Release UE if no activity in DRB (#2658)

* Count user activity with DRB only and SRBs for initial procedures. Add counter to release user after max KO in UL.

lib/include/srsran/interfaces/enb_rrc_interfaces.h

@@ -102,7 +102,9 @@ public:
   /* Radio Link failure */
   virtual int  add_user(uint16_t rnti, const sched_interface::ue_cfg_t& init_ue_cfg) = 0;
   virtual void upd_user(uint16_t new_rnti, uint16_t old_rnti)                        = 0;
-  virtual void set_activity_user(uint16_t rnti, bool ack_info)                       = 0;
+  virtual void set_activity_user(uint16_t rnti)                                      = 0;
+  virtual void set_radiolink_dl_state(uint16_t rnti, bool crc_res)                   = 0;
+  virtual void set_radiolink_ul_state(uint16_t rnti, bool crc_res)                   = 0;
   virtual bool is_paging_opportunity(uint32_t tti, uint32_t* payload_len)            = 0;
 
   ///< Provide packed SIB to MAC (buffer is managed by RRC)

srsenb/hdr/enb.h

@@ -94,6 +94,7 @@ struct general_args_t {
   std::string eia_pref_list;
   std::string eea_pref_list;
   uint32_t    max_mac_dl_kos;
+  uint32_t    max_mac_ul_kos;
 };
 
 struct all_args_t {

srsenb/hdr/stack/rrc/rrc.h

@@ -68,7 +68,9 @@ public:
   // rrc_interface_mac
   int      add_user(uint16_t rnti, const sched_interface::ue_cfg_t& init_ue_cfg) override;
   void     upd_user(uint16_t new_rnti, uint16_t old_rnti) override;
-  void     set_activity_user(uint16_t rnti, bool ack_info) override;
+  void     set_activity_user(uint16_t rnti) override;
+  void     set_radiolink_dl_state(uint16_t rnti, bool crc_res) override;
+  void     set_radiolink_ul_state(uint16_t rnti, bool crc_res) override;
   bool     is_paging_opportunity(uint32_t tti, uint32_t* payload_len) override;
   uint8_t* read_pdu_bcch_dlsch(const uint8_t cc_idx, const uint32_t sib_index) override;
 
@@ -184,6 +186,7 @@ private:
   typedef struct {
     uint16_t                     rnti;
     uint32_t                     lcid;
+    uint32_t                     arg;
     srsran::unique_byte_buffer_t pdu;
   } rrc_pdu;
 
@@ -192,7 +195,8 @@ private:
   const static uint32_t LCID_REL_USER    = 0xffff0002;
   const static uint32_t LCID_ACT_USER    = 0xffff0004;
   const static uint32_t LCID_RTX_USER    = 0xffff0005;
-  const static uint32_t LCID_MAC_KO_USER = 0xffff0006;
+  const static uint32_t LCID_RADLINK_DL  = 0xffff0006;
+  const static uint32_t LCID_RADLINK_UL  = 0xffff0007;
 
   bool                                running = false;
   srsran::dyn_blocking_queue<rrc_pdu> rx_pdu_queue;

srsenb/hdr/stack/rrc/rrc_config.h

@@ -60,6 +60,7 @@ struct rrc_cfg_t {
   cell_list_t                                                                             cell_list;
   cell_list_t                                                                             cell_list_nr;
   uint32_t                                                                                max_mac_dl_kos;
+  uint32_t                                                                                max_mac_ul_kos;
 };
 
 constexpr uint32_t UE_PCELL_CC_IDX = 0;

srsenb/hdr/stack/rrc/rrc_ue.h

@@ -42,7 +42,8 @@ public:
   void        set_activity_timeout(const activity_timeout_type_t type);
   void        set_rlf_timeout();
   void        set_activity();
-  void        mac_ko_activity();
+  void        set_radiolink_dl_state(bool crc_res);
+  void        set_radiolink_ul_state(bool crc_res);
   void        activity_timer_expired(const activity_timeout_type_t type);
   void        rlf_timer_expired();
   void        max_retx_reached();
@@ -185,7 +186,9 @@ private:
 
   const static uint32_t UE_PCELL_CC_IDX = 0;
 
