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SRSUE: Fix synch error correction for multiple channels

This commit is contained in:
Xavier Arteaga 2020-08-03 17:07:06 +02:00 committed by Andre Puschmann
parent 8e631131c0
commit 710700d0eb
1 changed files with 66 additions and 35 deletions
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101
lib/src/phy/ch_estimation/chest_dl.c
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@ -647,9 +647,9 @@ static void chest_interpolate_noise_est(srslte_chest_dl_t* q,
if (q->wiener_dl && ch_mode == SRSLTE_SF_NORM && cfg->estimator_alg == SRSLTE_ESTIMATOR_ALG_WIENER) {
bool ready = q->wiener_dl->ready;
uint32_t nre = q->cell.nof_prb * SRSLTE_NRE;
uint32_t nref = q->cell.nof_prb * 2;
uint32_t shift = srslte_refsignal_cs_fidx(q->cell, 0, port_id, 0);
uint32_t nre = q->cell.nof_prb * SRSLTE_NRE;
uint32_t nref = q->cell.nof_prb * 2;
uint32_t shift = srslte_refsignal_cs_fidx(q->cell, 0, port_id, 0);
uint32_t nsymb = srslte_refsignal_cs_nof_symbols(&q->csr_refs, sf, port_id);
float snr_lin = +INFINITY;
@ -727,6 +727,64 @@ static void chest_interpolate_noise_est(srslte_chest_dl_t* q,
}
}
static void
chest_dl_estimate_correct_sync_error(srslte_chest_dl_t* q, srslte_dl_sf_cfg_t* sf, cf_t* input, uint32_t rxant_id)
{
float pwr_sum = 0.0f;
float sync_err = 0.0f;
// For each cell port...
for (uint32_t cell_port_id = 0; cell_port_id < q->cell.nof_ports; cell_port_id++) {
uint32_t npilots = srslte_refsignal_cs_nof_re(&q->csr_refs, sf, cell_port_id);
uint32_t nsymb = srslte_refsignal_cs_nof_symbols(&q->csr_refs, sf, cell_port_id);
// Get references from the input signal
srslte_refsignal_cs_get_sf(&q->csr_refs, sf, cell_port_id, input, q->pilot_recv_signal);
// Use the known CSR signal to compute Least-squares estimates
srslte_vec_prod_conj_ccc(
q->pilot_recv_signal, q->csr_refs.pilots[cell_port_id / 2][sf->tti % 10], q->pilot_estimates, npilots);
// Estimate synchronization error from the phase shift
float k = (float)srslte_symbol_sz(q->cell.nof_prb) / 6.0f;
float sum = 0.0f;
for (uint32_t i = 0; i < nsymb; i++) {
sum += srslte_vec_estimate_frequency(q->pilot_estimates + i * npilots / nsymb, npilots / nsymb) * k;
}
float pwr = srslte_vec_avg_power_cf(q->pilot_estimates, npilots);
// Average symbol sum
q->sync_err[rxant_id][cell_port_id] = sum / nsymb;
// Accumulate if the result is valid
if (!isinf(sum) && !isnan(sum) && !isinf(pwr) && !isnan(pwr)) {
sync_err += q->sync_err[rxant_id][cell_port_id] * pwr;
pwr_sum += pwr;
}
}
// Average the valid measurements
if (isnormal(pwr_sum)) {
sync_err /= pwr_sum;
}
// Correct time synchronization error if estimated is not NAN, not INF and greater than 0.05 samples
if (isnormal(sync_err) && fabsf(sync_err) > 0.05f) {
// Compute required frequency shift, convert from sample error to normalised sine
float cfo = sync_err / (float)srslte_symbol_sz(q->cell.nof_prb);
uint32_t nre = SRSLTE_NRE * q->cell.nof_prb;
uint32_t nsymb = SRSLTE_CP_NSYMB(q->cell.cp) * SRSLTE_NOF_SLOTS_PER_SF;
// For each symbol...
for (uint32_t i = 0; i < nsymb; i++) {
// Do a frequency shift
cf_t* ptr = &input[i * nre];
srslte_vec_apply_cfo(ptr, cfo, ptr, nre);
}
}
}
static int estimate_port(srslte_chest_dl_t* q,
srslte_dl_sf_cfg_t* sf,
srslte_chest_dl_cfg_t* cfg,
@ -744,38 +802,6 @@ static int estimate_port(srslte_chest_dl_t* q,
srslte_vec_prod_conj_ccc(
q->pilot_recv_signal, q->csr_refs.pilots[port_id / 2][sf->tti % 10], q->pilot_estimates, npilots);
// Estimate synchronization error
if (cfg->sync_error_enable) {
uint32_t nsymb = srslte_refsignal_cs_nof_symbols(&q->csr_refs, sf, port_id);
float k = (float)srslte_symbol_sz(q->cell.nof_prb) / 6.0f;
float sum = 0.0f;
for (uint32_t i = 0; i < nsymb; i++) {
sum += srslte_vec_estimate_frequency(q->pilot_estimates + i * npilots / nsymb, npilots / nsymb) * k;
}
q->sync_err[rxant_id][port_id] = sum / nsymb;
} else {
q->sync_err[rxant_id][port_id] = NAN;
}
// Correct time synchronization error if estimated
if (isnormal(q->sync_err[rxant_id][port_id])) {
uint32_t nsymb = SRSLTE_CP_NSYMB(q->cell.cp) * SRSLTE_NOF_SLOTS_PER_SF;
float cfo = q->sync_err[rxant_id][port_id] / (float)srslte_symbol_sz(q->cell.nof_prb);
uint32_t nre = SRSLTE_NRE * q->cell.nof_prb;
for (uint32_t i = 0; i < nsymb; i++) {
cf_t* ptr = &input[i * nre];
srslte_vec_apply_cfo(ptr, cfo, ptr, nre);
}
/* Get references from the input signal */
srslte_refsignal_cs_get_sf(&q->csr_refs, sf, port_id, input, q->pilot_recv_signal);
/* Use the known CSR signal to compute Least-squares estimates */
srslte_vec_prod_conj_ccc(
q->pilot_recv_signal, q->csr_refs.pilots[port_id / 2][sf->tti % 10], q->pilot_estimates, npilots);
}
/* Compute RSRP for the channel estimates in this port */
if (cfg->rsrp_neighbour) {
double energy = cabsf(srslte_vec_acc_cc(q->pilot_estimates, npilots) / npilots);
@ -964,6 +990,11 @@ int srslte_chest_dl_estimate_cfg(srslte_chest_dl_t* q,
{
for (uint32_t rxant_id = 0; rxant_id < q->nof_rx_antennas; rxant_id++) {
// Estimate and correct synchronization error if enabled
if (cfg->sync_error_enable) {
chest_dl_estimate_correct_sync_error(q, sf, input[rxant_id], rxant_id);
}
for (uint32_t port_id = 0; port_id < q->cell.nof_ports; port_id++) {
if (sf->sf_type == SRSLTE_SF_MBSFN) {
if (estimate_port_mbsfn(q, sf, cfg, input[rxant_id], res->ce[port_id][rxant_id], port_id, rxant_id)) {