diff --git a/openair1/PHY/LTE_ESTIMATION/lte_adjust_sync_eNB.c b/openair1/PHY/LTE_ESTIMATION/lte_adjust_sync_eNB.c
index 07f417ad98..28879cae27 100644
--- a/openair1/PHY/LTE_ESTIMATION/lte_adjust_sync_eNB.c
+++ b/openair1/PHY/LTE_ESTIMATION/lte_adjust_sync_eNB.c
@@ -119,13 +119,10 @@ int lte_est_timing_advance_pusch(PHY_VARS_eNB *eNB,module_id_t UE_id)
 
   RU_t *ru;
   ru = RC.ru[UE_id];
-  //LTE_DL_FRAME_PARMS *frame_parms = &eNB->frame_parms;
   LTE_DL_FRAME_PARMS *frame_parms = (eNB==NULL) ? &ru->frame_parms : &eNB->frame_parms;
   LTE_eNB_PUSCH *eNB_pusch_vars = eNB->pusch_vars[UE_id];
   RU_CALIBRATION *calibration = &ru->calibration;
-  //int32_t **ul_ch_estimates_time=  eNB_pusch_vars->drs_ch_estimates_time;
-  int32_t **ul_ch_estimates_time = calibration->drs_ch_estimates_time;
-  //int32_t **ul_ch_estimates_time = (eNB==NULL) ? calibration->drs_ch_estimates_time : eNB_pusch_vars->drs_ch_estimates_time;
+  int32_t **ul_ch_estimates_time = (eNB==NULL) ? calibration->drs_ch_estimates_time : eNB_pusch_vars->drs_ch_estimates_time;
   uint8_t cyclic_shift = 0;
   int sync_pos = (frame_parms->ofdm_symbol_size-cyclic_shift*frame_parms->ofdm_symbol_size/12)%(frame_parms->ofdm_symbol_size);
   
diff --git a/openair1/PHY/LTE_ESTIMATION/lte_ul_channel_estimation.c b/openair1/PHY/LTE_ESTIMATION/lte_ul_channel_estimation.c
index 44d8832e7a..e52da92f92 100644
--- a/openair1/PHY/LTE_ESTIMATION/lte_ul_channel_estimation.c
+++ b/openair1/PHY/LTE_ESTIMATION/lte_ul_channel_estimation.c
@@ -41,21 +41,20 @@ int32_t lte_ul_channel_estimation(PHY_VARS_eNB *eNB,
                                   unsigned char Ns) {
   RU_t *ru;
   ru = RC.ru[UE_id];
-  LTE_DL_FRAME_PARMS *frame_parms = (eNB==NULL) ? &eNB->frame_parms : &ru->frame_parms;
-  //LTE_DL_FRAME_PARMS *frame_parms = &eNB->frame_parms;
-  LTE_eNB_PUSCH *pusch_vars = eNB->pusch_vars[UE_id];
+  LTE_DL_FRAME_PARMS *frame_parms = (eNB!=NULL) ? &eNB->frame_parms : &ru->frame_parms;
+  LTE_eNB_PUSCH *pusch_vars = (eNB!=NULL) ? eNB->pusch_vars[UE_id] : NULL;
   RU_CALIBRATION *calibration = &ru->calibration;
-  //int32_t **ul_ch_estimates=pusch_vars->drs_ch_estimates;
-  int32_t **ul_ch_estimates = (eNB==NULL) ? pusch_vars->drs_ch_estimates : calibration->drs_ch_estimates;
+  int32_t **ul_ch_estimates = (eNB!=NULL) ? pusch_vars->drs_ch_estimates : calibration->drs_ch_estimates;
 
-  //int32_t **ul_ch_estimates_time=  pusch_vars->drs_ch_estimates_time;
-  int32_t **ul_ch_estimates_time = (eNB==NULL) ? pusch_vars->drs_ch_estimates_time : calibration->drs_ch_estimates_time;
-  
-  //int32_t **rxdataF_ext=  pusch_vars->rxdataF_ext;
-  int32_t **rxdataF_ext = (eNB==NULL) ? pusch_vars->rxdataF_ext : calibration->rxdataF_ext;
+  AssertFatal(ul_ch_estimates != NULL, "ul_ch_estimates is null (eNB %p, pusch %p, pusch->drs_ch_estimates %p, pusch->drs_ch_estimates[0] %p ul_ch_estimates %p UE_id %d)\n",eNB,pusch_vars,pusch_vars->drs_ch_estimates,pusch_vars->drs_ch_estimates[0],ul_ch_estimates,UE_id);
 
