Clouds of Small Things: Provisioning Infrastructure-as-a-Service from within Community Networks

Community networks offer a shared communication infrastructure where communities of citizens build and own open networks. While the IP connectivity of the networking devices is successfully achieved, the number of services and applications available from within the community network is typically small and the usage of the community network is often limited to providing Internet access to remote areas through wireless links. In this paper we propose to apply the principle of resource sharing of community networks, currently limited to the network bandwidth, to other computing resources, which leads to cloud computing in community networks. Towards this vision, we review some characteristics of community networks and identify potential scenarios for community clouds. We simulate a cloud computing infrastructure service and discuss different aspects of its performance in comparison to a commercial centralized cloud system. We note that in community clouds the computing resources are heterogeneous and less powerful, which affects the time needed to assign resources. Response time of the infrastructure service is high in community clouds even for a small number of resources since resources are distributed, but tends to get closer to that of a centralized cloud when the number of resources requested increases. Our initial results suggest that the performance of the community clouds highly depends on the community network conditions, but has some potential for improvement with network-aware cloud services. The main strength compared to commercial cloud services, however, is that community cloud services hosted on community-owned resources will follow the principles of community network and will be neutral and open

A Survey of Access Control Models in Wireless Sensor Networks

Copyright 2014 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/)Wireless sensor networks (WSNs) have attracted considerable interest in the research community, because of their wide range of applications. However, due to the distributed nature of WSNs and their deployment in remote areas, these networks are vulnerable to numerous security threats that can adversely affect their proper functioning. Resource constraints in sensor nodes mean that security mechanisms with a large overhead of computation and communication are impractical to use in WSNs; security in sensor networks is, therefore, a challenge. Access control is a critical security service that offers the appropriate access privileges to legitimate users and prevents illegitimate users from unauthorized access. However, access control has not received much attention in the context of WSNs. This paper provides an overview of security threats and attacks, outlines the security requirements and presents a state-of-the-art survey on access control models, including a comparison and evaluation based on their characteristics in WSNs. Potential challenging issues for access control schemes in WSNs are also discussed.Peer reviewe

Qualitative Comparison of Community Detection Algorithms

Community detection is a very active field in complex networks analysis, consisting in identifying groups of nodes more densely interconnected relatively to the rest of the network. The existing algorithms are usually tested and compared on real-world and artificial networks, their performance being assessed through some partition similarity measure. However, artificial networks realism can be questioned, and the appropriateness of those measures is not obvious. In this study, we take advantage of recent advances concerning the characterization of community structures to tackle these questions. We first generate networks thanks to the most realistic model available to date. Their analysis reveals they display only some of the properties observed in real-world community structures. We then apply five community detection algorithms on these networks and find out the performance assessed quantitatively does not necessarily agree with a qualitative analysis of the identified communities. It therefore seems both approaches should be applied to perform a relevant comparison of the algorithms.Comment: DICTAP 2011, The International Conference on Digital Information and Communication Technology and its Applications, Dijon : France (2011

Organizational performance in hierarchies and communities of practice

In a preceding article we have studied the Communities of Practice and their conditions of emergence using an Agent based model of a set of agents facing a continuous flow of problems. We center now our analysis on the performance of this organizational structure in comparison with a two-level hierarchical delegation structure. Our results show the crucial role played by the communication and the specialisation of the agents. Our main result shows that community structures are efficient for competence building, and particularly, if one considers learning in the long term. This paper backs the claim made by Bowles and Gintis [2000] that hierarchy and communities are complementary rather than substitute modes of governance.Communities of practice, learning, emergence of networks

Outage performance analysis of non-orthogonal multiple access systems with RF energy harvesting

Non-orthogonal multiple access (NOMA) has drawn enormous attention from the research community as a promising technology for future wireless communications with increasing demands of capacity and throughput. Especially, in the light of fifth-generation (5G) communication where multiple internet-of-things (IoT) devices are connected, the application of NOMA to indoor wireless networks has become more interesting to study. In view of this, we investigate the NOMA technique in energy harvesting (EH) half-duplex (HD) decode-and-forward (DF) power-splitting relaying (PSR) networks over indoor scenarios which are characterized by log-normal fading channels. The system performance of such networks is evaluated in terms of outage probability (OP) and total throughput for delay-limited transmission mode whose expressions are derived herein. In general, we can see in details how different system parameters affect such networks thanks to the results from Monte Carlo simulations. For illustrating the accuracy of our analytical results, we plot them along with the theoretical ones for comparison

The role of regional surveillance networks in enhancing global outbreak reporting

BACKGROUND: The Program for Monitoring Emerging Diseases (ProMED) is a moderated electronic reporting system dedicated to the rapid, global dissemination of outbreak reports. Its moderators are globally diverse, carefully selected, highly trained specialists. To improve cross-border communication and rapidly identify regional health threats, ProMED created regional networks where locally-based moderators use their access to local and regional medical and public health networks and media sources to obtain information not readily available outside of their region. In this analysis, we assess the impact of the establishment of ProMED's Middle East/North Africa (MENA) and South Asia (SoAs) regional networks in April 2014 on ProMED's outbreak reports for these regions. METHODS & MATERIALS: Outbreak reports in countries within the two regions were extracted from ProMED's database, and included country, disease name, species type, spatial coordinates, and report issue date. Data analysis included visualizing spatial information, identifying unique reports, and reporting trends per country and region. Data processing and analysis were conducted using R 3.4.0 statistical software. Rates of outbreak events per total number of ProMED reports per year were calculated to adjust for temporal trends in the total number of reports posted on ProMED. Rate comparison used a two-sided t-test; P < 0.05 was considered statistically significant. RESULTS: The mean monthly incidence of ProMED reports concerning outbreaks in the MENA region increased from 28 reports (May 2012 - April 2014) to 83 reports after the establishment of the networks (May 2014 - April 2016), and from 29 reports to 101 reports concerning outbreaks in the SoAs region over the same time period. The number of reports per total number of ProMED reports increased by 259% for MENA, and 289% for SoAs (P < 0.01). MENA reports most often addressed MERS (32.3%), foot-and-mouth disease (7.0%), avian influenza (6.7%), and measles (3.8%); whereas SoAs most often addressed dengue (14.9%), anthrax (7.3%), Japanese encephalitis (7.0%), CCHF (4.9%), and rabies (4.8%). CONCLUSION: The establishment of MENA and SoAs regional networks with locally-based, expert moderators resulted in a significant increase in ProMED's outbreak reports from these regions and an increased flow of disease information across regional borders and to the global public health community

The Naming Game in Social Networks: Community Formation and Consensus Engineering

We study the dynamics of the Naming Game [Baronchelli et al., (2006) J. Stat. Mech.: Theory Exp. P06014] in empirical social networks. This stylized agent-based model captures essential features of agreement dynamics in a network of autonomous agents, corresponding to the development of shared classification schemes in a network of artificial agents or opinion spreading and social dynamics in social networks. Our study focuses on the impact that communities in the underlying social graphs have on the outcome of the agreement process. We find that networks with strong community structure hinder the system from reaching global agreement; the evolution of the Naming Game in these networks maintains clusters of coexisting opinions indefinitely. Further, we investigate agent-based network strategies to facilitate convergence to global consensus.Comment: The original publication is available at http://www.springerlink.com/content/70370l311m1u0ng3