Survey on Quality of Observation within Sensor Web Systems

The Sensor Web vision refers to the addition of a middleware layer between sensors and applications. To bridge the gap between these two layers, Sensor Web systems must deal with heterogeneous sources, which produce heterogeneous observations of disparate quality. Managing such diversity at the application level can be complex and requires high levels of expertise from application developers. Moreover, as an information-centric system, any Sensor Web should provide support for Quality of Observation (QoO) requirements. In practice, however, only few Sensor Webs provide satisfying QoO support and are able to deliver high-quality observations to end consumers in a specific manner. This survey aims to study why and how observation quality should be addressed in Sensor Webs. It proposes three original contributions. First, it provides important insights into quality dimensions and proposes to use the QoO notion to deal with information quality within Sensor Webs. Second, it proposes a QoO-oriented review of 29 Sensor Web solutions developed between 2003 and 2016, as well as a custom taxonomy to characterise some of their features from a QoO perspective. Finally, it draws four major requirements required to build future adaptive and QoO-aware Sensor Web solutions

Sensor Observation Streams Within Cloud-based IoT Platforms: Challenges and Directions

Observation streams can be considered as a special case of data streams produced by sensors. With the growth of the Internet of Things (IoT), more and more connected sensors will produce unbounded observation streams. In order to bridge the gap between sensors and observation consumers, we have witnessed the design and the development of Cloud-based IoT platforms. Such systems raise new research challenges, in particular regarding observation collection, processing and consumption. These new research challenges are related to observation streams and should be addressed from the implementation phase by developers to build platforms able to meet other non-functional requirements later. Unlike existing surveys, this paper is intended for developers that would like to design and implement a Cloud-based IoT platform capable of handling sensor observation streams. It provides a comprehensive way to understand main observation-related challenges, as well as non-functional requirements of IoT platforms such as platform adaptation, scalability and availability. Last but not the least, it gives recommendations and compares some relevant open-source software that can speed up the development process

LISACode : A scientific simulator of LISA

A new LISA simulator (LISACode) is presented. Its ambition is to achieve a new degree of sophistication allowing to map, as closely as possible, the impact of the different sub-systems on the measurements. LISACode is not a detailed simulator at the engineering level but rather a tool whose purpose is to bridge the gap between the basic principles of LISA and a future, sophisticated end-to-end simulator. This is achieved by introducing, in a realistic manner, most of the ingredients that will influence LISA's sensitivity as well as the application of TDI combinations. Many user-defined parameters allow the code to study different configurations of LISA thus helping to finalize the definition of the detector. Another important use of LISACode is in generating time series for data analysis developments

Making Trustable Satellite Experiments: an Application to a VoIP Scenario

How many times have ever asked yourself: "Can I trust my satellite experiments' outcome?". Performing experiments on real satellite system can either be (1)~costly, as the radio resource may be scarce or (2)~not possible, as you can hardly change the waveforms transmitted by the satellite platform. Moreover, assessing user applications QoE can hardly be done using only simulated environments while the QoS modeling of a satellite system can often lead to non-conclusive or ambiguous results. The aim of this paper is to bring out representative solutions allowing the networking community to drive consistent experiments using open-source tools. To this end, we compare Mininet and OpenSAND satellite emulator to a real satellite access provided by CNES. We consider VoIP traffic to analyze the trade-off between reliability of the results, ease of use and reproducibility of the experiments

iQAS: An Integration Platform for QoI Assessment as a Service for Smart Cities

While reducing costs and improving sustainability, a common goal for Smart Cities is to become more "liveable" for their citizens. By taking advantage of new information sources offered by the Internet of Things (IoT), cities can rely on sensing platforms to improve their service offer. These sensing platforms, however, raise new research challenges, in particular regarding Quality of Information (QoI). To cope with this issue, common platforms generally provide quality-oriented internal mechanisms. Nevertheless, the configuration of such platforms is complex, especially for Smart City stakeholders that may have various skill levels and different areas of expertise. As a result, QoI assessment is often delegated to end applications where developers have to implement their own adaptation mechanisms. This paper proposes and describes iQAS, an integration platform for QoI Assessment as a Service for Smart Cities. iQAS is autonomic, extensible and configurable, allowing Smart City stakeholders to collaboratively assess and improve (when possible) QoI in real-time. While the platform development is at its early stages, we illustrate within a concrete case study the need for QoI assessment and the benefits to implement adaptation mechanisms

Towards the Internet of Everything: Deployment Scenarios for a QoO-aware Integration Platform

Built upon the Internet of Things (IoT), the Internet of Everything (IoE) acknowledges the importance of data quality within sensor-based systems, alongside with people, processes and Things. Nevertheless, the impact of many technologies and paradigms that pertain to the IoE is still unknown regarding Quality of Observation (QoO). This paper proposes to study experimental results from three IoE-related deployment scenarios in order to promote the QoO notion and raise awareness about the need for characterizing observation quality within sensor-based systems. We specifically tailor the definition of QoO attributes to each use case, assessing observation accuracy within Smart Cities, observation rate for virtual sensors and observation freshness within post-disaster areas. To emulate these different experiments, we rely on a custom-developed integration platform for the assessment of QoO as a service called iQAS. We show that QoO attributes should be used to specify what is an observation of "good quality", that virtual sensors may have specific and limiting capabilities impacting QoO and that network QoS and QoO are two complementary quality dimensions that should be used together to improve the overall service provided to end-users

A Generic Framework for Quality-based Autonomic Adaptation within Sensor-based Systems

With the growth of the Internet of Things (IoT), sensor-based systems deal with heterogeneous sources, which produce heterogeneous observations of disparate quality. Since network QoS is rarely sufficient to expertise Quality of Observation (QoO), managing such diversity at the application level is a very complex task and requires high levels of experience from application developers. Given this statement, this paper proposes a generic framework for QoO-based autonomic adaptation within sensor-based systems. An abstract architecture is first introduced, intended to bridge the gap between sensors capabilities and application needs thanks to the Autonomic Computing paradigm. Then, the framework is instantiated and practical considerations when implementing an autonomous sensor-based system are given. We illustrate this instantiation with concrete examples of sensor middlewares and IoT platforms

The specifier–head relationship: negation and French subject proforms

This article1 and the three others in this thematic collection are about heads and specifiers, the relationship between them, and how this relationship can change over time. A theme which emerges is the notion that the spec(ifier)–head relationship is cyclic, in other words, the synchronic relationship between the head and its specifier within a given phrase in a given language can be characterised as a location at a particular point on a cycle, while the diachronic development of the relationship can be seen as a directional stepwise shift around that cycle. The article is organised as follows. Section 2 introduces the theoretical framework. Section 3.1 sketches a well-known diachronic phenomenon – the history of sentential negation – which readily lends itself to an analysis in terms of a cyclic spec–head relationship, and shows how the stages in the cycle have been characterised theoretically. Section 3.2 considers another set of data − pre- and postverbal subject proforms in French − which is similarly suitable for such an approach. Section 4, finally, introduces the three other contributions to the collection

Demo: Using the HINT Network Emulator to Develop Opportunistic Applications

In this work, we show how to use HINT, a real-time event-driven network emulator, to support the development process of opportunistic applications. In this demo, we use this emulator in conjunction with an example Android chat application to demonstrate its features