Design Considerations for a Mobile Testbed∗

Today’s cellular technologies allow users to access the Internet in a car or on a high-speed train, albeit the access bandwidth is far lower than that through a typical wired access technology such as Ethernet. Numerous new applications and services are under development for users of wireless technologies. Locationbased services (e.g, GPS navigation) and streaming media services are just two examples from the vast set of candidate applications and services. Not only researchers, but application and service developers could benefit from a testbed where they could experiment with mobility in the network. A typical testbed for a mobile wireless technology has no mobile component in it. Notable exceptions are: mobile Emulab [6] and DOME [1]. Mobile Emulab consists of mobile robots mounted with an 802.11 interface in a confined indoor setting. It offers 1 cm accuracy in robot maneuvering and location reporting. Mobile Emulab has the same access policy as Emulab: users request and are granted fixed resources in advance [9]. DOME (Diverse Outdoor Mobile Environment) has multiple DTN (Disruption Tolerant Networking) testbeds. One of them, DieselNet, consists of computers that are mounted on buses and have multiple radio interfaces. They connect with computers on other buses or scan for DHCP (Dynamic Host Configuration Protocol) offers. Another DTN in DOME is TurtleNet, which actually has Wood turtles as the carrying medium of sensors. These sensors monitor the turtles’ behavior and habitats, and upload the data whenever the turtles pass by the collection post. While Mobile Emulab is open for public access, all networks in DOME are for special-purpose. The limited number of mobile testbeds is a clear demonstration of difficulties in building and maintaining a mobile testbed. A mobile testbed poses chal-