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Part 9: Learning and Education; International audience; While the need for the moderation of examination scripts as part of quality assurance is globally undisputable, moderation associated risks and challenges are more pronounced in developing countries. eModeration (online moderation of examination scripts) can improve the user experience of an examination moderation process while lowering the risk of losing scripts and delaying the moderation process. Various factors could contribute to resistance against implementing and adopting eModerate systems in Higher Education Institutions, ranging from human factors to technical issues and organisational resistance to change. The focus of this study is on the human factors involved in eModeration, i.e. the factors influencing the user experience when using eModeration. The research uses a design science research methodology, which includes the design, development and testing of a User Experience Evaluation Framework for eModeration. The contribution of this paper is the demonstration of how eModeration (e-Service) is relevant to Higher Education management, as well as the provision of some insights regarding eModerators’ user experience of an existing system. The resultant artifact is a validated User Experience Evaluation Framework for eModeration, which can be used to improve human experience of electronic moderation with an emphasis on improving the quality of educational assessment practices in developing countries.

Part 9: Learning and Education; International audience; While a number of advantages have been discussed on e-learning/e-assessment tools, little research has been reported on programming courses. Today, the different types of questions have been used in exams based on course type, e.g., Text-based questions, mathematical questions, and programming questions. All these question types require supporting plug-ins for e-assessments. In this study, we provide our practical experience on programming exams in Inspera Assessment and Blackboard Learn, especially focusing on Parsons problems (drag-and-drop questions) and code writing questions. Our findings indicate that currently, tools have basic support for programming exams, and also there is a low-level integration between the tools. However, the adaptability of any exam system could depend on the interoperability between the platforms and external plugins. Hence, more improvements can be made with the implementation of e-assessments in digital ecosystems while it requires a lot of changes internally and outside institutions. In the paper, we will explain how a digital ecosystem within e-assessment could improve assessments and how it supports diverse needs of programming exams.

Part 1: E-Business; International audience; Product reviews are a type of user-generated content that can be beneficial for both customers and product designers. Without quantifying the design knowledge present in product reviews, however, it is hard for the companies to integrate reviews into the design process. Several studies investigated review helpfulness in general, but few works explored the problem of review quality from the perspective of product designers. In this study, a theoretical model is presented and a system is proposed to assess the quality of online product reviews from the viewpoint of product designers. The system involves an original similarity-based metric to quantify the design information content of reviews on a continuous scale. Experiments are performed on a large number of digital camera reviews, with results indicating that the proposed system is capable of recognizing high-quality content, and would potentially assist companies in product improvement and innovation.

Part 6: Social Media and Analytics; International audience; This study examined the relationship between work-related exhaustion and the recovery experiences of psychological detachment and relaxation during leisure, and the moderating role of emotion (positive & negative) when using Twitter during and after work. Participants were asked to rate their emotion based on the tweets they posted each day, together with their exhaustion at work and their recovery experiences at the end of the day. Results from the multilevel analyses showed that experiencing positive emotion when tweeting at work buffered the negative relationship of exhaustion and psychological detachment, but not relaxation. Negative emotion did not moderate the relationship significantly. The results show that social media can play a significant role in the recovery process and offer interesting insights both for employees and organisations.

Part 13: Online Communities; International audience; Crime is a reality that effects everyone in the world. Even developed countries such as the United Kingdom, Canada and Germany are not exempted from crime occurrences. Although these indicators are substantially less than developing countries such as South Africa, the existence of crime is a worldwide phenomenon. In this paper we explore the extent to which social media, in particular Facebook are used in the fight against crime.The study adopts a social technical approach in its investigation, considering the symbiotic relationship between communities (the organisation), Facebook and the utilisation of Facebook to complete tasks (technical subsystem), team members and structure to report crime in virtual communities (social subsystem) and current governance structures (environmental system). Based on a study of 297 crime fighting Facebook communities in South Africa, we found a positive correlation between the number of Facebook crime fighting communities per region and the crime rates for a particular region. Furthermore, we noticed that the regions with the most crime communities also had the most Internet connectivity per household. Both findings are indicative of a functional symbiotic relationship between the technical subsystem and the social subsystem. However, it highlights the fact that these structures are initiated by communities therefore lacking strong intervention from the environmental system, in this instance governmental bodies. We propose that governmental agencies formally recognise social media platforms as social crime fighting tool. Secondly, we suggest that governmental entities should focus on infrastructure related challenges as part of their attempt to combat crime.

Part 6: Social Media and Analytics; International audience; Nowadays, most of the organizations and businesses develop online services, which add value in their business and even increase their customer base. Social Media has changed the dynamics of digital marketing. Social media gives power to customers to post, share, and review content. Customers can directly interact with other customers and companies. In this paper, we will analysis huge user-generated content which can be used by organizations for their customer engagement strategies. The purpose of this study is to derive insights using Twitter Analytics on Twitter data to understand how businesses use Twitter for customer engagement strategies. Data collected from Twitter. The present paper uses descriptive and content analysis techniques for analyzing the tweets. The analysis will help in identifying the gaps in the priorities of the stakeholders. With the right customer engagement strategies, companies can make benefits.

