diff --git a/openair1/PHY/defs_UE.h b/openair1/PHY/defs_UE.h
index 0a4bd36731..d6da512e9a 100755
--- a/openair1/PHY/defs_UE.h
+++ b/openair1/PHY/defs_UE.h
@@ -204,6 +204,12 @@ typedef struct {
 	/// condition variable for timer_thread;
 	pthread_cond_t cond_ticking;
 	//time_stats_t timer_stats;
+
+	// below 3 members is used for waiting each UE threads(multiple UEs test) in L2 FAPI simulator.
+	// This used in UE_phy_stub_single_thread_rxn_txnp4
+	pthread_mutex_t mutex_single_thread;
+	pthread_cond_t  cond_single_thread;
+	int             num_single_thread[NUMBER_OF_UE_MAX];
 } SF_ticking;
 
 typedef struct {
diff --git a/openair2/PHY_INTERFACE/IF_Module.h b/openair2/PHY_INTERFACE/IF_Module.h
old mode 100644
new mode 100755
index 0390a90551..f89fcda568
--- a/openair2/PHY_INTERFACE/IF_Module.h
+++ b/openair2/PHY_INTERFACE/IF_Module.h
@@ -128,6 +128,17 @@ typedef struct IF_Module_s{
   pthread_mutex_t if_mutex;
 }IF_Module_t;
 
+// These mutex is used for multiple UEs L2 FAPI simulator.
+// Each UEs set these value in UL and UL_INFO is shared in all UE's thread.
+typedef struct {
+  pthread_mutex_t rx_mutex;
+  pthread_mutex_t crc_mutex;
+  pthread_mutex_t sr_mutex;
+  pthread_mutex_t harq_mutex;
+  pthread_mutex_t cqi_mutex;
+  pthread_mutex_t rach_mutex;
+}FILL_UL_INFO_MUTEX_t;
+
 /*Initial */
 IF_Module_t *IF_Module_init(int Mod_id);
 void IF_Module_kill(int Mod_id);
diff --git a/openair2/PHY_INTERFACE/phy_stub_UE.h b/openair2/PHY_INTERFACE/phy_stub_UE.h
old mode 100644
new mode 100755
index 9060951b26..1afb82add3
--- a/openair2/PHY_INTERFACE/phy_stub_UE.h
+++ b/openair2/PHY_INTERFACE/phy_stub_UE.h
@@ -17,6 +17,9 @@
 //#include "openair1/PHY/defs.h"
 //#include "openair1/PHY/LTE_TRANSPORT/defs.h"
 
+// this mutex is used to set multiple UE's UL value in L2 FAPI simulator.
+FILL_UL_INFO_MUTEX_t fill_ul_mutex;
+
 UL_IND_t *UL_INFO;
 
 nfapi_tx_request_pdu_t* tx_request_pdu_list;