diff --git a/matlab/common/read_trace_uint.m b/matlab/common/read_trace_uint.m
new file mode 100644
index 000000000..cdaeea99a
--- /dev/null
+++ b/matlab/common/read_trace_uint.m
@@ -0,0 +1,19 @@
+function [ tti, values ] = read_trace_uint( filename, count )
+
+    [tidin msg]=fopen(filename,'r');
+    if (tidin==-1)
+        fprintf('error opening %s: %s\n',filename, msg);
+        out=[];
+        return
+    end
+
+    if (nargin==1) 
+        count=inf;
+    end
+
+    x=fread(tidin,2*count,'uint');
+    i=1:2:length(x);
+    tti=x(i);
+    values=x(i+1);
+end
+
diff --git a/srsapps/common/include/srsapps/common/threads.h b/srsapps/common/include/srsapps/common/threads.h
index 2cebb77f7..f8ad2c43b 100644
--- a/srsapps/common/include/srsapps/common/threads.h
+++ b/srsapps/common/include/srsapps/common/threads.h
@@ -26,12 +26,14 @@
  */
 
 #include <pthread.h>
+#include <stdint.h>
 
 #ifdef __cplusplus
     extern "C" {
 #endif
   bool threads_new_rt(pthread_t *thread, void *(*start_routine) (void*), void *arg);
-  bool threads_new_rt_cpu(pthread_t *thread, void *(*start_routine) (void*), void *arg, int cpu);
+  bool threads_new_rt_prio(pthread_t *thread, void *(*start_routine) (void*), void *arg, uint32_t prio_offset);
+  bool threads_new_rt_cpu(pthread_t *thread, void *(*start_routine) (void*), void *arg, int cpu, uint32_t prio_offset);
   void threads_print_self();
 
 #ifdef __cplusplus
diff --git a/srsapps/common/include/srsapps/common/trace.h b/srsapps/common/include/srsapps/common/trace.h
new file mode 100644
index 000000000..af0f52a9b
--- /dev/null
+++ b/srsapps/common/include/srsapps/common/trace.h
@@ -0,0 +1,98 @@
+/**
+ *
+ * \section COPYRIGHT
+ *
+ * Copyright 2013-2015 The srsLTE Developers. See the
+ * COPYRIGHT file at the top-level directory of this distribution.
+ *
+ * \section LICENSE
+ *
+ * This file is part of the srsLTE library.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+
+#include <stdio.h>
+#include <string>
+#include <vector>
+
+#ifndef TRACE_H
+#define TRACE_H
+
+namespace srslte {
+  
+template<class elemType>
+class trace
+{
+public:
+  
+  trace(uint32_t nof_elems_) : tti(nof_elems_), data(nof_elems_) {
+    rpm=0;
+    nof_elems=nof_elems_;
+    wrapped = false;
+  };
+  void push_cur_time_us(uint32_t cur_tti) {
+    struct timeval t; 
+    gettimeofday(&t, NULL); 
+    elemType us = t.tv_sec*1e6+t.tv_usec;
+    push(cur_tti, us);
+  }
+  void push(uint32_t value_tti, elemType value) {
+    tti[rpm]  = value_tti;
+    data[rpm] = value;
+    rpm++;
+    if (rpm >= nof_elems) {
+      rpm = 0; 
+      wrapped = true;
+    }
+  }
+  bool writeToBinary(std::string filename) {
+    FILE *f = fopen(filename.c_str(), "w");
+    if (f != NULL) {
+      uint32_t st=wrapped?(rpm+1):0;
+      do {
+        writeToBinaryValue(f, st++);        
+        if (st >= nof_elems) {
+          st=0;
+        }
+      } while(st<rpm);
+      fclose(f);
+      return true; 
+    } else {
+      perror("fopen");
+      return false; 
+    }
+  }
+   
+private:
+  std::vector<uint32_t> tti;
+  std::vector<elemType> data;
+  uint32_t rpm;
+  uint32_t nof_elems;
+  bool wrapped; 
+  
+  void writeToBinaryValue(FILE *f, uint32_t idx) {
+    fwrite(&tti[idx],  1, sizeof(uint32_t), f);
+    fwrite(&data[idx], 1, sizeof(elemType), f);
+  }
+
+};
+
+  
+}
+  
+#endif
\ No newline at end of file
diff --git a/srsapps/common/src/threads.c b/srsapps/common/src/threads.c
index 25b5d42f6..408595f49 100644
--- a/srsapps/common/src/threads.c
+++ b/srsapps/common/src/threads.c
@@ -35,15 +35,19 @@
 #include "srsapps/common/threads.h"
 