Part 9: Learning and Education; International audience; We have experienced in the past few years massive use of various kinds of e-Learning methodology, such as m-learning and blended learning etc. Despite this ubiquitous implementation of these modern approaches, we still lack their proper use regarding their full exploitation in the virtual learning environment. M-learning platforms are ubiquitous, however, they lack the potential which is given to us from computational linguistics, deep learning, and artificial intelligence. The paper attempts to highlight this fact and brings this neglected topic to the attention of the creators and designers of these mobile apps because their potential is much greater and we should put our undivided attention to this issue if we want to improve the technology which we use.

Part 8: Digital Divide and Social Inclusion; International audience; This study pursued two objectives: (1) it comprehensively investigated the role of the factors facilitating social exchange, reciprocity expectation and social value in use behaviour, and (2) it examined the effect of the sharing economy on social inclusion and subjective well-being. The data were collected from 487 users of different sharing economy platforms in the United States. Structural equation modelling was employed to analyse the correlation of the examined variables. The results demonstrated the positive effect of egoistic belief, reciprocity norm, social value, and the negative effect of identification on the use of the sharing economy. In addition, strong relationships between use behaviour and outcomes were identified. Future research suggestions are provided.

Part 8: Digital Divide and Social Inclusion; International audience; Autism, also known as autism spectrum disorder (ASD), is an incurable brain-based disorder that refers to a wide range of complex neurodevelopment disorders characterised by marked difficulties in communication and social skills, repetitive behaviour, highly focused interests and sensory sensitivity. Autism can present challenges for affected people at the work environment and in everyday life. The barrier for individuals with ASD increases further with changing environmental situations. Individuals with ASD have limited abilities to isolate their Five senses and often experience over- or under-sensitivity to sounds, touch, tastes, smells, light, colours or temperatures. In this perspective, individuals with autism may experience extraordinary challenges during a regular day for most people, especially in non-conductive crowded environments like workplaces.This work presents a survey of the state-of-the-art implementation as well as research challenges of assisting technology for people with ASD in the workplace and in everyday life. An overview of relevant key technologies and methods is outlined by focusing both on the therapeutic perspective as well as on the technological viewpoint. The aim of this paper is to provide a better understanding of the design challenges and to identify important research directions in this increasingly important area.

Part 11: Modelling and Managing the Digital Enterprise; International audience; German enterprises are often characterised by low levels of digital maturity. One reason for this is a lack of required structural changes on the path towards digital transformation. We consider a prescriptive framework, the digital transformation framework (DTF), which contains four structural requirements for digital transformation. Based on 16 interviews with German digitalisation experts, we aim at an evaluation of the DTF. The outcome is an enriched version of it containing seven structural requirements including the newly identified factors culture of change, agility of organizational structure, and integration of cloud computing and platforms. The extended DTF sheds light on additional facets of the digital transformation and thus supports managers in navigating their undertaking in this dynamic environment. Corresponding implications for research and practice are discussed.

Part 11: Modelling and Managing the Digital Enterprise; International audience; For several decades, maturity models have been regarded as a magic bullet for enterprises’ economic growth processes. In these models, domains are structured and divided into (mostly linear) levels that are used as benchmarks for enterprise development. However, this approach has its shortcomings in the context of complex topics like digitalization. As we understand it, digitalization defines a conceptual approach to a phenomenon that is individually important and promising in different ways for different enterprises. Consequently, existing maturity models in their current form are not able to reproduce the full extent of digitalization for enterprises, as the models are too general—especially for SMEs of different sizes and from different sectors. In our research, we propose a maturity model approach that introduces the concept of roles as a possibility to depict enterprises’ specific components, which are then added to a static core model. By doing so, the resulting maturity model is more flexible and scalable for SMEs’ specific needs. Furthermore, we introduce a new assessment approach for defining whether improving digitalization is truly relevant and worthwhile for the enterprise.

Part 3: Open Science and Open Data; International audience; The public expects government institutions to open their data to enable society to reap the benefits of these data. However, governments are often reluctant to disclose their data due to possible disadvantages. These disadvantages, at the same time, can be circumstances by processing the data before disclosing. Investments are needed to be able to pre-process a dataset. Hence, a trade-off between the benefits and cost of opening data needs to be made. Decisions to disclose are often made based on binary options like “open” or “closed” the data, whereas also parts of a dataset can be opened or only pre-processed data. The objective of this study is to develop a decision tree analysis in open data (DTOD) to estimate the costs and benefits of disclosing data using a DTA approach. Experts’ judgment is used to quantify the pay-offs of possible consequences of the costs and benefits and to estimate the chance of occurrence. The result shows that for non-trivial decisions the DTOD helps, as it allows the creation of decision structures to show alternatives ways of opening data and the benefits and disadvantages of each alternative.

