A Data Sharing Facility for Mobile Ad-Hoc Emergency and Rescue Applications

2009 Tenth International Conference on Mobile Data Management: Systems, Services and Middleware

et al. 2009

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An approach to information sharing in mobile adhoc networks (MANETs) used e.g. in rescue operations, is to store on every node a small amount of metadata describing what information resources exist in the network and where they reside, allowing applications to first search locally for information about suitable resources, and next request relevant information from a node that contains the resource. The characteristics of MANETs in general and sparse, delay-tolerant networks in particular, make the task of maintaining and disseminating metadata across all nodes difficult, particularly in the presence of scarce resources. We have designed and implemented three protocols which use different approaches to metadata dissemination: epidemic oneto-one routing, one-to-many broadcasting that utilises the characteristics of the shared radio medium of wireless networks, and the semantic protocol where a group consisting of e.g. rescue team leaders is given priority in the dissemination process and afterwards serves as multiple starting points for further dissemination. In the MIDAS project we produce middleware that speeds up MANET application development. By prototyping the metadata management component of MIDAS and testing the prototype with each of the three protocols in the network emulator environment NEMAN, we have measured bandwidth usage and performance. The implemented broadcast protocol is measured to use substantially less bandwidth than epidemic routing. The semantic protocol shows that the group indeed gets priority; it is comparable to the broadcast protocol in terms of bandwidth usage. The broadcast protocol has been used successfully in field tests of the middleware.

Section: Midas Architecturementioning

confidence: 99%

Information Sharing in Mobile Ad-Hoc Networks: Metadata Management in the MIDAS Dataspace

Munthe-Kaas

Johannessen

2009 Tenth International Conference on Mobile Data Management: Systems, Services and Middleware

et al. 2009

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“…All of these also use optimistic replication. A detailed comparison of these related systems and MDS can be found in our earlier work describing the MDS architecture [4] and the MDS approach of versioning and consistency management [5]. The purpose of this paper is to report on the use of the MDS POC implementation for a detailed performance evaluation of a real system.…”

Section: Introductionmentioning

confidence: 98%

“…The main objective of the MIDAS project [2] is to define and implement a platform to simplify and speed up the task of developing and deploying highly specialised mobile services for such scenarios, where networks may consist of a variety of devices with regards to available resources. One central element of this platform is MIDAS Data Space (MDS [4]) for asynchronous information sharing. MDS is designed to work on mobile devices that together form potentially highly dynamic and unstable MANETs.…”

Section: Introductionmentioning

confidence: 99%

Information Sharing in Mobile Ad-Hoc Networks: Evaluation of the MIDAS Data Space Prototype

2009 29th IEEE International Conference on Distributed Computing Systems Workshops

Skjelsvik

Plagemann

et al. 2009

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Information sharing in dynamic mobile ad-hoc networks is a challenging task. High data availability in the presence of short and long term disconnections can be obtained by replicating shared data. The number of replicas must however be balanced against the cost of consistency management. In the MIDAS Data Space (MDS) we use optimistic replication together with internal versioning of data; this allows application-specific conflict resolution when reconciling replicas at network mergings. We have made a proof-of-concept implementation to perform experiments and to demonstrate through real-life field tests the usefulness of our design. In this paper we report our results. We have conducted a number of experiments on a small network formed by real devices to obtain a detailed performance evaluation. Using an emulation environment we have analysed and quantified the cost of consistency management, the impact of MDS operations, and the relationship between data availability and replication.

“…As part of the project, a working prototype of MIDAS has been implemented and used in two real world field tests. The MIDAS Data Space (MDS) [12] is a component in MIDAS providing a distributed data space, where the actual location of data is transparent to the applications. To the applications, MDS looks like a single ordinary relational database, with support for standard SQL queries.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Replica Placement Strategies for a Shared Data Space in Mobile Ad-Hoc Networks

2010 13th International Conference on Network-Based Information Systems

Plagemann

2010

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The dynamic nature of mobile ad-hoc networks (MANETs) can easily lead to data being inaccessible due to constant route changes and network partitions. One method often used for increasing reliability and availability of data is replication. However, replication comes with costs, those of transferring and storing data and keeping track of consistency between replicas. For that reason, we have identified the core factors impacting the resulting network traffic. We have performed experimental studies with a real world prototype of a distributed data management system for MANETs. Furthermore, we have done an extensive simulation study showing where table replicas should be placed in the network, in order to minimize network traffic generated by access to the databases and by the synchronization data. The results of the experiments are consistent and show that by using clustering techniques we can achieve close-to-optimal traffic by placing replicas on approximately 10 % of nodes.