diff --git a/gnss/2.1/default/GnssMeasurement.cpp b/gnss/2.1/default/GnssMeasurement.cpp
new file mode 100644
index 0000000..ebfa7dd
--- /dev/null
+++ b/gnss/2.1/default/GnssMeasurement.cpp
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "GnssMeasurement"
+
+#include "GnssMeasurement.h"
+#include <log/log.h>
+#include "Utils.h"
+
+namespace android {
+namespace hardware {
+namespace gnss {
+
+using common::Utils;
+
+namespace V2_1 {
+namespace implementation {
+
+sp<V2_1::IGnssMeasurementCallback> GnssMeasurement::sCallback = nullptr;
+
+GnssMeasurement::GnssMeasurement() : mMinIntervalMillis(1000) {}
+
+GnssMeasurement::~GnssMeasurement() {
+    stop();
+}
+
+// Methods from V1_0::IGnssMeasurement follow.
+Return<V1_0::IGnssMeasurement::GnssMeasurementStatus> GnssMeasurement::setCallback(
+        const sp<V1_0::IGnssMeasurementCallback>&) {
+    // TODO implement
+    return V1_0::IGnssMeasurement::GnssMeasurementStatus{};
+}
+
+Return<void> GnssMeasurement::close() {
+    ALOGD("close");
+    std::unique_lock<std::mutex> lock(mMutex);
+    stop();
+    sCallback = nullptr;
+    return Void();
+}
+
+// Methods from V1_1::IGnssMeasurement follow.
+Return<V1_0::IGnssMeasurement::GnssMeasurementStatus> GnssMeasurement::setCallback_1_1(
+        const sp<V1_1::IGnssMeasurementCallback>&, bool) {
+    // TODO implement
+    return V1_0::IGnssMeasurement::GnssMeasurementStatus{};
+}
+
+// Methods from V2_0::IGnssMeasurement follow.
+Return<V1_0::IGnssMeasurement::GnssMeasurementStatus> GnssMeasurement::setCallback_2_0(
+        const sp<V2_0::IGnssMeasurementCallback>&, bool) {
+    // TODO implement
+    return V1_0::IGnssMeasurement::GnssMeasurementStatus{};
+}
+
+// Methods from V2_1::IGnssMeasurement follow.
+Return<V1_0::IGnssMeasurement::GnssMeasurementStatus> GnssMeasurement::setCallback_2_1(
+        const sp<V2_1::IGnssMeasurementCallback>& callback, bool) {
+    ALOGD("setCallback_2_1");
+    std::unique_lock<std::mutex> lock(mMutex);
+    sCallback = callback;
+
+    if (mIsActive) {
+        ALOGW("GnssMeasurement callback already set. Resetting the callback...");
+        stop();
+    }
+    start();
+
+    return V1_0::IGnssMeasurement::GnssMeasurementStatus::SUCCESS;
+}
+
+void GnssMeasurement::start() {
+    ALOGD("start");
+    mIsActive = true;
+    mThread = std::thread([this]() {
+        while (mIsActive == true) {
+            auto measurement = Utils::getMockMeasurementV2_1();
+            this->reportMeasurement(measurement);
+
+            std::this_thread::sleep_for(std::chrono::milliseconds(mMinIntervalMillis));
+        }
+    });
+}
+
+void GnssMeasurement::stop() {
+    ALOGD("stop");
+    mIsActive = false;
+    if (mThread.joinable()) {
+        mThread.join();
+    }
+}
+
+void GnssMeasurement::reportMeasurement(const GnssDataV2_1& data) {
+    ALOGD("reportMeasurement()");
+    std::unique_lock<std::mutex> lock(mMutex);
+    if (sCallback == nullptr) {
+        ALOGE("%s: GnssMeasurement::sCallback is null.", __func__);
+        return;
+    }
+    auto ret = sCallback->gnssMeasurementCb_2_1(data);
+    if (!ret.isOk()) {
+        ALOGE("%s: Unable to invoke callback", __func__);
+    }
+}
+
+}  // namespace implementation
+}  // namespace V2_1
+}  // namespace gnss
+}  // namespace hardware
+}  // namespace android