Part 10: Security in Digital Environments; International audience; Technological advancements continue to disrupt how organizations compete and create value in almost every industry and society. The recent digital transformation movement has expanded the reliance of companies and organizations in software technologies, such as cloud computing, big data, artificial intelligence, internet-of-things, and also increase the risk associated with software usage. This work aims at identifying security risks associated with these technologies from an engineering management perspective. We conducted two focused groups and a literature review to gather and discuss the list of security risks. The findings have implications for both practitioners to manage software security risks and future research work.

Part 9: Learning and Education; International audience; The EU Commission for Higher Education through the Bologna Process declaration has put into action a series of reforms. One of the reforms is the development of learning outcomes in the European Credit Transfer and Accumulation System (ECTS). One part of these reforms requires European universities to identify and describe learning outcomes students will achieve after attending a course or program. There is no exact way of writing the learning outcomes, and there seems to be an indistinctly use of terms when explaining outcomes [1]. This can naturally cause some possible confusions in relation to what the learning outcomes should consist of, and make it difficult to write the learning outcomes for a course or a program. The purpose of this paper is to promote some explanations and clarifications that can ease the writing of the learning outcomes. The research question is How to write meaningful learning Outcomes? This paper presents a reflection on how the learning outcomes might be written. It is taken into account recommendations from relevant literature and framework intended for Europe. In this paper, the online course Applied Programming for Teachers is an example of how meaningful learning outcomes may be written with a focus on digital competence.

Part 6: Social Media and Analytics; International audience; In times of increasing importance of social media services, we have to rethink information literacy. One of the key assumptions of existing information literacy constructs is “static” information, meaning that information does not change. But compared to traditional and mostly unidirectional media services such as printed newspapers or television, this does not reflect the reality of a social media context. Here, information can be characterized as “dynamic”, meaning that, for example, every user can easily modify information before sharing it (again). A measurement construct covering these novel aspects of information literacy is missing, so far. Thus, the main objective of this paper is to develop a rigor and updated construct to measure and quantify social media information literacy of an individual social media user. We selected a comprehensive construct development framework that guided us through the investigation, and which includes qualitative as well as quantitative analyses. The outcome is a theoretically grounded and empirically derived social media information literacy (SMIL) construct. The paper ends with a discussion of potential future research directions.

Part 7: Digital Governance; International audience; Identity is one of the basic building blocks of the Fourth Industrial Revolution, and as the capability of digital technologies improves drastically in the last decade, identity in digital form has become unavoidable. Identity entitles an individual to various services like voting, education, employment, insurance, healthcare etc. Yet there are around 1 billion people in the world at present that do not possess any form of official identity. Lack of identity has a significant impact on people living in rural areas, especially women, children, and financially backward families. In recently released Sustainable Development Goal-16 by the UN, it has been recommended that by 2030, every individual should be given a legal identity. India’s digital identity program –Aadhaar is one significant contribution in this direction considering its coverage. Rolling out a national identity scheme needs a considerable budget, time and most importantly, domain knowledge for smooth implementation. This paper attempts to identify the overarching goals of Aadhaar. The study also ranks goals based on their significance. The research uses focus group for data collection along with secondary data. The research in total identified nine primary goals with uniqueness, privacy and security as the high priority goals and scalability and future-proofing of technology as low priority goals. Total Interpretive Structural Modeling (TISM) has been used to identify the significance of each goal. This study could be taken as a starting point by other nations that are desirous of having a similar biometric identity program for its citizens.

Part 11: Modelling and Managing the Digital Enterprise; International audience; This qualitative study focuses on how small- and medium-sized enterprises (SMEs) can realize benefits and create information technology (IT) value by investing in cloud enterprise resource planning (ERP) systems. We interviewed 19 respondents from cloud providers and cloud clients and found that their SMEs experienced both benefits and challenges when implementing cloud ERP systems. The digital value was obtained through work process automatization, fast updates of system functionalities, enhanced security of data storage, and increased access to critical business data from multiple digital units. Challenges in realizing these benefits related to organizational compliance with standard solutions and the need for organizational changes for employees to optimize system usage. The SMEs preferred an informal process for realizing benefits and creating digital value from the system. In contrast, the providers wanted to integrate benefits realization as part of their formal implementation methodology. Based on frameworks identified in the literature, we integrate a benefits realization model with an information systems value model to understand how SMEs realize benefits and create business value from cloud ERP systems. We contribute to the SME literature and explain the value creation process for SMEs implementing cloud ERP systems.

Part 5: Smart Cities and Smart Homes; International audience; Gamified persuasive system design refers to design solutions at the intersection of gamification and persuasive technology aiming at influencing attitude and behavior change. Although both concepts have been successfully applied in many domains to increase end-user engagement and satisfaction, results are often mixed and highly context specific. Consequently, there is a dearth of knowledge on how to design those solutions and how they are perceived by different types of users within certain application contexts. Thus, this paper investigates the relationship between the HEXAD gamification user types and persuasive principles within the context of energy saving. First results reveal (n = 206) that, three out of six persuasive principles (Reciprocity, Consistency & Commitment, Liking) have been perceived as persuasive by identified HEXAD user types, which highlights the importance of such user types models. Finally, this paper contributes to the present body of gamification literature by providing a human computer interaction (HCI) perspective which highlights guidelines for designing gamified persuasive systems to incentivize energy-saving.