 bool threads_new_rt(pthread_t *thread, void *(*start_routine) (void*), void *arg) {
-  return threads_new_rt_cpu(thread, start_routine, arg, -1);
+  return threads_new_rt_prio(thread, start_routine, arg, 0);
 }
 
-bool threads_new_rt_cpu(pthread_t *thread, void *(*start_routine) (void*), void *arg, int cpu) {
+bool threads_new_rt_prio(pthread_t *thread, void *(*start_routine) (void*), void *arg, uint32_t prio_offset) {
+  return threads_new_rt_cpu(thread, start_routine, arg, -1, prio_offset);
+}
+
+bool threads_new_rt_cpu(pthread_t *thread, void *(*start_routine) (void*), void *arg, int cpu, uint32_t prio_offset) {
   bool ret = false; 
   
   pthread_attr_t attr;
   struct sched_param param;
-  param.sched_priority = sched_get_priority_max(SCHED_FIFO);  
+  param.sched_priority = sched_get_priority_max(SCHED_FIFO) - prio_offset;  
 
   pthread_attr_init(&attr);
   if (pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED)) {
diff --git a/srsapps/radio/include/srsapps/radio/radio_uhd.h b/srsapps/radio/include/srsapps/radio/radio_uhd.h
index e7b33e6e3..1b560220f 100644
--- a/srsapps/radio/include/srsapps/radio/radio_uhd.h
+++ b/srsapps/radio/include/srsapps/radio/radio_uhd.h
@@ -30,6 +30,7 @@
 #include "srsapps/radio/radio.h"
 #include "srslte/srslte.h"
 #include "srslte/cuhd/cuhd.h"
+#include "srsapps/common/trace.h"
 
 #ifndef RADIO_UHD_H
 #define RADIO_UHD_H
@@ -42,6 +43,7 @@ namespace srslte {
   class radio_uhd : public radio
   {
     public: 
+      radio_uhd() : tr_local_time(1024*10), tr_usrp_time(1024*10), tr_tx_time(1024*10), tr_is_eob(1024*10) {};
       bool init();
       bool init(char *args);
       bool init_agc();
@@ -67,15 +69,19 @@ namespace srslte {
       float get_tx_gain();
       float get_rx_gain();
 
-      
+      void start_trace();
+      void write_trace(std::string filename);
       void start_rx();
       void stop_rx();
       
     private:
+      
+      void save_trace(uint32_t is_eob, srslte_timestamp_t *usrp_time);
+      
       void *uhd; 
       
       static const double lo_offset = 8e6; // LO offset (in Hz)      
-      static const double burst_settle_time = 0.4e-3; // Start of burst settle time (off->on RF transition time)      
+      static const double burst_settle_time = 0.3e-3; // Start of burst settle time (off->on RF transition time)      
       const static uint32_t burst_settle_max_samples = 12288;  // 30.72 MHz is maximum frequency
 
       srslte_timestamp_t end_of_burst_time; 
@@ -84,6 +90,13 @@ namespace srslte {
       double burst_settle_time_rounded; // settle time rounded to sample time
       cf_t zeros[burst_settle_max_samples]; 
       double cur_tx_srate;
+      
+      trace<uint32_t> tr_local_time;
+      trace<uint32_t> tr_usrp_time;
+      trace<uint32_t> tr_tx_time;
+      trace<uint32_t> tr_is_eob;
+      bool trace_enabled;
+      uint32_t my_tti;
   }; 
 }
 
