cu-cp: remove unused paging code from du_processor_impl

Author: frankist

lib/cu_cp/adapters/du_processor_adapters.h

@@ -110,27 +110,6 @@ class du_processor_f1ap_ue_context_adapter : public du_processor_f1ap_ue_context
   f1ap_ue_context_manager* handler = nullptr;
 };
 
-// Adapter between DU processor and F1AP for Paging
-class du_processor_f1ap_paging_adapter : public du_processor_f1ap_paging_notifier
-{
-public:
-  du_processor_f1ap_paging_adapter() = default;
-
-  void connect_f1(f1ap_paging_manager& handler_) { handler = &handler_; }
-
-  void on_paging_message(const cu_cp_paging_message& msg) override
-  {
-    if (handler == nullptr) {
-      srslog::fetch_basic_logger("CU-CP").info("DU not connected - dropping paging message");
-      return;
-    }
-    handler->handle_paging(msg);
-  }
-
-private:
-  f1ap_paging_manager* handler = nullptr;
-};
-
 // Adapter between DU processor and RRC DU
 class du_processor_rrc_du_adapter : public du_processor_rrc_du_ue_notifier
 {

lib/cu_cp/du_processor/du_processor.h

@@ -222,27 +222,6 @@ class du_processor_cu_cp_notifier
   virtual async_task<void> on_transaction_info_loss(const f1_ue_transaction_info_loss_event& ev) = 0;
 };
 
-/// DU processor Paging handler.
-class du_processor_paging_handler
-{
-public:
-  virtual ~du_processor_paging_handler() = default;
-
-  /// \brief Handles a Paging message.
-  virtual void handle_paging_message(cu_cp_paging_message& msg) = 0;
-};
-
-/// Interface for the NGAP to interface with the DU repository
-/// Useful for paging and handover
-class du_repository_ngap_handler
-{
-public:
-  virtual ~du_repository_ngap_handler() = default;
-
-  /// \brief Handles a Paging message notification.
-  virtual void handle_paging_message(cu_cp_paging_message& msg) = 0;
-};
-
 class du_processor : public du_processor_cell_info_interface
 {
 public:
@@ -251,7 +230,6 @@ class du_processor : public du_processor_cell_info_interface
   /// \brief Retrieve F1AP handler for the respective DU.
   virtual f1ap_cu& get_f1ap_handler() = 0;
 
-  virtual du_processor_paging_handler&   get_paging_handler()   = 0;
   virtual du_processor_mobility_handler& get_mobility_handler() = 0;
 
   /// \brief Get the F1AP message handler interface of the DU processor object.

lib/cu_cp/du_processor/du_processor_impl.cpp

@@ -135,19 +135,6 @@ du_setup_result du_processor_impl::handle_du_setup_request(const du_setup_reques
     return res;
   }
 
-  const du_configuration_context& du_config = cfg.du_cfg_hdlr->get_context();
-  for (const du_cell_configuration& cell : du_config.served_cells) {
-    // Add cell to lookup
-    if (tac_to_nr_cgi.find(cell.tac) == tac_to_nr_cgi.end()) {
-      tac_to_nr_cgi.emplace(cell.tac, std::vector<nr_cell_global_id_t>{cell.cgi});
-    } else {
-      tac_to_nr_cgi.at(cell.tac).push_back(cell.cgi);
-    }
-  }
-
-  // connect paging f1ap paging adapter
-  f1ap_paging_notifier.connect_f1(f1ap->get_f1ap_paging_manager());
-
   // Prepare DU response with accepted setup.
   auto& accepted              = res.result.emplace<du_setup_result::accepted>();
   accepted.gnb_cu_name        = cfg.cu_cp_cfg.node.ran_node_name;
@@ -287,88 +274,6 @@ void du_processor_impl::handle_du_initiated_ue_context_release_request(const f1a
       }));
 }
 