-  uint32_t consecutive_kos = 0;
+  // consecutive KO counter for DL and UL
+  uint32_t consecutive_kos_dl = 0;
+  uint32_t consecutive_kos_ul = 0;
 
   ue_cell_ded_list     ue_cell_list;
   bearer_cfg_handler   bearer_list;

srsenb/src/enb_cfg_parser.cc

@@ -1147,6 +1147,7 @@ int set_derived_args(all_args_t* args_, rrc_cfg_t* rrc_cfg_, phy_cfg_t* phy_cfg_
 
   // Set max number of KOs
   rrc_cfg_->max_mac_dl_kos = args_->general.max_mac_dl_kos;
+  rrc_cfg_->max_mac_ul_kos = args_->general.max_mac_ul_kos;
 
   // Set sync queue capacity to 1 for ZMQ
   if (args_->rf.device_name == "zmq") {

srsenb/src/main.cc

@@ -214,7 +214,9 @@ void parse_args(all_args_t* args, int argc, char* argv[])
     ("expert.eea_pref_list", bpo::value<string>(&args->general.eea_pref_list)->default_value("EEA0, EEA2, EEA1"), "Ordered preference list for the selection of encryption algorithm (EEA) (default: EEA0, EEA2, EEA1).")
     ("expert.eia_pref_list", bpo::value<string>(&args->general.eia_pref_list)->default_value("EIA2, EIA1, EIA0"), "Ordered preference list for the selection of integrity algorithm (EIA) (default: EIA2, EIA1, EIA0).")
     ("expert.max_nof_ues", bpo::value<uint32_t>(&args->stack.mac.max_nof_ues)->default_value(8), "Maximum number of connected UEs")
-    ("expert.max_mac_dl_kos", bpo::value<uint32_t>(&args->general.max_mac_dl_kos)->default_value(100), "Maximum number of consecutive KOs before triggering the UE's release")
+    ("expert.max_mac_dl_kos", bpo::value<uint32_t>(&args->general.max_mac_dl_kos)->default_value(100), "Maximum number of consecutive KOs in DL before triggering the UE's release")
+    ("expert.max_mac_ul_kos", bpo::value<uint32_t>(&args->general.max_mac_ul_kos)->default_value(100), "Maximum number of consecutive KOs in UL before triggering the UE's release")
+
 
     // eMBMS section
     ("embms.enable", bpo::value<bool>(&args->stack.embms.enable)->default_value(false), "Enables MBMS in the eNB")

srsenb/src/stack/mac/mac.cc

@@ -301,14 +301,8 @@ int mac::ack_info(uint32_t tti_rx, uint16_t rnti, uint32_t enb_cc_idx, uint32_t
   int nof_bytes = scheduler.dl_ack_info(tti_rx, rnti, enb_cc_idx, tb_idx, ack);
   ue_db[rnti]->metrics_tx(ack, nof_bytes);
 
-  if (ack) {
-    if (nof_bytes > 64) { // do not count RLC status messages only
-      rrc_h->set_activity_user(rnti, true);
-      logger.info("DL activity rnti=0x%x, n_bytes=%d", rnti, nof_bytes);
-    }
-  } else {
-    rrc_h->set_activity_user(rnti, false);
-  }
+  rrc_h->set_radiolink_dl_state(rnti, ack);
+
   return SRSRAN_SUCCESS;
 }
 
@@ -324,6 +318,8 @@ int mac::crc_info(uint32_t tti_rx, uint16_t rnti, uint32_t enb_cc_idx, uint32_t
   ue_db[rnti]->set_tti(tti_rx);
   ue_db[rnti]->metrics_rx(crc, nof_bytes);
 
