Browsing by Author "Harras, Khaled A."

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Exploiting Parallel Networks Using Dynamic Channel Scheduling
(Wireless Internet Conference (WICON), 2008-11) Deek, Lara B.; Almeroth, Kevin C.; Wittie, Mike P.; Harras, Khaled A.
Many researchers have been focusing on the outcomes and consequences of the rapid increase and proliferation of mobile wireless technologies. If it is not already the case, it will soon be rare for a user to be in a situation where absolutely no network connection exists. In fact, through numerous devices, users will soon expect to be connected in all places at all times. Through the great variety and increase in the capabilities of these devices, it is not a surprise to find a single user with many connection opportunities. As a result, we believe that the next major evolution of wireless mobile networks will be in the exploitation of multiple network connections in parallel. Due to network heterogeneity, the major challenge in such situations is to determine the way that these networks can be utilized to better serve different network applications. In this work, we propose a dynamic channel scheduling mechanism that adapts to the state of the available channels to provide more efficient usage of network connectivity. We do so by observing channel throughput, creating a set of channel usage combinations, and then choosing the most efficient combination. We evaluate an implementation of the proposed mechanism using emulation. Our results show that under realistic conditions our dynamic approach greatly improves cost delay metrics, and the overall user-perceived performance compared to a more static approach.
On The Implications of Routing Metric Staleness in Delay Tolerant Networks
(Elsevier, 2009) Wittie, Mike P.; Harras, Khaled A.; Almeroth, Kevin C.; Belding, Elizabeth M.
Delay Tolerant Network (DTN) routing addresses challenges of providing end-to-end service where end-to-end data forwarding paths may not exist. The performance of current DTN routing protocols is often limited by routing metric ‘‘staleness”, i.e., routing information that becomes out-of-date or inaccurate because of long propagation delays. Our previous work, ParaNets, proposed a new opportunistic network architecture in which the data channel is augmented by a thin end-to-end control channel. The control channel is adequate for the exchange of control traffic, but not data. In this paper we present Cloud Routing, a routing solution for the ParaNets architecture. We motivate the need for such a solution, not only because of stale routing metrics, but also because of congestion that can occur in DTNs. Unable to use up-to-date routing metrics to limit congestion, existing DTN routing solutions suffer from low goodput and long data delivery delays. We show how Cloud Routing avoids congestion by smart use of forwarding opportunities based on up-to-date routing metrics. We evaluate our solution using extensive OPNET simulations. Cloud Routing extends network performance past what is currently possible and motivates a new class of globally cognizant DTN routing solutions.
ParaNets: A parallel network architecture for challenged networks
(IEEE, 2007-03) Harras, Khaled A.; Wittie, Mike P.; Almeroth, Kevin C.; Belding, Elizabeth M.
Networks characterized by challenges, such as intermittent connectivity, network heterogeneity, and large delays, are called “challenged networks”. We propose a novel network architecture for challenged networks dubbed Parallel Networks, or, ParaNets. The vision behind ParaNets is to have challenged network protocols operate over multiple heterogenous networks, simultaneously available, through one or more devices. We present the ParaNets architecture and discuss its short-term challenges and long-term implications. We also argue, based on current research trends and the ParaNets architecture, for the evolution of the conventional protocol stack to a more flexible cross-layered protocol tree. To demonstrate the potential impact of ParaNets, we use Delay Tolerant Mobile Networks (DTMNs) as a representative challenged network over which we evaluate ParaNets. Our ultimate goal in this paper is to open the way for further work in challenged networks using ParaNets as the underlying architecture.