Do not perform ULSCH scheduling on slots where there is SRS scheduling

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler.c

@@ -383,6 +383,10 @@ void gNB_dlsch_ulsch_scheduler(module_id_t module_idP,
   if (slot == 0)
     nr_csi_meas_reporting(module_idP, frame, slot);
 
+  // Schedule SRS: check in slot 0 for the whole frame
+  if (slot == 0)
+    nr_schedule_srs(module_idP, frame);
+
   // This schedule RA procedure if not in phy_test mode
   // Otherwise already consider 5G already connected
   if (get_softmodem_params()->phy_test == 0) {
@@ -397,8 +401,6 @@ void gNB_dlsch_ulsch_scheduler(module_id_t module_idP,
 
   nr_schedule_pucch(module_idP, frame, slot);
 
-  nr_schedule_srs(module_idP, frame, slot);
-
   stop_meas(&RC.nrmac[module_idP]->eNB_scheduler);
   
   VCD_SIGNAL_DUMPER_DUMP_FUNCTION_BY_NAME(VCD_SIGNAL_DUMPER_FUNCTIONS_gNB_DLSCH_ULSCH_SCHEDULER,VCD_FUNCTION_OUT);

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_primitives.c

@@ -1961,6 +1961,11 @@ int add_new_nr_ue(module_id_t mod_idP, rnti_t rntiP, NR_CellGroupConfig_t *CellG
     sched_ctrl->pucch_consecutive_dtx_cnt = 0;
     sched_ctrl->pusch_consecutive_dtx_cnt = 0;
     sched_ctrl->ul_failure                = 0;
+
+    sched_ctrl->sched_srs.frame = -1;
+    sched_ctrl->sched_srs.slot = -1;
+    sched_ctrl->sched_srs.srs_scheduled = false;
+
     /* set illegal time domain allocation to force recomputation of all fields */
     sched_ctrl->pdsch_semi_static.time_domain_allocation = -1;
     sched_ctrl->pusch_semi_static.time_domain_allocation = -1;

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_srs.c

@@ -101,13 +101,12 @@ void nr_fill_nfapi_srs(int module_id, int CC_id, int UE_id, sub_frame_t slot, NR
 *
 * PARAMETERS :   module id
 *                frame number for possible SRS reception
-*                slot number for possible SRS reception
 *
 * DESCRIPTION :  It informs the PHY layer that has an SRS to receive.
 *                Only for periodic scheduling yet.
 *
 *********************************************************************/
-void nr_schedule_srs(int module_id, frame_t frame, sub_frame_t slot) {
+void nr_schedule_srs(int module_id, frame_t frame) {
 
   gNB_MAC_INST *nrmac = RC.nrmac[module_id];
   NR_UE_info_t *UE_info = &nrmac->UE_info;
@@ -120,6 +119,10 @@ void nr_schedule_srs(int module_id, frame_t frame, sub_frame_t slot) {
     NR_CellGroupConfig_t *cg = UE_info->CellGroup[UE_id];
     NR_UE_sched_ctrl_t *sched_ctrl = &UE_info->UE_sched_ctrl[UE_id];
 
+    sched_ctrl->sched_srs.frame = -1;
+    sched_ctrl->sched_srs.slot = -1;
+    sched_ctrl->sched_srs.srs_scheduled = false;
+
     if(!UE_info->active[UE_id]) {
       continue;
     }
@@ -170,10 +173,13 @@ void nr_schedule_srs(int module_id, frame_t frame, sub_frame_t slot) {
 
       int n_slots_frame = nr_slots_per_frame[ubwp.subcarrierSpacing];
 
