Decoding MIB and SIB1 in NR UE

In this commit, we changed the stub function of the NRUE
to handle the MIB and SIB1, which arrive in a single
DL_TTI_REQ. If we have not received the MIB, we first
call the scheduler, then we handle any received NFAPI
messages. The NFAPI message handler will then call
the nr_ue_dl_indication() again, which will process
first the MIB, then SIB1. It seems that we are not
properly sending the SIB1 response back to the gNB so
the NRUE eventually crashes. We are however, properly
decoding the MIB and SIB which is a step in the right
direction!

executables/nr-ue.c

@@ -434,15 +434,18 @@ static void *NRUE_phy_stub_standalone_pnf_task(void *arg)
 
     module_id_t mod_id = 0;
     NR_UE_MAC_INST_t *mac = get_mac_inst(mod_id);
-    if (mac->scc == NULL || mac->scc_SIB == NULL) //Melissa TODO this isnt correct
+    if (mac->mib == NULL)
     {
       if (get_softmodem_params()->sa && get_softmodem_params()->emulate_l2)
       {
-        LOG_D(NR_MAC, "We haven't gotten MIB or SIB yet. Lets see if we received it\n");
+        LOG_D(NR_MAC, "We haven't gotten MIB. Lets see if we received it\n");
         nr_ue_dl_indication(&mac->dl_info, &ul_time_alignment);
         process_queued_nr_nfapi_msgs(mac, sfn_slot);
       }
-      LOG_D(MAC, "mac->scc == NULL or mac->scc_SIB == NULL!\n");
+    }
+    if (mac->scc == NULL && mac->scc_SIB == NULL )
+    {
+      LOG_D(MAC, "[NSA] mac->scc == NULL and [SA] mac->scc_SIB == NULL!\n");
       continue;
     }
 
@@ -473,14 +476,20 @@ static void *NRUE_phy_stub_standalone_pnf_task(void *arg)
     mac->dl_info.dci_ind = NULL;
     mac->dl_info.rx_ind = NULL;
 
-    if (is_nr_DL_slot(mac->scc->tdd_UL_DL_ConfigurationCommon, ul_info.slot_rx))
+    if (is_nr_DL_slot(get_softmodem_params()->nsa ?
+                      mac->scc->tdd_UL_DL_ConfigurationCommon :
+                      mac->scc_SIB->tdd_UL_DL_ConfigurationCommon,
+                      ul_info.slot_rx))
     {
       nr_ue_dl_indication(&mac->dl_info, &ul_time_alignment);
     }
 
     if (pthread_mutex_unlock(&mac->mutex_dl_info)) abort();
 
-    if (is_nr_UL_slot(mac->scc->tdd_UL_DL_ConfigurationCommon, ul_info.slot_tx, mac->frame_type))
+    if (is_nr_UL_slot(get_softmodem_params()->nsa ?
+                      mac->scc->tdd_UL_DL_ConfigurationCommon :
+                      mac->scc_SIB->tdd_UL_DL_ConfigurationCommon,
+                      ul_info.slot_tx, mac->frame_type))
     {
       LOG_D(NR_MAC, "Slot %d. calling nr_ue_ul_ind() from %s\n", ul_info.slot_tx, __FUNCTION__);
       nr_ue_ul_indication(&ul_info);

openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c

@@ -887,10 +887,8 @@ NR_UE_L2_STATE_t nr_ue_scheduler(nr_downlink_indication_t *dl_info, nr_uplink_in
 
     nr_scheduled_response_t scheduled_response;
     nr_dcireq_t dcireq;
-    LOG_D(MAC,"Melissa we got herre %s():%d\n", __FUNCTION__, __LINE__);
 
     if(mac->cg != NULL){ // we have a cg
-      LOG_D(MAC,"Melissa we got herre %s():%d\n", __FUNCTION__, __LINE__);
       dcireq.module_id = mod_id;
       dcireq.gNB_index = gNB_index;
       dcireq.cc_id     = cc_id;

openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c

@@ -232,6 +232,28 @@ static void fill_dl_info_with_pdcch(fapi_nr_dci_indication_t *dci, nfapi_nr_dl_d
     dci->number_of_dcis = idx + 1;
 }
 
