Robert S. Gray

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All analytical and simulation research on ad~hoc wireless networks must necessarily model radio propagation using simplifying assumptions. We provide a comprehensive review of six assumptions that are still part of many ad hoc network simulation studies, despite increasing awareness of the need to represent more realistic features, including hills,(More)
Agent Tcl is a transportable-agent system that is under development at Dartmouth College. A transportable agent is a named program that can migrate from machine to machine in a heterogeneous network. Such programs are a powerful tool for implementing information agents since the electronic resources in a user's information space are often distributed across(More)
A mobile agent is an autonomous program that can migrate under its own control from machine to machine in a heterogeneous network. In other words, the program can suspend its execution at an arbitrary point, transport itself to another machine, and then resume execution from the point of suspension. Mobile agents have the potential to provide a single,(More)
Mobile-agent systems must address three security issues: protecting an individual machine, protecting a group of machines, and protecting an agent. In this chapter, we discuss these three issues in the context of D’Agents, a mobile-agent system whose agents can be written in Tcl, Java and Scheme. (D’Agents was formerly known as Agent Tcl.) First we discuss(More)
An information agent manages all or a portion of a user's information space. The electronic resources in this space are often distributed across a network and can contain tremendous quantities of data. Mobile agents provide e cient access to such resources and are a powerful tool for implementing information agents. A mobile agent is an autonomous program(More)
D’Agents is a general-purpose mobile-agent system that has been used in several informationretrieval applications. In this paper, we first examine one such application, operational support for military field personnel, where D’Agents greatly simplifies the task of providing efficient, applicationspecific access to remote information resources. After(More)
Use of the Internet has exploded in recent years with the appearance of the World-Wide Web. In this paper, we show how current technological trends may lead to a system based substantially on mobile code, and in many cases, mobile agents. We discuss several technical and non-technical hurdles along the path to that eventuality. It seems likely that, within(More)
Computer simulation is the most common approach to studying wireless ad-hoc routing algorithms. The results, however, are only as good as the models the simulation uses. One should not underestimate the importance of <i>validation</i>, as inaccurate models can lead to wrong conclusions. In this paper, we use direct-execution simulation to validate radio(More)