Part 12: Digital Innovation and Business Transformation; International audience; There are few studies conducted on personal processes within the Business Process Management (BPM) domain. Personal processes are looser and more context- and person-dependent compared to the clearly defined business processes. This makes it more challenging to create solutions in this domain. In this study, a taxonomy is developed for personal processes. We used the data collected from semi-structured interviews that we have conducted with a diverse population. We built a taxonomy with 4 classes and 22 subclasses, further organized by 6 characteristics and 3 dimensions. The proposed taxonomy is intended to guide practitioners and researchers by identifying the range of processes, by understanding the relationship among process types, and by organizing the knowledge within the Personal Process Management (PPM) domain. As such, our work would lead to creating new methods, tools, and approaches for increased effectiveness of PPM solutions.

Part 9: Learning and Education; International audience; The paper deals with the process of acquiring professional vocabulary and grammar in English for Specific Purposes (ESP) in pre-service teacher preparation. The main objective of the research was to (1) discover how much students learn in the ICT-enhanced process of instruction, where autonomous work and collaborative learning are applied so that to build preconcepts and re-construct misconceptions in ESP; (2) detect the sources students exploited towards acquiring the learning content. The research was conducted at the Faculty of Education, University of Jan Evangelista Purkyne, Usti nad Labem, Czech Republic. Research sample consists of 62 probands enrolled in bachelor and master study programmes English Language and Literature and Teaching English Language and Literature. The research process is structured into three phases, and didactic tests are applied after each of them. Moreover, types of sources students used for acquiring the learning content were monitored and analyzed. Six hypotheses were tested and results showed statistically significant increase in knowledge after each phase.

International audience; Conflict-free replicated data types (CRDTs) aid programmers develop highly available and scalable distributed systems. However, the literature describes only a limited portfolio of conflict-free data types and implementing custom ones requires additional knowledge of replication and consistency techniques. As a result, programmers resort to ad hoc solutions which are error-prone and result in brittle systems. In this paper, we introduce strong eventually consistent replicated objects (SECROs), a general-purpose data type for building available data structures that guarantee strong eventual consistency (SEC) without restrictions on the operations. To evaluate our solution we compare a real-time collaborative text editor built atop SECROs with a state-of-the-art implementation that uses JSON CRDTs. This comparison quantifies various performance aspects. The results show that SECROs are truly general-purpose and memory efficient.

Part 5: Tools (2); International audience; VirtuosoNext$^{\text {TM}}$ TMis a distributed real-time operating system (RTOS) featuring a generic programming model dubbed Interacting Entities. This paper focuses on these interactions, implemented as so-called Hubs. Hubs act as synchronisation and communication mechanisms between the application tasks and implement the services provided by the kernel as a kind of Guarded Protected Action with a well defined semantics. While the kernel provides the most basic services, each carefully designed, tested and optimised, tasks are limited to this handful of basic hubs, leaving the development of more complex synchronization and communication mechanisms up to application specific implementations. In this work we investigate how to support a programming paradigm to compositionally build new services, using notions borrowed from the Reo coordination language, and relieving tasks from coordination aspects while delegating them to the hubs. We formalise the semantics of hubs using an automata model, identify the behaviour of existing hubs, and propose an approach to build new hubs by composing simpler ones. We also provide tools and methods to analyse and simplify hubs under our automata interpretation. In a first experiment several hub interactions are combined into a single more complex hub, which raises the level of abstraction and contributes to a higher productivity for the programmer. Finally, we investigate the impact on the performance by comparing different implementations on an embedded board.

t Part 4: Coordination Patterns; International audience; We provide a solution for the design of safe concurrent systems by compositional application of verified design patterns-called ar-chitectures-to a small set of functional components. To this end, we extend the theory of architectures developed previously for the BIP framework with the elements necessary for handling data: definition and operations on data domains, syntax and semantics of composition operators involving data transfer. We provide a set of conditions under which composition of architectures preserves their characteristic safety properties. To verify that individual architectures do enforce their associated properties , we provide an encoding into open pNets, an intermediate model that supports SMT-based verification. The approach is illustrated by a case study based on a previously developed BIP model of a nanosatellite on-board software.

Part 1: The Internet of Things and WLANs; International audience; In Industry 4.0 scenarios, novel applications are enabled by the capability to gather large amount of data from pervasive sensors and to process them in order to devise the “digital twin” of a physical equipment. The heterogeneity of hardware sensors, communication protocols and data formats constitutes one of the main challenge toward the large-scale adoption of the Internet of Things (IoT) paradigm on industrial environments. To this purpose, the W3C Web of Things (WoT) group is working on the definition of some reference standards intended to describe in a uniform way the software interfaces of IoT devices and services, and hence to achieve the full interoperability among different IoT components regardless of their implementation. At the same time, due also to the recent appearance of the WoT W3C draft, few testbed and real-world deployments of the W3C WoT architecture has been proposed so far in the literature. In this paper, we attempt to fill such gap by describing the realization of a WoT monitoring application of a generic indoor production site: the system is able to orchestrate the sensing operations from three heterogeneous Wireless Sensor Networks (WSNs). We describe how the components of the W3C WoT architecture have been instantiated in our scenario. Moreover, we demonstrate the possibility to decouple the mash-up policies from the network functionalities, and we evaluate the overhead introduced by the WoT approach.

