static void corr_all_zs(cf_t z[SRSLTE_SSS_N], float s[SRSLTE_SSS_N][SRSLTE_SSS_N-1], float output[SRSLTE_SSS_N]) {
uint32_t m;
cf_t tmp[SRSLTE_SSS_N];
for (m = 0; m < SRSLTE_SSS_N; m++) {
tmp[m] = srslte_vec_dot_prod_cfc(z, s[m], SRSLTE_SSS_N - 1);
}
srslte_vec_abs_square_cf(tmp, output, SRSLTE_SSS_N);
}
/* Complex division is conjugate multiplication + real division */
void srslte_vec_div_ccc(cf_t *x, cf_t *y, float *y_mod, cf_t *z, float *z_real, float *z_imag, uint32_t len) {
#ifdef DIV_USE_VEC
srslte_vec_prod_conj_ccc(x,y,z,len);
srslte_vec_abs_square_cf(y,y_mod,len);
srslte_vec_div_cfc(z,y_mod,z,z_real,z_imag,len);
#else
int i;
for (i=0;i<len;i++) {
z[i] = x[i] / y[i];
}
#endif
}
static void corr_all_sz_partial(cf_t z[SRSLTE_SSS_N], float s[SRSLTE_SSS_N][SRSLTE_SSS_N], uint32_t M, float output[SRSLTE_SSS_N]) {
uint32_t Nm = SRSLTE_SSS_N/M;
cf_t tmp[SRSLTE_SSS_N];
float tmp_abs[MAX_M-1][SRSLTE_SSS_N];
int j, m;
float *ptr;
for (j=0;j<M;j++) {
for (m = 0; m < SRSLTE_SSS_N; m++) {
tmp[m] = srslte_vec_dot_prod_cfc(&z[j*Nm], &s[m][j*Nm], Nm);
}
if (j == 0) {
ptr = output;
} else {
ptr = tmp_abs[j-1];
}
srslte_vec_abs_square_cf(tmp, ptr, SRSLTE_SSS_N);
}
for (j=1;j<M;j++) {
srslte_vec_sum_fff(tmp_abs[j-1], output, output, SRSLTE_SSS_N);
}
}
/** Performs time-domain PSS correlation.
* Returns the index of the PSS correlation peak in a subframe.
* The frame starts at corr_peak_pos-subframe_size/2.
* The value of the correlation is stored in corr_peak_value.
*
* Input buffer must be subframe_size long.
*/
int srslte_pss_synch_find_pss(srslte_pss_synch_t *q, cf_t *input, float *corr_peak_value)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL)
{
uint32_t corr_peak_pos;
uint32_t conv_output_len;
if (!srslte_N_id_2_isvalid(q->N_id_2)) {
fprintf(stderr, "Error finding PSS peak, Must set N_id_2 first\n");
return SRSLTE_ERROR;
}
/* Correlate input with PSS sequence */
if (q->frame_size >= q->fft_size) {
#ifdef CONVOLUTION_FFT
memcpy(q->tmp_input, input, q->frame_size * sizeof(cf_t));
conv_output_len = srslte_conv_fft_cc_run(&q->conv_fft, q->tmp_input, q->pss_signal_time[q->N_id_2], q->conv_output);
#else
conv_output_len = srslte_conv_cc(input, q->pss_signal_time[q->N_id_2], q->conv_output, q->frame_size, q->fft_size);
#endif
} else {
for (int i=0;i<q->frame_size;i++) {
q->conv_output[i] = srslte_vec_dot_prod_ccc(q->pss_signal_time[q->N_id_2], &input[i], q->fft_size);
}
conv_output_len = q->frame_size;
}
#ifdef SRSLTE_PSS_ABS_SQUARE
srslte_vec_abs_square_cf(q->conv_output, q->conv_output_abs, conv_output_len-1);
#else
srslte_vec_abs_cf(q->conv_output, q->conv_output_abs, conv_output_len-1);
#endif
srslte_vec_sc_prod_fff(q->conv_output_abs, q->ema_alpha, q->conv_output_abs, conv_output_len-1);
srslte_vec_sc_prod_fff(q->conv_output_avg, 1-q->ema_alpha, q->conv_output_avg, conv_output_len-1);
srslte_vec_sum_fff(q->conv_output_abs, q->conv_output_avg, q->conv_output_avg, conv_output_len-1);
/* Find maximum of the absolute value of the correlation */
corr_peak_pos = srslte_vec_max_fi(q->conv_output_avg, conv_output_len-1);
// save absolute value
q->peak_value = q->conv_output_avg[corr_peak_pos];
#ifdef SRSLTE_PSS_RETURN_PSR
// Find second side lobe
// Find end of peak lobe to the right
int pl_ub = corr_peak_pos+1;
while(q->conv_output_avg[pl_ub+1] <= q->conv_output_avg[pl_ub] && pl_ub < conv_output_len) {