-void du_processor_impl::handle_paging_message(cu_cp_paging_message& msg)
-{
-  // Add assist data for paging
-  // This will go through all tai items in the paging message and add the related NR CGI to the assist data for paging
-  // if it doesn't exist yet.
-  // This way the F1AP will always receive messages with the assist data for paging set.
-
-  bool nr_cgi_for_tac_found = false;
-
-  for (const auto& tai_list_item : msg.tai_list_for_paging) {
-    if (tac_to_nr_cgi.find(tai_list_item.tai.tac) == tac_to_nr_cgi.end()) {
-      logger.debug("Could not find nr cgi for tac={}", tai_list_item.tai.tac);
-      continue;
-    }
-
-    nr_cgi_for_tac_found = true;
-
-    for (const auto& cgi : tac_to_nr_cgi.at(tai_list_item.tai.tac)) {
-      // Setup recommended cell item to add in case it doesn't exist
-      cu_cp_recommended_cell_item cell_item;
-      cell_item.ngran_cgi = cgi;
-
-      // Check if assist data for paging is already present
-      if (msg.assist_data_for_paging.has_value()) {
-        // Check if assist data for recommended cells is already present
-        if (msg.assist_data_for_paging.value().assist_data_for_recommended_cells.has_value()) {
-          // Check if recommended cell list already contains values
-          if (!msg.assist_data_for_paging.value()
-                   .assist_data_for_recommended_cells.value()
-                   .recommended_cells_for_paging.recommended_cell_list.empty()) {
-            // Check if NR CGI already present
-            bool is_present = false;
-            for (const auto& present_cell_item : msg.assist_data_for_paging.value()
-                                                     .assist_data_for_recommended_cells.value()
-                                                     .recommended_cells_for_paging.recommended_cell_list) {
-              if (present_cell_item.ngran_cgi.nci == cgi.nci) {
-                is_present = true;
-                continue;
-              }
-            }
-            if (is_present) {
-              // NR CGI for TAC is already present
-              continue;
-            }
-          }
-
-          // NR CGI for TAC is not present so we add it
-          msg.assist_data_for_paging.value()
-              .assist_data_for_recommended_cells.value()
-              .recommended_cells_for_paging.recommended_cell_list.push_back(cell_item);
-        } else {
-          // Assist data for recommended cells is not present, we need to add it
-          cu_cp_assist_data_for_recommended_cells assist_data_for_recommended_cells;
-          assist_data_for_recommended_cells.recommended_cells_for_paging.recommended_cell_list.push_back(cell_item);
-
-          msg.assist_data_for_paging.value().assist_data_for_recommended_cells = assist_data_for_recommended_cells;
-        }
-      } else {
-        // Assist data for paging is not present, we need to add it
-        cu_cp_assist_data_for_paging assist_data_for_paging;
-
-        // Add assist data for recommended cells
-        cu_cp_assist_data_for_recommended_cells assist_data_for_recommended_cells;
-        // Add cell item
-        assist_data_for_recommended_cells.recommended_cells_for_paging.recommended_cell_list.push_back(cell_item);
-
-        assist_data_for_paging.assist_data_for_recommended_cells = assist_data_for_recommended_cells;
-
-        msg.assist_data_for_paging = assist_data_for_paging;
-      }
-    }
-  }
-
-  // If not nr cgi for a tac from the paging message is found paging message is not forwarded to DU
-  if (!nr_cgi_for_tac_found) {
-    logger.info("du_index={}: No NR CGI for paging TACs available at this DU", cfg.du_index);
-    return;
-  }
-
-  f1ap_paging_notifier.on_paging_message(msg);
-}
-
 bool du_processor_impl::has_cell(pci_t pci)
 {
   return cfg.du_cfg_hdlr->get_context().find_cell(pci) != nullptr;

lib/cu_cp/du_processor/du_processor_impl.h

@@ -27,10 +27,7 @@
 namespace srsran {
 namespace srs_cu_cp {
 
-class du_processor_impl : public du_processor,
-                          public du_metrics_handler,
-                          public du_processor_paging_handler,
-                          public du_processor_mobility_handler
+class du_processor_impl : public du_processor, public du_metrics_handler, public du_processor_mobility_handler
 {
 public:
   du_processor_impl(du_processor_config_t               du_processor_config_,
@@ -53,17 +50,13 @@ class du_processor_impl : public du_processor,
   std::optional<nr_cell_global_id_t> get_cgi(pci_t pci) override;
   byte_buffer                        get_packed_sib1(nr_cell_global_id_t cgi) override;
 
