diff --git a/include/autoware_v2x/cpm_application.hpp b/include/autoware_v2x/cpm_application.hpp
index c9183d0..c11c5ed 100644
--- a/include/autoware_v2x/cpm_application.hpp
+++ b/include/autoware_v2x/cpm_application.hpp
@@ -24,7 +24,7 @@ namespace v2x
         void updateObjectsList(const autoware_auto_perception_msgs::msg::PredictedObjects::ConstSharedPtr);
         void updateMGRS(double *, double *);
         void updateRP(double *, double *, double *);
-        void updateGenerationDeltaTime(int *, long long *);
+        void updateGenerationTime(int *, long *);
         void updateHeading(double *);
         void printObjectsList(int);
         void send();
@@ -92,8 +92,8 @@ namespace v2x
 
         Ego_station ego_;
         
-        int generationDeltaTime_;
-        long long gdt_timestamp_;
+        int generationTime_;
+        long gdt_timestamp_;
 
         double objectConfidenceThreshold_;
 
diff --git a/src/cpm_application.cpp b/src/cpm_application.cpp
index 0a89efe..53568a5 100644
--- a/src/cpm_application.cpp
+++ b/src/cpm_application.cpp
@@ -36,7 +36,7 @@ namespace v2x {
     node_(node),
     runtime_(rt),
     ego_(),
-    generationDeltaTime_(0),
+    generationTime_(0),
     updating_objects_list_(false),
     sending_(false),
     is_sender_(is_sender),
@@ -101,10 +101,10 @@ namespace v2x {
 
 
       // Calculate GDT and get GDT from CPM and calculate the "Age of CPM"
-      GenerationDeltaTime_t gdt_cpm = message->cpm.generationDeltaTime;
-      const auto time_now = duration_cast<milliseconds> (runtime_.now().time_since_epoch());
-      uint16_t gdt = time_now.count();
-      int gdt_diff = (65536 + (gdt - gdt_cpm) % 65536) % 65536;
+      TimestampIts_t gt_cpm = message->cpm.generationTime;
+      // const auto time_now = duration_cast<milliseconds> (runtime_.now().time_since_epoch());
+      // uint16_t gdt = time_now.count();
+      // int gdt_diff = (65536 + (gdt - gdt_cpm) % 65536) % 65536;
       // RCLCPP_INFO(node_->get_logger(), "[CpmApplication::indicate] [measure] GDT_CPM: %ld", gdt_cpm);
       // RCLCPP_INFO(node_->get_logger(), "[CpmApplication::indicate] [measure] GDT: %u", gdt);
       // RCLCPP_INFO(node_->get_logger(), "[CpmApplication::indicate] [measure] T_R1R2: %d", gdt_diff);
@@ -218,8 +218,8 @@ namespace v2x {
     ego_.altitude = *altitude;
   }
 
-  void CpmApplication::updateGenerationDeltaTime(int *gdt, long long *gdt_timestamp) {
-    generationDeltaTime_ = *gdt;
+  void CpmApplication::updateGenerationTime(int *gdt, long *gdt_timestamp) {
+    generationTime_ = *gdt;
     gdt_timestamp_ = *gdt_timestamp; // ETSI-epoch milliseconds timestamp
   }
 
@@ -458,8 +458,9 @@ namespace v2x {
 
       CollectivePerceptionMessage_t &cpm = message->cpm;
 
-      // Set GenerationDeltaTime
-      cpm.generationDeltaTime = generationDeltaTime_ * GenerationDeltaTime_oneMilliSec;
+      // Set GenerationTime
+      RCLCPP_INFO(node_->get_logger(), "[CpmApplication::send] %ld", gdt_timestamp_);
+      asn_long2INTEGER(&cpm.generationTime, (long) gdt_timestamp_);
 
       CpmManagementContainer_t &management = cpm.cpmParameters.managementContainer;
       management.stationType = StationType_passengerCar;
diff --git a/src/v2x_app.cpp b/src/v2x_app.cpp
index 0eaf010..c687bc7 100644
--- a/src/v2x_app.cpp
+++ b/src/v2x_app.cpp
@@ -54,10 +54,10 @@ namespace v2x
     double y = msg->transforms[0].transform.translation.y;
     double z = msg->transforms[0].transform.translation.z;
 
-    long long timestamp_sec = msg->transforms[0].header.stamp.sec; // seconds
-    long long timestamp_nsec = msg->transforms[0].header.stamp.nanosec; // nanoseconds
+    long timestamp_sec = msg->transforms[0].header.stamp.sec; // seconds
+    long timestamp_nsec = msg->transforms[0].header.stamp.nanosec; // nanoseconds
     timestamp_sec -= 1072915200; // convert to etsi-epoch
-    long long timestamp_msec = timestamp_sec * 1000 + timestamp_nsec / 1000000;
+    long timestamp_msec = timestamp_sec * 1000 + timestamp_nsec / 1000000;
     int gdt = timestamp_msec % 65536;
 
     double rot_x = msg->transforms[0].transform.rotation.x;
@@ -92,7 +92,7 @@ namespace v2x
       cp->updateMGRS(&x, &y);
       cp->updateRP(&lat, &lon, &z);
       cp->updateHeading(&yaw);
-      cp->updateGenerationDeltaTime(&gdt, &timestamp_msec);
+      cp->updateGenerationTime(&gdt, &timestamp_msec);
     }
   }