float srslte_ue_sync_get_cfo(srslte_ue_sync_t *q) {
return 15000 * srslte_sync_get_cfo(&q->strack);
}
/* Returns 1 if the subframe is synchronized in time, 0 otherwise */
int srslte_ue_sync_zerocopy(srslte_ue_sync_t *q, cf_t *input_buffer) {
int ret = SRSLTE_ERROR_INVALID_INPUTS;
uint32_t track_idx;
if (q != NULL &&
input_buffer != NULL)
{
if (q->file_mode) {
int n = srslte_filesource_read(&q->file_source, input_buffer, q->sf_len);
if (n < 0) {
fprintf(stderr, "Error reading input file\n");
return SRSLTE_ERROR;
}
if (n == 0) {
return 7;
// srslte_filesource_seek(&q->file_source, 0);
// q->sf_idx = 9;
// int n = srslte_filesource_read(&q->file_source, input_buffer, q->sf_len);
// if (n < 0) {
// fprintf(stderr, "Error reading input file\n");
// return SRSLTE_ERROR;
// }
}
if (q->correct_cfo) {
srslte_cfo_correct(&q->file_cfo_correct,
input_buffer,
input_buffer,
q->file_cfo / 15000 / q->fft_size);
}
q->sf_idx++;
if (q->sf_idx == 10) {
q->sf_idx = 0;
}
INFO("Reading %d samples. sf_idx = %d\n", q->sf_len, q->sf_idx);
ret = 1;
} else {
if (receive_samples(q, input_buffer)) {
fprintf(stderr, "Error receiving samples\n");
return SRSLTE_ERROR;
}
switch (q->state) {
case SF_FIND:
switch(srslte_sync_find(&q->sfind, input_buffer, 0, &q->peak_idx)) {
case SRSLTE_SYNC_ERROR:
ret = SRSLTE_ERROR;
fprintf(stderr, "Error finding correlation peak (%d)\n", ret);
return SRSLTE_ERROR;
case SRSLTE_SYNC_FOUND:
ret = find_peak_ok(q, input_buffer);
break;
case SRSLTE_SYNC_FOUND_NOSPACE:
/* If a peak was found but there is not enough space for SSS/CP detection, discard a few samples */
printf("No space for SSS/CP detection. Realigning frame...\n");
q->recv_callback(q->stream, dummy_offset_buffer, q->frame_len/2, NULL);
srslte_sync_reset(&q->sfind);
ret = SRSLTE_SUCCESS;
break;
default:
ret = SRSLTE_SUCCESS;
break;
}
if (q->do_agc) {
srslte_agc_process(&q->agc, input_buffer, q->sf_len);
}
break;
case SF_TRACK:
ret = 1;
srslte_sync_sss_en(&q->strack, q->decode_sss_on_track);
q->sf_idx = (q->sf_idx + q->nof_recv_sf) % 10;
/* Every SF idx 0 and 5, find peak around known position q->peak_idx */
if (q->sf_idx == 0 || q->sf_idx == 5) {
if (q->do_agc && (q->agc_period == 0 ||
(q->agc_period && (q->frame_total_cnt%q->agc_period) == 0)))
{
srslte_agc_process(&q->agc, input_buffer, q->sf_len);
}
#ifdef MEASURE_EXEC_TIME
struct timeval t[3];
gettimeofday(&t[1], NULL);
#endif
track_idx = 0;
/* Track PSS/SSS around the expected PSS position
* In tracking phase, the subframe carrying the PSS is always the last one of the frame
*/
switch(srslte_sync_find(&q->strack, input_buffer,
q->frame_len - q->sf_len/2 - q->fft_size - q->strack.max_offset/2,
&track_idx))
{
case SRSLTE_SYNC_ERROR:
ret = SRSLTE_ERROR;
fprintf(stderr, "Error tracking correlation peak\n");
return SRSLTE_ERROR;
case SRSLTE_SYNC_FOUND:
ret = track_peak_ok(q, track_idx);
break;
case SRSLTE_SYNC_FOUND_NOSPACE:
// It's very very unlikely that we fall here because this event should happen at FIND phase only
ret = 0;
q->state = SF_FIND;
printf("Warning: No space for SSS/CP while in tracking phase\n");
break;
case SRSLTE_SYNC_NOFOUND:
ret = track_peak_no(q);
break;
}
#ifdef MEASURE_EXEC_TIME
gettimeofday(&t[2], NULL);
get_time_interval(t);
q->mean_exec_time = (float) SRSLTE_VEC_CMA((float) t[0].tv_usec, q->mean_exec_time, q->frame_total_cnt);
#endif
if (ret == SRSLTE_ERROR) {
fprintf(stderr, "Error processing tracking peak\n");
q->state = SF_FIND;
return SRSLTE_SUCCESS;
}
q->frame_total_cnt++;
} else {
if (q->correct_cfo) {
srslte_cfo_correct(&q->sfind.cfocorr,
input_buffer,
input_buffer,
-srslte_sync_get_cfo(&q->strack) / q->fft_size);
}
}
break;
}
}
}
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 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;
}