diff --git a/srsapps/radio/src/radio_uhd.cc b/srsapps/radio/src/radio_uhd.cc
index a5a0cd17a..9be56289a 100644
--- a/srsapps/radio/src/radio_uhd.cc
+++ b/srsapps/radio/src/radio_uhd.cc
@@ -92,18 +92,23 @@ void radio_uhd::get_time(srslte_timestamp_t *now) {
 bool radio_uhd::tx(void* buffer, uint32_t nof_samples, srslte_timestamp_t tx_time)
 {
   if (is_start_of_burst) {
+    
     if (burst_settle_samples != 0) {
       srslte_timestamp_t tx_time_pad; 
       srslte_timestamp_copy(&tx_time_pad, &tx_time);
       srslte_timestamp_sub(&tx_time_pad, 0, burst_settle_time_rounded); 
+      save_trace(1, &tx_time_pad);
       cuhd_send_timed2(uhd, zeros, burst_settle_samples, tx_time_pad.full_secs, tx_time_pad.frac_secs, true, false);
     }        
     is_start_of_burst = false; 
-    srslte_timestamp_copy(&end_of_burst_time, &tx_time);
-    srslte_timestamp_add(&end_of_burst_time, 0, nof_samples*cur_tx_srate); 
   }
   
-  if (cuhd_send_timed2(uhd, buffer, nof_samples, tx_time.full_secs, tx_time.frac_secs, false, false) > 0) {
+  // Save possible end of burst time 
+  srslte_timestamp_copy(&end_of_burst_time, &tx_time);
+  srslte_timestamp_add(&end_of_burst_time, 0, (double) nof_samples/cur_tx_srate); 
+  
+  save_trace(0, &tx_time);
+  if (cuhd_send_timed2(uhd, buffer, nof_samples, tx_time.full_secs, tx_time.frac_secs, true, false) > 0) {
     return true; 
   } else {
     return false; 
@@ -112,10 +117,36 @@ bool radio_uhd::tx(void* buffer, uint32_t nof_samples, srslte_timestamp_t tx_tim
 
 bool radio_uhd::tx_end()
 {
+  save_trace(2, &end_of_burst_time);
   cuhd_send_timed2(uhd, zeros, burst_settle_samples, end_of_burst_time.full_secs, end_of_burst_time.frac_secs, false, true);
   is_start_of_burst = true; 
 }
 
+void radio_uhd::start_trace() {
+  trace_enabled = true; 
+  my_tti = 0; 
+}
+
+void radio_uhd::write_trace(std::string filename)
+{
+  tr_local_time.writeToBinary(filename + ".local");
+  tr_is_eob.writeToBinary(filename + ".eob");
+  tr_usrp_time.writeToBinary(filename + ".usrp");
+  tr_tx_time.writeToBinary(filename + ".tx");
+}
+
+void radio_uhd::save_trace(uint32_t is_eob, srslte_timestamp_t *tx_time) {
+  if (trace_enabled) {
+    tr_local_time.push_cur_time_us(my_tti);
+    srslte_timestamp_t usrp_time; 
+    cuhd_get_time(uhd, &usrp_time.full_secs, &usrp_time.frac_secs);
+    tr_usrp_time.push(my_tti, srslte_timestamp_uint32(&usrp_time));
+    tr_tx_time.push(my_tti, srslte_timestamp_uint32(tx_time));
+    tr_is_eob.push(my_tti, is_eob);
+    my_tti++;
+  }
+}
+
 void radio_uhd::set_rx_freq(float freq)
 {
   cuhd_set_rx_freq(uhd, freq);
diff --git a/srsapps/ue/mac/include/srsapps/ue/mac/mac.h b/srsapps/ue/mac/include/srsapps/ue/mac/mac.h
index 739374c81..621390bdd 100644
--- a/srsapps/ue/mac/include/srsapps/ue/mac/mac.h
+++ b/srsapps/ue/mac/include/srsapps/ue/mac/mac.h
@@ -45,6 +45,8 @@
 #include "srsapps/ue/mac/mux.h"
 #include "srsapps/ue/mac/demux.h"
 #include "srsapps/ue/mac/sdu_handler.h"
+#include "srsapps/common/trace.h"
+
 