Part 5: Distributed Applications; International audience; The authors investigate a network emulator performance versus the variability of hardware/software features of the hosting machine. In particular, the evaluation of static and dynamic delays is carried out considering several testing conditions. In detail, as concerns emulator configurations, the influence of packet rates on imposed delays values and distributions are analyzed; as for hardware and software, different values for RAM, CPU cores and operating system are tested. Results, reported as mean values and standard deviation, show two main trends: the resource availability has an important impact on the emulation stability and on the measurement repeatability; secondly, higher differences in performance levels for low imposed delay values, which is the most interesting zone in a few milliseconds latency world. The paper aims to show that the capability to emulate network impairments is generally influenced by hardware/software capabilities and it must be considered when using network emulation for specific test purposes.

Part 2: Short and “Journal First” Papers; International audience; Computational fields have been proposed as an effective abstraction to fill the gap between the macro-level of distributed systems (specifying a system’s collective behaviour) and the micro-level (individual devices’ actions of computation and interaction to implement that collective specification), thereby providing a basis to better facilitate the engineering of collective APIs and complex systems at higher levels of abstraction. This approach is particularly suited to complex large-scale distributed systems, like the Internet-of-Things and Cyber-Physical Systems, where new mechanisms are needed to address composability and reusability of collective adaptive behaviour. This work introduces a full formal foundation for field computations, in terms of a core calculus equipped with typing, denotational, and operational semantics. Critically, we apply techniques for formal programming languages to collective adaptive systems: we provide formal establishment of a link between the micro- and macro-levels of collective adaptive systems, via a result of computational adequacy and abstraction for the (aggregate) denotational semantics with respect to the (per-device) operational semantics.

Part 1: Full Papers; International audience; Unmanned Aerial Vehicles (UAV) are now widespread in our society and are often used in a context where they can put people at risk. Studying their reliability, in particular in the context of flight above a crowd, thus becomes a necessity. In this paper, we study the modeling and analysis of UAV in the context of their flight plan. To this purpose, we build a parametric probabilistic model of the UAV and use it, as well as a given flight plan, in order to model its trajectory. This model takes into account parameters such as potential filter or sensor (like GPS) failure as well as wind force and direction. Because of the nature and complexity of the successive obtained models, their exact verification using tools such as PRISM or PARAM is impossible. We therefore develop a new approximation method, called Parametric Statistical Model Checking, in order to compute failure probabilities. This method has been implemented in a prototype tool, which we use to resolve complex issues in a practical case study.

Part 1: Full Papers; International audience; With the emergence of cryptocurrencies, Blockchain architectures have become more and more important. In such architectures, components maintain and exchange a list of records in a way which makes the entries persistent, i.e., resistant to modifications. Thereby, the architecture is dynamic in the sense that components may join or leave the network and connections between them may change over time. The dynamic nature of Blockchain architectures makes their verification a challenge, since it involves reasoning about potentially unbounded number of components. To this end, we developed FACTum, an approach for the specification and interactive verification of dynamic architectures based on the interactive theorem prover Isabelle. In this paper we report on the outcome of applying the approach to formally specify a version of Blockchain architectures and verify that the list entries of such architectures are indeed persistent.

Part 2: Security and Network Management; International audience; Various applications used by mobile users today need seamless connectivity for providing a good quality user experience. Enterprise Wireless Local Area Network (WLAN) is one of the technologies used by mobile devices to connect to the Internet in several environments. For providing seamless connectivity and communication, mobility management becomes an important aspect of such deployments. In this paper, we propose a client-unaware handover process for NAT (Network Address Translation) operation mode of the access points in a Software Defined Networking (SDN) based enterprise WLAN framework. The proposed mechanism has been implemented in simulation and the results show that the proposed mobility management mechanism is able to achieve seamless handover and provide uninterrupted connectivity and communication to the mobile devices.

International audience; Transactional data structures allow data structures to support transactional execution, in which a sequence of operations appears to execute atomically. We consider a paradigm in which a transaction commits its changes to the data structure only if all of its operations succeed; if one operation fails, then the transaction aborts. In this work, we introduce an optimization technique called Check-Wait-Pounce that increases performance by avoiding aborts that occur due to failed operations. Check-Wait-Pounce improves upon existing methodologies by delaying the execution of transactions until they are expected to succeed, using a thread-unsafe representation of the data structure as a heuristic. Our evaluation reveals that Check-Wait-Pounce reduces the number of aborts by an average of 49.0%. Because of this reduction in aborts, the tested transactional linked lists achieve average gains in throughput of 2.5x, while some achieve gains as high as 4x.

