Handle Msg3 carrying a DCCH or DTCH message

openair2/LAYER2/NR_MAC_gNB/config.c

@@ -521,6 +521,7 @@ int rrc_mac_config_req_gNB(module_id_t Mod_idP,
       RC.nrmac[Mod_idP]->sib1_tda = sib1_tda;
       for (int n=0;n<NR_NB_RA_PROC_MAX;n++ ) {
 	       cc->ra[n].cfra = false;
+         cc->ra[n].msg3_dcch_dtch = false;
 	       cc->ra[n].rnti = 0;
 	       cc->ra[n].preambles.num_preambles = MAX_NUM_NR_PRACH_PREAMBLES;
 	       cc->ra[n].preambles.preamble_list = (uint8_t *) malloc(MAX_NUM_NR_PRACH_PREAMBLES*sizeof(uint8_t));
@@ -603,6 +604,7 @@ int rrc_mac_config_req_gNB(module_id_t Mod_idP,
         for (int i = 0; i < MAX_NUM_NR_PRACH_PREAMBLES; i++)
           ra->preambles.preamble_list[i] = i;
       }
+      ra->msg3_dcch_dtch = false;
       LOG_I(NR_MAC,"Added new RA process for UE RNTI %04x with initial CellGroup\n", rnti);
     } else { // CellGroup has been updated
       const int UE_id = find_nr_UE_id(Mod_idP,rnti);

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_RA.c

@@ -1407,7 +1407,7 @@ void nr_generate_Msg4(module_id_t module_idP, int CC_id, frame_t frameP, sub_fra
 
     // If UE is known by the network, to use C-RNTI instead of TC-RNTI
     rnti_t tc_rnti = ra->rnti;
-    if(ra->crnti != 0) {
+    if(ra->msg3_dcch_dtch) {
       ra->rnti = ra->crnti;
     }
 
@@ -1484,15 +1484,21 @@ void nr_generate_Msg4(module_id_t module_idP, int CC_id, frame_t frameP, sub_fra
     uint8_t *buf = (uint8_t *) harq->tb;
     // Bytes to be transmitted
     if (harq->round == 0) {
-      uint16_t mac_pdu_length = nr_write_ce_dlsch_pdu(module_idP, nr_mac->sched_ctrlCommon, buf, 255, ra->cont_res_id);
-      LOG_D(NR_MAC,"Encoded contention resolution mac_pdu_length %d\n",mac_pdu_length);
-      uint16_t mac_sdu_length = mac_rrc_nr_data_req(module_idP, CC_id, frameP, CCCH, ra->rnti, 1, &buf[mac_pdu_length+2]);
-      ((NR_MAC_SUBHEADER_SHORT *) &buf[mac_pdu_length])->R = 0;
-      ((NR_MAC_SUBHEADER_SHORT *) &buf[mac_pdu_length])->F = 0;
-      ((NR_MAC_SUBHEADER_SHORT *) &buf[mac_pdu_length])->LCID = DL_SCH_LCID_CCCH;
-      ((NR_MAC_SUBHEADER_SHORT *) &buf[mac_pdu_length])->L = mac_sdu_length;
-      ra->mac_pdu_length = mac_pdu_length + mac_sdu_length + sizeof(NR_MAC_SUBHEADER_SHORT);
-      LOG_D(NR_MAC,"Encoded RRCSetup Piggyback (%d + %d bytes), mac_pdu_length %d\n", mac_sdu_length, (int)sizeof(NR_MAC_SUBHEADER_SHORT), ra->mac_pdu_length);
+      if (ra->msg3_dcch_dtch) {
+        // If the UE used MSG3 to transfer a DCCH or DTCH message, then contention resolution is successful if the UE receives a PDCCH transmission which has its CRC bits scrambled by the C-RNTI
+        // Just send padding LCID
+        ra->mac_pdu_length = 0;
+      } else {
+        uint16_t mac_pdu_length = nr_write_ce_dlsch_pdu(module_idP, nr_mac->sched_ctrlCommon, buf, 255, ra->cont_res_id);
+        LOG_D(NR_MAC,"Encoded contention resolution mac_pdu_length %d\n",mac_pdu_length);
+        uint16_t mac_sdu_length = mac_rrc_nr_data_req(module_idP, CC_id, frameP, CCCH, ra->rnti, 1, &buf[mac_pdu_length+2]);
+        ((NR_MAC_SUBHEADER_SHORT *) &buf[mac_pdu_length])->R = 0;
+        ((NR_MAC_SUBHEADER_SHORT *) &buf[mac_pdu_length])->F = 0;
+        ((NR_MAC_SUBHEADER_SHORT *) &buf[mac_pdu_length])->LCID = DL_SCH_LCID_CCCH;
+        ((NR_MAC_SUBHEADER_SHORT *) &buf[mac_pdu_length])->L = mac_sdu_length;
+        ra->mac_pdu_length = mac_pdu_length + mac_sdu_length + sizeof(NR_MAC_SUBHEADER_SHORT);
+        LOG_D(NR_MAC,"Encoded RRCSetup Piggyback (%d + %d bytes), mac_pdu_length %d\n", mac_sdu_length, (int)sizeof(NR_MAC_SUBHEADER_SHORT), ra->mac_pdu_length);
+      }
     }
 