-      // Check if UE transmitted the SRS here
-      if ((frame * n_slots_frame + slot - offset) % period == 0) {
-        LOG_D(NR_MAC,"(%d.%d) Scheduling SRS reception\n", frame, slot);
-        nr_fill_nfapi_srs(module_id, CC_id, UE_id, slot, srs_resource);
+      // Check if UE will transmit the SRS in this frame
+      if ( ((frame - offset/n_slots_frame)*n_slots_frame)%period == 0) {
+        LOG_D(NR_MAC,"(%d.%d) Scheduling SRS reception\n", frame, offset%n_slots_frame);
+        nr_fill_nfapi_srs(module_id, CC_id, UE_id, offset%n_slots_frame, srs_resource);
+        sched_ctrl->sched_srs.frame = frame;
+        sched_ctrl->sched_srs.slot = offset%n_slots_frame;
+        sched_ctrl->sched_srs.srs_scheduled = true;
       }
     }
   }

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

@@ -1274,6 +1274,15 @@ bool nr_fr1_ulsch_preprocessor(module_id_t module_id, frame_t frame, sub_frame_t
   if (sched_ctrl->active_ubwp==NULL && is_mixed_slot)
     return false;
 
+  // Avoid slots with the SRS
+  const NR_list_t *UE_list = &UE_info->list;
+  for (int UE_idx = UE_list->head; UE_idx >= 0; UE_idx = UE_list->next[UE_idx]) {
+    NR_sched_srs_t sched_srs = UE_info->UE_sched_ctrl[UE_idx].sched_srs;
+    if(sched_srs.srs_scheduled && sched_srs.frame==sched_frame && sched_srs.slot==sched_slot) {
+      return false;
+    }
+  }
+
   sched_ctrl->sched_pusch.slot = sched_slot;
   sched_ctrl->sched_pusch.frame = sched_frame;
   for (UE_id = UE_info->list.next[UE_id]; UE_id >= 0; UE_id = UE_info->list.next[UE_id]) {
@@ -1513,7 +1522,7 @@ void nr_schedule_ulsch(module_id_t module_id, frame_t frame, sub_frame_t slot)
     memset(pusch_pdu, 0, sizeof(nfapi_nr_pusch_pdu_t));
     future_ul_tti_req->n_pdus += 1;
 
-    LOG_D(NR_MAC, "%4d.%2d Scheduling UE specific PUSCH for sched %d.%d, ul_tto_req %d.%d\n", frame, slot,
+    LOG_D(NR_MAC, "%4d.%2d Scheduling UE specific PUSCH for sched %d.%d, ul_tti_req %d.%d\n", frame, slot,
     sched_pusch->frame,sched_pusch->slot,future_ul_tti_req->SFN,future_ul_tti_req->Slot);
 
     pusch_pdu->pdu_bit_map = PUSCH_PDU_BITMAP_PUSCH_DATA;

openair2/LAYER2/NR_MAC_gNB/mac_proto.h

@@ -190,7 +190,7 @@ void nr_schedule_pucch(int Mod_idP,
                        frame_t frameP,
                        sub_frame_t slotP);
 
-void nr_schedule_srs(int module_id, frame_t frame, sub_frame_t slot);
+void nr_schedule_srs(int module_id, frame_t frame);
 
 void nr_csirs_scheduling(int Mod_idP,
                          frame_t frame,

openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h

@@ -360,6 +360,12 @@ typedef struct NR_sched_pusch {
   int time_domain_allocation;
 } NR_sched_pusch_t;
 
+typedef struct NR_sched_srs {
+  int frame;
+  int slot;
+  bool srs_scheduled;
+} NR_sched_srs_t;
+
 /* PDSCH semi-static configuratio: as long as the TDA/DMRS/mcsTable remains the
  * same, there is no need to recalculate all S/L or DMRS-related parameters
  * over and over again.  Hence, we store them in this struct for easy
@@ -546,9 +552,12 @@ typedef struct {
 
   /// PUSCH semi-static configuration: is not cleared across TTIs
   NR_pusch_semi_static_t pusch_semi_static;
-  /// Sched PDSCH: scheduling decisions, copied into HARQ and cleared every TTI
+  /// Sched PUSCH: scheduling decisions, copied into HARQ and cleared every TTI
   NR_sched_pusch_t sched_pusch;
 
+  /// Sched SRS: scheduling decisions
+  NR_sched_srs_t sched_srs;
+
   /// uplink bytes that are currently scheduled
   int sched_ul_bytes;
   /// estimation of the UL buffer size