Tetherless Communication Architecture

Abstract

In the emerging paradigm of tetherless computing, client applications running on small, inexpensive, and smart mobile devices maintain opportunistic wireless connectivity with back-end services running on centralized computers, enabling novel classes of applications. These applications require a communications infrastructure that is mobility-aware, disconnection-resilient and provides sup- port for an opportunistic style of communication. It should even be able to function across network partitions that might arise when end-to-end communication is not possible. We outline, design, and evaluate the implementation of an architecture that provides this functionality.

Overview

In the emerging paradigm of tetherless computing, client applications running on small, inexpensive, and intelligent mobile devices maintain opportunistic wireless connectivity with back-end services running on central- ized computers, enabling novel classes of applications that can address problems ranging from rural development, to environmental monitoring, healthcare and education. For instance:

• A bus carrying an 802.11 access point can wirelessly pick up data as it drives past rural areas that are far from Internet connectivity. Later, the bus can forward the data to the Internet when it passes an Internet-connected wireless hot spot. Symmetrically, the bus may also deliver data to an otherwise disconnected endpoint as it drives past.

• A health care provider can record vitals and test results of home-care patients in a mobile device. When driving past an access point, this information can be relayed to a central database for archiving and also sent to the attending physician for follow-up diagnosis. Symmetrically, instructions for patient care can be given to the provider during this opportunistic contact.

• Solar- or wind-powered sensors in remote areas can collect and store data at a base station, and this data can be picked up by vehicle driving past, or an aircraft flying overhead. This would be both efficient and costeffective, for instance, in monitoring ground-water or stream contamination in remote or rural watersheds.

In these examples, an edge application client opportunistically and wirelessly communicates with a mobile router (also called a ’ferry’ or ’data mule’) that carries data to and from a centralized server. This is the basic building block for tetherless communication.

For more details of our solution, please refer to: A. Seth, P. Darragh, S. Liang, Y. Lin, and S. Keshav, An Architecture for Tetherless Communication (http://blizzard.cs.uwaterloo.ca/keshav/home/Papers/data/05/tca.pdf), Manuscript, July 2005.