     // Calculate number of symbols
@@ -1752,8 +1758,22 @@ void nr_generate_Msg4(module_id_t module_idP, int CC_id, frame_t frameP, sub_fra
     LOG_D(NR_MAC,"precoderGranularity: %i\n", pdcch_pdu_rel15->precoderGranularity);
     LOG_D(NR_MAC,"numDlDci: %i\n", pdcch_pdu_rel15->numDlDci);
 
-    ra->state = WAIT_Msg4_ACK;
-    LOG_D(NR_MAC,"[gNB %d][RAPROC] Frame %d, Subframe %d: RA state %d\n", module_idP, frameP, slotP, ra->state);
+    if(ra->msg3_dcch_dtch) {
+      LOG_I(NR_MAC, "(ue %i, rnti 0x%04x) CBRA procedure succeeded!\n", UE_id, ra->rnti);
+      nr_clear_ra_proc(module_idP, CC_id, frameP, ra);
+      UE_info->active[UE_id] = true;
+      UE_info->Msg4_ACKed[UE_id] = true;
+
+      remove_front_nr_list(&sched_ctrl->feedback_dl_harq);
+      harq->feedback_slot = -1;
+      harq->is_waiting = false;
+      add_tail_nr_list(&sched_ctrl->available_dl_harq, current_harq_pid);
+      harq->round = 0;
+      harq->ndi ^= 1;
+    } else {
+      ra->state = WAIT_Msg4_ACK;
+      LOG_D(NR_MAC,"[gNB %d][RAPROC] Frame %d, Subframe %d: RA state %d\n", module_idP, frameP, slotP, ra->state);
+    }
   }
 }
 
@@ -1773,16 +1793,16 @@ void nr_check_Msg4_Ack(module_id_t module_id, int CC_id, frame_t frame, sub_fram
     if (harq->round == 0) {
       if (stats->dlsch_errors == 0) {
         LOG_I(NR_MAC, "(ue %i, rnti 0x%04x) Received Ack of RA-Msg4. CBRA procedure succeeded!\n", UE_id, ra->rnti);
-        nr_clear_ra_proc(module_id, CC_id, frame, ra);
         UE_info->active[UE_id] = true;
         UE_info->Msg4_ACKed[UE_id] = true;
-        if(sched_ctrl->retrans_dl_harq.head>=0)
-          remove_nr_list(&sched_ctrl->retrans_dl_harq, current_harq_pid);
       }
       else {
         LOG_I(NR_MAC, "(ue %i, rnti 0x%04x) RA Procedure failed at Msg4!\n", UE_id, ra->rnti);
-        nr_mac_remove_ra_rnti(module_id, ra->rnti);
-        nr_clear_ra_proc(module_id, CC_id, frame, ra);
+      }
+
+      nr_clear_ra_proc(module_id, CC_id, frame, ra);
+      if(sched_ctrl->retrans_dl_harq.head >= 0) {
+        remove_nr_list(&sched_ctrl->retrans_dl_harq, current_harq_pid);
       }
     }
     else {
@@ -1800,6 +1820,7 @@ void nr_clear_ra_proc(module_id_t module_idP, int CC_id, frame_t frameP, NR_RA_t
   ra->timing_offset = 0;
   ra->RRC_timer = 20;
   ra->msg3_round = 0;
+  ra->msg3_dcch_dtch = false;
   ra->crnti = 0;
   if(ra->cfra == false) {
     ra->rnti = 0;

