UE RA procedures changes to preamble selection:

- get preamble from rach_ConfigDedicated in contention free mode
- do preamble selection only in prach slot

openair2/LAYER2/NR_MAC_UE/config_ue.c

@@ -350,6 +350,7 @@ int nr_rrc_mac_config_req_ue(
     if(spCell_ConfigP != NULL ){
       mac->servCellIndex = *spCell_ConfigP->servCellIndex;
       if (spCell_ConfigP->reconfigurationWithSync) {
+        mac->rach_ConfigDedicated = spCell_ConfigP->reconfigurationWithSync->rach_ConfigDedicated->choice.uplink;
         mac->scc = spCell_ConfigP->reconfigurationWithSync->spCellConfigCommon;
         config_common_ue(mac,module_id,cc_idP);
         mac->crnti = spCell_ConfigP->reconfigurationWithSync->newUE_Identity;

openair2/LAYER2/NR_MAC_UE/mac_defs.h

@@ -156,6 +156,7 @@ typedef struct {
 
   NR_ServingCellConfigCommon_t    *scc;
   NR_ServingCellConfig_t          *scd;
+  NR_RACH_ConfigDedicated_t       *rach_ConfigDedicated;
   int                             servCellIndex;
   ////  MAC config
   NR_DRX_Config_t                 *drx_Config;

openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c

@@ -88,6 +88,10 @@ void nr_get_prach_resources(module_id_t mod_id,
   int messagePowerOffsetGroupB, messageSizeGroupA, PLThreshold, sizeOfRA_PreamblesGroupA, numberOfRA_Preambles, i, deltaPreamble_Msg3;
   uint8_t noGroupB = 0, s_id, f_id, ul_carrier_id, prach_ConfigIndex, SFN_nbr, Msg3_size;
 
+  AssertFatal(scc->uplinkConfigCommon->initialUplinkBWP->rach_ConfigCommon->choice.setup != NULL, "[UE %d] FATAL nr_rach_ConfigCommon is NULL !!!\n", mod_id);
+  nr_rach_ConfigCommon = scc->uplinkConfigCommon->initialUplinkBWP->rach_ConfigCommon->choice.setup;
+  rach_ConfigGeneric = &nr_rach_ConfigCommon->rach_ConfigGeneric;
+
   // NR_RSRP_Range_t rsrp_ThresholdSSB; // todo
 
   ///////////////////////////////////////////////////////////
@@ -104,13 +108,18 @@ void nr_get_prach_resources(module_id_t mod_id,
   // -- RA initiated for SI request:
   // --- SSB selection, set prach_resources->ra_PreambleIndex
 
-  // if (rach_ConfigDedicated) {  // This is for network controlled Mobility
+  if (rach_ConfigDedicated) {
-  //   // operation for contention-free RA resources when:
+    //////////* Contention free RA *//////////
-  //   // - available SSB with SS-RSRP above rsrp-ThresholdSSB: SSB selection
+    // - the PRACH preamble for the UE to transmit is set through RRC configuration
-  //   // - availalbe CSI-RS with CSI-RSRP above rsrp-ThresholdCSI-RS: CSI-RS selection
+    // - this is the default mode in current implementation!
-  //   prach_resources->ra_PreambleIndex = rach_ConfigDedicated->ra_PreambleIndex;
+    // Operation for contention-free RA resources when:
-  // }
+    // - available SSB with SS-RSRP above rsrp-ThresholdSSB: SSB selection
-
+    // - available CSI-RS with CSI-RSRP above rsrp-ThresholdCSI-RS: CSI-RS selection
+    // - network controlled Mobility
+    uint8_t cfra_ssb_resource_idx = 0;
+    prach_resources->ra_PreambleIndex = rach_ConfigDedicated->cfra->resources.choice.ssb->ssb_ResourceList.list.array[cfra_ssb_resource_idx]->ra_PreambleIndex;
+    LOG_D(MAC, "[RAPROC] - Selected RA preamble index %d for contention-free random access procedure... \n", prach_resources->ra_PreambleIndex);
+  } else {
     //////////* Contention-based RA preamble selection *//////////
     // todo:
     // - selection of SSB with SS-RSRP above rsrp-ThresholdSSB else select any SSB
@@ -118,11 +127,6 @@ void nr_get_prach_resources(module_id_t mod_id,
 
     // rsrp_ThresholdSSB = *nr_rach_ConfigCommon->rsrp_ThresholdSSB;
 