-  // du_processor paging handler
-  void handle_paging_message(cu_cp_paging_message& msg) override;
-
   // du_processor_cell_info_interface
   bool                            has_cell(pci_t pci) override;
   bool                            has_cell(nr_cell_global_id_t cgi) override;
   const du_configuration_context& get_context() const override { return cfg.du_cfg_hdlr->get_context(); }
 
   metrics_report::du_info handle_du_metrics_report_request() const override;
 
-  du_processor_paging_handler&           get_paging_handler() override { return *this; }
   du_processor_mobility_handler&         get_mobility_handler() override { return *this; }
   du_processor_f1ap_ue_context_notifier& get_f1ap_ue_context_notifier() override { return f1ap_ue_context_notifier; }
   du_metrics_handler&                    get_metrics_handler() override { return *this; }
@@ -100,13 +93,10 @@ class du_processor_impl : public du_processor,
   rrc_ue_nas_notifier&                 rrc_ue_nas_pdu_notifier;
   ue_manager&                          ue_mng;
   du_processor_f1ap_ue_context_adapter f1ap_ue_context_notifier;
-  du_processor_f1ap_paging_adapter     f1ap_paging_notifier;
 
   // F1AP to DU processor adapter
   std::unique_ptr<f1ap_du_processor_notifier> f1ap_ev_notifier;
 
-  std::map<uint32_t, std::vector<nr_cell_global_id_t>> tac_to_nr_cgi;
-
   // F1AP to RRC UE adapters
   std::unordered_map<ue_index_t, f1ap_rrc_ue_adapter> f1ap_rrc_ue_adapters;
 

lib/cu_cp/du_processor/du_processor_repository.cpp

@@ -133,14 +133,6 @@ du_processor& du_processor_repository::get_du_processor(du_index_t du_index)
   return *du_db.at(du_index).processor;
 }
 
-void du_processor_repository::handle_paging_message(cu_cp_paging_message& msg)
-{
-  // Forward paging message to all DU processors
-  for (auto& du : du_db) {
-    du.second.processor->get_paging_handler().handle_paging_message(msg);
-  }
-}
-
 std::vector<metrics_report::du_info> du_processor_repository::handle_du_metrics_report_request() const
 {
   std::vector<metrics_report::du_info> du_reports;

lib/cu_cp/du_processor/du_processor_repository.h

@@ -42,7 +42,7 @@ struct du_repository_config {
   srslog::basic_logger&                  logger;
 };
 
-class du_processor_repository : public du_repository_ngap_handler, public du_repository_metrics_handler
+class du_processor_repository : public du_repository_metrics_handler
 {
 public:
   explicit du_processor_repository(du_repository_config cfg_);
@@ -59,8 +59,6 @@ class du_processor_repository : public du_repository_ngap_handler, public du_rep
 
   du_processor& get_du_processor(du_index_t du_index);
 
-  void handle_paging_message(cu_cp_paging_message& msg) override;
-
   std::vector<metrics_report::du_info> handle_du_metrics_report_request() const override;
 
   size_t get_nof_f1ap_ues();

lib/cu_cp/paging/paging_message_handler.h

@@ -11,6 +11,7 @@
 #pragma once
 
 #include "srsran/cu_cp/cu_cp_types.h"
+#include "srsran/srslog/logger.h"
 
 namespace srsran {
 namespace srs_cu_cp {
@@ -24,6 +25,7 @@ class paging_message_handler
 public:
   paging_message_handler(du_processor_repository& dus_);
 
+  /// Handle Paging message sent by the core network and distribute across the served DU cells.
   void handle_paging_message(const cu_cp_paging_message& msg);
 
 private:
@@ -34,4 +36,4 @@ class paging_message_handler
 };
 
 } // namespace srs_cu_cp
-} // namespace srsran
+} // namespace srsran