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16
Contact-based mobility metric for delay-tolerant ad-hoc networking
- In Proceedings of IEEE MASCOTS
, 2005
"... Mobility plays a major role in mobile ad hoc networks (MANETs) since it stresses networking tasks such as routing on one hand but aids to increase the network capacity and to overcome network partitioning on the other hand. To benefit from node mobility, a new class of MANET protocols and applicatio ..."
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Cited by 20 (1 self)
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Mobility plays a major role in mobile ad hoc networks (MANETs) since it stresses networking tasks such as routing on one hand but aids to increase the network capacity and to overcome network partitioning on the other hand. To benefit from node mobility, a new class of MANET protocols and applications are designed to be delay-tolerant and mobility-aided. For delay-tolerant mobility-aided networking mobility on a large time-scale is a key feature. So far, in MANETs, the mobility is investigated on a short time-scale. That is why we present novel mobility metrics that quantify a large time-scale mobility. Our approach is based on the pair-wise contacts between mobile nodes. We present a detailed statistical study of our novel metrics using the widely used random waypoint mobility model as an example. For the random waypoint model we introduce an analytical model, which allows protocol developers to analytically compute some of the designed metrics. In order to provide an easy access to these metrics in a network simulator, we provide a framework for ns-2. 1
A Partition-tolerant Manycast Algorithm for Disaster Area Networks
"... Abstract—Information dissemination in disaster scenarios requires timely and energy-efficient communication in intermittently connected networks. When the existing infrastructure is damaged or overloaded, we suggest the use of a manycast algorithm that runs over a wireless mobile ad hoc network, and ..."
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Cited by 15 (10 self)
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Abstract—Information dissemination in disaster scenarios requires timely and energy-efficient communication in intermittently connected networks. When the existing infrastructure is damaged or overloaded, we suggest the use of a manycast algorithm that runs over a wireless mobile ad hoc network, and overcomes partitions using a store-and-forward mechanism. This paper presents a random walk gossip protocol that uses an efficient data structure to keep track of already informed nodes with minimal signalling. Avoiding unnecessary transmissions also makes it less prone to overloads. Experimental evaluation shows higher delivery ratio, lower latency, and lower overhead compared to a recently published algorithm. I.
Evaluation of partitionaware MANET protocols and applications with ns-2
- In: Proc. of the 2005 International Symposium on Performance Evaluation of Computer and Telecommunication Systems (SPECTS
, 2005
"... Mobile Ad Hoc Networks (MANET) are composed of mobile devices equipped with short range radio capabilities. Communication is possible between devices located in each other’s transmission range. Especially in sparse MANETs, node mobility leads to frequent network partitioning, which makes typical net ..."
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Cited by 4 (2 self)
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Mobile Ad Hoc Networks (MANET) are composed of mobile devices equipped with short range radio capabilities. Communication is possible between devices located in each other’s transmission range. Especially in sparse MANETs, node mobility leads to frequent network partitioning, which makes typical networking tasks much more difficult. Although we observe an increasing need for partitioning information, the widely used network simulator ns-2 does not support protocol developers to easily evaluate their protocols concerning network partitioning. To simplify the evaluation of MANET partition-aware protocols and applications in ns-2, we extend the simulator to provide partitioning information at the simulation time. Developers might be interested in using this information to evaluate their partition-aware protocols and applications and to compare their performance to the optimal case. Hypergossiping is a partition-aware broadcast protocol for MANETs. Nodes rebroadcast messages upon joining the partitions that have not yet received these messages. Hypergossiping uses a heuristic to detect partition joins. We show the feasibility of our approach and the applicability of the partitioning information we provide for ns-2 users to compare the performance of our approach to the optimal case.
Encounter-Based Message Propagation in Mobile Ad-Hoc Networks
"... A family of message propagation protocols for highly mobile ad-hoc networks is defined, and is studied analytically and by simulation. The coverage of a message (the fraction of nodes that receive it), can be made arbitrarily close to 1, at a moderate cost of extra message traffic. Under certain sim ..."
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Cited by 3 (1 self)
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A family of message propagation protocols for highly mobile ad-hoc networks is defined, and is studied analytically and by simulation. The coverage of a message (the fraction of nodes that receive it), can be made arbitrarily close to 1, at a moderate cost of extra message traffic. Under certain simplifying assumptions, it is shown that a high coverage is achieved by making a total of O(n ln n) broadcasts, where n is the number of nodes, and the time to propagate a message is O(ln n). Mechanisms for making the protocols more efficient, by reducing the number of redundant transmissions without affecting the achievable coverage, are presented and evaluated. The generalisation to multiple broadcasts proceeding in parallel is derived. Finally, an attempt to validate the proposals in the context of a real-life mobile ad-hoc network is described. Results of this validation exercise and simulations point out that the proposed protocols can cost-effectively achieve high-coverage in networks of varying degrees of node densities and mobilities. We acknowledge the financial support from the UK EPSRC Projects “Networked Computing in Inter-organisation Settings ” (EP/D037743/1) and “Protocols for
Wireless Ad Hoc Dissemination for Search and Rescue
- 7th International ISCRAM Conference. http://www.iscram.org/ISCRAM2010/Papers/214Asplund_etal.pdf
, 2010
"... ABSTRACT In search and rescue scenarios local information on victims and other finds needs to be disseminated rapidly to other rescue workers and team leaders. However, post disaster scenarios may imply the collapse of information infrastructure including cellular communication and Internet connect ..."
