implementing triggering RA after SR failure

openair2/LAYER2/NR_MAC_UE/mac_defs.h

@@ -308,7 +308,7 @@ typedef struct {
   /// number of attempt for rach
   uint8_t RA_attempt_number;
   /// Random-access procedure flag
-  uint8_t RA_active;
+  bool RA_active;
   /// Random-access preamble index
   int ra_PreambleIndex;
   // When multiple SSBs per RO is configured, this indicates which one is selected in this RO -> this is used to properly compute the PRACH preamble
@@ -341,6 +341,8 @@ typedef struct {
   /// Msg3 buffer
   uint8_t *Msg3_buffer;
 
+  bool msg3_C_RNTI;
+
   /// Random-access Contention Resolution Timer
   NR_timer_t contention_resolution_timer;
   /// Transmitted UE Contention Resolution Identifier

openair2/LAYER2/NR_MAC_UE/mac_proto.h

@@ -312,6 +312,7 @@ void init_RA(NR_UE_MAC_INST_t *mac,
 
 int16_t get_prach_tx_power(NR_UE_MAC_INST_t *mac);
 void free_rach_structures(NR_UE_MAC_INST_t *nr_mac, int bwp_id);
+void schedule_RA_after_SR_failure(NR_UE_MAC_INST_t *mac);
 void nr_Msg1_transmitted(NR_UE_MAC_INST_t *mac);
 void nr_Msg3_transmitted(NR_UE_MAC_INST_t *mac, uint8_t CC_id, frame_t frameP, slot_t slotP, uint8_t gNB_id);
 void nr_get_msg3_payload(NR_UE_MAC_INST_t *mac, uint8_t *buf, int TBS_max);
@@ -335,7 +336,7 @@ void remove_ul_config_last_item(fapi_nr_ul_config_request_pdu_t *pdu);
 fapi_nr_ul_config_request_pdu_t *fapiLockIterator(fapi_nr_ul_config_request_t *ul_config, frame_t frame_tx, int slot_tx);
 
 void release_ul_config(fapi_nr_ul_config_request_pdu_t *pdu, bool clearIt);
-
+void clear_ul_config_request(NR_UE_MAC_INST_t *mac, int scs);
 int16_t compute_nr_SSB_PL(NR_UE_MAC_INST_t *mac, short ssb_rsrp_dBm);
 
 // PUSCH scheduler:

openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c

@@ -61,7 +61,7 @@ void init_RA(NR_UE_MAC_INST_t *mac,
 {
   mac->state = UE_PERFORMING_RA;
   RA_config_t *ra = &mac->ra;
-  ra->RA_active = 1;
+  ra->RA_active = true;
   ra->ra_PreambleIndex = -1;
   ra->RA_usedGroupA = 1;
   ra->RA_RAPID_found = 0;
@@ -582,17 +582,25 @@ void nr_Msg3_transmitted(NR_UE_MAC_INST_t *mac, uint8_t CC_id, frame_t frameP, s
   ra->ra_state = nrRA_WAIT_CONTENTION_RESOLUTION;
 }
 
-void nr_get_msg3_payload(NR_UE_MAC_INST_t *mac, uint8_t *buf, int TBS_max)
+static uint8_t *fill_msg3_crnti_pdu(RA_config_t *ra, uint8_t *pdu, uint16_t crnti)
 {
-  RA_config_t *ra = &mac->ra;
+  // RA triggered by UE MAC with C-RNTI in MAC CE
+  LOG_D(NR_MAC, "Generating MAC CE with C-RNTI for MSG3 %x\n", crnti);
+  *(NR_MAC_SUBHEADER_FIXED *)pdu = (NR_MAC_SUBHEADER_FIXED){.LCID = UL_SCH_LCID_C_RNTI, .R = 0};
+  pdu += sizeof(NR_MAC_SUBHEADER_FIXED);
 
-  // we already stored MSG3 in the buffer, we can use that
-  if (ra->Msg3_buffer) {
-    buf = ra->Msg3_buffer;
-    return;
-  }
+  // C-RNTI MAC CE (2 octets)
+  uint16_t rnti_pdu = ((crnti & 0xFF) << 8) | ((crnti >> 8) & 0xFF);
+  memcpy(pdu, &rnti_pdu, sizeof(rnti_pdu));
+  pdu += sizeof(rnti_pdu);
+  ra->t_crnti = crnti;
+  return pdu;
+}
 
