Add Delay Mechanism for Initial MIB/SIB Transmission in gNB Scheduler

This commit introduces a delay mechanism for the first MIB/SIB transmission
in the gNB scheduler to allow PRACH noise estimate to converge stabilize
before first PRACH preamble reception.

Key changes:
- Added the `num_scheduled_prach_rx` variable to gNB_MAC_INST to keep track
  of total number scheduled of PRACH receptions. Using uint64_t type to avoid
  overflow.
- Updated the `gNB_dlsch_ulsch_scheduler` function to conditionally schedule
  MIB/SIB transmissions if `num_scheduled_prach_rx` is at least 100.
  The value comes from OAIs implementation of PRACH noise estimate.

common/platform_constants.h

@@ -93,5 +93,6 @@
 #define RETURNerror (-1)
 #define DEFAULT_NAS_PATH "PWD"
 #define UNUSED_VARIABLE(vARIABLE) (void)(vARIABLE)
+#define NUM_PRACH_RX_FOR_NOISE_ESTIMATE 100
 
 #endif /* __PLATFORM_CONSTANTS_H__ */

openair1/SCHED/prach_procedures.c

@@ -120,7 +120,8 @@ void prach_procedures(PHY_VARS_eNB *eNB,
     */
 
     if (eNB->frame_parms.prach_emtc_config_common.prach_ConfigInfo.prach_CElevel_enable[0] == 1) {
-      if ((eNB->prach_energy_counter == 100) && (max_preamble_energy[0] > eNB->measurements.prach_I0 + eNB->prach_DTX_threshold_emtc[0])) {
+      if ((eNB->prach_energy_counter == NUM_PRACH_RX_FOR_NOISE_ESTIMATE)
+          && (max_preamble_energy[0] > eNB->measurements.prach_I0 + eNB->prach_DTX_threshold_emtc[0])) {
         eNB->UL_INFO.rach_ind_br.rach_indication_body.number_of_preambles++;
         eNB->preamble_list_br[ind].preamble_rel8.timing_advance = max_preamble_delay[ind];      //
         eNB->preamble_list_br[ind].preamble_rel8.preamble = max_preamble[ind];
@@ -142,7 +143,7 @@ void prach_procedures(PHY_VARS_eNB *eNB,
     }
     } */// ce_level
   } else {
-    if ((eNB->prach_energy_counter == 100) &&
+    if ((eNB->prach_energy_counter == NUM_PRACH_RX_FOR_NOISE_ESTIMATE) &&
         (max_preamble_energy[0] > eNB->measurements.prach_I0+eNB->prach_DTX_threshold)) {
       LOG_D(PHY,"[eNB %d/%d][RAPROC] Frame %d, subframe %d Initiating RA procedure with preamble %d, energy %d.%d dB, delay %d\n",
             eNB->Mod_id,
@@ -186,7 +187,8 @@ void prach_procedures(PHY_VARS_eNB *eNB,
 
       if (frame==0) LOG_D(PHY,"prach_I0 = %d.%d dB\n",eNB->measurements.prach_I0/10,eNB->measurements.prach_I0%10);
 
-      if (eNB->prach_energy_counter < 100) eNB->prach_energy_counter++;
+      if (eNB->prach_energy_counter < NUM_PRACH_RX_FOR_NOISE_ESTIMATE)
+        eNB->prach_energy_counter++;
     }
   } // else br_flag
 

openair1/SCHED_NR/nr_prach_procedures.c

@@ -145,7 +145,8 @@ void L1_nr_prach_procedures(PHY_VARS_gNB *gNB, int frame, int slot, nfapi_nr_rac
 	    max_preamble_delay[0],
 	    gNB->prach_energy_counter);
 