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Cited by 2 (0 self)
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ABSTRACT In search and rescue scenarios local information on victims and other finds needs to be disseminated rapidly to other rescue workers and team leaders. However, post disaster scenarios may imply the collapse of information infrastructure including cellular communication and Internet connectivity. Even if we consider wireless ad hoc communication as a means of information dissemination we should count on frequent loss of connectivity in the network due to unpredictable mobility and sparse network topologies. In this paper we present the realization of an existing manycast protocol (random walk gossip) on commodity handheld devices running the Android platform. This communication mode is used to demonstrate the potential for distributed information dissemination on victims and finds. The application layer is an adaptation of an existing surveying information tool (POSIT) which is now fully decentralized and relies on text communication to achieve energy efficiency.
A Survey of Message Diffusion Protocols in Mobile Ad Hoc Networks
"... For the last twenty years, mobile communications have experienced an explosive growth. In particular, one area of mobile communication, the Mobile Ad hoc Networks (MANETs), has attracted significant attention due to its multiple applications and its challenging research problems. On the other hand, ..."
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Cited by 2 (0 self)
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For the last twenty years, mobile communications have experienced an explosive growth. In particular, one area of mobile communication, the Mobile Ad hoc Networks (MANETs), has attracted significant attention due to its multiple applications and its challenging research problems. On the other hand, the nodes mobility in these networks has introduced new challenges for the routing protocols, especially when the mobility induces multiple disconnections in the network. In this survey, we present an overview of this issue and a detailed discussion of the major factors involved. In particular, we show how messages can be efficiently disseminated in different types of MANETs. Keywords Mobile computing, mobile ad-hoc networks, opportunistic
ParTAC: A Partition-Tolerant Atomic Commit Protocol for MANETs
, 2010
"... The support of distributed atomic transactions in mobile ad-hoc networks (MANET) is a key requirement for many mobile application scenarios. Atomicity is a fundamental property that ensures that all nodes decide a consistent outcome. As MANETs are characterized by frequent perturbations due to netw ..."
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The support of distributed atomic transactions in mobile ad-hoc networks (MANET) is a key requirement for many mobile application scenarios. Atomicity is a fundamental property that ensures that all nodes decide a consistent outcome. As MANETs are characterized by frequent perturbations due to network partitioning and the fragility of nodes, providing atomicity is challenging. Existing protocols that ensure strict atomicity in MANETs are either bound to specific mobility pattern or based on building blocks such as consensus or group membership, not allowing arbitrary partitions or requiring exact knowledge about the members of a partition. These assumptions limit the deployment of these protocols to very restricted MANET scenarios, and may lead to poor commit rate, high message overhead or blocking related to intolerably long Commit/Abort decision times. In this paper, we present the first Partition-Tolerant Atomic Commit protocol (ParTAC) for MANETs which does not rely on consensus or group partition membership. As a consequence, ParTAC supports a significantly wider range of mobility patterns and partitioning scenarios than existing protocols. To reduce Commit/Abort decision times and prevent the protocol from blocking, ParTAC follows a best-effort strategy by defining a lifetime for every transaction after which the transaction is aborted. Further, we introduce a new coordination strategy based on a flexible pre-selection of multiple coordinators among the participating nodes. Thus, the failure of a single coordinator can be tolerated in the presence of network partitioning. Moreover, transactions can be aborted by any coordinator based on lifetime expiration. ParTAC is evaluated using simulations to demonstrate the performance of the protocol in terms of commit rate, message efficiency and Commit/Abort decision time.
Delay-Aware Mobile Transactions
- 6 th IFIP Workshop on Software Technologies for Future Embedded & Ubiquitous Systems (SEUS
, 2008
"... Abstract. In the expanding e-society, mobile embedded systems are increasingly used to support transactions such as for banking, stock or database applications. Such systems entail a range of heterogeneous entities- both the embedded devices and the networks connecting them. While these systems are ..."
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Abstract. In the expanding e-society, mobile embedded systems are increasingly used to support transactions such as for banking, stock or database applications. Such systems entail a range of heterogeneous entities- both the embedded devices and the networks connecting them. While these systems are exposed to frequent and varied perturbations, the support of atomic distributed transactions is still a fundamental requirement to achieve consistent decisions. Guaranteeing atomicity and high performance in traditional fixed wired networks is based on the assumption that faults like node and link failures occur rarely. This assumption is not supported in current and future mobile embedded systems where the heterogeneity and mobility often result in link and node failures as a dominant operational scenario. In order to continue guaranteeing strict atomicity while providing for high efficiency (low resource blocking time and message overhead) and acceptable commit rate, transactional fault-tolerance techniques need to be revisited perhaps at the cost of transaction execution time. In this paper, a comprehensive classification of perturbations and their impact on the design of mobile transactions is provided. In particular we argue for the delay-awareness of mobile transactions to allow for the fault-tolerance mechanisms to ensure resilience to the various and frequent perturbations. Key words: Transactions, mobile database systems, dependability 1
Random-walk gossip-based manycast with partition detection
"... Communication is vital for successful cooperation in the event of a disaster. Such a situation calls for dissemination methods that provide partition-tolerant, energyefficient, timely, and reliable delivery. We present a protocol that meets these requirements by combining a novel random walk gossip ..."
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Communication is vital for successful cooperation in the event of a disaster. Such a situation calls for dissemination methods that provide partition-tolerant, energyefficient, timely, and reliable delivery. We present a protocol that meets these requirements by combining a novel random walk gossip with a partition detection mechanism. The protocol is able to guarantee that at least M nodes will be reached by the message without having to know which nodes are in the system. 1
Budapest, 2008. Declaration
"... I hereby certify that this material, which I now submit for assessment on the programme of study leading to the award of PhD is entirely my own work and has not been taken from the work of others save and to the extent that such work has been cited and acknowledged within the text of my work. ..."
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I hereby certify that this material, which I now submit for assessment on the programme of study leading to the award of PhD is entirely my own work and has not been taken from the work of others save and to the extent that such work has been cited and acknowledged within the text of my work.