Impact of persistent storage on the DTN routing performance

Performance Modeling of Delay-Tolerant Network Routing via Queueing Petri Nets

Abstract: The performance of Delay-Tolerant Networks (DTNs) is governed by the interplay of diverse factors such as bundle fragmentation, scheduling, and buffer spacing. However, a comprehensive study of DTN routing performance taking into account such realistic limitations seldom performed in the literature. In this paper, we look at Queueing Petri Nets (QPNs) as a candidate framework for modeling the performance of DTN routing, taking into account all the realistic factors impacting performance. We envisage a three-fold validation scheme to assert the veracity of our model, via comparison of results obtained from simulations of the QPN vis-a-vis those obtained from direct simulation of the underlying DTN and experimental results obtained from a testbed of Android devices that employ a mobility emulation scheme. We also solve the QPN, by deriving the underlying reachability graph and constructing an equivalent stochastic jump process. We identify the stochastic process to be a Semi-Markov Process (SMP) and hence arrive at a closed form expression for the end-to-end delivery latency by computing the hitting time of the SMP. We find that the model accurately captures the behavior of a DTN in numerous realistic scenarios, showing the efficacy of QPNs as a suitable analytical framework for evaluating DTNs.

Performance modeling of Delay Tolerant Network routing via Queueing Petri Nets

Abstract: With the advent of wireless technologies such as Wi-Fi Direct and Near Field Communication (NFC), Peer-to-Peer (P2P) content sharing among mobile devices is set to become more ubiquitous Delay-Tolerant Networks (DTNs)-with their rudimentary direct delivery routing protocol-can be leveraged to provide seamless connectivity in such scenarios To the best of our knowledge, little has been done to understand the performance of DTNs under realistic settings involving the interplay of diverse factors such as bundle fragmentation, scheduling, and buffer spacing In this paper, we present a Queueing Petri Net (QPN) abstraction of DTNs that enables us to evaluate the underlying network's performance Our model is novel in its ability to capture bundle fragmentation, scheduling, and buffer spacing put together We proceed to evaluate the veracity of the model by involving QPN evaluation using the SimQPN tool and simulation of the underlying DTN using the ONE simulator We find that the model successfully predicts the performance of the underlying network to a high degree of accuracy

On storage dynamics of space delay/disruption tolerant network node

Abstract: Delay/disruption tolerant network (DTN) plays a promising role in prospected information infrastructures for future space activities, such as Interplanetary Internet (IPN) or Solar System Internet (SSI). Over such long-haul and intermittent links, DTN technique makes scientific data return end-to-end reliable by the typical custody transfer and store-and-forward mechanism. Due to lack of enough space spacecrafts deployed for DTN, now and in the near decades, there will be some intermediary nodes which would carry a large proportion of network traffic as DTN routers. Consequently, the behaviors and capabilities of managing bundles in the intermediary nodes would have impacts on the data transport over space DTN. Focusing on the storage dynamics of bundles, in this paper, we propose an analytical framework based on two-dimension Markov chain to evaluate the behaviors of bundles delivery in DTN intermediate nodes. Accordingly, a delay model and a transmission success probability model for bundles delivery over space DTN are developed separately, both dependent closely on the sojourn time in node storages. The evaluation results indicate that: (1) Dividing the source files into bigger bundles for transmission causes a longer storage-occupancy time on intermediary nodes; (2) bundle sizes have more explicit impacts on the storage-occupancy time at a node than segment sizes do; and (3) the transmission success probability of a bundle is more dependent on a DTN bundle size than on a LTP segment size.

Performance Analysis of DTN Routing Protocol for Vehicular Sensor Networks

Abstract: Vehicular sensor network (VSN) has become an active research topic in the field of networking. VSN is the application of vehicular ad hoc networks (VANETs). Vehicular delay-tolerant network (VDTN) has evolved from delay-tolerant network (DTN) and is formed by vehicular nodes with sensors embedded in it. Many routing protocols have been implemented in VDTN, each having its benefits and shortcomings in the implementation domain. In this paper, performance of two routing protocols, namely MaxProp and packet-oriented routing (POR), are analysed and compared on the basis of different parameters. Both the protocols are simulated on MATLAB.

A pragmatic node based DTN performance modeling

Abstract: Unlike traditional mobile networks, the store, carry, and forward paradigm of DTN architecture, enables a resource hungry DTN node (such as mobile phone) to carry the messages until it physically meets the destination node or a potential relay node. The storage and communication of the node are precious resources that play a vital role in the DTN routing. The state-of-the-art DTN research, models the node as a monolithic storage structure with the single communication antenna for data transfer. However, the practical bi-level hierarchical storage structure and the latest wireless technologies such as MIMO in the mobile phones, exemplify the oversimplified nature of the existing node abstraction. To this end, my PhD research focuses on the DTN performance modeling with a pragmatic node abstraction.