 #ifndef UEMAC_H
 #define UEMAC_H
@@ -57,7 +59,7 @@ typedef _Complex float cf_t;
 class mac : public timer_callback
 {
 public:
-  mac() : timers_db((uint32_t) NOF_MAC_TIMERS) {}
+  mac() : timers_db((uint32_t) NOF_MAC_TIMERS), tr_end_time(1024*10), tr_start_time(1024*10) {started=false;}
   bool init(phy *phy_h, tti_sync *ttisync, log *log_h);
   void stop();
   int  get_tti();
@@ -83,6 +85,9 @@ public:
   void reconfiguration(); 
   void reset(); 
   
+  void start_trace();
+  void write_trace(std::string filename); 
+  
   void timer_expired(uint32_t timer_id); 
     
   enum {
@@ -110,7 +115,7 @@ private:
   static void*  mac_thread_fnc(void*);
   
   int           tti; 
-  bool          started = false; 
+  bool          started; 
   bool          is_synchronized; 
   uint16_t      last_temporal_crnti;
   
@@ -144,6 +149,12 @@ private:
   void          setup_timers();
   void          timeAlignmentTimerExpire();
     
+  trace<uint32_t> tr_start_time;
+  trace<uint32_t> tr_end_time;
+  bool tr_enabled; 
+  void tr_log_start(uint32_t tti);
+  void tr_log_end(uint32_t tti);    
+
 };
 
 } 
diff --git a/srsapps/ue/mac/src/mac.cc b/srsapps/ue/mac/src/mac.cc
index 33908642d..8f93215a2 100644
--- a/srsapps/ue/mac/src/mac.cc
+++ b/srsapps/ue/mac/src/mac.cc
@@ -79,6 +79,32 @@ int mac::get_tti()
   }
 }
 
+void mac::start_trace()
+{
+  tr_enabled = true; 
+}
+
+void mac::write_trace(std::string filename)
+{
+  tr_start_time.writeToBinary(filename + ".start");
+  tr_end_time.writeToBinary(filename + ".end");
+}
+
+void mac::tr_log_start(uint32_t tti)
+{
+  if (tr_enabled) {
+    tr_start_time.push_cur_time_us(tti);
+  }
+}
+
+void mac::tr_log_end(uint32_t tti)
+{
+  if (tr_enabled) {
+    tr_end_time.push_cur_time_us(tti);
+  }
+}
+
+
 // Implement Section 5.8
 void mac::reconfiguration()
 {
@@ -164,7 +190,9 @@ void mac::main_radio_loop() {
     }
     if (is_synchronized) {
       /* Warning: Here order of invocation of procedures is important!! */
+      tr_log_end(tti);
       tti = ttisync->wait();
+      tr_log_start(tti);
       log_h->step(tti);
       
       // Step all procedures 
diff --git a/srsapps/ue/mac/test/mac_test.cc b/srsapps/ue/mac/test/mac_test.cc
index cb76013ed..3ee4ed96d 100644
--- a/srsapps/ue/mac/test/mac_test.cc
+++ b/srsapps/ue/mac/test/mac_test.cc
@@ -27,6 +27,7 @@
 
 
 #include <unistd.h>
+#include <signal.h>
 
 #include "liblte_rrc.h"
 #include "srsapps/radio/radio_uhd.h"
@@ -46,6 +47,7 @@ typedef struct {
   float uhd_rx_gain;
   float uhd_tx_gain;
   int   verbose; 
+  bool  do_trace; 
 }prog_args_t;
 
 void args_default(prog_args_t *args) {
@@ -54,19 +56,21 @@ void args_default(prog_args_t *args) {
   args->uhd_rx_gain = -1; // set to autogain
   args->uhd_tx_gain = -1; 
   args->verbose     = 0; 
+  args->do_trace    = false; 
 }
 
 void usage(prog_args_t *args, char *prog) {
-  printf("Usage: %s [gv] -f rx_frequency (in Hz) -F tx_frequency (in Hz)\n", prog);
+  printf("Usage: %s [gGtv] -f rx_frequency (in Hz) -F tx_frequency (in Hz)\n", prog);
   printf("\t-g UHD RX gain [Default AGC]\n");
   printf("\t-G UHD TX gain [Default same as RX gain (AGC)]\n");
+  printf("\t-t Enable trace [Default disabled]\n");
   printf("\t-v [increase verbosity, default none]\n");
 }
 
