Agoston Petz

Network coded routing in delay tolerant networks: an experience report

In delay-tolerant networks, end-to-end routes are rarely available, and routing protocols must take advantage of the opportunistic interactions among nodes to deliver packets. Probabilistic routing performs well in such networks and has been the dominant focus of research in this area. However, creating efficient routing protocols is challenging because to reduce latency, one often needs to replicate messages thus increasing routing overhead. Network coding has been explored as a way to increase throughput in DTNs without a significant increase in overhead, and network coded routing approaches have shown promising results. In this paper, we report on our experience integrating both erasure coded and network coded routing into the well-adopted DTN2 Reference Implementation. We implement our routing module and evaluate it via small real-world field tests.

An adaptive middleware to support delay tolerant networking

Delay Tolerant Networks are emerging as a new form of network in which sending and receiving nodes may not be reliably connected to each other in a traditional sense but must instead rely on mobile nodes to ferry messages through the network. Applications operating in these dynamic mixed environments would like their connections to be supported by the network technology best suited to the combination of the communication sessions requirements and instantaneous network context. In this paper, we explore the systems issues related to enabling such a symbiotic network architecture. We develop an adaptive middleware that enables connections to seamlessly migrate from one communication style to another in response to changing network or application conditions. We delineate the properties of the middleware architecture, describe an initial implementation, and provide a simulation analysis that demonstrates that, given perfect context-awareness, significant performance improvements can be made by using such an adaptive middleware.

Rethinking Context for Pervasive Computing: Adaptive Shared Perspectives

Mobile and pervasive computing applications depend on environmental awareness, not just of their own local system and immediate surroundings, but increasingly of the network as a whole. Traditional models of context do not sufficiently account for the trade-off between accuracy, availability, and efficiency when considering the mechanisms by which context can be gathered and shared in mobile, ad-hoc networks. Traditional approaches to context remain egocentric, but next generation environments demand coordination among entities and access to shared context resources, and thus context must be treated as a combination of local and shared information. We motivate our perspective on the future of context in mobile pervasive environments staring with historical framing of the problem, and present our recent efforts in adaptive shared context perspectives.

Passive network-awareness for dynamic resource-constrained networks

As computing becomes increasingly mobile, the demand for information about the environment, or context, becomes of significant importance. Applications must adapt to the changing environment, however acquiring the necessary context information can be very expensive because collecting it usually requires communication among devices. We explore collecting reasonably accurate context information passively by defining passively sensed context through network overhearing, defining context metrics without added communication cost. We use this framework to build a small suite of commonly used context metrics and evaluate the quality with which they can reflect ground truth using simulation. We also provide an implementation of this passive sensing framework for Linux, which we evaluate on a real mobile ad-hoc network using mobile autonomous robots with commodity 802.11 b/g wireless cards.