+static void fill_mib_in_rx_ind(nfapi_nr_dl_tti_request_pdu_t *pdu_list, fapi_nr_rx_indication_t *rx_ind, int pdu_idx, int pdu_type)
+{
+    AssertFatal(pdu_list->PDUSize < sizeof(rx_ind->rx_indication_body) / sizeof(rx_ind->rx_indication_body[0]),
+                "PDU size (%d) is greater than rx_indication_body size!\n", pdu_list->PDUSize);
+    nfapi_nr_dl_tti_ssb_pdu_rel15_t *ssb_pdu = &pdu_list->ssb_pdu.ssb_pdu_rel15;
+
+    LOG_D(NR_MAC, "Recevied an SSB and are filling rx_ind with the MIB!\n");
+    rx_ind->rx_indication_body[pdu_idx].ssb_pdu.cell_id = ssb_pdu->PhysCellId;
+    rx_ind->rx_indication_body[pdu_idx].ssb_pdu.pdu = CALLOC(3,
+                                                      sizeof(*rx_ind->rx_indication_body[pdu_idx].ssb_pdu.pdu));
+    rx_ind->rx_indication_body[pdu_idx].ssb_pdu.pdu[0] = (ssb_pdu->bchPayload) & 0xffff;
+    rx_ind->rx_indication_body[pdu_idx].ssb_pdu.pdu[1] = (ssb_pdu->bchPayload >> 8) & 0xffff;
+    rx_ind->rx_indication_body[pdu_idx].ssb_pdu.pdu[2] = (ssb_pdu->bchPayload >> 16) & 0xffff;
+    rx_ind->rx_indication_body[pdu_idx].ssb_pdu.rsrp_dBm = ssb_pdu->ssbRsrp;
+    rx_ind->rx_indication_body[pdu_idx].ssb_pdu.ssb_index = ssb_pdu->SsbBlockIndex;
+    rx_ind->rx_indication_body[pdu_idx].ssb_pdu.ssb_length = pdu_list->PDUSize;
+    rx_ind->rx_indication_body[pdu_idx].ssb_pdu.ssb_start_subcarrier = ssb_pdu->SsbSubcarrierOffset;
+    rx_ind->rx_indication_body[pdu_idx].pdu_type = pdu_type;
+    rx_ind->number_pdus = pdu_idx + 1;
+
+}
+
 static void copy_dl_tti_req_to_dl_info(nr_downlink_indication_t *dl_info, nfapi_nr_dl_tti_request_t *dl_tti_request)
 {
     NR_UE_MAC_INST_t *mac = get_mac_inst(dl_info->module_id);
@@ -240,6 +262,7 @@ static void copy_dl_tti_req_to_dl_info(nr_downlink_indication_t *dl_info, nfapi_
     int pdu_idx = 0;
 
