/* Returns 1 if the SSS is found, 0 if not and -1 if there is not enough space
* to correlate
*/
int sync_sss(sync_t *q, cf_t *input, uint32_t peak_pos, lte_cp_t cp) {
int sss_idx, ret;
sss_synch_set_N_id_2(&q->sss, q->N_id_2);
/* Make sure we have enough room to find SSS sequence */
sss_idx = (int) peak_pos-2*q->fft_size-CP(q->fft_size, (CP_ISNORM(q->cp)?CPNORM_LEN:CPEXT_LEN));
if (sss_idx < 0) {
INFO("Not enough room to decode CP SSS (sss_idx=%d, peak_pos=%d)\n", sss_idx, peak_pos);
return LIBLTE_ERROR;
}
DEBUG("Searching SSS around sss_idx: %d, peak_pos: %d\n", sss_idx, peak_pos);
switch(q->sss_alg) {
case SSS_DIFF:
sss_synch_m0m1_diff(&q->sss, &input[sss_idx], &q->m0, &q->m0_value, &q->m1, &q->m1_value);
break;
case SSS_PARTIAL_3:
sss_synch_m0m1_partial(&q->sss, &input[sss_idx], 3, NULL, &q->m0, &q->m0_value, &q->m1, &q->m1_value);
break;
case SSS_FULL:
sss_synch_m0m1_partial(&q->sss, &input[sss_idx], 1, NULL, &q->m0, &q->m0_value, &q->m1, &q->m1_value);
break;
}
q->sf_idx = sss_synch_subframe(q->m0, q->m1);
ret = sss_synch_N_id_1(&q->sss, q->m0, q->m1);
if (ret >= 0) {
q->N_id_1 = (uint32_t) ret;
DEBUG("SSS detected N_id_1=%d, sf_idx=%d, %s CP\n",
q->N_id_1, q->sf_idx, CP_ISNORM(q->cp)?"Normal":"Extended");
return 1;
} else {
q->N_id_1 = 1000;
return LIBLTE_SUCCESS;
}
}
/* In this function, input points to the beginning of the subframe. Saves result in subframe_idx and N_id_1
* Return 1 if the sequence was found, 0 if the peak is not found, -1 if the subframe_sz or symbol_sz are
* invalid or not configured.
* Before calling this function, the correlation threshold and symbol size duration need to be set
* using sss_synch_set_threshold() and sss_synch_set_symbol_sz().
*/
int sss_synch_frame(sss_synch_t *q, cf_t *input, int *subframe_idx,
int *N_id_1) {
int m0,m1;
float m0_value, m1_value;
if (q->subframe_sz <= 0 || q->symbol_sz <= 0) {
return -1;
}
sss_synch_m0m1(q, &input[SSS_SYMBOL_ST(q->subframe_sz, q->symbol_sz)],
&m0, &m0_value, &m1, &m1_value);
if (m0_value > q->corr_peak_threshold && m1_value > q->corr_peak_threshold) {
if (subframe_idx) {
*subframe_idx = sss_synch_subframe(m0, m1);
}
if (N_id_1) {
*N_id_1 = sss_synch_N_id_1(q, m0, m1);
}
return 1;
} else {
return 0;
}
}
int sync_run(sync_t *q, cf_t *input) {
int N_id_2, peak_pos[3], sss_idx_n, sss_idx_e;
int m0, m1;
float m0_value_e, m1_value_e,m0_value_n, m1_value_n;
int slot_id_e, N_id_1_e, slot_id_n, N_id_1_n;
float peak_value[3];
float mean_value[3];
float max=-999;
int i;
int peak_detected;
if (q->force_N_id_2 == -1) {
for (N_id_2=0;N_id_2<3;N_id_2++) {
peak_pos[N_id_2] = pss_synch_find_pss(&q->pss[N_id_2], input,
