Forming parallel internets and enabling ultra-local economies

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 105-109).Internet-based mobile communications have been increasing rapidly [5], yet there is little or no progress in platforms that enable applications for discovery, context-awareness and sharing of data and services in a peer-wise manner among collections of devices in the same physical area. This is important because proximate devices may need to communicate directly when no infrastructure is available, and because such local access may be an efficient alternative to connecting a large number of sensors, effectors, and people to a readily accessible, universal central system. This thesis presents the design, implementation and evaluation of Cerebro, a system that allows suitably equipped humans and objects in the same physical area to discover each other and share data and services. Cerebro offers two basic services: a presence service that propagates information about local devices through an automatically generated mesh network and an innovative data transport service to transfer data via this network. On top of these services, Cerebro offers an extensible Application Programming Interface (API). In a mobile mesh network with N devices, Cerebro offers an upper bound of O(N) on traffic overhead to maintain presence information at any part of the network and responsiveness to device arrival/departure events that take at most O(N) time to propagate throughout the network. This makes Cerebro a scalable and useful addition to mobile service delivery.by Polychronis Panagiotis Ypodimatopoulos.S.M

Ethical implication of emerging technologies

Titre de l'écran-titre (visionné le 3 mai 2007

Experimental evaluation of wireless mesh network with the Intel classmate pcs

This paper shows performance evaluation results of a wireless mesh network employing an 802.11s standard and low cost Intel Classmate PCs. The experiments consist of throughput and coverage range determination, in indoor and outdoor scenarios, in which net and communication multihop coverage tests were done. The results show maximum throughput of 14 Mbps for TCP and 12 Mbps for UDP respectively, proving the proposed solution's viability for the digital inclusion process in public schools.Este artigo apresenta os resultados da avaliação de uma rede mesh empregando o padrão 802.11s e laptops de baixo custo para inclusão digital fabricados pela Intel - os Classmate PCs. Os experimentos de avaliação contemplaram tanto testes em ambientes internos como externos, nos quais foram realizados testes de cobertura da rede e comunicação multihop. Os experimentos realizados mostram uma taxa máxima obtida na transferência de pacotes de 14Mbps e 12Mbps para TCP e UDP, respectivamente, comprovando a viabilidade da solução proposta para o processo de inclusão digital nas escolas públicas

Concept and design of the hybrid distributed embedded systems testbed

Wireless mesh networks are an emerging and versatile communication technology. The most common application of these networks is to provide access of any number of users to the world wide Internet. They can be set up by Internet service providers or even individuals joined in communities. Due to the wireless medium that is shared by all participants, effects like short-time fading, or the multi-hop property of the network topology many issues are still in the focus of research. Testbeds are a powerful tool to study wireless mesh networks as close as possible to real world application scenarios. In this technical report we describe the design, architecture, and implementation of our work-in-progress wireless testbed at Freie Universität Berlin consisting of 100 mesh routers that span multiple buildings. The testbed is hybrid as it combines wireless mesh network routers with a wireless sensor network

A system dynamics approach to educational technology introduction in Developing countries

Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, 2008.Includes bibliographical references.Developing nations around the globe are focused on ways to use Information and Computing Technologies (ICTs) as springboards to advance their national development in all areas, including education. There are multiple ways in which various organizations are tackling the unique challenges these nations face in equipping their schools with modem educational technologies. This study evaluates two examples of computing technology intended for wide-scale deployment in developing nations. It aims to test the hypothesis that in order to be successful, ICT implementations require adequate funding, available electrical and telecommunication infrastructure, the presence of strong local champions and a local support ecosystem. Interviews were conducted with stakeholders involved in two pilot implementations in Nigeria. A system dynamics model was used to investigate into the relative effects of relevant factors on the speed of ICT deployment. The results from the modeling show the need for a significant increase in financial investment, in order to cover all costs associated with ICT deployments. The results also revealed the daunting task nations face in equipping all students with individual laptops and it presents some alternatives to a wide-scale deployment of one-to-one computing. Finally, the results highlight the necessity of providing economical means of completely powering ICTs in order to rapidly deploy these technologies to the nation's schools. A number of recommendations were made for the consideration of any developing nation undertaking ICT implementations in education.by Trinidad Grange-Kyner.S.M