+  rrc_h->set_radiolink_ul_state(rnti, crc);
+
   // Scheduler uses eNB's CC mapping
   return scheduler.ul_crc_info(tti_rx, rnti, enb_cc_idx, crc);
 }

srsenb/src/stack/mac/ue.cc

@@ -383,9 +383,9 @@ void ue::process_pdu(uint8_t* pdu, uint32_t nof_bytes, srsran::pdu_queue::channe
       // Indicate scheduler to update BSR counters
       // sched->ul_recv_len(rnti, mac_msg_ul.get()->get_sdu_lcid(), mac_msg_ul.get()->get_payload_size());
 
-      // Indicate RRC about successful activity if valid RLC message is received
-      if (mac_msg_ul.get()->get_payload_size() > 64) { // do not count RLC status messages only
-        rrc->set_activity_user(rnti, true);
+      // Indicate DRB activity in UL to RRC
+      if (mac_msg_ul.get()->get_sdu_lcid() > 2) {
+        rrc->set_activity_user(rnti);
         logger.debug("UL activity rnti=0x%x, n_bytes=%d", rnti, nof_bytes);
       }
 
@@ -517,6 +517,13 @@ void ue::allocate_sdu(srsran::sch_pdu* pdu, uint32_t lcid, uint32_t total_sdu_le
         if (n > 0) { // new SDU could be added
           sdu_len -= n;
           logger.debug("SDU:   rnti=0x%x, lcid=%d, nbytes=%d, rem_len=%d", rnti, lcid, n, sdu_len);
+
+          // Indicate DRB activity in DL to RRC
+          if (lcid > 2) {
+            rrc->set_activity_user(rnti);
+            logger.debug("DL activity rnti=0x%x, n_bytes=%d", rnti, sdu_len);
+          }
+
         } else {
           logger.debug("Could not add SDU lcid=%d nbytes=%d, space=%d", lcid, sdu_len, sdu_space);
           pdu->del_subh();

srsenb/src/stack/rrc/rrc.cc

@@ -90,7 +90,7 @@ void rrc::stop()
 {
   if (running) {
     running   = false;
-    rrc_pdu p = {0, LCID_EXIT, nullptr};
+    rrc_pdu p = {0, LCID_EXIT, false, nullptr};
     rx_pdu_queue.push_blocking(std::move(p));
   }
   users.clear();
@@ -126,14 +126,29 @@ uint8_t* rrc::read_pdu_bcch_dlsch(const uint8_t cc_idx, const uint32_t sib_index
   return nullptr;
 }
 
-void rrc::set_activity_user(uint16_t rnti, bool ack_info)
+void rrc::set_radiolink_dl_state(uint16_t rnti, bool crc_res)
 {
-  rrc_pdu p;
-  if (ack_info) {
-    p = {rnti, LCID_ACT_USER, nullptr};
-  } else {
-    p = {rnti, LCID_MAC_KO_USER, nullptr};
+  // embed parameters in arg value
+  rrc_pdu p = {rnti, LCID_RADLINK_DL, crc_res, nullptr};
+
+  if (not rx_pdu_queue.try_push(std::move(p))) {
+    logger.error("Failed to push UE activity command to RRC queue");
+  }
+}
+
+void rrc::set_radiolink_ul_state(uint16_t rnti, bool crc_res)
+{
+  // embed parameters in arg value
+  rrc_pdu p = {rnti, LCID_RADLINK_UL, crc_res, nullptr};
+
+  if (not rx_pdu_queue.try_push(std::move(p))) {
+    logger.error("Failed to push UE activity command to RRC queue");
   }
+}
+
+void rrc::set_activity_user(uint16_t rnti)
+{
+  rrc_pdu p = {rnti, LCID_ACT_USER, false, nullptr};
 