 void parse_args(prog_args_t *args, int argc, char **argv) {
   int opt;
   args_default(args);
-  while ((opt = getopt(argc, argv, "gGfFv")) != -1) {
+  while ((opt = getopt(argc, argv, "gGftFv")) != -1) {
     switch (opt) {
     case 'g':
       args->uhd_rx_gain = atof(argv[optind]);
@@ -80,6 +84,9 @@ void parse_args(prog_args_t *args, int argc, char **argv) {
     case 'F':
       args->uhd_tx_freq = atof(argv[optind]);
       break;
+    case 't':
+      args->do_trace = true;
+      break;
     case 'v':
       args->verbose++;
       break;
@@ -202,7 +209,6 @@ void setup_mac_phy_sib2(LIBLTE_RRC_SYS_INFO_BLOCK_TYPE_2_STRUCT *sib2, srslte::u
     phy->set_param(srslte::ue::phy_params::SRS_CS_BWCFG, sib2->rr_config_common_sib.srs_ul_cnfg.bw_cnfg);
     phy->set_param(srslte::ue::phy_params::SRS_CS_SFCFG, sib2->rr_config_common_sib.srs_ul_cnfg.subfr_cnfg);
     phy->set_param(srslte::ue::phy_params::SRS_CS_ACKNACKSIMUL, sib2->rr_config_common_sib.srs_ul_cnfg.ack_nack_simul_tx);
-    phy->set_param(srslte::ue::phy_params::SRS_IS_CS_CONFIGURED, 1);
   }
 
   printf("Set SRS ConfigCommon: BW-Configuration=%d, SF-Configuration=%d, ACKNACK=%d\n", 
@@ -233,7 +239,6 @@ void process_connsetup(LIBLTE_RRC_CONNECTION_SETUP_STRUCT *msg, srslte::ue::mac
       phy->set_param(srslte::ue::phy_params::SRS_UE_HOP, msg->rr_cnfg.phy_cnfg_ded.srs_ul_cnfg_ded.srs_hopping_bandwidth);
       phy->set_param(srslte::ue::phy_params::SRS_UE_TXCOMB, msg->rr_cnfg.phy_cnfg_ded.srs_ul_cnfg_ded.tx_comb);
       phy->set_param(srslte::ue::phy_params::SRS_BETA, 10);
-      phy->set_param(srslte::ue::phy_params::SRS_IS_UE_CONFIGURED, 1);
     }
   }
   printf("Set PHY configuration: SR-n_pucch=%d, SR-ConfigIndex=%d, SRS-ConfigIndex=%d, SRS-bw=%d, SRS-Nrcc=%d, SRS-hop=%d, SRS-Ncs=%d\n", 
@@ -299,13 +304,23 @@ uint32_t lengths[2] = {37, 41};
 uint8_t reply[2] = {0x00, 0x04};
 
 
+srslte::radio_uhd radio_uhd; 
+srslte::ue::phy phy; 
+srslte::ue::mac mac; 
+  
+void sig_int_handler(int signo)
+{
+  //radio_uhd.write_trace("radio");
+  phy.write_trace("phy");
+  mac.write_trace("mac");
+  exit(0);
+}
+
+
 int main(int argc, char *argv[])
 {
   prog_args_t prog_args; 
   srslte::ue::tti_sync_cv ttisync(10240); 
-  srslte::radio_uhd radio_uhd; 
-  srslte::ue::phy phy; 
-  srslte::ue::mac mac; 
   srslte::log_stdout mac_log("MAC"), phy_log("PHY"); 
   