-      if ((gNB->prach_energy_counter == 100) && (max_preamble_energy[0] > gNB->measurements.prach_I0 + gNB->prach_thres)
+      if ((gNB->prach_energy_counter == NUM_PRACH_RX_FOR_NOISE_ESTIMATE)
+          && (max_preamble_energy[0] > gNB->measurements.prach_I0 + gNB->prach_thres)
           && (rach_ind->number_of_pdus < MAX_NUM_NR_RX_RACH_PDUS)) {
         LOG_A(NR_PHY,
               "[RAPROC] %d.%d Initiating RA procedure with preamble %d, energy %d.%d dB (I0 %d, thres %d), delay %d start symbol "
@@ -185,7 +186,8 @@ void L1_nr_prach_procedures(PHY_VARS_gNB *gNB, int frame, int slot, nfapi_nr_rac
       }
       gNB->measurements.prach_I0 = ((gNB->measurements.prach_I0*900)>>10) + ((max_preamble_energy[0]*124)>>10); 
       if (frame==0) LOG_I(PHY,"prach_I0 = %d.%d dB\n",gNB->measurements.prach_I0/10,gNB->measurements.prach_I0%10);
-      if (gNB->prach_energy_counter < 100) gNB->prach_energy_counter++;
+      if (gNB->prach_energy_counter < NUM_PRACH_RX_FOR_NOISE_ESTIMATE)
+        gNB->prach_energy_counter++;
     } //if prach_id>0
     rach_ind->slot = prach_start_slot;
   } // for NUMBER_OF_NR_PRACH_OCCASION_MAX

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler.c

@@ -212,14 +212,16 @@ void gNB_dlsch_ulsch_scheduler(module_id_t module_idP, frame_t frame, slot_t slo
 
   nr_mac_update_timers(module_idP, frame, slot);
 
-  // This schedules MIB
+  if (gNB->num_scheduled_prach_rx >= NUM_PRACH_RX_FOR_NOISE_ESTIMATE || get_softmodem_params()->phy_test) {
-  schedule_nr_mib(module_idP, frame, slot, &sched_info->DL_req);
+    // This schedules MIB
+    schedule_nr_mib(module_idP, frame, slot, &sched_info->DL_req);
 
-  // This schedules SIB1
+    // This schedules SIB1
-  // SIB19 will be scheduled if ntn_Config_r17 is initialized
+    // SIB19 will be scheduled if ntn_Config_r17 is initialized
-  if (IS_SA_MODE(get_softmodem_params())) {
+    if (IS_SA_MODE(get_softmodem_params())) {
-    schedule_nr_sib1(module_idP, frame, slot, &sched_info->DL_req, &sched_info->TX_req);
+      schedule_nr_sib1(module_idP, frame, slot, &sched_info->DL_req, &sched_info->TX_req);
-    schedule_nr_other_sib(module_idP, frame, slot, &sched_info->DL_req, &sched_info->TX_req);
+      schedule_nr_other_sib(module_idP, frame, slot, &sched_info->DL_req, &sched_info->TX_req);
+    }
   }
 
   // This schedule PRACH if we are not in phy_test mode

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_RA.c

@@ -430,6 +430,7 @@ void schedule_nr_prach(module_id_t module_idP, frame_t frameP, slot_t slotP)
             }
           }
           if(td_index == 0) {
+            gNB->num_scheduled_prach_rx++;
             AssertFatal(UL_tti_req->n_pdus < sizeof(UL_tti_req->pdus_list) / sizeof(UL_tti_req->pdus_list[0]),
                         "Invalid UL_tti_req->n_pdus %d\n", UL_tti_req->n_pdus);
 

openair2/LAYER2/NR_MAC_gNB/main.c

@@ -275,6 +275,7 @@ void mac_top_init_gNB(ngran_node_t node_type,
       RC.nrmac[i]->common_channels[0].pre_ServingCellConfig = scd;
 
       RC.nrmac[i]->first_MIB = true;
+      RC.nrmac[i]->num_scheduled_prach_rx = 0;
       RC.nrmac[i]->common_channels[0].mib = get_new_MIB_NR(scc);
 
       RC.nrmac[i]->cset0_bwp_start = 0;

openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h

@@ -936,7 +936,7 @@ typedef struct gNB_MAC_INST_s {
   pthread_mutex_t sched_lock;
 
   mac_stats_t mac_stats;
-
+  uint64_t num_scheduled_prach_rx;
 } gNB_MAC_INST;
 
 #endif /*__LAYER2_NR_MAC_GNB_H__ */