Implement basic F1 release procedure using F1 internally

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_primitives.c

@@ -2785,6 +2785,16 @@ void nr_mac_update_timers(module_id_t module_id,
   NR_UEs_t *UE_info = &RC.nrmac[module_id]->UE_info;
   UE_iterator(UE_info->list, UE) {
     NR_UE_sched_ctrl_t *sched_ctrl = &UE->UE_sched_ctrl;
+
+    if (nr_mac_check_release(sched_ctrl, UE->rnti)) {
+      nr_rlc_remove_ue(UE->rnti);
+      mac_remove_nr_ue(RC.nrmac[module_id], UE->rnti);
+      // go back to examine the next UE, which is at the position the
+      // current UE was
+      UE--;
+      continue;
+    }
+
     if (sched_ctrl->rrc_processing_timer > 0) {
       sched_ctrl->rrc_processing_timer--;
       if (sched_ctrl->rrc_processing_timer == 0) {
@@ -2946,3 +2956,17 @@ void prepare_initial_ul_rrc_message(gNB_MAC_INST *mac, NR_UE_info_t *UE)
   DevAssert(bearer->servedRadioBearer->choice.srb_Identity == 1);
   nr_rlc_add_srb(UE->rnti, DCCH, bearer);
 }
+
+void nr_mac_trigger_release_timer(NR_UE_sched_ctrl_t *sched_ctrl, NR_SubcarrierSpacing_t subcarrier_spacing)
+{
+  // trigger 60ms
+  sched_ctrl->release_timer = 60 << subcarrier_spacing;
+}
+
+bool nr_mac_check_release(NR_UE_sched_ctrl_t *sched_ctrl, int rnti)
+{
+  if (sched_ctrl->release_timer == 0)
+    return false;
+  sched_ctrl->release_timer--;
+  return sched_ctrl->release_timer == 0;
+}

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

@@ -671,8 +671,6 @@ static void _nr_rx_sdu(const module_id_t gnb_mod_idP,
       if (!get_softmodem_params()->phy_test && UE->UE_sched_ctrl.pusch_consecutive_dtx_cnt >= pusch_failure_thres) {
          LOG_W(NR_MAC,"Detected UL Failure on PUSCH after %d PUSCH DTX, stopping scheduling\n",
                UE->UE_sched_ctrl.pusch_consecutive_dtx_cnt);
-         UE->UE_sched_ctrl.ul_failure = 1;
-
          nr_mac_gNB_rrc_ul_failure(gnb_mod_idP,CC_idP,frameP,slotP,rntiP);
       }
     }

openair2/LAYER2/NR_MAC_gNB/mac_proto.h

@@ -440,4 +440,7 @@ void send_initial_ul_rrc_message(gNB_MAC_INST *mac, int rnti, const uint8_t *sdu
 
 void abort_nr_dl_harq(NR_UE_info_t* UE, int8_t harq_pid);
 
+void nr_mac_trigger_release_timer(NR_UE_sched_ctrl_t *sched_ctrl, NR_SubcarrierSpacing_t subcarrier_spacing);
+bool nr_mac_check_release(NR_UE_sched_ctrl_t *sched_ctrl, int rnti);
+
 #endif /*__LAYER2_NR_MAC_PROTO_H__*/

openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c

@@ -149,7 +149,29 @@ void ue_context_setup_request(const f1ap_ue_context_setup_t *req)
 
 void ue_context_release_command(const f1ap_ue_context_release_cmd_t *cmd)
 {
-  AssertFatal(false, "not implemented\n");
+  /* mark UE as to be deleted after PUSCH failure */
+  gNB_MAC_INST *mac = RC.nrmac[0];
+  pthread_mutex_lock(&mac->sched_lock);
+  NR_UE_info_t *UE = find_nr_UE(&mac->UE_info, cmd->rnti);
+  if (UE->UE_sched_ctrl.ul_failure > 0 || cmd->rrc_container_length == 0) {
+    /* The UE is already not connected anymore or we have nothing to forward*/
+    nr_rlc_remove_ue(cmd->rnti);
+    mac_remove_nr_ue(mac, cmd->rnti);
+  } else {
+    /* UE is in sync: forward release message and mark to be deleted
+     * after UL failure */
+    nr_rlc_srb_recv_sdu(cmd->rnti, cmd->srb_id, cmd->rrc_container, cmd->rrc_container_length);
+    nr_mac_trigger_release_timer(&UE->UE_sched_ctrl, UE->current_UL_BWP.scs);
+  }
+  pthread_mutex_unlock(&mac->sched_lock);
+
+  f1ap_ue_context_release_complete_t complete = {
+    .rnti = cmd->rnti,
+  };
+  mac->mac_rrc.ue_context_release_complete(&complete);
+
+  if (cmd->rrc_container)
+    free(cmd->rrc_container);
 }
 
 int dl_rrc_message(module_id_t module_id, const f1ap_dl_rrc_message_t *dl_rrc)

openair2/LAYER2/NR_MAC_gNB/mac_rrc_ul_direct.c

@@ -62,7 +62,10 @@ static void ue_context_release_request_direct(const f1ap_ue_context_release_req_
 
 static void ue_context_release_complete_direct(const f1ap_ue_context_release_complete_t *complete)
 {
-  AssertFatal(false, "not implemented\n");
+  MessageDef *msg = itti_alloc_new_message(TASK_MAC_GNB, 0, F1AP_UE_CONTEXT_RELEASE_COMPLETE);
+  f1ap_ue_context_release_complete_t *f1ap_msg = &F1AP_UE_CONTEXT_RELEASE_COMPLETE(msg);
+  *f1ap_msg = *complete;
+  itti_send_msg_to_task(TASK_RRC_GNB, 0, msg);
 }
 
 static void initial_ul_rrc_message_transfer_direct(module_id_t module_id, const f1ap_initial_ul_rrc_message_t *ul_rrc)

openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h

@@ -592,6 +592,7 @@ typedef struct {
   int pusch_consecutive_dtx_cnt;
   int pucch_consecutive_dtx_cnt;
   int ul_failure;
+  int release_timer;
   struct CSI_Report CSI_report;
   bool SR;
   /// information about every HARQ process