eCall inactivity implementation

src/ue/mm/base.cpp

@@ -53,6 +53,9 @@ void NasMm::performMmCycle()
 
     if (m_mmSubState == EMmSubState::MM_DEREGISTERED_NA)
     {
+        if (switchToECallInactivityIfNeeded())
+            return;
+
         if (m_storage.isSimValid())
         {
             if (m_cmState == ECmState::CM_IDLE)
@@ -87,16 +90,11 @@ void NasMm::performMmCycle()
         return;
     }
 
-    if (m_mmState == EMmState::MM_REGISTERED_INITIATED)
-        return;
-    if (m_mmSubState == EMmSubState::MM_REGISTERED_NORMAL_SERVICE)
-        return;
-    if (m_mmState == EMmState::MM_DEREGISTERED_INITIATED)
-        return;
-    if (m_mmSubState == EMmSubState::MM_DEREGISTERED_NA)
-        return;
-    if (m_mmSubState == EMmSubState::MM_DEREGISTERED_NO_SUPI)
-        return;
+    if (m_mmState == EMmState::MM_REGISTERED)
+    {
+        if (startECallInactivityIfNeeded())
+            return;
+    }
 }
 
 void NasMm::switchMmState(EMmState state, EMmSubState subState)

src/ue/mm/ecall.cpp

+//
+// This file is a part of UERANSIM open source project.
+// Copyright (c) 2021 ALİ GÜNGÖR.
+//
+// The software and all associated files are licensed under GPL-3.0
+// and subject to the terms and conditions defined in LICENSE file.
+//
+
+#include "mm.hpp"
+
+#include <nas/utils.hpp>
+#include <stdexcept>
+#include <ue/app/task.hpp>
+#include <ue/nas/task.hpp>
+#include <ue/rrc/task.hpp>
+
+namespace nr::ue
+{
+
+bool NasMm::startECallInactivityIfNeeded()
+{
+    // 5.5.3 eCall inactivity procedure
+
+    // "The eCall inactivity procedure is performed only in 3GPP access and applicable only to a UE configured for eCall
+    // only mode as specified in 3GPP TS 31.102 [22].
+    if (!m_storage.isECallOnly)
+        return false;
+
+    // The procedure shall be started when
+    // a) the UE is in any 5GMM-REGISTERED substate except substates 5GMM-REGISTERED.PLMN-SEARCH or
+    // 5GMM-REGISTERED.NO-CELL-AVAILABLE;"
+    if (m_mmState != EMmState::MM_REGISTERED)
+        return false;
+    if (m_mmSubState == EMmSubState::MM_REGISTERED_PLMN_SEARCH ||
+        m_mmSubState == EMmSubState::MM_REGISTERED_NO_CELL_AVAILABLE)
+        return false;
+    // "b) the UE is in 5GMM-IDLE mode; and"
+    if (m_cmState != ECmState::CM_IDLE)
+        return false;
+    // c) one of the following conditions applies:
+    // 1) timer T3444 expires or is found to have already expired and timer T3445 is not running;
+    // 2) timer T3445 expires or is found to have already expired and timer T3444 is not running; or
+    // 3) timers T3444 and T3445 expire or are found to have already expired.
+    if (!(!m_timers->t3444.isRunning() && m_timers->t3445.isRunning()) ||
+        (!m_timers->t3445.isRunning() && m_timers->t3444.isRunning()) ||
+        (!m_timers->t3444.isRunning() && !m_timers->t3445.isRunning()))
+        return false;
+
+    // "The UE shall then perform the following actions:
+    // a) stop other running timers (e.g. T3511, T3512);
+    // b) if the UE is currently registered to the network for 5GS services, perform a de-registration procedure;
+    // c) delete any 5G-GUTI, TAI list, last visited registered TAI, list of equivalent PLMNs, and ngKSI; and
+    // d) enter 5GMM-DEREGISTERED.eCALL-INACTIVE state."
+
+    // TODO: Spec says 'other running timers' in item a), what are those timers other than 3511 and 3512?
+    m_timers->t3511.stop();
+    m_timers->t3512.stop();
+
+    // Spec says if the UE is currently registered to the network for 5GS services, but it also says procedure shall
+    // be started if ... and 5GMM-REGISTERED ....
+    if (m_rmState != ERmState::RM_REGISTERED)
+    {
+        // Therefore just assert that the UE is registered
+        throw std::runtime_error("UE MM eCall - MM and RM state inconsistent");
+    }
+    // And perform de-registration.
+    // NOTE: The items c) and d) is performed after de-registration by the other function, therefore we are just
+    // performing de-registration for now.
+    sendDeregistration(EDeregCause::ECALL_INACTIVITY);
+    return true;
+}
+
+bool NasMm::switchToECallInactivityIfNeeded()
+{
+    if (!m_storage.isECallOnly)
+        return false;
+
+    if (m_mmState != EMmState::MM_DEREGISTERED)
+        return false;
+
+    if (m_cmState != ECmState::CM_IDLE)
+        return false;
+    if (!(!m_timers->t3444.isRunning() && m_timers->t3445.isRunning()) ||
+        (!m_timers->t3445.isRunning() && m_timers->t3444.isRunning()) ||
+        (!m_timers->t3444.isRunning() && !m_timers->t3445.isRunning()))
+        return false;
+
+    // Perform item c) in 5.5.3
+    m_storage.m_storedGuti = {};
+    m_storage.m_taiList = {};
+    m_storage.m_lastVisitedRegisteredTai = {};
+    m_storage.m_equivalentPlmnList = {};
+    m_storage.m_currentNsCtx = {};
+    m_storage.m_nonCurrentNsCtx = {};
+
+    // Perform item d) in 5.5.3
+    switchMmState(EMmState::MM_DEREGISTERED, EMmSubState::MM_DEREGISTERED_ECALL_INACTIVE);
+    return true;
+}
+
+} // namespace nr::ue

src/ue/mm/mm.hpp

@@ -154,6 +154,10 @@ class NasMm
     bool isHighPriority();
     bool hasEmergency();
 
+  private: /* eCall */
+    bool startECallInactivityIfNeeded();
+    bool switchToECallInactivityIfNeeded();
+
   public: /* Timer */
     void onTimerExpire(nas::NasTimer &timer);
 };

src/ue/nas/storage.hpp

@@ -55,6 +55,9 @@ class MobileStorage
     std::optional<nas::IETimeZoneAndTime> universalTimeAndLocalTimeZone{};
     std::optional<nas::IEDaylightSavingTime> networkDaylightSavingTime{};
 
+    // eCall related
+    bool isECallOnly{};
+
   public:
     void initialize(bool hasSupi, const UeConfig::Initials &initials)
     {

src/utils/common_types.cpp

@@ -67,6 +67,8 @@ Json ToJson(const EDeregCause &v)
         return "USIM-REMOVAL";
     case EDeregCause::DISABLE_5G:
         return "DISABLE-5G";
+    case EDeregCause::ECALL_INACTIVITY:
+        return "ECALL-INACTIVITY";
     default:
         return "?";
     }

src/utils/common_types.hpp

@@ -116,6 +116,7 @@ enum class EDeregCause
     SWITCH_OFF,
     USIM_REMOVAL,
     DISABLE_5G,
+    ECALL_INACTIVITY,
 };
 
 Json ToJson(const Supi &v);