-  AssertFatal(scc->uplinkConfigCommon->initialUplinkBWP->rach_ConfigCommon->choice.setup != NULL, "[UE %d] FATAL nr_rach_ConfigCommon is NULL !!!\n", mod_id);
-
-  nr_rach_ConfigCommon = scc->uplinkConfigCommon->initialUplinkBWP->rach_ConfigCommon->choice.setup;
-  rach_ConfigGeneric = &nr_rach_ConfigCommon->rach_ConfigGeneric;
-
     Msg3_size = mac->RA_Msg3_size;
 
     numberOfRA_Preambles = 64;
@@ -237,6 +241,8 @@ void nr_get_prach_resources(module_id_t mod_id,
         prach_resources->ra_PreambleIndex = sizeOfRA_PreamblesGroupA + (taus()) % (numberOfRA_Preambles - sizeOfRA_PreamblesGroupA);
       }
     }
+    LOG_D(MAC, "[RAPROC] - Selected RA preamble index %d for contention-based random access procedure... \n", prach_resources->ra_PreambleIndex);
+  }
 
   // todo determine next available PRACH occasion
   // - if RA initiated for SI request and ra_AssociationPeriodIndex and si-RequestPeriod are configured
@@ -284,7 +290,7 @@ void nr_get_prach_resources(module_id_t mod_id,
    prach_resources->ra_RNTI = 1 + s_id + 14 * t_id + 1120 * f_id + 8960 * ul_carrier_id;
    mac->ra_rnti = prach_resources->ra_RNTI;
 
-   LOG_D(MAC, "Computed ra_RNTI is %d", prach_resources->ra_RNTI);
+   LOG_D(MAC, "Computed ra_RNTI is %x \n", prach_resources->ra_RNTI);
 }
 
 // TbD: RA_attempt_number not used
@@ -311,6 +317,7 @@ void nr_Msg3_transmitted(module_id_t mod_id, uint8_t CC_id, frame_t frameP, uint
 /// Handling inizialization by PDCCH order, MAC entity or RRC (TS 38.300)
 /// Only one RA procedure is ongoing at any point in time in a MAC entity
 /// the RA procedure on a SCell shall only be initiated by PDCCH order
+/// in the current implementation, RA is contention free only
 
 // WIP
 // todo TS 38.321:
@@ -324,7 +331,6 @@ void nr_Msg3_transmitted(module_id_t mod_id, uint8_t CC_id, frame_t frameP, uint
 // - retrieve TBS
 // - add mac_rrc_nr_data_req_ue, etc ...
 // - add the backoff condition here if we have it from a previous RA reponse which failed (i.e. backoff indicator)
-
 void nr_ue_get_rach(NR_PRACH_RESOURCES_t *prach_resources,
                     module_id_t mod_id,
                     int CC_id,
@@ -345,6 +351,8 @@ void nr_ue_get_rach(NR_PRACH_RESOURCES_t *prach_resources,
   NR_RACH_ConfigCommon_t *setup = scc->uplinkConfigCommon->initialUplinkBWP->rach_ConfigCommon->choice.setup;
   NR_RACH_ConfigGeneric_t *rach_ConfigGeneric = &setup->rach_ConfigGeneric;
   NR_FrequencyInfoDL_t *frequencyInfoDL = scc->downlinkConfigCommon->frequencyInfoDL;
+  NR_RACH_ConfigDedicated_t *rach_ConfigDedicated = mac->rach_ConfigDedicated;
+
   // int32_t frame_diff = 0;
 
   uint8_t sdu_lcids[NB_RB_MAX] = {0};
@@ -485,7 +493,8 @@ void nr_ue_get_rach(NR_PRACH_RESOURCES_t *prach_resources,
         }
 
         // Fill in preamble and PRACH resources
-        nr_get_prach_resources(mod_id, CC_id, gNB_id, nr_tti_tx, 1, prach_resources, NULL);
+        if (is_nr_prach_slot)
+          nr_get_prach_resources(mod_id, CC_id, gNB_id, nr_tti_tx, 1, prach_resources, rach_ConfigDedicated);
 
         offset = nr_generate_ulsch_pdu((uint8_t *) mac_sdus,              // sdus buffer
                                        (uint8_t *) payload,               // UL MAC pdu pointer
@@ -601,8 +610,11 @@ void nr_ue_get_rach(NR_PRACH_RESOURCES_t *prach_resources,
 
         mac->RA_tx_frame = frame;
         mac->RA_tx_subframe = nr_tti_tx;
+
         // Fill in preamble and PRACH resources
-        nr_get_prach_resources(mod_id, CC_id, gNB_id, nr_tti_tx, 0, prach_resources, NULL);
+        if (is_nr_prach_slot)
+          nr_get_prach_resources(mod_id, CC_id, gNB_id, nr_tti_tx, 0, prach_resources, rach_ConfigDedicated);
+
       }
     }
   } else if (UE_mode == PUSCH) {