/* Map PUCCH symbols to physical resources according to 5.4.3 in 36.211 */
static int pucch_put(srslte_pucch_t *q, srslte_pucch_format_t format, uint32_t n_pucch, cf_t *output) {
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q && output) {
ret = SRSLTE_ERROR;
uint32_t nsymbols = SRSLTE_CP_ISNORM(q->cell.cp)?SRSLTE_CP_NORM_NSYMB:SRSLTE_CP_EXT_NSYMB;
// Determine m
uint32_t m = srslte_pucch_m(&q->pucch_cfg, format, n_pucch, q->cell.cp);
uint32_t N_sf_0 = get_N_sf(format, 0, q->shortened);
for (uint32_t ns=0;ns<2;ns++) {
uint32_t N_sf = get_N_sf(format, ns%2, q->shortened);
// Determine n_prb
uint32_t n_prb = m/2;
if ((m+ns)%2) {
n_prb = q->cell.nof_prb-1-m/2;
}
if (n_prb < q->cell.nof_prb) {
for (uint32_t i=0;i<N_sf;i++) {
uint32_t l = get_pucch_symbol(i, format, q->cell.cp);
memcpy(&output[SRSLTE_RE_IDX(q->cell.nof_prb, l+ns*nsymbols, n_prb*SRSLTE_NRE)],
&q->z[i*SRSLTE_NRE+ns*N_sf_0*SRSLTE_NRE],
SRSLTE_NRE*sizeof(cf_t));
}
} else {
return SRSLTE_ERROR;
}
}
ret = SRSLTE_SUCCESS;
}
return ret;
}
int srslte_chest_ul_estimate_pucch(srslte_chest_ul_t *q, cf_t *input, cf_t *ce,
srslte_pucch_format_t format, uint32_t n_pucch, uint32_t sf_idx,
uint8_t *pucch2_ack_bits)
{
if (!q->dmrs_signal_configured) {
fprintf(stderr, "Error must call srslte_chest_ul_set_cfg() before using the UL estimator\n");
return SRSLTE_ERROR;
}
int n_rs = srslte_refsignal_dmrs_N_rs(format, q->cell.cp);
if (!n_rs) {
fprintf(stderr, "Error computing N_rs\n");
return SRSLTE_ERROR;
}
int nrefs_sf = SRSLTE_NRE*n_rs*2;
/* Get references from the input signal */
srslte_refsignal_dmrs_pucch_get(&q->dmrs_signal, format, n_pucch, input, q->pilot_recv_signal);
/* Generate known pilots */
uint8_t pucch2_bits[2] = {0, 0};
if (format == SRSLTE_PUCCH_FORMAT_2A || format == SRSLTE_PUCCH_FORMAT_2B) {
float max = -1e9;
int i_max = 0;
int m = 0;
if (format == SRSLTE_PUCCH_FORMAT_2A) {
m = 2;
} else {
m = 4;
}
for (int i=0;i<m;i++) {
pucch2_bits[0] = i%2;
pucch2_bits[1] = i/2;
srslte_refsignal_dmrs_pucch_gen(&q->dmrs_signal, format, n_pucch, sf_idx, pucch2_bits, q->pilot_known_signal);
srslte_vec_prod_conj_ccc(q->pilot_recv_signal, q->pilot_known_signal, q->pilot_estimates_tmp[i], nrefs_sf);
float x = cabsf(srslte_vec_acc_cc(q->pilot_estimates_tmp[i], nrefs_sf));
if (x >= max) {
max = x;
i_max = i;
}
}
memcpy(q->pilot_estimates, q->pilot_estimates_tmp[i_max], nrefs_sf*sizeof(cf_t));
pucch2_ack_bits[0] = i_max%2;
pucch2_ack_bits[1] = i_max/2;
} else {
srslte_refsignal_dmrs_pucch_gen(&q->dmrs_signal, format, n_pucch, sf_idx, pucch2_bits, q->pilot_known_signal);
/* Use the known DMRS signal to compute Least-squares estimates */
srslte_vec_prod_conj_ccc(q->pilot_recv_signal, q->pilot_known_signal, q->pilot_estimates, nrefs_sf);
}
if (ce != NULL) {
/* FIXME: Currently averaging entire slot, performance good enough? */
for (int ns=0;ns<2;ns++) {
// Average all slot
for (int i=1;i<n_rs;i++) {
srslte_vec_sum_ccc(&q->pilot_estimates[ns*n_rs*SRSLTE_NRE], &q->pilot_estimates[(i+ns*n_rs)*SRSLTE_NRE],
&q->pilot_estimates[ns*n_rs*SRSLTE_NRE],
SRSLTE_NRE);
}
srslte_vec_sc_prod_ccc(&q->pilot_estimates[ns*n_rs*SRSLTE_NRE], (float) 1.0/n_rs,
&q->pilot_estimates[ns*n_rs*SRSLTE_NRE],
SRSLTE_NRE);
// Average in freq domain
srslte_chest_average_pilots(&q->pilot_estimates[ns*n_rs*SRSLTE_NRE], &q->pilot_recv_signal[ns*n_rs*SRSLTE_NRE],
q->smooth_filter, SRSLTE_NRE, 1, q->smooth_filter_len);
// Determine n_prb
uint32_t n_prb = srslte_pucch_n_prb(&q->dmrs_signal.pucch_cfg, format, n_pucch, q->cell.nof_prb, q->cell.cp, ns);
// copy estimates to slot
for (int i=0;i<SRSLTE_CP_NSYMB(q->cell.cp);i++) {
memcpy(&ce[SRSLTE_RE_IDX(q->cell.nof_prb, i+ns*SRSLTE_CP_NSYMB(q->cell.cp), n_prb*SRSLTE_NRE)],
&q->pilot_recv_signal[ns*n_rs*SRSLTE_NRE], sizeof(cf_t)*SRSLTE_NRE);
}
}
}
return 0;
}