   if (not rx_pdu_queue.try_push(std::move(p))) {
     logger.error("Failed to push UE activity command to RRC queue");
@@ -142,7 +157,7 @@ void rrc::set_activity_user(uint16_t rnti, bool ack_info)
 
 void rrc::rem_user_thread(uint16_t rnti)
 {
-  rrc_pdu p = {rnti, LCID_REM_USER, nullptr};
+  rrc_pdu p = {rnti, LCID_REM_USER, false, nullptr};
   if (not rx_pdu_queue.try_push(std::move(p))) {
     logger.error("Failed to push UE remove command to RRC queue");
   }
@@ -155,7 +170,7 @@ uint32_t rrc::get_nof_users()
 
 void rrc::max_retx_attempted(uint16_t rnti)
 {
-  rrc_pdu p = {rnti, LCID_RTX_USER, nullptr};
+  rrc_pdu p = {rnti, LCID_RTX_USER, false, nullptr};
   if (not rx_pdu_queue.try_push(std::move(p))) {
     logger.error("Failed to push max Retx event to RRC queue");
   }
@@ -253,7 +268,7 @@ void rrc::send_rrc_connection_reject(uint16_t rnti)
 *******************************************************************************/
 void rrc::write_pdu(uint16_t rnti, uint32_t lcid, srsran::unique_byte_buffer_t pdu)
 {
-  rrc_pdu p = {rnti, lcid, std::move(pdu)};
+  rrc_pdu p = {rnti, lcid, false, std::move(pdu)};
   if (not rx_pdu_queue.try_push(std::move(p))) {
     logger.error("Failed to push Release command to RRC queue");
   }
@@ -290,7 +305,7 @@ void rrc::write_dl_info(uint16_t rnti, srsran::unique_byte_buffer_t sdu)
 
 void rrc::release_ue(uint16_t rnti)
 {
-  rrc_pdu p = {rnti, LCID_REL_USER, nullptr};
+  rrc_pdu p = {rnti, LCID_REL_USER, false, nullptr};
   if (not rx_pdu_queue.try_push(std::move(p))) {
     logger.error("Failed to push Release command to RRC queue");
   }
@@ -1007,8 +1022,11 @@ void rrc::tti_clock()
       case LCID_ACT_USER:
         user_it->second->set_activity();
         break;
-      case LCID_MAC_KO_USER:
-        user_it->second->mac_ko_activity();
+      case LCID_RADLINK_DL:
+        user_it->second->set_radiolink_dl_state(p.arg);
+        break;
+      case LCID_RADLINK_UL:
+        user_it->second->set_radiolink_ul_state(p.arg);
         break;
       case LCID_RTX_USER:
         user_it->second->max_retx_reached();

srsenb/src/stack/rrc/rrc_ue.cc

@@ -88,15 +88,24 @@ void rrc::ue::set_activity()
 {
   // re-start activity timer with current timeout value
   activity_timer.run();
-  rlf_timer.stop();
-  consecutive_kos = 0;
   if (parent) {
     parent->logger.debug("Activity registered for rnti=0x%x (timeout_value=%dms)", rnti, activity_timer.duration());
   }
 }
 
-void rrc::ue::mac_ko_activity()
+void rrc::ue::set_radiolink_dl_state(bool crc_res)
 {
+  parent->logger.debug(
+      "Radio-Link downlink state for rnti=0x%x: crc_res=%d, consecutive_ko=%d", rnti, crc_res, consecutive_kos_dl);
+
+  // If received OK, restart counter and stop RLF timer
+  if (crc_res) {
+    consecutive_kos_dl = 0;
+    consecutive_kos_ul = 0;
+    rlf_timer.stop();
+    return;
+  }
+
   // Count KOs in MAC and trigger release if it goes above a certain value.
   // This is done to detect out-of-coverage UEs
   if (rlf_timer.is_running()) {
@@ -104,9 +113,36 @@ void rrc::ue::mac_ko_activity()
     return;
   }
 
