Implement RB suspend at gNB MAC

Add a flag for each RB that tracks suspension state. Mark all RBs
(except SRB1) as suspended on reestablishment, and de-suspend on
reconfiguration. Only check RLC status for non-suspended RBs. For UL
data traffic, check that DRB/SRB2 exist (SRB1 should be there as soon as
the UE context exists).

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c

@@ -335,6 +335,9 @@ static void nr_store_dlsch_buffer(module_id_t module_id, frame_t frame, slot_t s
       const int lcid = c->lcid;
       const uint16_t rnti = UE->rnti;
       LOG_D(NR_MAC, "In %s: UE %x: LCID %d\n", __FUNCTION__, rnti, lcid);
+      memset(&sched_ctrl->rlc_status[lcid], 0, sizeof(sched_ctrl->rlc_status[lcid]));
+      if (c->suspended)
+        continue;
       if (lcid == DL_SCH_LCID_DTCH && nr_timer_is_active(&sched_ctrl->transm_interrupt))
         continue;
       start_meas(&RC.nrmac[module_id]->rlc_status_ind);

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_primitives.c

@@ -3477,6 +3477,16 @@ static int cmp_lc_config(const void *va, const void *vb)
   return 1;
 }
 
+nr_lc_config_t *nr_mac_get_lc_config(NR_UE_sched_ctrl_t* sched_ctrl, int lcid)
+{
+  nr_lc_config_t c = {.lcid = lcid};
+  elm_arr_t elm = find_if(&sched_ctrl->lc_config, &c, eq_lcid_config);
+  if (elm.found)
+    return elm.it;
+  else
+    return NULL;
+}
+
 bool nr_mac_add_lcid(NR_UE_sched_ctrl_t* sched_ctrl, const nr_lc_config_t *c)
 {
   elm_arr_t elm = find_if(&sched_ctrl->lc_config, (void *) c, eq_lcid_config);

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

@@ -390,10 +390,15 @@ static int nr_process_mac_pdu(instance_t module_idP,
                     slot,
                     lcid);
 
-        nr_mac_rlc_data_ind(module_idP, UE->rnti, true, lcid, (char *)(pduP + mac_subheader_len), mac_len);
+        const nr_lc_config_t *srbc = nr_mac_get_lc_config(sched_ctrl, lcid);
+        if (!srbc || srbc->suspended) {
+          LOG_I(NR_MAC, "RNTI %04x LCID %d: ignoring %d bytes\n", UE->rnti, lcid, mac_len);
+        } else {
+          nr_mac_rlc_data_ind(module_idP, UE->rnti, true, lcid, (char *)(pduP + mac_subheader_len), mac_len);
 
-        UE->mac_stats.ul.total_sdu_bytes += mac_len;
-        UE->mac_stats.ul.lc_bytes[lcid] += mac_len;
+          UE->mac_stats.ul.total_sdu_bytes += mac_len;
+          UE->mac_stats.ul.lc_bytes[lcid] += mac_len;
+        }
         break;
 
       case UL_SCH_LCID_DTCH ...(UL_SCH_LCID_DTCH + 28):
@@ -406,16 +411,21 @@ static int nr_process_mac_pdu(instance_t module_idP,
               lcid,
               module_idP,
               mac_len);
-        UE->mac_stats.ul.lc_bytes[lcid] += mac_len;
+        const nr_lc_config_t *c = nr_mac_get_lc_config(sched_ctrl, lcid);
+        if (!c || c->suspended) {
+          LOG_I(NR_MAC, "RNTI %04x LCID %d: ignoring %d bytes\n", UE->rnti, lcid, mac_len);
+        } else {
+          UE->mac_stats.ul.lc_bytes[lcid] += mac_len;
 
-        nr_mac_rlc_data_ind(module_idP, UE->rnti, true, lcid, (char *)(pduP + mac_subheader_len), mac_len);
+          nr_mac_rlc_data_ind(module_idP, UE->rnti, true, lcid, (char *)(pduP + mac_subheader_len), mac_len);
 
-        sdus += 1;
-        /* Updated estimated buffer when receiving data */
-        if (sched_ctrl->estimated_ul_buffer >= mac_len)
-          sched_ctrl->estimated_ul_buffer -= mac_len;
-        else
-          sched_ctrl->estimated_ul_buffer = 0;
+          sdus += 1;
+          /* Updated estimated buffer when receiving data */
+          if (sched_ctrl->estimated_ul_buffer >= mac_len)
+            sched_ctrl->estimated_ul_buffer -= mac_len;
+          else
+            sched_ctrl->estimated_ul_buffer = 0;
+        }
         break;
 
       case UL_SCH_LCID_RECOMMENDED_BITRATE_QUERY:

openair2/LAYER2/NR_MAC_gNB/mac_proto.h

@@ -451,6 +451,7 @@ void process_addmod_bearers_cellGroupConfig(NR_UE_sched_ctrl_t *sched_ctrl,
                                             const struct NR_CellGroupConfig__rlc_BearerToAddModList *addmod);
 
 bool nr_mac_add_lcid(NR_UE_sched_ctrl_t *sched_ctrl, const nr_lc_config_t *c);
+nr_lc_config_t *nr_mac_get_lc_config(NR_UE_sched_ctrl_t* sched_ctrl, int lcid);
 bool nr_mac_remove_lcid(NR_UE_sched_ctrl_t *sched_ctrl, long lcid);
 
 bool nr_mac_get_new_rnti(NR_UEs_t *UEs, rnti_t *rnti);

openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c

@@ -777,6 +777,10 @@ void ue_context_modification_request(const f1ap_ue_context_modif_req_t *req)
     // we re-configure the BWP to apply the CellGroup and to use UE specific Search Space with DCIX1
     nr_mac_clean_cellgroup(UE->CellGroup);
     configure_UE_BWP(mac, scc, UE, false, NR_SearchSpace__searchSpaceType_PR_ue_Specific, -1, -1);
+    for (int i = 1; i < seq_arr_size(&UE->UE_sched_ctrl.lc_config); ++i) {
+      nr_lc_config_t *c = seq_arr_at(&UE->UE_sched_ctrl.lc_config, i);
+      c->suspended = false;
+    }
   }
 
   if (ue_cap != NULL) {
@@ -965,7 +969,9 @@ void dl_rrc_message_transfer(const f1ap_dl_rrc_message_t *dl_rrc)
     oldUE->uid = temp_uid;
     for (int i = 1; i < seq_arr_size(&oldUE->UE_sched_ctrl.lc_config); ++i) {
       const nr_lc_config_t *c = seq_arr_at(&oldUE->UE_sched_ctrl.lc_config, i);
-      nr_mac_add_lcid(&UE->UE_sched_ctrl, c);
+      nr_lc_config_t new = *c;
+      new.suspended = true;
+      nr_mac_add_lcid(&UE->UE_sched_ctrl, &new);
     }
     ASN_STRUCT_FREE(asn_DEF_NR_CellGroupConfig, UE->CellGroup);
     UE->CellGroup = oldUE->CellGroup;

openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h

@@ -564,6 +564,8 @@ typedef struct NR_QoS_config_s {
 
 typedef struct nr_lc_config {
   uint8_t lcid;
+  /// flag if corresponding RB is suspended
+  bool suspended;
   /// priority as specified in 38.321
   int priority;
   /// associated NSSAI for DRB