Set RA offset at UE to compensate for 2 frames offset introduced by gNB

openair2/LAYER2/NR_MAC_UE/mac_defs.h

@@ -188,6 +188,8 @@ typedef struct {
   /* Random Access parameters */
   /// state of RA procedure
   RA_state_t ra_state;
+  /// RA rx frame offset: compensate RA rx offset introduced by OAI gNB.
+  uint8_t RA_offset;
   /// RA-rnti
   uint16_t ra_rnti;
   /// Temporary CRNTI

openair2/LAYER2/NR_MAC_UE/nr_ue_procedures.c

@@ -887,6 +887,8 @@ void nr_ue_prach_scheduler(module_id_t module_idP, frame_t frameP, sub_frame_t s
   NR_RACH_ConfigGeneric_t *rach_ConfigGeneric = &setup->rach_ConfigGeneric;
   config_index = rach_ConfigGeneric->prach_ConfigurationIndex;
 
+  mac->RA_offset = 2; // to compensate the rx frame offset at the gNB
+
   if (is_nr_UL_slot(scc, slotP)) {
 
     if (setup->msg1_SubcarrierSpacing)

openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c

@@ -120,7 +120,7 @@ int nr_ue_ul_indication(nr_uplink_indication_t *ul_info){
     if (mac->generate_nr_prach){
       uint16_t monitoring_slot_period, monitoring_offset;
       uint16_t rach_frame = mac->scheduled_response.ul_config->sfn;
-      uint16_t rx_rach_frame = (rach_frame + 2) % MAX_FRAME_NUMBER; // compensate 2 frames offset delay at gNB side
+      uint16_t rx_rach_frame = (rach_frame + mac->RA_offset) % MAX_FRAME_NUMBER; // compensate 2 frames offset delay at gNB side
       uint16_t rach_slot  = mac->scheduled_response.ul_config->slot;
       nr_ue_msg2_scheduler(module_id, rx_rach_frame, rach_slot, &mac->msg2_rx_frame, &mac->msg2_rx_slot);
     }