3,949 research outputs found
Towards Opportunistic Data Dissemination in Mobile Phone Sensor Networks
Recently, there has been a growing interest within the research community in developing opportunistic routing protocols. Many schemes have been proposed; however, they differ greatly in assumptions and in type of network for which they are evaluated. As a result, researchers have an ambiguous understanding of how these schemes compare against each other in their specific applications. To investigate the performance of existing opportunistic routing algorithms in realistic scenarios, we propose a heterogeneous architecture including fixed infrastructure, mobile infrastructure, and mobile nodes. The proposed architecture focuses on how to utilize the available, low cost short-range radios of mobile phones for data gathering and dissemination. We also propose a new realistic mobility model and metrics. Existing opportunistic routing protocols are simulated and evaluated with the proposed heterogeneous architecture, mobility models, and transmission interfaces. Results show that some protocols suffer long time-to-live (TTL), while others suffer short TTL. We show that heterogeneous sensor network architectures need heterogeneous routing algorithms, such as a combination of Epidemic and Spray and Wait
Time-Varying Graphs and Dynamic Networks
The past few years have seen intensive research efforts carried out in some
apparently unrelated areas of dynamic systems -- delay-tolerant networks,
opportunistic-mobility networks, social networks -- obtaining closely related
insights. Indeed, the concepts discovered in these investigations can be viewed
as parts of the same conceptual universe; and the formal models proposed so far
to express some specific concepts are components of a larger formal description
of this universe. The main contribution of this paper is to integrate the vast
collection of concepts, formalisms, and results found in the literature into a
unified framework, which we call TVG (for time-varying graphs). Using this
framework, it is possible to express directly in the same formalism not only
the concepts common to all those different areas, but also those specific to
each. Based on this definitional work, employing both existing results and
original observations, we present a hierarchical classification of TVGs; each
class corresponds to a significant property examined in the distributed
computing literature. We then examine how TVGs can be used to study the
evolution of network properties, and propose different techniques, depending on
whether the indicators for these properties are a-temporal (as in the majority
of existing studies) or temporal. Finally, we briefly discuss the introduction
of randomness in TVGs.Comment: A short version appeared in ADHOC-NOW'11. This version is to be
published in Internation Journal of Parallel, Emergent and Distributed
System
Orion Routing Protocol for Delay-Tolerant Networks
In this paper, we address the problem of efficient routing in delay tolerant
network. We propose a new routing protocol dubbed as ORION. In ORION, only a
single copy of a data packet is kept in the network and transmitted, contact by
contact, towards the destination. The aim of the ORION routing protocol is
twofold: on one hand, it enhances the delivery ratio in networks where an
end-to-end path does not necessarily exist, and on the other hand, it minimizes
the routing delay and the network overhead to achieve better performance. In
ORION, nodes are aware of their neighborhood by the mean of actual and
statistical estimation of new contacts. ORION makes use of autoregressive
moving average (ARMA) stochastic processes for best contact prediction and
geographical coordinates for optimal greedy data packet forwarding. Simulation
results have demonstrated that ORION outperforms other existing DTN routing
protocols such as PRoPHET in terms of end-to-end delay, packet delivery ratio,
hop count and first packet arrival
Efficient Mobile Data Collection with Mobile Collect
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