Start PCCH Only when switching cell in IDLE mode

srsue/hdr/upper/rrc.h

@@ -564,7 +564,13 @@ private:
   float         get_srxlev(float Qrxlevmeas);
   float         get_squal(float Qqualmeas);
 
-  bool          cell_selection();
+  typedef enum {
+    CHANGED_CELL = 0,
+    SAME_CELL    = 1,
+    NO_CELL      = 2
+  } cs_ret_t;
+
+  cs_ret_t      cell_selection();
   bool          cell_selection_criteria(float rsrp, float rsrq = 0);
   void          cell_reselection(float rsrp, float rsrq);
 

srsue/src/upper/gw.cc

@@ -280,8 +280,7 @@ void gw::run_thread()
             if (!attach_wait) {
               gw_log->info("LCID=%d not active, requesting NAS attach (%d/%d)\n", cfg.lcid, attach_wait, ATTACH_WAIT_TOUT);
               if (!nas->attach_request()) {
-                gw_log->info("Could not re-establish the connection\n");
-                break;
+                gw_log->warning("Could not re-establish the connection\n");
               }
             }
             usleep(100000);

srsue/src/upper/nas.cc

@@ -138,7 +138,7 @@ bool nas::attach_request() {
           nas_log->info("NAS attached successfully.\n");
           return true;
         } else {
-          nas_log->error("Could not attach\n");
+          nas_log->error("Could not attach in attach request\n");
         }
       } else {
         nas_log->error("PLMN is not selected because no suitable PLMN was found\n");
@@ -154,7 +154,7 @@ bool nas::attach_request() {
           nas_log->info("NAS attached successfully.\n");
           return true;
         } else {
-          nas_log->error("Could not attach\n");
+          nas_log->error("Could not attach from attach_request\n");
         }
       }
       break;
@@ -181,7 +181,7 @@ void nas::paging(LIBLTE_RRC_S_TMSI_STRUCT *ue_identiy) {
     if (rrc_connect()) {
       nas_log->info("Attached successfully\n");
     } else {
-      nas_log->error("Could not attach\n");
+      nas_log->error("Could not attach from paging\n");
     }
   } else {
     nas_log->warning("Received paging while in state %s\n", emm_state_text[state]);

srsue/src/upper/rrc.cc

@@ -220,11 +220,16 @@ void rrc::run_tti(uint32_t tti) {
         // If attached but not camping on the cell, perform cell reselection
         if (nas->is_attached()) {
           rrc_log->debug("Running cell selection and reselection in IDLE\n");
-          if (cell_selection()) {
+          switch(cell_selection()) {
+            case rrc::CHANGED_CELL:
               // New cell has been selected, start receiving PCCH
               mac->pcch_start_rx();
-          } else {
+              break;
+            case rrc::NO_CELL:
               rrc_log->warning("Could not find any cell to camp on\n");
+              break;
+            case rrc::SAME_CELL:
+              break;
           }
         }
         break;
@@ -768,7 +773,7 @@ phy_interface_rrc::cell_search_ret_t rrc::cell_search()
 /* Cell selection procedure 36.304 5.2.3
  * Select the best cell to camp on among the list of known cells
  */
-bool rrc::cell_selection()
+rrc::cs_ret_t rrc::cell_selection()
 {
   // Neighbour cells are sorted in descending order of RSRP
   for (uint32_t i = 0; i < neighbour_cells.size(); i++) {
@@ -791,7 +796,7 @@ bool rrc::cell_selection()
         if (phy->cell_select(&serving_cell->phy_cell)) {
           if (configure_serving_cell()) {
             rrc_log->info("Selected and configured cell successfully\n");
-            return true;
+            return CHANGED_CELL;
           } else {
             rrc_log->error("While configuring serving cell\n");
           }
@@ -803,14 +808,14 @@ bool rrc::cell_selection()
     }
   }
   if (serving_cell->in_sync) {
-    return true;
+    return SAME_CELL;
   }
   // If can not find any suitable cell, search again
   rrc_log->info("Cell selection and reselection in IDLE did not find any suitable cell. Searching again\n");
   // If can not camp on any cell, search again for new cells
   phy_interface_rrc::cell_search_ret_t ret = cell_search();
 
-  return ret.found == phy_interface_rrc::cell_search_ret_t::CELL_FOUND;
+  return (ret.found == phy_interface_rrc::cell_search_ret_t::CELL_FOUND)?CHANGED_CELL:NO_CELL;
 }
 
 // Cell selection criteria Section 5.2.3.2 of 36.304