Part 4: Forwarding and Congestion Control; International audience; Novel interactive applications require small end-to-end latency for providing end users with good Quality of Experience. To prevent the bufferbloat problem causing increased delay, various AQM solutions have recently emerged. One of the most widely adopted method is called CoDel that detects the increased delay by maintaining the per packet sojourn times and compering them to a desired target delay. Accordingly, congestion situation is indicated when the sojourn time exceeds the target delay. CoDel applies a drop-based feedback to notify the responsive sources about congestion only when the deviation from the target delay is permanent. Dropping packets is then compensated by packet re-transmissions in case of TCP which worsens utilization. In this paper, we propose an ECN-enhanced CoDel that distinguishes between low and high levels of congestion, and ECN-marks or drops the packets, respectively. The performance of the proposed method is analyzed in thorough NS-3 simulations with variable number of flows. The proposed ECN-marking reduces the number of packets re-transmissions and provides similarly good characteristics including convergence time and fairness to the original drop-based CoDel.

We present in this paper a novel framework for the definition of formal software component models, called the Hypercell framework. Models in this framework (hypercell models) allow the definition of dynamic software architectures featuring shared components, and different forms of encapsulation policies. Encapsulation policies in an hypercell model are enforced by means of runtime checks that prevent a component, in a given context, to evolve in violation of these policies. We present the main elements of the framework, its operational semantics and the first elements of its behavioral theory. We give some results concerning its ability to express different forms of composition, and show by means of examples its ability to deal with sharing and different forms of encapsulation.

Part 4: Forwarding and Congestion Control; International audience; Device-to-device (D2D) communications and cellular solutions represent key technologies for the development of a future infrastructure in which fifth-generation (5G) systems and the Internet of Things (IoT) will converge. A tricky issue to be carefully investigated in D2D communications is the prevention of threats to privacy and security caused by malicious devices. Thus, security mechanisms must be implemented in order to assure a reliable data exchange among involved devices. In this paper, we propose MtMS-sD2D (Machine-type Multicast Service with secure D2D), an architecture for the delivery of multicast traffic in an IoT scenario that takes advantage from D2D communications made reliable by means of a security mechanism. Furthermore, we discuss the procedures that must be followed to efficiently deliver multicast traffic. Finally, we provide some preliminary yet insightful simulation results.

Part 1: Full Papers; International audience; Composition is a fundamental tool when dealing with complex systems. We study the hierarchical collateral composition which is used to combine self-stabilizing distributed algorithms. The PADEC library is a framework developed with the Coq proof assistant and dedicated to the certification of self-stabilizing algorithms. We enrich PADEC with the composition operator and a sufficient condition to show its correctness. The formal proof of the condition leads us to develop new tools and methods on potentially infinite streams, these latter ones being used to model the algorithms’ executions. The cornerstone has been the definition of the function which removes duplicates from streams.

Part 1: Full Papers; International audience; Debugging of concurrent systems is a tedious and error-proneactivity. A main issue is that there is no guarantee that a bug that appears in the original computation is replayed inside the debugger. This problem is usually tackled by so-called replay debugging, which allows the user to record a program execution and replay it inside the debugger. In this paper, we present a novel technique for replay debugging that we call controlled causal-consistent replay. Controlled causal-consistent replay allows the user to record a program execution and, in contrast to traditional replay debuggers, to reproduce a visible misbehavior inside the debugger including alland only its causes. In this way, the user is not distracted by the actions of others, unrelated processes.

Part 3: Exploring New Frontiers; International audience; Serverless computing, also known as Functions-as-a-Service, is a recent paradigm aimed at simplifying the programming of cloud applications. The idea is that developers design applications in terms of functions, which are then deployed on a cloud infrastructure. The infrastructure takes care of executing the functions whenever requested by remote clients, dealing automatically with distribution and scaling with respect to inbound traffic.While vendors already support a variety of programming languages for serverless computing (e.g. Go, Java, Javascript, Python), as far as we know there is no reference model yet to formally reason on this paradigm. In this paper, we propose the first core formal programming model for serverless computing, which combines ideas from both the lambda-calculus (for functions) and the pi-calculus (for communication). To illustrate our proposal, we model a real-world serverless system. Thanks to our model, we capture limitations of current vendors and formalise possible amendments.

Part 2: Security and Network Management; International audience; Several Internet of Things (IoT) applications have strict performance requirements, in terms of reliability and power consumption. IEEE 802.15.4 Time Slotted Channel Hopping (TSCH) is a recently stan-dardised Medium Access Control (MAC) protocol that supports these requirements by keeping the nodes time-synchronised. In order to ensure successful communication between a sender and a receiver, the latter starts listening shortly before the expected frame's arrival. This time offset is called guard time and it aims to reduce the probability of missed frames due to clock drift. This paper investigates the impact of the guard time on the energy consumption and proposes a scheme for the decen-tralised adaptation of the guard time in each node depending on its hop-distance from the sink. Simulations and test-bed experiments demonstrate that guard time adaptation can reduce the energy consumption by up to 50%, without compromising the reliability of the network.