pl_ub ++;
}
// Find end of peak lobe to the left
int pl_lb;
if (corr_peak_pos > 2) {
pl_lb = corr_peak_pos-1;
while(q->conv_output_avg[pl_lb-1] <= q->conv_output_avg[pl_lb] && pl_lb > 1) {
pl_lb --;
}
} else {
pl_lb = 0;
}
int sl_distance_right = conv_output_len-1-pl_ub;
if (sl_distance_right < 0) {
sl_distance_right = 0;
}
int sl_distance_left = pl_lb;
int sl_right = pl_ub+srslte_vec_max_fi(&q->conv_output_avg[pl_ub], sl_distance_right);
int sl_left = srslte_vec_max_fi(q->conv_output_avg, sl_distance_left);
float side_lobe_value = SRSLTE_MAX(q->conv_output_avg[sl_right], q->conv_output_avg[sl_left]);
if (corr_peak_value) {
*corr_peak_value = q->conv_output_avg[corr_peak_pos]/side_lobe_value;
DEBUG("peak_pos=%2d, pl_ub=%2d, pl_lb=%2d, sl_right: %2d, sl_left: %2d, PSR: %.2f/%.2f=%.2f\n", corr_peak_pos, pl_ub, pl_lb,
sl_right,sl_left, q->conv_output_avg[corr_peak_pos], side_lobe_value,*corr_peak_value);
}
#else
if (corr_peak_value) {
*corr_peak_value = q->conv_output_avg[corr_peak_pos];
}
#endif
if (q->frame_size >= q->fft_size) {
ret = (int) corr_peak_pos;
} else {
ret = (int) corr_peak_pos + q->fft_size;
}
}
return ret;
}
/** Performs time-domain PSS correlation.
* Returns the index of the PSS correlation peak in a subframe.
* The frame starts at corr_peak_pos-subframe_size/2.
* The value of the correlation is stored in corr_peak_value.
*
* Input buffer must be subframe_size long.
*/
int srslte_pss_find_pss(srslte_pss_t *q, const cf_t *input, float *corr_peak_value)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL)
{
uint32_t corr_peak_pos;
uint32_t conv_output_len;
if (!srslte_N_id_2_isvalid(q->N_id_2)) {
ERROR("Error finding PSS peak, Must set N_id_2 first\n");
return SRSLTE_ERROR;
}
/* Correlate input with PSS sequence
*
* We do not reverse time-domain PSS signal because it's conjugate is symmetric.
* The conjugate operation on pss_signal_time has been done in srslte_pss_init_N_id_2
* This is why we can use FFT-based convolution
*/
if (q->frame_size >= q->fft_size) {
#ifdef CONVOLUTION_FFT
memcpy(q->tmp_input, input, (q->frame_size * q->decimate) * sizeof(cf_t));
if(q->decimate > 1) {
srslte_filt_decim_cc_execute(&(q->filter), q->tmp_input, q->filter.downsampled_input, q->filter.filter_output , (q->frame_size * q->decimate));
conv_output_len = srslte_conv_fft_cc_run_opt(&q->conv_fft, q->filter.filter_output,q->pss_signal_freq_full[q->N_id_2], q->conv_output);
} else {
conv_output_len = srslte_conv_fft_cc_run_opt(&q->conv_fft, q->tmp_input, q->pss_signal_freq_full[q->N_id_2], q->conv_output);
}
#else
conv_output_len = srslte_conv_cc(input, q->pss_signal_time[q->N_id_2], q->conv_output, q->frame_size, q->fft_size);
#endif
} else {
for (int i=0;i<q->frame_size;i++) {
q->conv_output[i] = srslte_vec_dot_prod_ccc(q->pss_signal_time[q->N_id_2], &input[i], q->fft_size);
}
conv_output_len = q->frame_size;
}
// Compute modulus square
srslte_vec_abs_square_cf(q->conv_output, q->conv_output_abs, conv_output_len-1);
// If enabled, average the absolute value from previous calls
if (q->ema_alpha < 1.0 && q->ema_alpha > 0.0) {
srslte_vec_sc_prod_fff(q->conv_output_abs, q->ema_alpha, q->conv_output_abs, conv_output_len-1);
srslte_vec_sc_prod_fff(q->conv_output_avg, 1-q->ema_alpha, q->conv_output_avg, conv_output_len-1);
