/* Differential SSS estimation.
* Returns m0 and m1 estimates
*
* Source: "SSS Detection Method for Initial Cell Search in 3GPP LTE FDD/TDD Dual Mode Receiver"
* Jung-In Kim, Jung-Su Han, Hee-Jin Roh and Hyung-Jin Choi
*
*/
int srslte_sss_synch_m0m1_diff_coh(srslte_sss_synch_t *q, cf_t *input, cf_t ce[2*SRSLTE_SSS_N], uint32_t *m0, float *m0_value,
uint32_t *m1, float *m1_value)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL &&
m0 != NULL &&
m1 != NULL)
{
cf_t yprod[SRSLTE_SSS_N];
cf_t y[2][SRSLTE_SSS_N];
extract_pair_sss(q, input, ce, y);
srslte_vec_prod_conj_ccc(&y[0][1], y[0], yprod, SRSLTE_SSS_N - 1);
corr_all_zs(yprod, q->fc_tables[q->N_id_2].sd, q->corr_output_m0);
*m0 = srslte_vec_max_fi(q->corr_output_m0, SRSLTE_SSS_N);
if (m0_value) {
*m0_value = q->corr_output_m0[*m0];
}
srslte_vec_prod_cfc(y[1], q->fc_tables[q->N_id_2].z1[*m0], y[1], SRSLTE_SSS_N);
srslte_vec_prod_conj_ccc(&y[1][1], y[1], yprod, SRSLTE_SSS_N - 1);
corr_all_zs(yprod, q->fc_tables[q->N_id_2].sd, q->corr_output_m1);
*m1 = srslte_vec_max_fi(q->corr_output_m1, SRSLTE_SSS_N);
if (m1_value) {
*m1_value = q->corr_output_m1[*m1];
}
ret = SRSLTE_SUCCESS;
}
return ret;
}
/* Assumes input points to the beginning of the SSS symbol. The SSS symbol start is
* given by SSS_SYMBOL_ST() macro in sss.h.
* Estimates the m0 and m1 values and saves in m0_value and m1_value
* the resulted correlation (higher is more likely)
*
*
* Source: "SSS Detection Method for Initial Cell Search in 3GPP LTE FDD/TDD Dual Mode Receiver"
* Jung-In Kim, Jung-Su Han, Hee-Jin Roh and Hyung-Jin Choi
*
*/
void sss_synch_m0m1(sss_synch_t *q, cf_t *input, int *m0, float *m0_value,
int *m1, float *m1_value) {
/* This is aprox 3-4 kbytes of stack. Consider moving to sss_synch_t?? */
cf_t zdelay[N_SSS+1],zconj[N_SSS+1],zprod[N_SSS+1];
cf_t y[2][N_SSS+1], z[N_SSS+1], tmp[N_SSS+1];
float tmp_real[N_SSS+1];
cf_t input_fft[SSS_DFT_LEN];
int i;
dft_run_c2c(&q->dftp_input, input, input_fft);
for (i = 0; i < N_SSS; i++) {
y[0][i] = input_fft[SSS_POS_SYMBOL + 2 * i];
y[1][i] = input_fft[SSS_POS_SYMBOL + 2 * i + 1];
}
vec_prod_ccc(y[0], q->fc_tables.c[0], z, N_SSS);
memcpy(zdelay, &z[1], (N_SSS - 1) * sizeof(cf_t));
vec_conj_cc(z, zconj, N_SSS - 1);
vec_prod_ccc(zdelay, zconj, zprod, N_SSS - 1);
corr_all_zs(zprod, q->fc_tables.s, tmp);
vec_abs_cf(tmp, tmp_real, N_SSS);
*m0 = vec_max_fi(tmp_real, N_SSS);
if (m0_value) {
*m0_value = tmp_real[*m0];
}
vec_prod_ccc(y[1], q->fc_tables.c[1], tmp, N_SSS);
vec_prod_ccc(tmp, q->fc_tables.z1[*m0], z, N_SSS);
memcpy(zdelay, &z[1], (N_SSS - 1) * sizeof(cf_t));
vec_conj_cc(z, zconj, N_SSS - 1);
vec_prod_ccc(zdelay, zconj, zprod, N_SSS - 1);
corr_all_zs(zprod, q->fc_tables.s, tmp);
vec_abs_cf(tmp, tmp_real, N_SSS);
*m1 = vec_max_fi(tmp_real, N_SSS);
if (m1_value) {
*m1_value = tmp_real[*m1];
}
}