-  consecutive_kos++;
-  if (consecutive_kos > parent->cfg.max_mac_dl_kos) {
-    parent->logger.info("Max KOs reached, triggering release rnti=0x%x", rnti);
+  consecutive_kos_dl++;
+  if (consecutive_kos_dl > parent->cfg.max_mac_dl_kos) {
+    parent->logger.info("Max KOs in DL reached, triggering release rnti=0x%x", rnti);
+    max_retx_reached();
+  }
+}
+
+void rrc::ue::set_radiolink_ul_state(bool crc_res)
+{
+  parent->logger.debug(
+      "Radio-Link uplink state for rnti=0x%x: crc_res=%d, consecutive_ko=%d", rnti, crc_res, consecutive_kos_ul);
+
+  // If received OK, restart counter and stop RLF timer
+  if (crc_res) {
+    consecutive_kos_dl = 0;
+    consecutive_kos_ul = 0;
+    rlf_timer.stop();
+    return;
+  }
+
+  // Count KOs in MAC and trigger release if it goes above a certain value.
+  // This is done to detect out-of-coverage UEs
+  if (rlf_timer.is_running()) {
+    // RLF timer already running, no need to count KOs
+    return;
+  }
+
+  consecutive_kos_ul++;
+  if (consecutive_kos_ul > parent->cfg.max_mac_ul_kos) {
+    parent->logger.info("Max KOs in UL reached, triggering release rnti=0x%x", rnti);
     max_retx_reached();
   }
 }
@@ -227,8 +263,6 @@ bool rrc::ue::is_idle()
 
 void rrc::ue::parse_ul_dcch(uint32_t lcid, srsran::unique_byte_buffer_t pdu)
 {
-  set_activity();
-
   ul_dcch_msg_s  ul_dcch_msg;
   asn1::cbit_ref bref(pdu->msg, pdu->N_bytes);
   if (ul_dcch_msg.unpack(bref) != asn1::SRSASN_SUCCESS or
@@ -252,10 +286,12 @@ void rrc::ue::parse_ul_dcch(uint32_t lcid, srsran::unique_byte_buffer_t pdu)
     case ul_dcch_msg_type_c::c1_c_::types::rrc_conn_setup_complete:
       save_ul_message(std::move(original_pdu));
       handle_rrc_con_setup_complete(&ul_dcch_msg.msg.c1().rrc_conn_setup_complete(), std::move(pdu));
+      set_activity();
       break;
     case ul_dcch_msg_type_c::c1_c_::types::rrc_conn_reest_complete:
       save_ul_message(std::move(original_pdu));
       handle_rrc_con_reest_complete(&ul_dcch_msg.msg.c1().rrc_conn_reest_complete(), std::move(pdu));
+      set_activity();
       break;
     case ul_dcch_msg_type_c::c1_c_::types::ul_info_transfer:
       pdu->N_bytes = ul_dcch_msg.msg.c1()

srsenb/test/mac/sched_test_common.h

@@ -34,7 +34,9 @@ struct rrc_dummy : public rrc_interface_mac {
 public:
   int      add_user(uint16_t rnti, const sched_interface::ue_cfg_t& init_ue_cfg) { return SRSRAN_SUCCESS; }
   void     upd_user(uint16_t new_rnti, uint16_t old_rnti) {}
-  void     set_activity_user(uint16_t rnti, bool ack_info) {}
+  void     set_activity_user(uint16_t rnti) {}
+  void     set_radiolink_ul_state(uint16_t rnti, bool crc_res) {}
+  void     set_radiolink_dl_state(uint16_t rnti, bool crc_res) {}
   bool     is_paging_opportunity(uint32_t tti, uint32_t* payload_len) { return false; }
   uint8_t* read_pdu_bcch_dlsch(const uint8_t enb_cc_idx, const uint32_t sib_index) { return nullptr; }
 };