srslte_vec_sum_fff(q->conv_output_abs, q->conv_output_avg, q->conv_output_avg, conv_output_len-1);
} else {
memcpy(q->conv_output_avg, q->conv_output_abs, sizeof(float)*(conv_output_len-1));
}
/* Find maximum of the absolute value of the correlation */
corr_peak_pos = srslte_vec_max_fi(q->conv_output_avg, conv_output_len-1);
// save absolute value
q->peak_value = q->conv_output_avg[corr_peak_pos];
#ifdef SRSLTE_PSS_RETURN_PSR
if (corr_peak_value) {
*corr_peak_value = compute_peak_sidelobe(q, corr_peak_pos, conv_output_len);
}
#else
if (corr_peak_value) {
*corr_peak_value = q->conv_output_avg[corr_peak_pos];
}
#endif
if(q->decimate >1) {
int decimation_correction = (q->filter.num_taps - 2);
corr_peak_pos = corr_peak_pos - decimation_correction;
corr_peak_pos = corr_peak_pos*q->decimate;
}
if (q->frame_size >= q->fft_size) {
ret = (int) corr_peak_pos;
} else {
ret = (int) corr_peak_pos + q->fft_size;
}
}
return ret;
}
int srslte_prach_detect_offset(srslte_prach_t *p,
uint32_t freq_offset,
cf_t *signal,
uint32_t sig_len,
uint32_t *indices,
float *t_offsets,
float *peak_to_avg,
uint32_t *n_indices)
{
int ret = SRSLTE_ERROR;
if(p != NULL &&
signal != NULL &&
sig_len > 0 &&
indices != NULL)
{
if(sig_len < p->N_ifft_prach){
fprintf(stderr, "srslte_prach_detect: Signal length is %d and should be %d\n", sig_len, p->N_ifft_prach);
return SRSLTE_ERROR_INVALID_INPUTS;
}
// FFT incoming signal
srslte_dft_run(p->fft, signal, p->signal_fft);
*n_indices = 0;
// Extract bins of interest
uint32_t N_rb_ul = srslte_nof_prb(p->N_ifft_ul);
uint32_t k_0 = freq_offset*N_RB_SC - N_rb_ul*N_RB_SC/2 + p->N_ifft_ul/2;
uint32_t K = DELTA_F/DELTA_F_RA;
uint32_t begin = PHI + (K*k_0) + (K/2);
memcpy(p->prach_bins, &p->signal_fft[begin], p->N_zc*sizeof(cf_t));
for(int i=0;i<p->N_roots;i++){
cf_t *root_spec = p->dft_seqs[p->root_seqs_idx[i]];
srslte_vec_prod_conj_ccc(p->prach_bins, root_spec, p->corr_spec, p->N_zc);
srslte_dft_run(p->zc_ifft, p->corr_spec, p->corr_spec);
srslte_vec_abs_square_cf(p->corr_spec, p->corr, p->N_zc);
float corr_ave = srslte_vec_acc_ff(p->corr, p->N_zc)/p->N_zc;
uint32_t winsize = 0;
if(p->N_cs != 0){
winsize = p->N_cs;
}else{
winsize = p->N_zc;
}
uint32_t n_wins = p->N_zc/winsize;
float max_peak = 0;
for(int j=0;j<n_wins;j++) {
uint32_t start = (p->N_zc-(j*p->N_cs))%p->N_zc;
uint32_t end = start+winsize;
if (end>p->deadzone) {
end-=p->deadzone;
}
start += p->deadzone;
p->peak_values[j] = 0;
for(int k=start;k<end;k++) {
if(p->corr[k] > p->peak_values[j]) {
p->peak_values[j] = p->corr[k];
p->peak_offsets[j] = k-start;
if (p->peak_values[j] > max_peak) {
max_peak = p->peak_values[j];
}
}
}
}
if (max_peak > p->detect_factor*corr_ave) {
for (int j=0;j<n_wins;j++) {
if(p->peak_values[j] > p->detect_factor*corr_ave)
{
printf("ncs=%d, nzc=%d, nwins=%d, Nroot=%d, i=%d, j=%d, start=%d, peak_value=%f, peak_offset=%d, tseq=%f\n",
p->N_cs, p->N_zc, n_wins, p->N_roots, i, j, (p->N_zc-(j*p->N_cs))%p->N_zc, p->peak_values[j],
p->peak_offsets[j], p->T_seq*1e6);
memcpy(save_corr, p->corr, p->N_zc*sizeof(float));
if (indices) {
indices[*n_indices] = (i*n_wins)+j;
}
if (peak_to_avg) {
peak_to_avg[*n_indices] = p->peak_values[j]/corr_ave;
}
if (t_offsets) {
t_offsets[*n_indices] = (float) p->peak_offsets[j]*p->T_seq/p->N_zc;
}
(*n_indices)++;
}
}
}
}
ret = SRSLTE_SUCCESS;
}
return ret;
}