   parse_args(&prog_args, argc, argv);
@@ -320,7 +335,15 @@ int main(int argc, char *argv[])
       phy_log.set_level_debug();
       break;
   }
-
+ 
+  if (prog_args.do_trace) {
+    // Capture SIGINT to write traces 
+    signal(SIGINT, sig_int_handler);
+    //radio_uhd.start_trace();
+    phy.start_trace();
+    mac.start_trace();
+  }
+  
   // Init Radio and PHY
   if (prog_args.uhd_rx_gain > 0 && prog_args.uhd_tx_gain > 0) {
     radio_uhd.init();
@@ -449,6 +472,8 @@ int main(int argc, char *argv[])
         // Wait for ConnectionSetup
         n = mac.recv_dcch0_sdu(bit_msg.msg, LIBLTE_MAX_MSG_SIZE); 
         if (n > 0) {
+          phy.set_param(srslte::ue::phy_params::SRS_IS_CS_CONFIGURED, 1);
+          phy.set_param(srslte::ue::phy_params::SRS_IS_UE_CONFIGURED, 1);
           printf("Received on DCCH0 %d bytes\n", n/8);
           printf("Send RLC ACK\n");
           srslte_bit_pack_vector(reply, bit_msg.msg, 2*8);
diff --git a/srsapps/ue/phy/include/srsapps/ue/phy/phy.h b/srsapps/ue/phy/include/srsapps/ue/phy/phy.h
index f93e65f64..8bfbd8e0e 100644
--- a/srsapps/ue/phy/include/srsapps/ue/phy/phy.h
+++ b/srsapps/ue/phy/include/srsapps/ue/phy/phy.h
@@ -38,6 +38,7 @@
 #include "srsapps/ue/phy/sched_grant.h"
 #include "srsapps/common/queue.h"
 #include "srsapps/radio/radio.h"
+#include "srsapps/common/trace.h"
 
 #ifndef UEPHY_H
 #define UEPHY_H
@@ -119,6 +120,9 @@ public:
   ul_buffer* get_ul_buffer(uint32_t tti);
   dl_buffer* get_dl_buffer(uint32_t tti);
 
+  void start_trace();
+  void write_trace(std::string filename); 
+  
   void main_radio_loop(); 
   
 private:
@@ -166,6 +170,11 @@ private:
 
   bool         is_first_of_burst; 
   
+  trace<uint32_t> tr_start_time;
+  trace<uint32_t> tr_end_time;
+  bool tr_enabled; 
+  void tr_log_start();
+  void tr_log_end();    
 };
 
 } 
diff --git a/srsapps/ue/phy/include/srsapps/ue/phy/prach.h b/srsapps/ue/phy/include/srsapps/ue/phy/prach.h
index 6ece0489b..149a0966a 100644
--- a/srsapps/ue/phy/include/srsapps/ue/phy/prach.h
+++ b/srsapps/ue/phy/include/srsapps/ue/phy/prach.h
@@ -56,11 +56,11 @@ namespace ue {
     bool           send(srslte::radio* radio_handler, float cfo, srslte_timestamp_t rx_time);
   private: 
     static const uint32_t tx_advance_sf = 1; // Number of subframes to advance transmission
-    phy_params    *params_db     = NULL; 
+    phy_params    *params_db; 
     log           *log_h; 
     int            preamble_idx;  
     int            allowed_subframe; 
-    bool           initiated     = false;   
+    bool           initiated;   
     uint32_t       len; 
     cf_t          *buffer[64]; 
     srslte_prach_t prach_obj; 
diff --git a/srsapps/ue/phy/src/dl_buffer.cc b/srsapps/ue/phy/src/dl_buffer.cc
index d3379862f..de2aa8734 100644
--- a/srsapps/ue/phy/src/dl_buffer.cc
+++ b/srsapps/ue/phy/src/dl_buffer.cc
@@ -116,15 +116,16 @@ bool dl_buffer::get_ul_grant(ul_sched_grant *grant)
       if (srslte_ue_dl_find_ul_dci(&ue_dl, &dci_msg, cfi, tti%10, grant->get_rnti()) != 1) {
         return false; 
       }
-      /*
+      
       grant->set_shortened(false);
       if (params_db->get_param(phy_params::SRS_IS_CS_CONFIGURED)) {
-        if (srslte_refsignal_srs_send_cs((uint32_t) params_db->get_param(phy_params::SRS_CS_SFCFG), tti%10) == 1) {
+        if (srslte_refsignal_srs_send_cs((uint32_t) params_db->get_param(phy_params::SRS_CS_SFCFG), (tti+4)%10) == 1) {
           grant->set_shortened(true);
-          printf("UL grant tti=%d is shortened. SF-CFG=%d\n", tti, (int) params_db->get_param(phy_params::SRS_CS_SFCFG));
+          printf("UL grant tti=%d is shortened. SF-CFG=%d\n", tti+4, 
+                 (int) params_db->get_param(phy_params::SRS_CS_SFCFG));
         }
       }
-      */
+      
       return grant->create_from_dci(&dci_msg, cell, params_db->get_param(phy_params::PUSCH_HOPPING_OFFSET));     
     }      
   }
diff --git a/srsapps/ue/phy/src/phy.cc b/srsapps/ue/phy/src/phy.cc
index fd6449311..ea05abfa0 100644
--- a/srsapps/ue/phy/src/phy.cc
+++ b/srsapps/ue/phy/src/phy.cc
@@ -43,7 +43,7 @@
 namespace srslte {
 namespace ue {
 
