Today’s smartphone not only serves as the key
computing and communication mobile device of
choice, but it also comes with a rich set of
embedded sensors, such as an accelerometer,
digital compass, gyroscope, GPS, microphone,
and camera. Collectively, these sensors are
enabling new applications across a wide variety
of domains, such as healthcare [1], social networks
[2], safety, environmental monitoring [3],
and transportation [4, 5], and give rise to a new
area of research called mobile phone sensing.