  Assessing mobility in a thorough fashion is a crucial step toward more
efficient mobile network design. Recent research on mobility has focused on two
main points: analyzing models and studying their impact on data transport.
These works investigate the consequences of mobility. In this paper, instead,
we focus on the causes of mobility. Starting from established research in
sociology, we propose SIMPS, a mobility model of human crowd motion. This model
defines two complimentary behaviors, namely socialize and isolate, that
regulate an individual with regard to her/his own sociability level. SIMPS
leads to results that agree with scaling laws observed both in small-scale and
large-scale human motion. Although our model defines only two simple individual
behaviors, we observe many emerging collective behaviors (group
formation/splitting, path formation, and evolution). To our knowledge, SIMPS is
the first model in the networking community that tackles the roots governing
mobility.