-  uint8_t *pdu = buf;
+static uint8_t *fill_msg3_pdu_from_rlc(NR_UE_MAC_INST_t *mac, uint8_t *pdu, int TBS_max)
+{
+  RA_config_t *ra = &mac->ra;
+  // regular MSG3 with PDU coming from higher layers
   *(NR_MAC_SUBHEADER_FIXED *)pdu = (NR_MAC_SUBHEADER_FIXED){.LCID = UL_SCH_LCID_CCCH};
   pdu += sizeof(NR_MAC_SUBHEADER_FIXED);
   tbs_size_t len = mac_rlc_data_req(mac->ue_id,
@@ -613,6 +621,25 @@ void nr_get_msg3_payload(NR_UE_MAC_INST_t *mac, uint8_t *buf, int TBS_max)
   // We copy from persisted memory to another persisted memory
   memcpy(ra->cont_res_id, pdu, sizeof(uint8_t) * 6);
   pdu += len;
+  return pdu;
+}
+
+void nr_get_msg3_payload(NR_UE_MAC_INST_t *mac, uint8_t *buf, int TBS_max)
+{
+  RA_config_t *ra = &mac->ra;
+
+  // we already stored MSG3 in the buffer, we can use that
+  if (ra->Msg3_buffer) {
+    buf = ra->Msg3_buffer;
+    return;
+  }
+
+  uint8_t *pdu = buf;
+  if (ra->msg3_C_RNTI)
+    pdu = fill_msg3_crnti_pdu(ra, pdu, mac->crnti);
+  else 
+    pdu = fill_msg3_pdu_from_rlc(mac, pdu, TBS_max);
+
   AssertFatal(TBS_max >= pdu - buf, "Allocated resources are not enough for Msg3!\n");
   // Padding: fill remainder with 0
   LOG_D(NR_MAC, "Remaining %ld bytes, filling with padding\n", pdu - buf);
@@ -657,7 +684,7 @@ void nr_ue_get_rach(NR_UE_MAC_INST_t *mac, int CC_id, frame_t frame, uint8_t gNB
   LOG_D(NR_MAC, "[UE %d][%d.%d]: ra_state %d, RA_active %d\n", mac->ue_id, frame, nr_slot_tx, ra->ra_state, ra->RA_active);
 
   if (ra->ra_state > nrRA_UE_IDLE && ra->ra_state < nrRA_SUCCEEDED) {
-    if (ra->RA_active == 0) {
+    if (!ra->RA_active) {
       NR_RACH_ConfigCommon_t *setup = mac->current_UL_BWP->rach_ConfigCommon;
       NR_RACH_ConfigGeneric_t *rach_ConfigGeneric = &setup->rach_ConfigGeneric;
       init_RA(mac, &ra->prach_resources, setup, rach_ConfigGeneric, ra->rach_ConfigDedicated);
@@ -825,7 +852,8 @@ void nr_ra_succeeded(NR_UE_MAC_INST_t *mac, const uint8_t gNB_index, const frame
   }
 
   LOG_D(MAC, "[UE %d] clearing RA_active flag...\n", mac->ue_id);
-  ra->RA_active = 0;
+  ra->RA_active = false;
+  ra->msg3_C_RNTI = false;
   ra->ra_state = nrRA_SUCCEEDED;
   mac->state = UE_CONNECTED;
   free_and_zero(ra->Msg3_buffer);
@@ -875,6 +903,25 @@ void nr_ra_failed(NR_UE_MAC_INST_t *mac, uint8_t CC_id, NR_PRACH_RESOURCES_t *pr
   }
 }
 
+void schedule_RA_after_SR_failure(NR_UE_MAC_INST_t *mac)
+{
+  LOG_W(NR_MAC, "Triggering new RA procedure for UE with RNTI %x\n", mac->crnti);
+  mac->state = UE_SYNC;
+  reset_ra(mac, false);
+  mac->ra.msg3_C_RNTI = true;
+  // release PUCCH for all Serving Cells;
+  // release SRS for all Serving Cells;
+  release_PUCCH_SRS(mac);
+  // clear any configured downlink assignments and uplink grants;
+  int scs = mac->current_UL_BWP->scs;
+  if (mac->dl_config_request)
+    memset(mac->dl_config_request, 0, sizeof(*mac->dl_config_request));
+  if (mac->ul_config_request)
+    clear_ul_config_request(mac, scs);
+  // clear any PUSCH resources for semi-persistent CSI reporting
+  // TODO we don't have semi-persistent CSI reporting
+}
+
 void prepare_msg4_feedback(NR_UE_MAC_INST_t *mac, int pid, int ack_nack)
 {
   NR_UE_HARQ_STATUS_t *current_harq = &mac->dl_harq_info[pid];

openair2/LAYER2/NR_MAC_UE/nr_ue_procedures.c

@@ -2434,7 +2434,7 @@ bool trigger_periodic_scheduling_request(NR_UE_MAC_INST_t *mac, PUCCH_sched_t *p
 
   if(!pucch_Config ||
      !pucch_Config->schedulingRequestResourceToAddModList ||
-     pucch_Config->schedulingRequestResourceToAddModList->list.count==0)
+     pucch_Config->schedulingRequestResourceToAddModList->list.count == 0)
     return false; // SR not configured
 
