Exploiting content centric networking to develop topic-based, publish-subscribe MANET systems

Mobile Ad-hoc NETworks (MANETs) connect mobile wireless devices without an underlying communication infrastructure. Communications occur in a multi-hop fashion, using mobile devices as routers. Several MANET distributed applications require to exchange data (GPS position, messages, pictures, etc.) by using a topic-based publish-subscribe interaction. Participants of these applications can publish information items on a given topic (identified by a name) and can subscribe to a topic to receive the related published information. An efficient dissemination of publish-subscribe data in MANET environments demands for robust systems, able to face radio resource scarcity, network partitioning, frequent topology changes. Many MANET publish-subscribe systems have been proposed so far in the literature assuming an underlying TCP/IP network. In this paper, we discuss the benefits of building a MANET publish-subscribe system exploiting Content Centric Networking (CCN) technology, rather than TCP/IP. We show how CCN functionality, such as in-network caching and multicasting can be used to achieve an efficient and reliable data dissemination in MANET environments, including the support of delay tolerant delivery. We present different design approaches, describe our topic-based publish-subscribe CCN system, and report the results of a performance evaluation study carried out with real software in an emulated environment. The emulation environment is based on Linux virtual machines. The performance evaluation required also a CCN MANET routing engine, which we developed as a plug-in of the OLSR Linux daemon

Impact of mobility in cooperative spectrum sensing: Theory vs. simulation

This work addresses the problem of cooperative spectrum sensing in cognitive radio networks, focusing on the impact of mobility on performance of cooperative sensing. First, a review of the most recent results on cooperative spectrum sensing is provided, resulting in the identification of measurement correlation and frame error rate in the reporting channel as the main parameters influencing the performance of cooperative sensing schemes. Next, the paper discusses the extension of the analysis to the case of mobile sensors, and determines the set of assumptions made in existing literature when taking into account mobility in sensing. The paper moves then to remove some of such assumptions, by presenting simulation results obtained in presence of realistic models for propagation in the considered area, as well as of a realistic mobility model. A comparison between theoretical derivation and simulation results shows that correlation among measurements taken by different sensors and the selected mobility model may significantly affect the sensing performance. © 2012 IEEE

Neighbour and network discovery in cognitive radio networks: research activities and results in the ACROPOLIS Network of Excellence

Cognitive radio networks operation relies on the capability to gather information about the surrounding environment, as regards both internal network status (presence and capabilities of other devices belonging to the same network) and external systems potentially coexisting with the cognitive network. In particular, retrieving information at the local level is a function required to all wireless networks, and goes under the name of neighbour discovery. Under this aspect, cognitive networks make no exception. Similarly, cognitive networks share with traditional wireless networks the necessity of a function for retrieving and exchanging information on a network wide scale, referred to in the following as network discovery. The definition of efficient neighbour and network discovery strategies for cognitive networks, taking into account their specific characteristics, is one of the goals of the research activities undergoing within the framework of the ACROPOLIS NoE. In this work, neighbour and network discovery solutions currently under investigation within the ACROPOLIS joint research activities are presented, and future research lines are identified. The paper first presents algorithms and results on neighbour discovery and Medium Access Control, and moves then to network wide protocols by presenting the work carried out in ACROPOLIS on routing for underlay cognitive networks. The paper provides then an overview on the common simulation platform developed within ACROPOLIS to investigate neighbour and network discovery, and finally discusses future research directions on such topics. © VDE VERLAG GMBH

Antiviral immunity in Drosophila requires systemic RNA interference spread.

Contains fulltext : 80137.pdf (publisher's version ) (Closed access)Multicellular organisms evolved sophisticated defence systems to confer protection against pathogens. An important characteristic of these immune systems is their ability to act both locally at the site of infection and at distal uninfected locations. In insects, such as Drosophila melanogaster, RNA interference (RNAi) mediates antiviral immunity. However, the antiviral RNAi defence in flies seems to be a local, cell-autonomous process, as flies are thought to be unable to generate a systemic RNAi response. Here we show that a recently defined double-stranded RNA (dsRNA) uptake pathway is essential for effective antiviral RNAi immunity in adult flies. Mutant flies defective in this dsRNA uptake pathway were hypersensitive to infection with Drosophila C virus and Sindbis virus. Mortality in dsRNA-uptake-defective flies was accompanied by 100-to 10(5)-fold increases in viral titres and higher levels of viral RNA. Furthermore, inoculating naked dsRNA into flies elicited a sequence-specific antiviral immune response that required an intact dsRNA uptake pathway. These findings suggest that spread of dsRNA to uninfected sites is essential for effective antiviral immunity. Notably, infection with green fluorescent protein (GFP)-tagged Sindbis virus suppressed expression of host-encoded GFP at a distal site. Thus, similar to protein-based immunity in vertebrates, the antiviral RNAi response in flies also relies on the systemic spread of a virus-specific immunity signal

Magnitude and Determinants of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Household Transmission: A Longitudinal Cohort Study.

BackgroundHouseholds have emerged as important venues for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. Little is known, however, regarding the magnitude and determinants of household transmission in increasingly vaccinated populations.MethodsFrom September 2020 to January 2022, symptomatic nonhospitalized individuals with SARS-CoV-2 infection by RNA detection were identified within 5 days of symptom onset; all individuals resided with at least 1 other SARS-CoV-2-uninfected household member. These infected persons (cases) and their household members (contacts) were subsequently followed with questionnaire-based measurement and serial nasal specimen collection. The primary outcome was SARS-CoV-2 infection among contacts.ResultsWe evaluated 42 cases and their 74 household contacts. Among the contacts, 32 (43%) became infected, of whom 5 (16%) were asymptomatic; 81% of transmissions occurred by 5 days after the case's symptom onset. From 21 unvaccinated cases, 14-day cumulative incidence of SARS-CoV-2 infection among contacts was 18/40 (45% [95% confidence interval {CI}, 29%-62%]), most of whom were unvaccinated. From 21 vaccinated cases, 14-day cumulative incidence of SARS-CoV-2 infection was 14/34 (41% [95% CI, 25%-59%]) among all contacts and 12/29 (41% [95% CI, 24%-61%]) among vaccinated contacts. At least 1 comorbid condition among cases and 10 or more days of RNA detection in cases were associated with increased risk of infection among contacts.ConclusionsAmong households including individuals with symptomatic SARS-CoV-2 infection, both vaccinated-to-vaccinated and unvaccinated-to-unvaccinated transmission of SARS-CoV-2 to household contacts was common. Because vaccination alone did not notably reduce risk of infection, household contacts will need to employ additional interventions to avoid infection

Association of Culturable-Virus Detection and Household Transmission of SARS-CoV-2, California and Tennessee, 2020-2022.

From 2 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) household transmission studies (enrolling April 2020 to January 2022) with rapid enrollment and specimen collection for 14 days, 61% (43/70) of primary cases had culturable virus detected ≥6 days post-onset. Risk of secondary infection among household contacts tended to be greater when primary cases had culturable virus detected after onset. Regardless of duration of culturable virus, most secondary infections (70%, 28/40) had serial intervals <6 days, suggesting early transmission. These data examine viral culture as a proxy for infectiousness, reaffirm the need for rapid control measures after infection, and highlight the potential for prolonged infectiousness (≥6 days) in many individuals