printf("[%5d]: Pos: %5d, PSR: %4.1f (~%4.1f) Pdet: %4.2f, "
"FA: %4.2f, CFO: %+4.1f KHz SSSmiss: %4.2f/%4.2f/%4.2f CPNorm: %.0f%%\r",
frame_cnt,
peak_idx,
peak_value, mean_peak,
(float) nof_det/frame_cnt,
(float) nof_nopeakdet/frame_cnt, mean_cfo*15,
(float) sss_error1/nof_det,(float) sss_error2/nof_det,(float) sss_error3/nof_det,
(float) cp_is_norm/nof_det * 100);
if (SRSLTE_VERBOSE_ISINFO()) {
printf("\n");
}
#ifndef DISABLE_GRAPHICS
if (!disable_plots)
do_plots(pss.conv_output_avg, pss.conv_output_avg[peak_idx], pss.fft_size+pss.frame_size-1, ce);
#endif
last_peak = peak_idx;
}
srslte_pss_synch_free(&pss);
free(buffer);
cuhd_close(uhd);
printf("Ok\n");
exit(0);
}
/** Finds the PSS sequence previously defined by a call to srslte_sync_set_N_id_2()
* around the position find_offset in the buffer input.
*
* Returns 1 if the correlation peak exceeds the threshold set by srslte_sync_set_threshold()
* or 0 otherwise. Returns a negative number on error (if N_id_2 has not been set)
*
* The input signal is not modified. Any CFO correction is done in internal buffers
*
* The maximum of the correlation peak is always stored in *peak_position
*/
srslte_sync_find_ret_t srslte_sync_find(srslte_sync_t *q, const cf_t *input, uint32_t find_offset, uint32_t *peak_position)
{
srslte_sync_find_ret_t ret = SRSLTE_SYNC_ERROR;
int peak_pos = 0;
if (!q) {
return SRSLTE_ERROR_INVALID_INPUTS;
}
if (input != NULL &&
srslte_N_id_2_isvalid(q->N_id_2) &&
fft_size_isvalid(q->fft_size))
{
if (peak_position) {
*peak_position = 0;
}
const cf_t *input_ptr = input;
/* First CFO estimation stage is integer.
* Finds max PSS correlation for shifted +1/0/-1 integer versions.
* This should only used once N_id_2 is set
*/
if (q->cfo_i_enable) {
if (cfo_i_estimate(q, input_ptr, find_offset, &peak_pos, &q->cfo_i_value) < 0) {
fprintf(stderr, "Error calling finding PSS sequence at : %d \n", peak_pos);
return SRSLTE_ERROR;
}
// Correct it using precomputed signal and store in buffer (don't modify input signal)
if (q->cfo_i_value != 0) {
srslte_vec_prod_ccc((cf_t*) input_ptr, q->cfo_i_corr[q->cfo_i_value<0?0:1], q->temp, q->frame_size);
INFO("Compensating cfo_i=%d\n", q->cfo_i_value);
input_ptr = q->temp;
}
}
/* Second stage is coarse fractional CFO estimation using CP.
* In case of multi-cell, this can lead to incorrect estimations if CFO from different cells is different
*/
if (q->cfo_cp_enable) {
float cfo_cp = cfo_cp_estimate(q, input_ptr);
if (!q->cfo_cp_is_set) {
q->cfo_cp_mean = cfo_cp;
q->cfo_cp_is_set = true;
} else {
/* compute exponential moving average CFO */
q->cfo_cp_mean = SRSLTE_VEC_EMA(cfo_cp, q->cfo_cp_mean, q->cfo_ema_alpha);
}
INFO("CP-CFO: estimated=%f, mean=%f\n", cfo_cp, q->cfo_cp_mean);
/* Correct CFO with the averaged CFO estimation */
srslte_cfo_correct(&q->cfo_corr_frame, input_ptr, q->temp, -q->cfo_cp_mean / q->fft_size);
input_ptr = q->temp;
}
/* Find maximum of PSS correlation. If Integer CFO is enabled, correlation is already done
*/
if (!q->cfo_i_enable) {
srslte_pss_set_N_id_2(&q->pss, q->N_id_2);
peak_pos = srslte_pss_find_pss(&q->pss, &input_ptr[find_offset], q->threshold>0?&q->peak_value:NULL);
