Merge remote-tracking branch 'origin/fix-fill_srs_channel_matrix' into integration_2026_w16 (!4024)

Fix fill_srs_channel_matrix

Fix incorrect SRS subcarrier mapping in fill_srs_channel_matrix

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.

openair1/SCHED_NR/phy_procedures_nr_gNB.c

@@ -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;
+  uint8_t *channel_matrix = nr_srs_channel_iq_matrix->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++) {
 
-      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;
-      }
+      // 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];
 
-      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);