     int num_pdus = dl_tti_request->dl_tti_request_body.nPDUs;
+    LOG_D(NR_MAC, "This is the total number of PDUS in dl_tti_req = %d\n", num_pdus);
     if (num_pdus <= 0)
     {
         LOG_E(NR_PHY, "%s: dl_tti_request number of PDUS <= 0\n", __FUNCTION__);
@@ -286,6 +309,24 @@ static void copy_dl_tti_req_to_dl_info(nr_downlink_indication_t *dl_info, nfapi_
                 }
             }
         }
+        if (pdu_list->PDUType == NFAPI_NR_DL_TTI_SSB_PDU_TYPE)
+        {
+            /* If we get a MIB, we want to handle it right away and then come back.
+               The MIB and SIB come in the same dl_tti_req but the MIB should be
+               processed first and then the DCI and payload of the SIB1 can be
+               processed. The MIB should be handled first and then the rx_ind
+               will be freed after handling. This is why the PDU index will
+               always be zero for the RX_IND becasue we should not have more than
+               one MIB. */
+            dl_info->rx_ind = CALLOC(1, sizeof(*dl_info->rx_ind));
+            fapi_nr_rx_indication_t *rx_ind = dl_info->rx_ind;
+            rx_ind->sfn = dl_tti_request->SFN;
+            rx_ind->slot = dl_tti_request->Slot;
+            fill_mib_in_rx_ind(pdu_list, rx_ind, 0, FAPI_NR_RX_PDU_TYPE_SSB);
+            NR_UL_TIME_ALIGNMENT_t ul_time_alignment;
+            memset(&ul_time_alignment, 0, sizeof(ul_time_alignment));
+            nr_ue_dl_indication(&mac->dl_info, &ul_time_alignment);
+        }
     }
     dl_info->slot = dl_tti_request->Slot;
     dl_info->frame = dl_tti_request->SFN;
@@ -342,7 +383,7 @@ static void copy_tx_data_req_to_dl_info(nr_downlink_indication_t *dl_info, nfapi
     for (int i = 0; i < num_pdus; i++)
     {
         nfapi_nr_pdu_t *pdu_list = &tx_data_request->pdu_list[i];
-        if (dl_info->dci_ind->number_of_dcis > 0 && dl_info->dci_ind->dci_list[i].rnti == 0xffff) //Melissa this is bad find a better way
+        if (dl_info->dci_ind->dci_list[i].rnti == 0xffff)
         {
             fill_rx_ind(pdu_list, rx_ind, pdu_idx, FAPI_NR_RX_PDU_TYPE_SIB);
             pdu_idx++;
@@ -554,11 +595,6 @@ void check_and_process_dci(nfapi_nr_dl_tti_request_t *dl_tti_request,
     int slot = 0;
     NR_UE_MAC_INST_t *mac = get_mac_inst(0);
 
-    if (mac->scc == NULL) //Melissa, if we comment this out, we see the SIB!
-    {
-      return;
-    }
-
     if (pthread_mutex_lock(&mac->mutex_dl_info)) abort();
 
     if (dl_tti_request)
@@ -619,8 +655,13 @@ void check_and_process_dci(nfapi_nr_dl_tti_request_t *dl_tti_request,
     ul_info.slot_tx = (slot + slot_ahead) % slots_per_frame;
     ul_info.frame_tx = (ul_info.slot_rx + slot_ahead >= slots_per_frame) ? ul_info.frame_rx + 1 : ul_info.frame_rx;
     ul_info.ue_sched_mode = SCHED_ALL;
-    if (mac->scc && is_nr_UL_slot(mac->scc->tdd_UL_DL_ConfigurationCommon, ul_info.slot_tx, mac->frame_type))
+    if (mac->scc || mac->scc_SIB)
     {
+        if (is_nr_UL_slot(mac->scc ?
+                          mac->scc->tdd_UL_DL_ConfigurationCommon :
+                          mac->scc_SIB->tdd_UL_DL_ConfigurationCommon,
+                          ul_info.slot_tx,
+                          mac->frame_type))
         nr_ue_ul_indication(&ul_info);
     }
 }
@@ -1051,7 +1092,7 @@ nr_ue_if_module_t *nr_ue_if_module_init(uint32_t module_id){
     nr_ue_if_module_inst[module_id]->current_frame = 0;
     nr_ue_if_module_inst[module_id]->current_slot = 0;
     nr_ue_if_module_inst[module_id]->phy_config_request = nr_ue_phy_config_request;
-    if (get_softmodem_params()->nsa) //TODO: Get a better flag for using stub
+    if (get_softmodem_params()->emulate_l2)
       nr_ue_if_module_inst[module_id]->scheduled_response = nr_ue_scheduled_response_stub;
     else
       nr_ue_if_module_inst[module_id]->scheduled_response = nr_ue_scheduled_response;