-  int subframe = (eNB==NULL) ? proc->subframe_rx : ru->proc.subframe_rx;
-  //int subframe = proc->subframe_rx;
+  int32_t **ul_ch_estimates_time = (eNB!=NULL) ? pusch_vars->drs_ch_estimates_time : calibration->drs_ch_estimates_time;
+ 
+  AssertFatal(ul_ch_estimates_time != NULL, "ul_ch_estimates_time is null\n");
+ 
+  int32_t **rxdataF_ext = (eNB!=NULL) ? pusch_vars->rxdataF_ext : calibration->rxdataF_ext;
+
+  int subframe = (eNB!=NULL) ? proc->subframe_rx : ru->proc.subframe_rx;
 
   uint8_t harq_pid = subframe2harq_pid(frame_parms,proc->frame_rx,subframe);
 
@@ -122,14 +121,11 @@ int32_t temp_in_ifft_0[2048*2] __attribute__((aligned(32)));
 
 #endif
 
-
   if (l == (3 - frame_parms->Ncp)) {
 
     symbol_offset = frame_parms->N_RB_UL*12*(l+((7-frame_parms->Ncp)*(Ns&1)));
 
     for (aa=0; aa<nb_antennas_rx; aa++) {
-      //           msg("Componentwise prod aa %d, symbol_offset %d,ul_ch_estimates %p,ul_ch_estimates[aa] %p,ul_ref_sigs_rx[0][0][Msc_RS_idx] %p\n",aa,symbol_offset,ul_ch_estimates,ul_ch_estimates[aa],ul_ref_sigs_rx[0][0][Msc_RS_idx]);
-
 #if defined(__x86_64__) || defined(__i386__)
       rxdataF128 = (__m128i *)&rxdataF_ext[aa][symbol_offset];
       ul_ch128   = (__m128i *)&ul_ch_estimates[aa][symbol_offset];
diff --git a/openair1/SIMULATION/LTE_PHY/ulsim.c b/openair1/SIMULATION/LTE_PHY/ulsim.c
index 24338e1370..e5e1d2f10c 100644
--- a/openair1/SIMULATION/LTE_PHY/ulsim.c
+++ b/openair1/SIMULATION/LTE_PHY/ulsim.c
@@ -750,9 +750,9 @@ int main(int argc, char **argv) {
   printf("ULSCH %p\n",UE->ulsch[0]);
 
   if(get_thread_worker_conf() == WORKER_ENABLE) {
-    extern void init_fep_thread(PHY_VARS_eNB *, pthread_attr_t *);
+    extern void init_fep_thread(RU_t *, pthread_attr_t *);
     extern void init_td_thread(PHY_VARS_eNB *);
-    init_fep_thread(eNB,NULL);
+    init_fep_thread(ru,NULL);
     init_td_thread(eNB);
   }
 
diff --git a/targets/RT/USER/lte-enb.c b/targets/RT/USER/lte-enb.c
index cd3d1a0ba2..a1b3899196 100644
--- a/targets/RT/USER/lte-enb.c
+++ b/targets/RT/USER/lte-enb.c
@@ -436,9 +436,10 @@ static void* L1_thread( void* param ) {
       if (rxtx(eNB,proc,thread_name) < 0) break;
     }
 
-    LOG_D(PHY,"L1_thread: RX done\n");
+    LOG_D(PHY,"L1_thread: RX done in %d.%d\n",proc->frame_rx,proc->subframe_rx);
     if(get_thread_parallel_conf() == PARALLEL_RU_L1_SPLIT)              phy_procedures_eNB_TX(eNB, proc, 1);
     if (release_thread(&proc->mutex,&proc->instance_cnt,thread_name)<0) break;
+    LOG_D(PHY,"L1_thread: IC %d\n",proc->instance_cnt);
 VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_L1_PROC_IC,proc->instance_cnt);
     if (nfapi_mode!=2){
     	if(get_thread_parallel_conf() == PARALLEL_RU_L1_TRX_SPLIT)      wakeup_tx(eNB);
@@ -589,7 +590,7 @@ int wakeup_rxtx(PHY_VARS_eNB *eNB,RU_t *ru) {
   L1_rxtx_proc_t *L1_proc=&proc->L1_proc;
   LTE_DL_FRAME_PARMS *fp = &eNB->frame_parms;
   
