A Cell-Based Distributed Location Management Protocol for Cell-Hopping Networks

We consider the problem of location management in cell-hopping networks, where the only infrastructure used for routing and switching user data is a set of ad-hoc basestations owned by small individual operators. Such networks do not have any reliable fixed infrastructure to host central or distributed location register databases. We propose a novel location management protocol, which obviates the need for location register database. The location of a mobile node can be determined by a simple two step process. The originating base station first broadcasts a location query message to all basestations in the area, and the basestation serving the mobile terminal in question responds to the originating basestation with a unicast reply message. Mean locating time as a function of coverage area for hexagonal cellular topology is obtained through an approximate analysis, which remains within 5% of exact solutions for large coverage areas. Our analysis reveals that locating time increases slower than linearly as a function of coverage area. We also conduct discrete event simulation of a 7-cell hexagonal topology with mobility patterns, representing pedestrian, suburban driving, and highway driving. A close match between simulation and analytical results confirm the validity of our analysis. Simulation results also confirm our intuition that speed of mobile node has no impact on locating time, but higher speed slightly increases the probability of not finding a mobile node in the destination cell even after a successful location resolution (misrouting).