   int sr_count = 0;
@@ -2458,7 +2458,12 @@ bool trigger_periodic_scheduling_request(NR_UE_MAC_INST_t *mac, PUCCH_sched_t *p
       pucch->pucch_resource = sr_pucch;
       pucch->n_sr = 1;
       /* sr_payload = 1 means that this is a positive SR, sr_payload = 0 means that it is a negative SR */
-      pucch->sr_payload = nr_ue_get_SR(mac, frame, slot, sr_Config->schedulingRequestID);
+      int ret = nr_ue_get_SR(mac, frame, slot, sr_Config->schedulingRequestID);
+      if (ret < 0) {
+        memset(pucch, 0, sizeof(*pucch));
+        return false;
+      }
+      pucch->sr_payload = ret;
       sr_count++;
       AssertFatal(sr_count < 2, "Cannot handle more than 1 SR per slot yet\n");
     }
@@ -2500,18 +2505,19 @@ int8_t nr_ue_get_SR(NR_UE_MAC_INST_t *mac, frame_t frame, slot_t slot, NR_Schedu
     return 1;
   }
 
-  // TODO
-  // notify RRC to release PUCCH for all Serving Cells;
-  // notify RRC to release SRS for all Serving Cells;
-  // clear any configured downlink assignments and uplink grants;
-  // clear any PUSCH resources for semi-persistent CSI reporting;
+  LOG_W(NR_MAC,
+        "[UE %d] SR not served! SR counter %d reached sr_MaxTransmissions %d\n",
+        mac->ue_id,
+        sr_info->counter,
+        sr_info->maxTransmissions);
+
   // initiate a Random Access procedure (see clause 5.1) on the SpCell and cancel all pending SRs.
-  LOG_E(NR_MAC, "[UE %d] SR not served. Triggering of new RA procedure not implemented yet.\n", mac->ue_id);
+  schedule_RA_after_SR_failure(mac);
   sr_info->pending = false;
   sr_info->counter = 0;
   nr_timer_stop(&sr_info->prohibitTimer);
 
-  return 0;
+  return -1;
 }
 
 // section 5.2.5 of 38.214
@@ -3511,7 +3517,7 @@ void nr_ue_process_mac_pdu(NR_UE_MAC_INST_t *mac, nr_downlink_indication_t *dl_i
         mac_len = 6;
 
         if (ra->ra_state == nrRA_WAIT_CONTENTION_RESOLUTION) {
-          LOG_I(MAC, "[UE %d][RAPROC] Frame %d : received contention resolution identity: 0x%02x%02x%02x%02x%02x%02x Terminating RA procedure\n",
+          LOG_I(MAC, "[UE %d]Frame %d Contention resolution identity: 0x%02x%02x%02x%02x%02x%02x Terminating RA procedure\n",
                 mac->ue_id,
                 frameP,
                 pduP[1],
@@ -3523,21 +3529,21 @@ void nr_ue_process_mac_pdu(NR_UE_MAC_INST_t *mac, nr_downlink_indication_t *dl_i
 
           bool ra_success = true;
 	  if (!IS_SOFTMODEM_IQPLAYER) { // Control is bypassed when replaying IQs (BMC)
-	    for(int i = 0; i<mac_len; i++) {
-	      if(ra->cont_res_id[i] != pduP[i+1]) {
+	    for(int i = 0; i < mac_len; i++) {
+	      if(ra->cont_res_id[i] != pduP[i + 1]) {
 		ra_success = false;
 		break;
 	      }
 	    }
 	  }
 
-          if ( (ra->RA_active == 1) && ra_success) {
+          if (ra->RA_active && ra_success) {
             nr_ra_succeeded(mac, gNB_index, frameP, slot);
-          } else if (!ra_success){
+          } else if (!ra_success) {
             // TODO: Handle failure of RA procedure @ MAC layer
             //  nr_ra_failed(module_idP, CC_id, prach_resources, frameP, slot); // prach_resources is a PHY structure
             ra->ra_state = nrRA_UE_IDLE;
-            ra->RA_active = 0;
+            ra->RA_active = false;
           }
         }
         break;
@@ -3978,6 +3984,7 @@ static void nr_ue_process_rar(NR_UE_MAC_INST_t *mac, nr_downlink_indication_t *d
       if (!ra->cfra) {
         ra->t_crnti = rar->TCRNTI_2 + (rar->TCRNTI_1 << 8);
         rnti = ra->t_crnti;
+        if (!ra->msg3_C_RNTI)
           nr_mac_rrc_msg3_ind(mac->ue_id, rnti, dl_info->gNB_index);
       }
       fapi_nr_ul_config_request_pdu_t *pdu = lockGet_ul_config(mac, frame_tx, slot_tx, FAPI_NR_UL_CONFIG_TYPE_PUSCH);

openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c

@@ -60,6 +60,17 @@
 static void nr_ue_prach_scheduler(NR_UE_MAC_INST_t *mac, frame_t frameP, sub_frame_t slotP);
 static void schedule_ta_command(fapi_nr_dl_config_request_t *dl_config, NR_UL_TIME_ALIGNMENT_t *ul_time_alignment);
 
