Towards pervasive connectivity in mobile computing settings

Abstract

Pervasive computing scenarios often assume pervasive connectivity. Yet, because of different communication technologies that are integrated into different devices (e.g., IrDA or Bluetooth), because of different high-level communication protocols (e.g., IPv4 vs. IPv6), and because of security and networking constraints (e.g., firewalls and NATs) pervasive connectivity is an illusion in most real-world environments. This is especially true for scenarios involving mobile users because there is no prior knowledge about the devices and users present. This paper presents a novel approach for dealing with these connectivity restrictions in environments where groups of people need to cooperate with each other in an ad-hoc fashion. The core idea is to establish an overlay among group members that is used to share information about the current network environment. This information is conveyed in the form of dynamically generated tag sequences that are displayed and captured by the digital cameras integrated into an increasing number of mobile devices. Users who want to invite others to a group invoke an application that displays multiple, dynamically generated tags on their mobile device's screen. People, who want to join the group, then point the camera integrated into their handheld devices to the other device's screen. Thus, the displayed tag sequence is captured and decoded in real time; and the information contained therein can be used to securely and robustly join the group. By transmitting information about the group, group participants, and communication parameters within a sequence of tags, it is possible to provide ad-hoc connectivity in various mobile computing settings.