WiFi bridge: wireless mobility framework supporting session continuity

Seamless mobility is a requirement whose importance for Internet users nowadays is growing faster than ever Thus many solutions to manage wireless IP mobile access and inter-working with the fixed Internet are already available and more are currently being studied and improved In this paper we described an actual wireless mobility framework we designed and implemented in our university campus, which is spread over a wide metropolitan area. The aim is to let a mobile host, that is a user equipped i.e. with a PDA device, experience real wireless IP mobility while moving on a large spatial scale, by means of a middleware that leverages from three main wireless access technologies: Bluetooth, WiFi and GPRS. In our framework, these are managed as a hierarch), of spatially overlapping access domains. While the user is on the move, the client-side of the middleware running on our mobile PDA device triggers smart switchings between the currently best available and more appropriate wireless access path, based on locally collected information. On the other hand, the network-side part of the middleware manages mobile host location paging and routing-update functions inside the whole campus area with an approach which extends from the Cellular IP micromobility protocol. We call this approach WiFi bridge since it also adds mobile hosts with the capability to seamlessly travel between disjunct WiFi access domains inside the campus by means of a temporary relay onto the GPRS access domain. We implemented and tested the system in a real testbed using IPaq devices running Linux, obtaining encouraging experimental results.