if (peak_pos < 0) {
fprintf(stderr, "Error calling finding PSS sequence at : %d \n", peak_pos);
return SRSLTE_ERROR;
}
}
INFO("PSS: id=%d, peak_pos=%d, peak_value=%f\n", q->N_id_2, peak_pos, q->peak_value);
// Save peak position
if (peak_position) {
*peak_position = (uint32_t) peak_pos;
}
// In case of decimation, this compensates for the constant time shift caused by the low pass filter
if(q->decimate && peak_pos < 0) {
peak_pos = 0 ;//peak_pos + q->decimate*(2);// replace 2 with q->filter_size -2;
}
/* If peak is over threshold, compute CFO and SSS */
if (q->peak_value >= q->threshold || q->threshold == 0) {
if (q->cfo_pss_enable && peak_pos >= q->fft_size) {
// Filter central bands before PSS-based CFO estimation
const cf_t *pss_ptr = &input_ptr[find_offset + peak_pos - q->fft_size];
if (q->pss_filtering_enabled) {
srslte_pss_filter(&q->pss, pss_ptr, q->pss_filt);
pss_ptr = q->pss_filt;
}
// PSS-based CFO estimation
q->cfo_pss = srslte_pss_cfo_compute(&q->pss, pss_ptr);
if (!q->cfo_pss_is_set) {
q->cfo_pss_mean = q->cfo_pss;
q->cfo_pss_is_set = true;
} else if (15000*fabsf(q->cfo_pss) < MAX_CFO_PSS_OFFSET) {
q->cfo_pss_mean = SRSLTE_VEC_EMA(q->cfo_pss, q->cfo_pss_mean, q->cfo_ema_alpha);
}
INFO("PSS-CFO: filter=%s, estimated=%f, mean=%f\n",
q->pss_filtering_enabled?"yes":"no", q->cfo_pss, q->cfo_pss_mean);
}
// If there is enough space for CP and SSS estimation
if (peak_pos + find_offset >= 2 * (q->fft_size + SRSLTE_CP_LEN_EXT(q->fft_size))) {
// If SSS search is enabled, correlate SSS sequence
if (q->sss_en) {
// Set an invalid N_id_1 indicating SSS is yet to be detected
q->N_id_1 = 1000;
int sss_idx = find_offset + peak_pos - 2 * q->fft_size -
SRSLTE_CP_LEN(q->fft_size, (SRSLTE_CP_ISNORM(q->cp) ? SRSLTE_CP_NORM_LEN : SRSLTE_CP_EXT_LEN));
const cf_t *sss_ptr = &input_ptr[sss_idx];
// Correct CFO if detected in PSS
if (q->cfo_pss_enable) {
srslte_cfo_correct(&q->cfo_corr_symbol, sss_ptr, q->sss_filt, -q->cfo_pss_mean / q->fft_size);
// Equalize channel if estimated in PSS
if (q->sss_channel_equalize && q->pss.chest_on_filter && q->pss_filtering_enabled) {
srslte_vec_prod_ccc(&q->sss_filt[q->fft_size/2-SRSLTE_PSS_LEN/2], q->pss.tmp_ce,
&q->sss_filt[q->fft_size/2-SRSLTE_PSS_LEN/2], SRSLTE_PSS_LEN);
}
sss_ptr = q->sss_filt;
}
if (sync_sss_symbol(q, sss_ptr) < 0) {
fprintf(stderr, "Error correlating SSS\n");
return -1;
}
}
// Detect CP length
if (q->detect_cp) {
srslte_sync_set_cp(q, srslte_sync_detect_cp(q, input_ptr, peak_pos + find_offset));
} else {
DEBUG("Not enough room to detect CP length. Peak position: %d\n", peak_pos);
}
ret = SRSLTE_SYNC_FOUND;
} else {
ret = SRSLTE_SYNC_FOUND_NOSPACE;
}
} else {
ret = SRSLTE_SYNC_NOFOUND;
}
DEBUG("SYNC ret=%d N_id_2=%d find_offset=%d frame_len=%d, pos=%d peak=%.2f threshold=%.2f sf_idx=%d, CFO=%.3f kHz\n",
ret, q->N_id_2, find_offset, q->frame_size, peak_pos, q->peak_value,
q->threshold, q->sf_idx, 15*(srslte_sync_get_cfo(q)));
} else if (srslte_N_id_2_isvalid(q->N_id_2)) {
fprintf(stderr, "Must call srslte_sync_set_N_id_2() first!\n");
}
return ret;
}