-phy::phy()
+phy::phy() : tr_end_time(1024*10), tr_start_time(1024*10)
 {
   started = false; 
   is_sfn_synched = false; 
@@ -59,6 +59,30 @@ bool phy::init_agc(srslte::radio* radio_handler_, srslte::ue::tti_sync* ttisync_
   return init_(radio_handler_, ttisync_, log_h, true);
 }
 
+void phy::start_trace()
+{
+  tr_enabled = true; 
+}
+
+void phy::write_trace(std::string filename)
+{
+  tr_start_time.writeToBinary(filename + ".start");
+  tr_end_time.writeToBinary(filename + ".end");
+}
+
+void phy::tr_log_start()
+{
+  if (tr_enabled) {
+    tr_start_time.push_cur_time_us(get_current_tti());
+  }
+}
+
+void phy::tr_log_end()
+{
+  if (tr_enabled) {
+    tr_end_time.push_cur_time_us(get_current_tti());
+  }
+}
 
 bool phy::init_(srslte::radio* radio_handler_, srslte::ue::tti_sync* ttisync_, log *log_h_, bool do_agc_)
 {
@@ -314,7 +338,7 @@ bool phy::init_prach() {
 
 ul_buffer* phy::get_ul_buffer(uint32_t tti)
 {
-  if (tti + 1 < get_current_tti()) {
+  if ((tti + 1)%10240 < get_current_tti() && tti > 6) {
     Warning("Warning access to PHY UL buffer too late. Requested TTI=%d while PHY is in %d\n", tti, get_current_tti());
   }
   return (ul_buffer*) ul_buffer_queue->get(tti);        
@@ -524,8 +548,9 @@ void phy::run_rx_tx_state()
     }
     
     // Receive alligned buffer for the current tti 
+    tr_log_end();
     get_dl_buffer(current_tti)->recv_ue_sync(&ue_sync, &last_rx_time);
-
+    tr_log_start();
     ttisync->increase();      
   }
 }
diff --git a/srslte/include/srslte/common/timestamp.h b/srslte/include/srslte/common/timestamp.h
index bc39f2c6a..7c4a98e45 100644
--- a/srslte/include/srslte/common/timestamp.h
+++ b/srslte/include/srslte/common/timestamp.h
@@ -39,6 +39,7 @@
 #define TIMESTAMP_
 
 #include <time.h>
+#include <stdint.h>
 #include "srslte/config.h"
 
 typedef struct SRSLTE_API{
@@ -63,4 +64,6 @@ SRSLTE_API int srslte_timestamp_sub(srslte_timestamp_t *t,
 
 SRSLTE_API double srslte_timestamp_real(srslte_timestamp_t *t);
 
+SRSLTE_API uint32_t srslte_timestamp_uint32(srslte_timestamp_t *t);
+
 #endif // TIMESTAMP_
diff --git a/srslte/lib/common/src/timestamp.c b/srslte/lib/common/src/timestamp.c
index 161f5cffa..670818979 100644
--- a/srslte/lib/common/src/timestamp.c
+++ b/srslte/lib/common/src/timestamp.c
@@ -80,3 +80,8 @@ int srslte_timestamp_sub(srslte_timestamp_t *t, time_t full_secs, double frac_se
 double srslte_timestamp_real(srslte_timestamp_t *t){
  return t->frac_secs + t->full_secs;
 }
+
+uint32_t srslte_timestamp_uint32(srslte_timestamp_t *t){
+ uint32_t x = t->full_secs*1e6 + (uint32_t) (t->frac_secs*1e6);
+ return x; 
+}