UE to recover from an sporadic loss of synchronization due to USRP overflow

srsue/hdr/phy/phch_common.h

@@ -47,7 +47,8 @@ namespace srsue {
     
     /* Common variables used by all phy workers */
     phy_interface_rrc::phy_cfg_t *config; 
-    phy_args_t                   *args; 
+    phy_args_t                   *args;
+    rrc_interface_phy *rrc;
     mac_interface_phy *mac;
     srslte_ue_ul_t     ue_ul; 
     
@@ -68,7 +69,8 @@ namespace srsue {
     void init(phy_interface_rrc::phy_cfg_t *config, 
               phy_args_t  *args, 
               srslte::log *_log, 
-              srslte::radio *_radio, 
+              srslte::radio *_radio,
+              rrc_interface_phy *rrc,
               mac_interface_phy *_mac);
     
     /* For RNTI searches, -1 means now or forever */    

srsue/src/phy/phch_common.cc

@@ -74,10 +74,11 @@ phch_common::phch_common(uint32_t max_mutex_) : tx_mutex(max_mutex_)
   sync_metrics_count = 0;
 }
   
-void phch_common::init(phy_interface_rrc::phy_cfg_t *_config, phy_args_t *_args, srslte::log *_log, srslte::radio *_radio, mac_interface_phy *_mac)
+void phch_common::init(phy_interface_rrc::phy_cfg_t *_config, phy_args_t *_args, srslte::log *_log, srslte::radio *_radio, rrc_interface_phy *_rrc, mac_interface_phy *_mac)
 {
   log_h     = _log; 
-  radio_h   = _radio; 
+  radio_h   = _radio;
+  rrc       = _rrc;
   mac       = _mac; 
   config    = _config;     
   args      = _args; 

srsue/src/phy/phch_recv.cc

@@ -454,7 +454,7 @@ void phch_recv::reset_sync() {
 
   wait_radio_reset();
 
-  Info("SYNC:  Resetting sync\n");
+  Warning("SYNC:  Resetting sync, cell_search_in_progress=%s\n", cell_search_in_progress?"yes":"no");
   srslte_ue_sync_reset(&ue_mib_sync.ue_sync);
   srslte_ue_sync_reset(&ue_sync);
   resync_sfn();
@@ -718,11 +718,6 @@ void phch_recv::run_thread() {
                 worker_com->cur_radio_power = SRSLTE_MIN(SRSLTE_PC_MAX, worker_com->pathloss+worker_com->p0_preamble);
               }
               workers_pool->start_worker(worker);
-              // Notify RRC in-sync every 1 frame
-              if ((tti % 10) == 0) {
-                rrc->in_sync();
-                log_h->debug("SYNC:  Sending in-sync to RRC\n");
-              }
               break;
             case 0:
               log_h->error("SYNC:  Sync error. Sending out-of-sync to RRC\n");

srsue/src/phy/phch_worker.cc

@@ -219,11 +219,14 @@ void phch_worker::work_imp()
   bzero(&ul_action, sizeof(mac_interface_phy::tb_action_ul_t));
 
   /* Do FFT and extract PDCCH LLR, or quit if no actions are required in this subframe */
-  if (extract_fft_and_pdcch_llr()) {
-    
-    
+  bool chest_ok = extract_fft_and_pdcch_llr();
+
+  bool snr_th_ok = 10*log10(srslte_chest_dl_get_snr(&ue_dl.chest))>1.0;
+
+  if (chest_ok && snr_th_ok) {
+
     /***** Downlink Processing *******/
-    
+
     /* PDCCH DL + PDSCH */
     dl_grant_available = decode_pdcch_dl(&dl_mac_grant); 
     if(dl_grant_available) {
@@ -360,6 +363,17 @@ void phch_worker::work_imp()
   }
 
   update_measurements();
+
+  if (chest_ok) {
+    if (snr_th_ok) {
+      phy->rrc->in_sync();
+      log_h->debug("SYNC:  Sending in-sync to RRC\n");
+    } else {
+      phy->rrc->out_of_sync();
+      log_h->debug("SNR=%.1f dB under threshold. Sending out-of-sync to RRC\n",
+                   10*log10(srslte_chest_dl_get_snr(&ue_dl.chest)));
+    }
+  }
   
   /* Tell the plotting thread to draw the plots */
 #ifdef ENABLE_GUI

srsue/src/phy/phy.cc

@@ -129,7 +129,7 @@ bool phy::init(srslte::radio_multi* radio_handler, mac_interface_phy *mac, rrc_i
 void phy::run_thread() {
 
   prach_buffer.init(&config.common.prach_cnfg, SRSLTE_MAX_PRB, args, log_h);
-  workers_common.init(&config, args, (srslte::log*) log_vec[0], radio_handler, mac);
+  workers_common.init(&config, args, (srslte::log*) log_vec[0], radio_handler, rrc, mac);
 
   // Add workers to workers pool and start threads
   for (uint32_t i=0;i<nof_workers;i++) {

srsue/src/upper/rrc.cc

@@ -478,6 +478,9 @@ void rrc::out_of_sync() {
   if (!mac_timers->timer_get(t311)->is_running() && !mac_timers->timer_get(t310)->is_running()) {
     n310_cnt++;
     if (n310_cnt == N310) {
+      // attempt resync
+      phy->sync_reset();
+
       mac_timers->timer_get(t310)->reset();
       mac_timers->timer_get(t310)->run();
       n310_cnt = 0;
@@ -656,8 +659,10 @@ void rrc::send_con_restablish_request() {
   mac_timers->timer_get(t311)->reset();
   mac_timers->timer_get(t311)->run();
 
+  phy->reset();
   set_phy_default();
   mac->reset();
+  set_mac_default();
 
   // FIXME: Cell selection should be different??