Epidemic routing for partially-connected ad hoc networks

Abstract: Mobile ad hoc routing protocols allow nodes with wireless adaptors to communicate with one another without any pre-existing network infrastructure. Existing ad hoc routing protocols, while robust to rapidly changing network topology, assume the presence of a connected path from source to destination. Given power limitations, the advent of short-range wireless networks, and the wide physical conditions over which ad hoc networks must be deployed, in some scenarios it is likely that this assumption is invalid. In this work, we develop techniques to deliver messages in the case where there is never a connected path from source to destination or when a network partition exists at the time a message is originated. To this end, we introduce Epidemic Routing, where random pair-wise exchanges of messages among mobile hosts ensure eventual message delivery. The goals of Epidemic Routing are to: i) maximize message delivery rate, ii) minimize message latency, and iii) minimize the total resources consumed in message delivery. Through an implementation in the Monarch simulator, we show that Epidemic Routing achieves eventual delivery of 100% of messages with reasonable aggregate resource consumption in a number of interesting scenarios.

A delay-tolerant network architecture for challenged internets

Abstract: The highly successful architecture and protocols of today's Internet may operate poorly in environments characterized by very long delay paths and frequent network partitions. These problems are exacerbated by end nodes with limited power or memory resources. Often deployed in mobile and extreme environments lacking continuous connectivity, many such networks have their own specialized protocols, and do not utilize IP. To achieve interoperability between them, we propose a network architecture and application interface structured around optionally-reliable asynchronous message forwarding, with limited expectations of end-to-end connectivity and node resources. The architecture operates as an overlay above the transport layers of the networks it interconnects, and provides key services such as in-network data storage and retransmission, interoperable naming, authenticated forwarding and a coarse-grained class of service.

Spray and wait: an efficient routing scheme for intermittently connected mobile networks

Abstract: Intermittently connected mobile networks are sparse wireless networks where most of the time there does not exist a complete path from the source to the destination. These networks fall into the general category of Delay Tolerant Networks. There are many real networks that follow this paradigm, for example, wildlife tracking sensor networks, military networks, inter-planetary networks, etc. In this context, conventional routing schemes would fail.To deal with such networks researchers have suggested to use flooding-based routing schemes. While flooding-based schemes have a high probability of delivery, they waste a lot of energy and suffer from severe contention, which can significantly degrade their performance. Furthermore, proposed efforts to significantly reduce the overhead of flooding-based schemes have often be plagued by large delays. With this in mind, we introduce a new routing scheme, called Spray and Wait, that "sprays" a number of copies into the network, and then "waits" till one of these nodes meets the destination.Using theory and simulations we show that Spray and Wait outperforms all existing schemes with respect to both average message delivery delay and number of transmissions per message delivered; its overall performance is close to the optimal scheme. Furthermore, it is highly scalable retaining good performance under a large range of scenarios, unlike other schemes. Finally, it is simple to implement and to optimize in order to achieve given performance goals in practice.

Delay-Tolerant Networking Architecture

Abstract: This document describes an architecture for delay-tolerant and disruption-tolerant networks, and is an evolution of the architecture originally designed for the Interplanetary Internet, a communication system envisioned to provide Internet-like services across interplanetary distances in support of deep space exploration. This document describes an architecture that addresses a variety of problems with internetworks having operational and performance characteristics that make conventional (Internet-like) networking approaches either unworkable or impractical. We define a message- oriented overlay that exists above the transport (or other) layers of the networks it interconnects. The document presents a motivation for the architecture, an architectural overview, review of state management required for its operation, and a discussion of application design issues. This document represents the consensus of the IRTF DTN research group and has been widely reviewed by that group. This memo provides information for the Internet community.

Stochastic properties of the random waypoint mobility model

Abstract: The random waypoint model is a commonly used mobility model for simulations of wireless communication networks. By giving a formal description of this model in terms of a discrete-time stochastic process, we investigate some of its fundamental stochastic properties with respect to: (a) the transition length and time of a mobile node between two waypoints, (b) the spatial distribution of nodes, (c) the direction angle at the beginning of a movement transition, and (d) the cell change rate if the model is used in a cellular-structured system area. The results of this paper are of practical value for performance analysis of mobile networks and give a deeper understanding of the behavior of this mobility model. Such understanding is necessary to avoid misinterpretation of simulation results. The movement duration and the cell change rate enable us to make a statement about the "degree of mobility" of a certain simulation scenario. Knowledge of the spatial node distribution is essential for all investigations in which the relative location of the mobile nodes is important. Finally, the direction distribution explains in an analytical manner the effect that nodes tend to move back to the middle of the system area.