Baseline implementation of RA 2-Step MsgA procedures at gNB

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_RA.c

@@ -640,18 +640,27 @@ void nr_initiate_ra_proc(module_id_t module_idP,
     ra->rnti = trial;
   }
 
-  ra->ra_state = nrRA_Msg2;
   ra->preamble_frame = frameP;
   ra->preamble_slot = slotP;
   ra->preamble_index = preamble_index;
   ra->timing_offset = timing_offset;
   uint8_t ul_carrier_id = 0; // 0 for NUL 1 for SUL
   ra->RA_rnti = nr_get_ra_rnti(symbol, slotP, freq_index, ul_carrier_id);
+
+  NR_ServingCellConfigCommon_t *scc = cc->ServingCellConfigCommon;
+  if (scc->uplinkConfigCommon->initialUplinkBWP->ext1 && scc->uplinkConfigCommon->initialUplinkBWP->ext1->msgA_ConfigCommon_r16) {
+    ra->ra_type = RA_2_STEP;
+    ra->ra_state = nrRA_WAIT_MsgA_PUSCH;
+    ra->MsgB_rnti = nr_get_MsgB_rnti(symbol, slotP, freq_index, ul_carrier_id);
+  } else {
+    ra->ra_type = RA_4_STEP;
+    ra->ra_state = nrRA_Msg2;
+  }
+
   int index = ra - cc->ra;
   LOG_I(NR_MAC, "%d.%d UE RA-RNTI %04x TC-RNTI %04x: Activating RA process index %d\n", frameP, slotP, ra->RA_rnti, ra->rnti, index);
 
   // Configure RA BWP
-  NR_ServingCellConfigCommon_t *scc = cc->ServingCellConfigCommon;
   configure_UE_BWP(nr_mac, scc, NULL, ra, NULL, -1, -1);
 
   uint8_t beam_index = ssb_index_from_prach(module_idP, frameP, slotP, preamble_index, freq_index, symbol);
@@ -1844,6 +1853,7 @@ static void nr_generate_Msg4(module_id_t module_idP,
   NR_COMMON_channels_t *cc = &nr_mac->common_channels[CC_id];
   NR_UE_DL_BWP_t *dl_bwp = &ra->DL_BWP;
 
+  AssertFatal(ra->ra_type == RA_4_STEP, "Scheduling of RA 2-Step MsgB not implemented yet!\n");
   // if it is a DL slot, if the RA is in MSG4 state
   if (is_xlsch_in_slot(nr_mac->dlsch_slot_bitmap[slotP / 64], slotP)) {
 
@@ -2085,7 +2095,7 @@ static void nr_generate_Msg4(module_id_t module_idP,
       vrb_map[BWPStart + rb + rbStart] |= SL_to_bitmap(msg4_tda.startSymbolIndex, msg4_tda.nrOfSymbols);
     }
 
-    ra->ra_state = nrRA_WAIT_Msg4_ACK;
+    ra->ra_state = nrRA_WAIT_Msg4_MsgB_ACK;
     LOG_I(NR_MAC,"UE %04x Generate msg4: feedback at %4d.%2d, payload %d bytes, next state WAIT_Msg4_ACK\n", ra->rnti, pucch->frame, pucch->ul_slot, harq->tb_size);
   }
 }
@@ -2278,7 +2288,7 @@ void nr_schedule_RA(module_id_t module_idP,
       LOG_D(NR_MAC, "RA[state:%d]\n", ra->ra_state);
 
       // Check RA Contention Resolution timer
-      if (ra->ra_state >= nrRA_WAIT_Msg3) {
+      if (ra->ra_type == RA_4_STEP && ra->ra_state >= nrRA_WAIT_Msg3) {
         ra->contention_resolution_timer--;
         if (ra->contention_resolution_timer < 0) {
           LOG_W(NR_MAC, "(%d.%d) RA Contention Resolution timer expired for UE 0x%04x, RA procedure failed...\n", frameP, slotP, ra->rnti);
@@ -2298,7 +2308,7 @@ void nr_schedule_RA(module_id_t module_idP,
         case nrRA_Msg4:
           nr_generate_Msg4(module_idP, CC_id, frameP, slotP, ra, DL_req, TX_req);
           break;
-        case nrRA_WAIT_Msg4_ACK:
+        case nrRA_WAIT_Msg4_MsgB_ACK:
           nr_check_Msg4_Ack(module_idP, CC_id, frameP, slotP, ra);
           break;
         default:

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

@@ -522,7 +522,7 @@ void handle_nr_ul_harq(const int CC_idP,
       }
     }
     NR_SCHED_UNLOCK(&nrmac->sched_lock);
-    LOG_E(NR_MAC, "no RA proc for RNTI 0x%04x in Msg3/PUSCH\n", crc_pdu->rnti);
+    LOG_D(NR_MAC, "no RA proc for RNTI 0x%04x in Msg3/PUSCH\n", crc_pdu->rnti);
     return;
   }
   NR_UE_sched_ctrl_t *sched_ctrl = &UE->UE_sched_ctrl;
@@ -712,7 +712,7 @@ static void _nr_rx_sdu(const module_id_t gnb_mod_idP,
      * it. */
     for (int i = 0; i < NR_NB_RA_PROC_MAX; ++i) {
       NR_RA_t *ra = &gNB_mac->common_channels[CC_idP].ra[i];
-      if (ra->ra_state != nrRA_WAIT_Msg3)
+      if (ra->ra_type == RA_4_STEP && ra->ra_state != nrRA_WAIT_Msg3)
         continue;
 