-  LOG_D(PHY,"ENTERED wakeup_rxtx\n");
+  LOG_D(PHY,"ENTERED wakeup_rxtx, %d.%d\n",ru_proc->frame_rx,ru_proc->subframe_rx);
   
   int i;
   struct timespec wait;
@@ -597,11 +598,6 @@ int wakeup_rxtx(PHY_VARS_eNB *eNB,RU_t *ru) {
   wait.tv_sec=0;
   wait.tv_nsec=5000000L;
 
-  if (L1_proc->instance_cnt == 0) {
-    LOG_E(PHY,"Frame %d, subframe %d: RXTX0 thread busy, dropping\n",L1_proc->frame_rx,L1_proc->subframe_rx);
-    return(-1);
-  }
-
   // wake up TX for subframe n+sf_ahead
   // lock the TX mutex and make sure the thread is ready
   if (pthread_mutex_lock(&L1_proc->mutex) != 0) {
@@ -609,9 +605,14 @@ int wakeup_rxtx(PHY_VARS_eNB *eNB,RU_t *ru) {
     exit_fun( "error locking mutex_rxtx" );
     return(-1);
   }
-  VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_L1_PROC_IC,L1_proc->instance_cnt);
-  ++L1_proc->instance_cnt;
-  VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_L1_PROC_IC,L1_proc->instance_cnt);
+  if (L1_proc->instance_cnt == 0) {
+    LOG_E(PHY,"Frame %d, subframe %d: RXTX0 thread busy, dropping\n",ru_proc->frame_rx,ru_proc->subframe_rx);
+    abort();
+  }
+  else {
+    VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_L1_PROC_IC,L1_proc->instance_cnt);
+    ++L1_proc->instance_cnt;
+    VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_L1_PROC_IC,L1_proc->instance_cnt);
 
   // We have just received and processed the common part of a subframe, say n. 
   // TS_rx is the last received timestamp (start of 1st slot), TS_tx is the desired 
@@ -619,26 +620,26 @@ int wakeup_rxtx(PHY_VARS_eNB *eNB,RU_t *ru) {
   // The last (TS_rx mod samples_per_frame) was n*samples_per_tti,
   // we want to generate subframe (n+sf_ahead), so TS_tx = TX_rx+sf_ahead*samples_per_tti,
   // and proc->subframe_tx = proc->subframe_rx+sf_ahead
-  L1_proc->timestamp_tx = ru_proc->timestamp_rx + (sf_ahead*fp->samples_per_tti);
-  L1_proc->frame_rx     = ru_proc->frame_rx;
-  L1_proc->subframe_rx  = ru_proc->subframe_rx;
-  L1_proc->frame_tx     = (L1_proc->subframe_rx > (9-sf_ahead)) ? (L1_proc->frame_rx+1)&1023 : L1_proc->frame_rx;
-  L1_proc->subframe_tx  = (L1_proc->subframe_rx + sf_ahead)%10;
+    L1_proc->timestamp_tx = ru_proc->timestamp_rx + (sf_ahead*fp->samples_per_tti);
+    L1_proc->frame_rx     = ru_proc->frame_rx;
+    L1_proc->subframe_rx  = ru_proc->subframe_rx;
+    L1_proc->frame_tx     = (L1_proc->subframe_rx > (9-sf_ahead)) ? (L1_proc->frame_rx+1)&1023 : L1_proc->frame_rx;
+    L1_proc->subframe_tx  = (L1_proc->subframe_rx + sf_ahead)%10;
 
-  //printf("wakeup_rxtx: L1_proc->subframe_rx %d, L1_proc->subframe_tx %d, RU %d\n",L1_proc->subframe_rx,L1_proc->subframe_tx,ru->idx);
+    LOG_D(PHY,"wakeup_rxtx: L1_proc->subframe_rx %d, L1_proc->subframe_tx %d, RU %d\n",L1_proc->subframe_rx,L1_proc->subframe_tx,ru->idx);
 