International audience; Mobile crowdsourcing is being increasingly used by industrial and research communities to build realistic datasets. By leveraging the capabilities of mobile devices, mobile crowdsourcing apps can be used to track participants' activity and to collect insightful reports from the environment (e.g., air quality, network quality). However, most of existing crowdsourced datasets systematically tag data samples with time and location stamps, which may inevitably lead to user privacy leaks by discarding sensitive information. This paper addresses this critical limitation of the state of the art by proposing a software library that improves user privacy without compromising the overall quality of the crowdsourced datasets. We propose a decentralized approach, named Fougere, to convey data samples from user devices to third-party servers. By introducing an a priori data anonymization process, we show that Fougere defeats state-of-the-art location-based privacy attacks with little impact on the quality of crowd-sourced datasets.

Part 5: Distributed Applications; International audience; We address the problem of devising an optimized energy aware flight plan for multiple Unmanned Aerial Vehicles (UAVs) mounted Base Stations (BS) within heterogeneous networks. The chosen approach makes use of Q-learning algorithms, through the definition of a reward related to relevant quality and battery consumption metrics, providing also service overlapping avoidance between UAVs, that is two or more UAVs serving the same cluster area. Numerical simulations and different training show the effectiveness of the devised flight paths in improving the general quality of the heterogeneous network users.

Part 2: Tools (1); International audience; Although many research efforts have been spent on the theory and implementation of data-based coordination languages, not much effort has been devoted to constructing programming environments to analyze and reason on programs written in these languages. This paper proposes a simple workbench for describing concurrent systems using a Linda-like language, for animating them and for reasoning on them using a fragment of linear temporal logic. In contrast to some tools developed for traditional process algebras like CCS, a key feature of our workbench is that it maintains a direct relation between what is written by the user and its internal representation in the workbench. Another feature, particularly useful for didactic purposes, is the production of trace examples, replayable, when LTL formulae are satisfied.

Part 2: Poster Papers; International audience; 5G advances the wireless communications by providing a significant improvement to the data rate, capability of connected devices and data volumes compared to the previous generations. While these advantages combine along with a wider range of applications to merit the end-user, the technologies to be used are not specified. Considering this problem and in order to efficiently support the 5G deployment researchers and engineers turned their attention on FPGA base band architectures that keep the implementation cost relatively low and at the same time they are reprogramable to provide solutions to the emerging requirements and their consequent modifications. Aiming at the contribution to the 5G technologies the current paper introduces the design of a base band DSP architecture that targets the required real time performance. Moreover, the proposed architecture is scalable by efficiently parallelizing and/or pipelining the corresponding data paths. The paper presents the pilot FPGA designs of the IFFT/FFT and Sampling Frequency Offset (SFO) functions that achieve a 500 Msps performance on a RF-SoC Xilinx ZCU111 board.

Part 1: Regular Papers; International audience; This study focuses on the provisioning of resilient Cloud Radio Access Network (C-RAN) services employing optical transport networks. In response to the high bandwidth requirements necessary for the protection of the C-RAN architecture from optical transport network and/or BBU failures, a novel approach based on Network Coding (NC) is proposed. A novel architectural and hardware framework to enable NC are also provided and a suitable implementation addressing the problem of fast NC-related operations processing at the edge is demonstrated. A global time stamping solution that can be used to address the strict synchronization requirements of FH flows arriving at the BBUs, keeping buffering at the edge as low as possible, has been developed. The performance of the proposed solution has been experimentally evaluated demonstrating negligible penalties. Network level modeling results demonstrate a reduction of the total optical network capacity required for this type of applications by 33%.

Part 1: Regular Papers; International audience; Next generation fronthaul interface has been recently proposed to support different functional splits in 5G access networks. Each split option is characterized by different requirements in terms of latency and bandwidth. The mapping of different functional splits on the nodes of 5G access network introduces several degrees of freedom in relation to the variation of the traffic during the day. This paper proposes a novel function location algorithm, which adopts dynamic function chaining in relation to the evolution of the traffic estimate. The obtained results show remarkable improvement in terms of bandwidth saving and multiplexing gain with respect to conventional C-RAN fronthaul and suggest design criteria for the emerging 5G access network.

Part 1: Regular Papers; International audience; The ability to assign functions that comprise the BBU processing in centralized softwarised Radio Access Networks into different servers the, have been proven to be beneficial, in terms of energy efficiency. This paper proposes a heuristic suitable for BBU functions allocation and evaluates the impact of dynamic resource management in these environments facilitated through Virtual Machine (VM) live migration. The benefits associated with VM migration are quantified through a series of experiments. Our results show notable improvement in terms of resource and energy efficiency.

