Internet access for mobile users: From drive-thru internet to delay-tolerant ad-hoc networking

When human users become really mobile and do not want to worry about when and how they are connected, mobile access to Internet services exhibits characteristics of ad-hoc networking in at least two ways: Firstly, infrastructure-based network connectivity becomes unpredictable with respect to occurrance and loss, duration, and performance so that opportunistic exploitation of even short-lived connectivity may be needed to satisfy user demands. Secondly, in the absence of immediately accessible network infrastructure, ad-hoc networking techniques are required to reach the next access point or peer user. In this chapter, we start by exploring the former style of networking to address mobile Internet access in the short-term as we have done in the Drive-thru Internet project. We then expand our scope and discuss more fundamental changes in mobile Internet access when applying the asynchronous communication paradigm of Delay-tolerant Networking (DTN) to improve communication capabilities in mobile and thus potentially disruptive environments. We observe that many typical mobile applications are basically suitable for ad-hoc operation in mobile enivonments, assuming proper support by their user interfaces. However, the application protocols are often overly restrictive and their (sometimes complex) adaptation to enable disconnected and delay-tolerant operation incurs some performance degradation, which may be addressed in the future by following some general protocol design rules.