diff --git a/src/util/rtt-estimator.cpp b/src/util/rtt-estimator.cpp
new file mode 100644
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+++ b/src/util/rtt-estimator.cpp
@@ -0,0 +1,80 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (C) 2016-2018, Arizona Board of Regents.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ *
+ * @author Shuo Yang
+ * @author Weiwei Liu
+ * @author Chavoosh Ghasemi
+ */
+
+#include "rtt-estimator.hpp"
+
+#include <cmath>
+#include <limits>
+
+namespace ndn {
+namespace util {
+
+RttEstimator::RttEstimator(const Options& options)
+  : m_options(options)
+  , m_sRtt(std::numeric_limits<double>::quiet_NaN())
+  , m_rttVar(std::numeric_limits<double>::quiet_NaN())
+  , m_rto(m_options.initialRto.count())
+  , m_rttMin(std::numeric_limits<double>::max())
+  , m_rttMax(std::numeric_limits<double>::min())
+  , m_rttAvg(0.0)
+  , m_nRttSamples(0)
+{
+}
+
+void
+RttEstimator::addMeasurement(MillisecondsDouble rtt, size_t nExpectedSamples)
+{
+  BOOST_ASSERT(nExpectedSamples > 0);
+
+  if (m_nRttSamples == 0) { // first measurement
+    m_sRtt = rtt;
+    m_rttVar = m_sRtt / 2;
+    m_rto = m_sRtt + m_options.k * m_rttVar;
+  }
+  else {
+    double alpha = m_options.alpha / nExpectedSamples;
+    double beta = m_options.beta / nExpectedSamples;
+    m_rttVar = (1 - beta) * m_rttVar + beta * time::abs(m_sRtt - rtt);
+    m_sRtt = (1 - alpha) * m_sRtt + alpha * rtt;
+    m_rto = m_sRtt + m_options.k * m_rttVar;
+  }
+
+  m_rto = clamp(m_rto, m_options.minRto, m_options.maxRto);
+
+  m_rttAvg = MillisecondsDouble((m_nRttSamples * m_rttAvg.count() + rtt.count()) / (m_nRttSamples + 1));
+  m_rttMax = std::max<MillisecondsDouble>(rtt, m_rttMax);
+  m_rttMin = std::min<MillisecondsDouble>(rtt, m_rttMin);
+  m_nRttSamples++;
+}
+
+void
+RttEstimator::backoffRto()
+{
+  m_rto = clamp(m_rto * m_options.rtoBackoffMultiplier,
+                m_options.minRto, m_options.maxRto);
+}
+
+} // namespace util
+} // namespace ndn