  We present a study on human mobility at small spatial scales. Differently
from large scale mobility, recently studied through dollar-bill tracking and
mobile phone data sets within one big country or continent, we report Brownian
features of human mobility at smaller scales. In particular, the scaling
exponents found at the smallest scales is typically close to one-half,
differently from the larger values for the exponent characterizing mobility at
larger scales. We carefully analyze $12$-month data of the Eduroam database
within the Portuguese university of Minho. A full procedure is introduced with
the aim of properly characterizing the human mobility within the network of
access points composing the wireless system of the university. In particular,
measures of flux are introduced for estimating a distance between access
points. This distance is typically non-euclidean, since the spatial constraints
at such small scales distort the continuum space on which human mobility
occurs. Since two different exponents are found depending on the scale human
motion takes place, we raise the question at which scale the transition from
Brownian to non-Brownian motion takes place. In this context, we discuss how
the numerical approach can be extended to larger scales, using the full Eduroam
in Europe and in Asia, for uncovering the transition between both dynamical
regimes.
