A mobility gateway for small-device networks

Networks of small devices, such as environmental sensors, introduce a number of new challenges for traditional protocols and approaches. In particular, the extreme resource constraints characteristics of these devices force the engineering of device and application-specific optimizations in order to reduce complexity. By offloading some, if not most, of the complexity out of the small device and into the network, we simplify the design of individual devices, and may make otherwise infeasible applications possible. We look specifically at the problem of global mobility, and its associated protocol Mobile IP (MIP). We introduce the mobility gateway which performs MIP processing on behalf of registered devices. The mobility gateway provides an interface between the optimized world of small devices and the larger Internet. Through simulation, we investigate the potential savings offered by this technique in terms of bandwidth and power. In a sample scenario, we find the total number of bytes transmitted over the wireless channel reduced by as much as 70%, and the battery life of the device extended by more than 100 hours.