On the symmetry of user mobility in wireless networks

In this paper analyzed WLAN-, GPS-, and synthetic traces that record mobility in a variety of network environments. We observe that from a macroscopic level, human mobility is symmetric. In other words, the number of users that move from point A to point B approximates the number of users that go in the opposite direction, i.e., from B to A. We show that this type of symmetry is more accentuated in synthetic mobility models, in particular, in random way-point mobility. We also study the direction of movement which also exhibits symmetric behavior in both real- as well as synthetic mobility. Additional contributions of our work include metrics to quantify mobility symmetry. We conclude the paper with a discussion of possible applications of our results in mobile networking.