&peak_value[N_id_2], &mean_value[N_id_2]);
}
for (i=0;i<3;i++) {
if (peak_value[i] > max) {
max = peak_value[i];
N_id_2 = i;
}
}
} else {
N_id_2 = q->force_N_id_2;
peak_pos[N_id_2] = pss_synch_find_pss(&q->pss[N_id_2], input,
&peak_value[N_id_2], &mean_value[N_id_2]);
}
q->peak_to_avg = peak_value[N_id_2] / mean_value[N_id_2];
DEBUG("PSS possible peak N_id_2=%d, pos=%d peak=%.2f par=%.2f threshold=%.2f\n",
N_id_2, peak_pos[N_id_2], peak_value[N_id_2], q->peak_to_avg, q->threshold);
/* If peak detected */
peak_detected = 0;
if (peak_pos[N_id_2] - 128 >= 0) {
if (q->pss_mode == ABSOLUTE) {
if (peak_value[N_id_2] > q->threshold) {
peak_detected = 1;
}
} else {
if (q->peak_to_avg > q->threshold) {
peak_detected = 1;
}
}
}
if (peak_detected) {
q->cfo = pss_synch_cfo_compute(&q->pss[N_id_2], &input[peak_pos[N_id_2]-128]);
INFO("PSS peak detected N_id_2=%d, pos=%d peak=%.2f par=%.2f th=%.2f cfo=%.4f\n", N_id_2,
peak_pos[N_id_2], peak_value[N_id_2], q->peak_to_avg, q->threshold, q->cfo);
if (q->sss_en) {
/* Make sure we have enough room to find SSS sequence */
sss_idx_n = peak_pos[N_id_2]-2*(128+CP(128,CPNORM_LEN));
sss_idx_e = peak_pos[N_id_2]-2*(128+CP(128,CPEXT_LEN));
if (q->detect_cp) {
if (sss_idx_n < 0 || sss_idx_e < 0) {
INFO("Not enough room to decode SSS (%d, %d)\n", sss_idx_n, sss_idx_e);
return -1;
}
} else {
if (CP_ISNORM(q->cp)) {
if (sss_idx_n < 0) {
INFO("Not enough room to decode SSS (%d)\n", sss_idx_n);
return -1;
}
} else {
if (sss_idx_e < 0) {
INFO("Not enough room to decode SSS (%d)\n", sss_idx_e);
return -1;
}
}
}
N_id_1_e = -1;
N_id_1_n = -1;
slot_id_e = -1;
slot_id_n = -1;
/* try Normal CP length */
if (q->detect_cp || CP_ISNORM(q->cp)) {
sss_synch_m0m1(&q->sss[N_id_2], &input[sss_idx_n],
&m0, &m0_value_n, &m1, &m1_value_n);
slot_id_n = 2 * sss_synch_subframe(m0, m1);
N_id_1_n = sss_synch_N_id_1(&q->sss[N_id_2], m0, m1);
}
if (q->detect_cp || CP_ISEXT(q->cp)) {
/* Now try Extended CP length */
sss_synch_m0m1(&q->sss[N_id_2], &input[sss_idx_e],
&m0, &m0_value_e, &m1, &m1_value_e);
slot_id_e = 2 * sss_synch_subframe(m0, m1);
N_id_1_e = sss_synch_N_id_1(&q->sss[N_id_2], m0, m1);
}
/* Correlation with extended CP hypoteshis is greater than with normal? */
if ((q->detect_cp && m0_value_e * m1_value_e > m0_value_n * m1_value_n)
|| CP_ISEXT(q->cp)) {
q->cp = CPEXT;
q->slot_id = slot_id_e;
q->N_id_1 = N_id_1_e;
/* then is normal CP */
} else {
q->cp = CPNORM;
q->slot_id = slot_id_n;
q->N_id_1 = N_id_1_n;
}
q->N_id_2 = N_id_2;
INFO("SSS detected N_id_1=%d, slot_idx=%d, %s CP\n",
q->N_id_1, q->slot_id, CP_ISNORM(q->cp)?"Normal":"Extended");
}
return peak_pos[N_id_2];
} else {
return -1;
}
}
