Review cell selection and SCell configuration during HO

srsue/hdr/phy/scell/scell_state.h

@@ -100,7 +100,6 @@ public:
     std::unique_lock<std::mutex> lock(mutex);
 
     switch (activation_state) {
-
       case idle:
         // waiting for receiving a command, do nothing
         break;
@@ -114,7 +113,6 @@ public:
       case transition:
         // Detect when the TTI has increased enough to make sure there arent workers, set the configuration
         if (TTI_SUB(tti, activation_tti) >= activation_margin_tti) {
-
           // Reload cell states
           for (uint32_t i = 1; i < SRSRAN_MAX_CARRIERS; i++) {
             // Get Activation command value
@@ -149,7 +147,6 @@ public:
 
   bool is_active(uint32_t cc_idx, uint32_t tti) const
   {
-
     if (cc_idx == 0) {
       return true;
     }
@@ -171,7 +168,6 @@ public:
 
   bool is_configured(uint32_t cc_idx) const
   {
-
     if (cc_idx == 0) {
       return true;
     }
@@ -185,6 +181,22 @@ public:
     return scell_cfg[cc_idx].status != cfg::none;
   }
 
+  void reset(uint32_t cc_idx)
+  {
+    if (cc_idx == 0 or cc_idx >= SRSRAN_MAX_CARRIERS) {
+      return;
+    }
+
+    std::unique_lock<std::mutex> lock(mutex);
+
+    activation_state = idle;
+
+    cfg& e   = scell_cfg[cc_idx];
+    e.status = cfg::none;
+    e.earfcn = 0;
+    e.pci    = UINT32_MAX;
+  }
+
   void reset()
   {
     std::unique_lock<std::mutex> lock(mutex);

srsue/src/phy/phy.cc

@@ -500,10 +500,10 @@ bool phy::set_scell(srsran_cell_t cell_info, uint32_t cc_idx, uint32_t earfcn)
   // Set inter-frequency measurement
   sfsync.set_inter_frequency_measurement(cc_idx, earfcn, cell_info);
 
-  // Store secondary serving cell EARFCN and PCI
-  common.cell_state.configure(cc_idx, earfcn, cell_info.id);
+  // Reset secondary serving cell state, prevents this component carrier from executing any PHY processing
+  common.cell_state.reset(cc_idx);
 
-  // Reset cell configuration
+  // Reset secondary serving cell configuration
   for (uint32_t i = 0; i < args.nof_phy_threads; i++) {
     lte_workers[i]->reset_cell_unlocked(cc_idx);
   }
@@ -534,6 +534,9 @@ bool phy::set_scell(srsran_cell_t cell_info, uint32_t cc_idx, uint32_t earfcn)
 
     logger_phy.info("Finished setting new SCell configuration cc_idx=%d, earfcn=%d", cc_idx, earfcn);
 
+    // Configure secondary serving cell, allows this component carrier to execute PHY processing
+    common.cell_state.configure(cc_idx, earfcn, cell_info.id);
+
     stack->set_scell_complete(true);
   });
   return true;

srsue/src/phy/sync.cc

@@ -301,7 +301,6 @@ bool sync::cell_select_init(phy_cell_t new_cell)
 
   Info("Cell Select: Going to IDLE");
   phy_state.go_idle();
-  worker_com->reset();
 
   // Stop intra-frequency measurements if need to change frequency
   if ((int)new_cell.earfcn != current_earfcn) {
@@ -325,11 +324,11 @@ bool sync::cell_select_start(phy_cell_t new_cell)
 
   rrc_proc_state = PROC_SELECT_RUNNING;
 
+  // Reset SFN and cell search FSMs. They can safely be done while it is CAMPING or IDLE
   sfn_p.reset();
   search_p.reset();
-  srsran_ue_sync_reset(&ue_sync);
 
-  /* Reconfigure cell if necessary */
+  // Reconfigure cell if necessary
   cell.id = new_cell.pci;
   if (not set_cell(new_cell.cfo_hz)) {
     Error("Cell Select: Reconfiguring cell");
@@ -796,6 +795,12 @@ bool sync::set_cell(float cfo)
     return false;
   }
 
+  // Reset UE sync. Attention: doing this reset when the FSM is NOT IDLE can cause PSS/SSS out-of-sync
+  srsran_ue_sync_reset(&ue_sync);
+
+  // Reset worker once SYNC is IDLE to flush any worker states such as ACKs and pending grants
+  worker_com->reset();
+
   if (!srsran_cell_isvalid(&cell)) {
     Error("SYNC:  Setting cell: invalid cell (nof_prb=%d, pci=%d, ports=%d)", cell.nof_prb, cell.id, cell.nof_ports);
     return false;