+void clear_ul_config_request(NR_UE_MAC_INST_t *mac, int scs)
+{
+  int slots = nr_slots_per_frame[scs];
+  for (int i = 0; i < slots ; i++) {
+    fapi_nr_ul_config_request_t *ul_config = mac->ul_config_request + i;
+    pthread_mutex_lock(&ul_config->mutex_ul_config);
+    ul_config->number_pdus = 0;
+    pthread_mutex_unlock(&ul_config->mutex_ul_config);
+  }
+}
+
 fapi_nr_ul_config_request_pdu_t *lockGet_ul_config(NR_UE_MAC_INST_t *mac, frame_t frame_tx, int slot_tx, uint8_t pdu_type)
 {
   NR_TDD_UL_DL_ConfigCommon_t *tdd_config = mac->tdd_UL_DL_ConfigurationCommon;

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c

@@ -132,9 +132,14 @@ int nr_write_ce_dlsch_pdu(module_id_t module_idP,
     // contention resolution identity MAC ce has a fixed 48 bit size
     // this contains the UL CCCH SDU. If UL CCCH SDU is longer than 48 bits,
     // it contains the first 48 bits of the UL CCCH SDU
-    LOG_T(NR_MAC, "[gNB ][RAPROC] Generate contention resolution msg: %x.%x.%x.%x.%x.%x\n",
-          ue_cont_res_id[0], ue_cont_res_id[1], ue_cont_res_id[2],
-          ue_cont_res_id[3], ue_cont_res_id[4], ue_cont_res_id[5]);
+    LOG_D(NR_MAC,
+          "[gNB ][RAPROC] Generate contention resolution msg: %x.%x.%x.%x.%x.%x\n",
+          ue_cont_res_id[0],
+          ue_cont_res_id[1],
+          ue_cont_res_id[2],
+          ue_cont_res_id[3],
+          ue_cont_res_id[4],
+          ue_cont_res_id[5]);
     // Copying bytes (6 octects) to CEs pointer
     mac_ce_size = 6;
     memcpy(ce_ptr, ue_cont_res_id, mac_ce_size);

openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c

@@ -1059,8 +1059,18 @@ static int handle_bcch_dlsch(NR_UE_MAC_INST_t *mac,
 }
 
 //  L2 Abstraction Layer
-static nr_dci_format_t handle_dci(NR_UE_MAC_INST_t *mac, frame_t frame, int slot, fapi_nr_dci_indication_pdu_t *dci)
+static nr_dci_format_t handle_dci(NR_UE_MAC_INST_t *mac,
+                                  unsigned int gNB_index,
+                                  frame_t frame,
+                                  int slot,
+                                  fapi_nr_dci_indication_pdu_t *dci)
 {
+  // if notification of a reception of a PDCCH transmission of the SpCell is received from lower layers
+  // if the C-RNTI MAC CE was included in Msg3
+  // consider this Contention Resolution successful
+  if (mac->ra.msg3_C_RNTI && mac->ra.ra_state == nrRA_WAIT_CONTENTION_RESOLUTION)
+    nr_ra_succeeded(mac, gNB_index, frame, slot);
+
   return nr_ue_process_dci_indication_pdu(mac, frame, slot, dci);
 }
 
@@ -1156,7 +1166,11 @@ static uint32_t nr_ue_dl_processing(nr_downlink_indication_t *dl_info)
     LOG_T(MAC, "[L2][IF MODULE][DL INDICATION][DCI_IND]\n");
     for (int i = 0; i < dl_info->dci_ind->number_of_dcis; i++) {
       LOG_T(MAC, ">>>NR_IF_Module i=%d, dl_info->dci_ind->number_of_dcis=%d\n", i, dl_info->dci_ind->number_of_dcis);
-      nr_dci_format_t dci_format = handle_dci(mac, dl_info->frame, dl_info->slot, dl_info->dci_ind->dci_list + i);
+      nr_dci_format_t dci_format = handle_dci(mac,
+                                              dl_info->gNB_index,
+                                              dl_info->frame,
+                                              dl_info->slot,
+                                              dl_info->dci_ind->dci_list + i);
 
       /* The check below filters out UL_DCIs which are being processed as DL_DCIs. */
       if (dci_format != NR_DL_DCI_FORMAT_1_0 && dci_format != NR_DL_DCI_FORMAT_1_1) {