       if (no_sig) {
@@ -720,22 +720,29 @@ static void _nr_rx_sdu(const module_id_t gnb_mod_idP,
         nr_clear_ra_proc(ra);
         continue;
       }
-
-      // random access pusch with TC-RNTI
-      if (ra->rnti != current_rnti) {
-        LOG_D(NR_MAC, "expected TC_RNTI %04x to match current RNTI %04x\n", ra->rnti, current_rnti);
-
-        if ((frameP == ra->Msg3_frame) && (slotP == ra->Msg3_slot)) {
-          LOG_W(NR_MAC,
-                "Random Access %i failed at state %s (TC_RNTI %04x RNTI %04x)\n",
-                i,
-                nrra_text[ra->ra_state],
-                ra->rnti,
-                current_rnti);
-          nr_clear_ra_proc(ra);
+      if (ra->ra_type == RA_2_STEP) {
+        // random access pusch with RA-RNTI
+        if (ra->RA_rnti != current_rnti) {
+          LOG_E(NR_MAC, "expected TC_RNTI %04x to match current RNTI %04x\n", ra->RA_rnti, current_rnti);
+          continue;
         }
+      } else {
+        // random access pusch with TC-RNTI
+        if (ra->rnti != current_rnti) {
+          LOG_D(NR_MAC, "expected TC_RNTI %04x to match current RNTI %04x\n", ra->rnti, current_rnti);
+
+          if ((frameP == ra->Msg3_frame) && (slotP == ra->Msg3_slot)) {
+            LOG_W(NR_MAC,
+                  "Random Access %i failed at state %s (TC_RNTI %04x RNTI %04x)\n",
+                  i,
+                  nrra_text[ra->ra_state],
+                  ra->rnti,
+                  current_rnti);
+            nr_clear_ra_proc(ra);
+          }
 
-        continue;
+          continue;
+        }
       }
 
       UE = UE ? UE : add_new_nr_ue(gNB_mac, ra->rnti, ra->CellGroup);
@@ -782,8 +789,8 @@ static void _nr_rx_sdu(const module_id_t gnb_mod_idP,
         process_CellGroup(ra->CellGroup, UE);
 
       } else {
-        LOG_A(NR_MAC, "[RAPROC] RA-Msg3 received (sdu_lenP %d)\n", sdu_lenP);
-        LOG_D(NR_MAC, "[RAPROC] Received Msg3:\n");
+        LOG_A(NR_MAC, "[RAPROC] RA %s received (sdu_lenP %d)\n",ra->ra_type == RA_2_STEP ? "MsgA-PUSCH" : "Msg3", sdu_lenP);
+        LOG_D(NR_MAC, "[RAPROC] Received %s:\n", ra->ra_type == RA_2_STEP ? "MsgA-PUSCH" : "Msg3");
         for (int k = 0; k < sdu_lenP; k++) {
           LOG_D(NR_MAC, "(%i): 0x%x\n", k, sduP[k]);
         }
@@ -869,7 +876,7 @@ static void _nr_rx_sdu(const module_id_t gnb_mod_idP,
         return;
       }
 
-      LOG_D(NR_MAC, "Random Access %i Msg3 CRC did not pass)\n", i);
+      LOG_D(NR_MAC, "Random Access %i Msg3 CRC did not pass\n", i);
 
       ra->msg3_round++;
       ra->ra_state = nrRA_Msg3_retransmission;

openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h

@@ -114,13 +114,15 @@ typedef struct {
 typedef enum {
   nrRA_gNB_IDLE = 0,
   nrRA_Msg2 = 1,
-  nrRA_WAIT_Msg3 = 2,
-  nrRA_Msg3_retransmission = 3,
-  nrRA_Msg4 = 4,
-  nrRA_WAIT_Msg4_ACK = 5,
+  nrRA_WAIT_MsgA_PUSCH = 2,
+  nrRA_WAIT_Msg3 = 3,
+  nrRA_Msg3_retransmission = 4,
+  nrRA_Msg4 = 5,
+  nrRA_MsgB = 6,
+  nrRA_WAIT_Msg4_MsgB_ACK = 7,
 } RA_gNB_state_t;
 static const char *const nrra_text[] =
-    {"IDLE", "Msg2", "WAIT_Msg3", "Msg3_retransmission", "Msg3_dcch_dtch", "Msg4", "WAIT_Msg4_ACK"};
+    {"IDLE", "Msg2", "WAIT_MsgA_PUSCH", "WAIT_Msg3", "Msg3_retransmission", "Msg3_dcch_dtch", "Msg4", "MsgB", "WAIT_Msg4_ACK"};
 typedef struct nr_pdsch_AntennaPorts_t {
   int N1;
   int N2;
@@ -188,6 +190,8 @@ typedef struct {
   rnti_t rnti;
   /// RA RNTI allocated from received PRACH
   uint16_t RA_rnti;
+  /// MsgB RNTI allocated from received PRACH
+  uint16_t MsgB_rnti;
   /// Received UE Contention Resolution Identifier
   uint8_t cont_res_id[6];
   /// Msg3 first RB
@@ -216,6 +220,7 @@ typedef struct {
   /// Preambles for contention-free access
   NR_preamble_ue_t preambles;
   int contention_resolution_timer;
+  nr_ra_type_t ra_type;
   /// CFRA flag
   bool cfra;
   // BWP for RA