check the mobility of mobile phone by accelerometer sensor

For every new accelerometer sample, we compute the

standard deviation of the magnitude of the acceleration

over a sliding window (w) of samples. The window slides

by one sample for each computation. If the standard de-

viation in a window exceeds a threshold (a), we detect

movement. When the standard deviation is within the

threshold for n successive sliding windows, we report

that the node is stationary.

We experimented with many values for w, a, and n and

determined that w = 5, a = 0.15 m/s2, and n = 10 gave

us few false hints.