-  VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_FRAME_NUMBER_WAKEUP_RXTX_RX_RU+ru->idx, L1_proc->frame_rx);
-  VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_SUBFRAME_NUMBER_WAKEUP_RXTX_RX_RU+ru->idx, L1_proc->subframe_rx);
-  VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_FRAME_NUMBER_WAKEUP_RXTX_TX_RU+ru->idx, L1_proc->frame_tx);
-  VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_SUBFRAME_NUMBER_WAKEUP_RXTX_TX_RU+ru->idx, L1_proc->subframe_tx);
+    VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_FRAME_NUMBER_WAKEUP_RXTX_RX_RU+ru->idx, L1_proc->frame_rx);
+    VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_SUBFRAME_NUMBER_WAKEUP_RXTX_RX_RU+ru->idx, L1_proc->subframe_rx);
+    VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_FRAME_NUMBER_WAKEUP_RXTX_TX_RU+ru->idx, L1_proc->frame_tx);
+    VCD_SIGNAL_DUMPER_DUMP_VARIABLE_BY_NAME(VCD_SIGNAL_DUMPER_VARIABLES_SUBFRAME_NUMBER_WAKEUP_RXTX_TX_RU+ru->idx, L1_proc->subframe_tx);
 
   // the thread can now be woken up
-  if (pthread_cond_signal(&L1_proc->cond) != 0) {
-    LOG_E( PHY, "[eNB] ERROR pthread_cond_signal for eNB RXn-TXnp4 thread\n");
-    exit_fun( "ERROR pthread_cond_signal" );
-    return(-1);
+    if (pthread_cond_signal(&L1_proc->cond) != 0) {
+      LOG_E( PHY, "[eNB] ERROR pthread_cond_signal for eNB RXn-TXnp4 thread\n");
+      exit_fun( "ERROR pthread_cond_signal" );
+      return(-1);
+    }
   }
-
   pthread_mutex_unlock( &L1_proc->mutex);
   return(0);
 }
diff --git a/targets/RT/USER/lte-ru.c b/targets/RT/USER/lte-ru.c
index d4a9c7614a..2e3da52fa3 100644
--- a/targets/RT/USER/lte-ru.c
+++ b/targets/RT/USER/lte-ru.c
@@ -224,28 +224,35 @@ void fh_if4p5_south_in(RU_t *ru,int *frame,int *subframe) {
   uint16_t packet_type;
   uint32_t symbol_number=0;
   uint32_t symbol_mask_full;
+  int pultick_received=0;
 
