| Abstract: | Physical human mobility has played an important role in the design and operation of mobile networks. Physical mobility, however, differs from mobility from a network or network-addressing perspective. A physically mobile user may be stationary (i.e., maintain its network address) from a network point of view, while a physically stationary multi-homed or multi-device user may transition among different access networks, possibly maintaining multiple contemporaneous connections to different networks. We perform a measurement study of such user transitioning among networks from a network-level point of view, characterizing the sequence of access networks to which a user is attached and from which it obtains its routable IP address, and discuss insights and implications drawn from these measurements. We characterize network transitioning in terms of network residency time, degree of multi-homing, transition rates and more. We find that users typically spend time attached to a small number of access networks, and that a surprisingly large number of users access two networks contemporaneously. We also develop and validate a parsimonious Markov chain model of canonical user transitioning among networks that can be used to provision network services and to analyze mobility protocols. |