Most deployed optical transport networks are proprietary, behaving as a closed, highly coupled, single-vendor managed domain. Although their control planes and management systems may export high-level and open northbound interfaces (NBI), the internal details and interfaces are not disclosed to the network operator. However, driven by the requirements of telecommunication and datacenter operators and the need to keep costs down while supporting sustained traffic increase, a trend known as disaggregation has steadily emerged during the past years. It involves composing and assembling open and available components, devices and sub-systems into optical infrastructures and networks, combining “best-in-class” devices, tailored to the specific needs of the aforementioned operators. It has been motivated by factors such as an increase in hardware commoditization, a perceived different rate of innovation of the different components, a promised acceleration in service deployment, or the consequent reduction in operational and capacity expenses. In practice, disaggregation brings multiple challenges, depending on the level that applies (e.g., partial or total, down to each of the optical components) and is taking place in stages. It is commonly accepted that disaggregation implies a trade-off between: i) the opportunities due to the new degree of flexibility provided by component migration and upgrades without vendor lock-in and ii) the potential decrease in performance compared to fully integrated systems and the underlying complexity – including interoperainteroperability-, critical in full disaggregation scenarios. From the point of view of control and management, disaggregation heavily relies on the adoption of open interfaces exporting hardware programmability. Disaggregated optical networks are an important use case for the adoption or a unified, model-driven development. In this paper, tutorial in nature, we will introduce the main concepts behind Software Defined Networking (SDN) for disaggregated optical networks, presenting reference architectures and industry common practices related to the adoption of a unified, model driven approach. The second part will cover an overview of selected deployment models (e.g., addressing transceiver and OLS disaggregation) as well as the OpenConfig and OpenROADM optical device models and Transport API (TAPI) interfaces, which constitute the main elements of the implemented SDN control plane. Such control plane targets mainly the metro segment, as defined within the EC Metro-Haul and ONF ODTN projects., Grant numbers : Experimental research testbed on high-performance and large-scale intelligent optical transport networks.

Part 2: Poster Papers; International audience; In this work, we exploit the spatial dimension of spectrally-spatially flexible optical networks (SS-FONs) to perform path selection. The existing path selection schemes in SS-FONs predominantly use k-shortest paths (KSP) method. However, in this work, we demonstrate that in SS-FONs, consideration of core selection along with link selection between source and destination nodes can significantly increase the spectrum utilization efficiency. We propose a k-core arrangement based paths (KCAP) scheme that performs path calculation and prioritization on the basis of core arrangement in different multicore fiber (MCF) structures, threshold crosstalk (XT) values, distance adaptive modulation (DAM), and the number of MCF links. The proposed KCAP achieves better spectrum utilization than the existing XT-aware and predefined core-prioritization schemes.

Part 1: Regular Papers; International audience; We experimentally demonstrate two Analog Mobile Fronthaul concepts exploiting coherent optical systems technology. Single Sideband generation and coherent detection of a 12 Gb/s signal with 6 subcarriers using an IQ modulator is presented along with an extended reach Fiber-Wireless transmission concept using IQM-DD system and V-band radio.

Part 1: Regular Papers; International audience; The concept of edge computing is vital in the 5G ecosystem, as a means of introducing application awareness in the network and enabling constructs such as slicing to be effectively implemented. In this scope, an efficient infrastructure dimensioning requires visibility of both network and data-center resources. While this joint optimization is becoming increasingly common even at the optical layer, some aspects of the dimensioning remain siloed between the network/IT worlds. Survivability mechanisms are one such example, where protection for lightpaths and/or virtual network functions (VNFs) is typically provisioned independently, potentially incurring in resource overprovisioning. This paper investigates the merits of exploiting a hybrid strategy where backup resources are selectively distributed between the IT and optical layers in metro ring scenarios, according to specific service requirements such as latency and bandwidth. Critically, this analysis incorporates, through an integer linear programming (ILP) model, the effect of optical path performance on the cost efficiency of protection mechanisms, which is shown to greatly influence the optimal resource distribution in each deployment scenario.

Part 1: Regular Papers; International audience; A wireless-optical broadband access network (WOBAN) shows promise as potential 5G access infrastructure. Since network slicing allows efficient sharing of physical network resources, we consider the provisioning of availability-guaranteed slices in a WOBAN supporting mobile edge computing (MEC). A new definition for the availability of a slice is proposed accounting for a slice that functions only partially because of the failure of a fiber link, a microwave link, a base station (BS) node, and/or an optical line terminal (OLT). An integer linear programming (ILP) model and a simple but effective heuristic algorithm that balances the network traffic load and maximizes the slice availability are developed to maximally provision availability-guaranteed slices. Simulation results show the efficiency of the proposed approaches.

Part 1: Regular Papers; International audience; Passive Optical Networks (PONs) are an economically efficient means of providing high bandwidth services to end users because end-points can share the cost and the benefit of fibre optic connection. There is a growing interest in the use of PONs as a bearer for services such as Long Term Evolution (LTE), however work remains to be done to ensure stable, low latency and low packet loss for full duplex Transmission. In this paper we are mostly concerned with the characteristics of the downstream channel so as to further the case for PON sharing. We review typical downstream schedulers used in the industry and propose a three-stage downstream scheduler that assures quality of service, accurately, across Virtual Network Operators (VNOs) in multi-tenant PONs environment. We benchmark our scheduler against other algorithms, obtaining almost ideal scheduling performance.