   if ((fp->frame_type == TDD) && (subframe_select(fp,*subframe)==SF_S))  
     symbol_mask_full = (1<<fp->ul_symbols_in_S_subframe)-1;   
   else     
     symbol_mask_full = (1<<fp->symbols_per_tti)-1; 
-  LOG_D(PHY,"fh_if4p5_south_in: RU %d, frame %d, subframe %d, ru %d\n",ru->idx,*frame,*subframe,ru->idx);
-  AssertFatal(proc->symbol_mask[*subframe]==0,"rx_fh_if4p5: proc->symbol_mask[%d] = %x\n",*subframe,proc->symbol_mask[*subframe]);
-  do {
-    recv_IF4p5(ru, &f, &sf, &packet_type, &symbol_number);
-    if (oai_exit == 1 || ru->cmd== STOP_RU) break;
-    if (packet_type == IF4p5_PULFFT) proc->symbol_mask[sf] = proc->symbol_mask[sf] | (1<<symbol_number);
-    else if (packet_type == IF4p5_PULTICK) {           
-      if ((proc->first_rx==0) && (f!=*frame)) LOG_E(PHY,"rx_fh_if4p5: PULTICK received frame %d != expected %d (RU %d)\n",f,*frame, ru->idx);       
-      if ((proc->first_rx==0) && (sf!=*subframe)) LOG_E(PHY,"rx_fh_if4p5: PULTICK received subframe %d != expected %d (first_rx %d)\n",sf,*subframe,proc->first_rx);       
-      break;     
-      
-    } else if (packet_type == IF4p5_PRACH) {
+  LOG_D(PHY,"fh_if4p5_south_in: RU %d, frame %d, subframe %d, ru %d, mask %x\n",ru->idx,*frame,*subframe,ru->idx,proc->symbol_mask[*subframe]);
+  AssertFatal(proc->symbol_mask[*subframe]==0 || proc->symbol_mask[*subframe]==symbol_mask_full,"rx_fh_if4p5: proc->symbol_mask[%d] = %x\n",*subframe,proc->symbol_mask[*subframe]);
+  if (proc->symbol_mask[*subframe]==0) { // this is normal case, if not true then we received a PULTICK before the previous subframe was finished 
+     do {
+       recv_IF4p5(ru, &f, &sf, &packet_type, &symbol_number);
+       if (oai_exit == 1 || ru->cmd== STOP_RU) break;
+       if (packet_type == IF4p5_PULFFT) proc->symbol_mask[sf] = proc->symbol_mask[sf] | (1<<symbol_number);
+       else if (packet_type == IF4p5_PULTICK) {           
+         proc->symbol_mask[sf] = symbol_mask_full;
+         pultick_received++;
+         if ((proc->first_rx==0) && (f!=*frame)) LOG_E(PHY,"rx_fh_if4p5: PULTICK received frame %d != expected %d (RU %d) \n",f,*frame, ru->idx);       
+         else if ((proc->first_rx==0) && (sf!=*subframe)) LOG_E(PHY,"rx_fh_if4p5: PULTICK received subframe %d != expected %d (first_rx %d)\n",sf,*subframe,proc->first_rx);       
+         else break;
+       } else if (packet_type == IF4p5_PRACH) {
       // nothing in RU for RAU
-    }
-    LOG_D(PHY,"rx_fh_if4p5: subframe %d symbol mask %x\n",*subframe,proc->symbol_mask[*subframe]);
-  } while(proc->symbol_mask[*subframe] != symbol_mask_full);    
-
+       }
+       LOG_D(PHY,"rx_fh_if4p5: subframe %d symbol mask %x\n",*subframe,proc->symbol_mask[*subframe]);
+     } while(proc->symbol_mask[*subframe] != symbol_mask_full);    
+  }
+  else {
+   f = *frame;
+   sf = *subframe;
+  }
   //calculate timestamp_rx, timestamp_tx based on frame and subframe
   proc->subframe_rx  = sf;
   proc->frame_rx     = f;
@@ -255,14 +262,17 @@ void fh_if4p5_south_in(RU_t *ru,int *frame,int *subframe) {
      proc->frame_tx     = (sf>(9-sf_ahead)) ? (f+1)&1023 : f;
   }
 
+  LOG_D(PHY,"Setting proc for (%d,%d)\n",sf,f);
+
   if (proc->first_rx == 0) {
    if (proc->subframe_rx != *subframe){
-      LOG_E(PHY,"Received Timestamp (IF4p5) doesn't correspond to the time we think it is (proc->subframe_rx %d, subframe %d)\n",proc->subframe_rx,*subframe);
-      exit_fun("Exiting");
+      LOG_E(PHY,"Received Timestamp (IF4p5) doesn't correspond to the time we think it is (proc->subframe_rx %d, subframe %d, symbol_mask %x)\n",proc->subframe_rx,*subframe,proc->symbol_mask[*subframe]);
+      *subframe=sf; 
+      //exit_fun("Exiting");
     }
     if (ru->cmd != WAIT_RESYNCH && proc->frame_rx != *frame) {
-      LOG_E(PHY,"Received Timestamp (IF4p5) doesn't correspond to the time we think it is (proc->frame_rx %d frame %d)\n",proc->frame_rx,*frame);
-      exit_fun("Exiting");
+      LOG_E(PHY,"Received Timestamp (IF4p5) doesn't correspond to the time we think it is (proc->frame_rx %d frame %d,symbol_mask %x\n",proc->frame_rx,*frame,proc->symbol_mask[*subframe]);
+      //exit_fun("Exiting");
     }
     else if (ru->cmd == WAIT_RESYNCH && proc->frame_rx != *frame){
        ru->cmd=EMPTY;