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_primitives.c

@@ -2053,7 +2053,7 @@ void mac_remove_nr_ue(module_id_t mod_id, rnti_t rnti)
     destroy_nr_list(&sched_ctrl->available_ul_harq);
     destroy_nr_list(&sched_ctrl->feedback_ul_harq);
     destroy_nr_list(&sched_ctrl->retrans_ul_harq);
-    LOG_I(NR_MAC, "[gNB %d] Remove NR UE_id %d : rnti %x\n",
+    LOG_I(NR_MAC, "[gNB %d] Remove NR UE_id %d: rnti 0x%04x\n",
           mod_id,
           UE_id,
           rnti);

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

@@ -303,7 +303,8 @@ int nr_process_mac_pdu(module_id_t module_idP,
             NR_RA_t *ra = &RC.nrmac[module_idP]->common_channels[CC_id].ra[i];
             if (ra->state >= WAIT_Msg3 && ra->rnti == UE_info->rnti[UE_id]) {
               ra->crnti = ((pduP[1]&0xFF)<<8)|(pduP[2]&0xFF);
-              LOG_D(NR_MAC, "Received UL_SCH_LCID_C_RNTI with CRNTI: 0x%04x\n", ra->crnti);
+              ra->msg3_dcch_dtch = true;
+              LOG_I(NR_MAC, "Received UL_SCH_LCID_C_RNTI with C-RNTI 0x%04x\n", ra->crnti);
               break;
             }
           }
@@ -777,13 +778,13 @@ void nr_rx_sdu(const module_id_t gnb_mod_idP,
         UE_info->UE_sched_ctrl[UE_id].ta_frame = frameP;
 
         LOG_D(NR_MAC,
-              "reset RA state information for RA-RNTI %04x/index %d\n",
+              "reset RA state information for RA-RNTI 0x%04x/index %d\n",
               ra->rnti,
               i);
 
         LOG_I(NR_MAC,
-              "[gNB %d][RAPROC] PUSCH with TC_RNTI %x received correctly, "
-              "adding UE MAC Context UE_id %d/RNTI %04x\n",
+              "[gNB %d][RAPROC] PUSCH with TC_RNTI 0x%04x received correctly, "
+              "adding UE MAC Context UE_id %d/RNTI 0x%04x\n",
               gnb_mod_idP,
               current_rnti,
               UE_id,
@@ -821,7 +822,8 @@ void nr_rx_sdu(const module_id_t gnb_mod_idP,
             ra->state = Msg4;
             ra->Msg4_frame = (frameP + 2) % 1024;
             ra->Msg4_slot = 1;
-            LOG_I(NR_MAC, "Scheduling RA-Msg4 for TC_RNTI 0x%04x (state %d, frame %d, slot %d)\n", ra->rnti, ra->state, ra->Msg4_frame, ra->Msg4_slot);
+            LOG_I(NR_MAC, "Scheduling RA-Msg4 for TC_RNTI 0x%04x (state %d, frame %d, slot %d)\n",
+                  (ra->msg3_dcch_dtch?ra->crnti:ra->rnti), ra->state, ra->Msg4_frame, ra->Msg4_slot);
           }
           else {
              nr_mac_remove_ra_rnti(gnb_mod_idP, ra->rnti);

openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h

@@ -155,6 +155,8 @@ typedef struct {
   uint8_t msg3_cqireq;
   /// Round of Msg3 HARQ
   uint8_t msg3_round;
+  /// Flag to indicate if Msg3 carries a DCCH or DTCH message
+  bool msg3_dcch_dtch;
   /// TBS used for Msg4
   int msg4_TBsize;
   /// MCS used for Msg4