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Fix incorrect SRS subcarrier mapping in fill_srs_channel_matrix

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The previous implementation of fill_srs_channel_matrix assumed an incorrect SRS subcarrier mapping, leading to wrong indexing of the estimated channel in frequency domain
This commit is contained in:
rmagueta
2026-04-06 10:19:34 +01:00
parent 2407c35633
commit 14cceed229
1 changed files with 27 additions and 38 deletions
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openair1/SCHED_NR/phy_procedures_nr_gNB.c
+27 -38
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@@ -712,56 +712,50 @@ static int fill_srs_reported_symbol(nfapi_nr_srs_reported_symbol_t *reported_sym
return 0;
}
static int fill_srs_channel_matrix(
nfapi_nr_srs_normalized_channel_iq_matrix_t *nr_srs_channel_iq_matrix,
const nfapi_nr_srs_pdu_t *srs_pdu,
const nr_srs_info_t *nr_srs_info,
const uint8_t normalized_iq_representation,
const uint16_t num_gnb_antenna_elements,
const uint16_t num_ue_srs_ports,
const uint16_t prg_size,
const uint16_t num_prgs,
const NR_DL_FRAME_PARMS *frame_parms,
const c16_t srs_estimated_channel_freq[][1 << srs_pdu->num_ant_ports]
[frame_parms->ofdm_symbol_size * (1 << srs_pdu->num_symbols)])
static int fill_srs_channel_matrix(nfapi_nr_srs_normalized_channel_iq_matrix_t *nr_srs_channel_iq_matrix,
const nfapi_nr_srs_pdu_t *srs_pdu,
const nr_srs_info_t *nr_srs_info,
const NR_DL_FRAME_PARMS *frame_parms,
const c16_t srs_estimated_channel_freq[][1 << srs_pdu->num_ant_ports][frame_parms->ofdm_symbol_size * (1 << srs_pdu->num_symbols)])
{
const uint16_t num_gnb_antenna_elements = frame_parms->nb_antennas_rx;
const uint16_t num_ue_srs_ports = srs_pdu->srs_parameters_v4.num_total_ue_antennas;
const uint8_t normalized_iq_representation = srs_pdu->srs_parameters_v4.iq_representation;
const uint16_t prg_size = srs_pdu->srs_parameters_v4.prg_size;
const uint16_t num_prgs = srs_pdu->srs_parameters_v4.srs_bandwidth_size / srs_pdu->srs_parameters_v4.prg_size;
const uint64_t first_subcarrier =
(frame_parms->first_carrier_offset - (frame_parms->ofdm_symbol_size >> 1)) + srs_pdu->bwp_start * NR_NB_SC_PER_RB;
const uint16_t step = prg_size * NR_NB_SC_PER_RB;
nr_srs_channel_iq_matrix->normalized_iq_representation = normalized_iq_representation;
nr_srs_channel_iq_matrix->num_gnb_antenna_elements = num_gnb_antenna_elements;
nr_srs_channel_iq_matrix->num_ue_srs_ports = num_ue_srs_ports;
nr_srs_channel_iq_matrix->prg_size = prg_size;
nr_srs_channel_iq_matrix->num_prgs = num_prgs;
uint8_t *channel_matrix = nr_srs_channel_iq_matrix->channel_matrix;
const uint64_t subcarrier_offset = frame_parms->first_carrier_offset + srs_pdu->bwp_start*NR_NB_SC_PER_RB;
const uint16_t step = prg_size*NR_NB_SC_PER_RB;
c16_t *channel_matrix16 = (c16_t *)channel_matrix;
c8_t *channel_matrix8 = (c8_t *)channel_matrix;
c16_t *channel_matrix16 = (c16_t*)channel_matrix;
c8_t *channel_matrix8 = (c8_t*)channel_matrix;
for (int uI = 0; uI < num_ue_srs_ports; uI++) {
for (int gI = 0; gI < num_gnb_antenna_elements; gI++) {
for(int uI = 0; uI < num_ue_srs_ports; uI++) {
for(int gI = 0; gI < num_gnb_antenna_elements; gI++) {
// channel_matrix8 or channel_matrix16 will only be populated for the symbol 0
uint16_t subcarrier_abs = first_subcarrier + nr_srs_info->k_0_p[uI][0];
uint16_t subcarrier = subcarrier_offset + nr_srs_info->k_0_p[uI][0];
if (subcarrier >= frame_parms->ofdm_symbol_size) {
subcarrier -= frame_parms->ofdm_symbol_size;
}
for(int pI = 0; pI < num_prgs; pI++) {
const c16_t *srs_estimated_channel16 = srs_estimated_channel_freq[gI][uI] + subcarrier;
uint16_t index = uI*num_gnb_antenna_elements*num_prgs + gI*num_prgs + pI;
for (int pI = 0; pI < num_prgs; pI++) {
const c16_t *srs_estimated_channel16 = srs_estimated_channel_freq[gI][uI] + subcarrier_abs;
uint16_t index = uI * num_gnb_antenna_elements * num_prgs + gI * num_prgs + pI;
if (normalized_iq_representation == 0) {
channel_matrix8[index].r = (int8_t)(srs_estimated_channel16->r>>8);
channel_matrix8[index].i = (int8_t)(srs_estimated_channel16->i>>8);
channel_matrix8[index].r = (int8_t)(srs_estimated_channel16->r >> 8);
channel_matrix8[index].i = (int8_t)(srs_estimated_channel16->i >> 8);
} else {
channel_matrix16[index].r = srs_estimated_channel16->r;
channel_matrix16[index].i = srs_estimated_channel16->i;
}
// Subcarrier increment
subcarrier += step;
if (subcarrier >= frame_parms->ofdm_symbol_size) {
subcarrier -= frame_parms->ofdm_symbol_size;
}
subcarrier_abs += step;
}
}
}
@@ -1312,11 +1306,6 @@ int phy_procedures_gNB_uespec_RX(PHY_VARS_gNB *gNB, int frame_rx, int slot_rx, N
fill_srs_channel_matrix(&nr_srs_channel_iq_matrix,
srs_pdu,
gNB->nr_srs_info[i],
srs_pdu->srs_parameters_v4.iq_representation,
nb_antennas_rx,
srs_pdu->srs_parameters_v4.num_total_ue_antennas,
srs_pdu->srs_parameters_v4.prg_size,
srs_pdu->srs_parameters_v4.srs_bandwidth_size / srs_pdu->srs_parameters_v4.prg_size,
frame_parms,
srs_estimated_channel_freq);