Mesh-Mon: a Monitoring and Management System for Wireless Mesh Networks

A mesh network is a network of wireless routers that employ multi-hop routing and can be used to provide network access for mobile clients. Mobile mesh networks can be deployed rapidly to provide an alternate communication infrastructure for emergency response operations in areas with limited or damaged infrastructure. In this dissertation, we present Dart-Mesh: a Linux-based layer-3 dual-radio two-tiered mesh network that provides complete 802.11b coverage in the Sudikoff Lab for Computer Science at Dartmouth College. We faced several challenges in building, testing, monitoring and managing this network. These challenges motivated us to design and implement Mesh-Mon, a network monitoring system to aid system administrators in the management of a mobile mesh network. Mesh-Mon is a scalable, distributed and decentralized management system in which mesh nodes cooperate in a proactive manner to help detect, diagnose and resolve network problems automatically. Mesh-Mon is independent of the routing protocol used by the mesh routing layer and can function even if the routing protocol fails. We demonstrate this feature by running Mesh-Mon on two versions of Dart-Mesh, one running on AODV (a reactive mesh routing protocol) and the second running on OLSR (a proactive mesh routing protocol) in separate experiments. Mobility can cause links to break, leading to disconnected partitions. We identify critical nodes in the network, whose failure may cause a partition. We introduce two new metrics based on social-network analysis: the Localized Bridging Centrality (LBC) metric and the Localized Load-aware Bridging Centrality (LLBC) metric, that can identify critical nodes efficiently and in a fully distributed manner. We run a monitoring component on client nodes, called Mesh-Mon-Ami, which also assists Mesh-Mon nodes in the dissemination of management information between physically disconnected partitions, by acting as carriers for management data. We conclude, from our experimental evaluation on our 16-node Dart-Mesh testbed, that our system solves several management challenges in a scalable manner, and is a useful and effective tool for monitoring and managing real-world mesh networks

Ant Algorithms for Routing in Wireless Multi-Hop Networks

Wireless Multi-Hop Networks (such as Mobile Ad hoc Networks, Wireless Sensor Networks, and Wireless Mesh Networks) promise improved flexibility, reliability, and performance compared to conventional Wireless Local Area Networks (WLAN) or sensor installations. They can be deployed quickly to provide network connectivity in areas without existing backbone/back-haul infrastructure, such as disaster areas, impassable terrain, or underserved communities. Due to their distributed nature, routing algorithms for these types of networks have to be self-organized. Ant routing is a bio-inspired self-organized method for routing, which is a promising approach for routing in such Wireless Multi-Hop Networks. This chapter provides an introduction to Wireless Multi-Hop Networks, their specific challenges, and an overview of the ant algorithms available for routing in such networks

The Application of Ant Colony Optimization

The application of advanced analytics in science and technology is rapidly expanding, and developing optimization technics is critical to this expansion. Instead of relying on dated procedures, researchers can reap greater rewards by utilizing cutting-edge optimization techniques like population-based metaheuristic models, which can quickly generate a solution with acceptable quality. Ant Colony Optimization (ACO) is one the most critical and widely used models among heuristics and meta-heuristics. This book discusses ACO applications in Hybrid Electric Vehicles (HEVs), multi-robot systems, wireless multi-hop networks, and preventive, predictive maintenance

State-of-the-art of distributed channel assignment

Channel assignment for Wireless Mesh Networks (WMNs) attempts to increase the network performance by decreasing the interference of simultaneous transmissions. The reduction of interference is achieved by exploiting the availability of fully or partially non-overlapping channels. Although it is still a young research area, many different approaches have already been developed. These approaches can be distinguished into centralized and distributed. Centralized algorithms rely on a central entity, usually called Channel Assignment Server (CAS), which calculates the channel assignment and sends the result to the mesh routers. In distributed approaches, each mesh router calculates its channel assignment decision based on local information. Distributed approaches can react faster to topology changes due to node failures or mobility and usually introduce less protocol overhead since communication with the CAS is not necessary. As a result, distributed approaches are more suitable once the network is operational and running. Distributed approaches can further be classified into static and dynamic, in regard to the modus of channel switching. In dynamic approaches, channels can be switched on a per-packet basis, whereas in static approaches radios stay on a specific channel for a longer period of time. Static assignments have been more in focus, since the channel switching time for current Institute of Electrical and Electronics Engineers (IEEE) 802.11 hardware is in the order of milliseconds which is two orders higher than the packet transmission time. Recently, surveys of channel assignment algorithms have been presented which cover certain aspects of the research field. The survey in [1] introduces the problem and presents a couple of distributed algorithms and [2] gives a broad introduction to centralized and distributed approaches. The survey herein is focused on distributed approaches for peer- to-peer network architectures. This report describes the problem formulation for channel assignment in WMNs and the fundamental concepts and challenges of this research area. We present different distributed channel assignment algorithms and characterize them according to a set of classification keys. Since channel assignment algorithms may change the connectivity and therefore the network topology, they may have a high impact on routing. Therefore, we present routing metrics that consider channel diversity and adapt better to the multi- radio multi-channel scenario than traditional routing metrics designed for single channel networks. The presented algorithms are discussed and compared focusing on practical evaluations in testbed and network environments. The implementation for real networks is a hard and labor-intensive task because the researcher has to deal with the complexity of the hardware, operating system, and wireless network interface drivers. As a result, frameworks emerged in order to simplify the implementation process. We describe these frameworks and the mechanisms used to help researchers implementing their algorithms and show their limitations and restrictions