Hybrid 5G optical-wireless SDN-based networks, challenges and open issues

The fifth-generation (5G) mobile networks are expected to bring higher capacity, higher density of mobile devices, lower battery consumption and improved coverage. 5G entails the convergence of wireless and wired communications in a unified and efficient architecture. Mobile nodes, as defined in fourth-generation era, are transformed in heterogeneous networks to make the front-haul wireless domains flexible and intelligent. This work highlights a set of critical challenges in advancing 5G networks, fuelled by the utilisation of the network function virtualisation, the software defined radio and the software defined networks techniques. Furthermore, a novel conceptual model is presented in terms of control and management planes, where the inner architectural components are introduced in detail

Identifying, categorizing and mitigating threats to validity in software engineering secondary studies

Context: Secondary studies are vulnerable to threats to validity. Although, mitigating these threats is crucial for the credibility of these studies, we currently lack a systematic approach to identify, categorize and mitigate threats to validity for secondary studies. Objective: In this paper, we review the corpus of secondary studies, with the aim to identify: (a) the trend of reporting threats to validity, (b) the most common threats to validity and corresponding mitigation actions, and (c) possible categories in which threats to validity can be classified. Method: To achieve this goal we employ the tertiary study research method that is used for synthesizing knowledge from existing secondary studies. In particular, we collected data from more than 100 studies, published until December 2016 in top quality software engineering venues (both journals and conference). Results: Our results suggest that in recent years, secondary studies are more likely to report their threats to validity. However, the presentation of such threats is rather ad hoc, e.g., the same threat may be presented with a different name, or under a different category. To alleviate this problem, we propose a classification schema for reporting threats to validity and possible mitigation actions. Both the classification of threats and the associated mitigation actions have been validated by an empirical study, i.e., Delphi rounds with experts. Conclusion: Based on the proposed schema, we provide a checklist, which authors of secondary studies can use for identifying and categorizing threats to validity and corresponding mitigation actions, while readers of secondary studies can use the checklist for assessing the validity of the reported results

UAV IoT frameworks views and challenges : towards protecting drones as "things"

Unmanned aerial vehicles (UAVs) have enormous potential in enabling new applications in various areas, ranging from military, security, medicine, and surveillance to traffic-monitoring applications. Lately, there has been heavy investment in the development of UAVs and multi-UAVs systems that can collaborate and complete missions more efficiently and economically. Emerging technologies such as 4G/5G networks have significant potential on UAVs equipped with cameras, sensors, and GPS receivers in delivering Internet of Things (IoT) services from great heights, creating an airborne domain of the IoT. However, there are many issues to be resolved before the effective use of UAVs can be made, including security, privacy, and management. As such, in this paper we review new UAV application areas enabled by the IoT and 5G technologies, analyze the sensor requirements, and overview solutions for fleet management over aerial-networking, privacy, and security challenges. Finally, we propose a framework that supports and enables these technologies on UAVs. The introduced framework provisions a holistic IoT architecture that enables the protection of UAVs as "flying" things in a collaborative networked environment

Estimation and prediction in software engineering with data analysis methods

An important issue for software development industry is the delivery of high quality software on time and within budget constraints. Software organizations recognize the need for adapting effective estimation methods regarding software development aspects, such as cost and quality in order to stay competitive. In practice, exploiting software development models is not an easy issue as problems regarding the adoption and interpretation of them may arise. Classical statistical methods present limited capabilities for modeling Software Engineering data, as they do not allow the extraction of interpretable models that can deal with the inherent uncertainty of the domain. In order to solve the above problems the current thesis explores the application of improved formal estimation methods. In particular this thesis consists of three parts: 1) Comparison of methods In this dissertation a series of comparisons regarding the suitability of formal methods in estimating software cost and quality issues are performed. The methods employed are Association Rules (AR), which are applied for the first time in the software estimation domain, Decision Trees (DT), Bayesian Belief Networks (BBN), Analogy based Cost Estimation (AbE). The comparisons performed pointed out the main advantages and disadvantages of the methods. Based on the conclusions drawn by the above comparisons this thesis suggests a framework for the selection of the most suitable formal estimation method according to the estimation context. 2) Suggestions for improvement Additionally based on the results of the comparisons performed, this thesis proposes certain improvement actions regarding the application of formal methods. The combination of AR and DT is suggested for creating conceptual, explanatory estimation models. Regression via Classification framework is presented in order to automatically apply formal methods. Also the selection of parameters of AbE method is suggested using Decision Rules. Finally the application of BBNs is explored in representing various estimation problems regarding software development, as the method is able to model the uncertainty of the domain and the subjective judgment of the human estimator. 3) Practical application Finally specialized estimation models regarding the predictions of development aspects of Decision Support Systems / Knowledge Based Systems, Telecommunication applications and Open Source Software are presented. Specialized estimation models are able to consider the unique attributes of the application domain and produce estimation models that present improved accuracy.Η παράδοση λογισμικού υψηλής ποιότητας, στα αναμενόμενα χρονικά περιθώρια και σε αποδεκτό κόστος είναι ένα σημαντικό ζήτημα για τη βιομηχανία λογισμικού. Οι εταιρείες λογισμικού για να εξασφαλίσουν την βιωσιμότητά τους αναγνωρίζουν την ανάγκη υιοθέτησης αποτελεσματικών μεθόδων εκτίμησης παραμέτρων ανάπτυξης λογισμικού, που σχετίζονται με το κόστος και την ποιότητά του. Ωστόσο στην πράξη η αξιοποίηση των μοντέλων εκτίμησης λογισμικού δεν είναι εύκολη υπόθεση καθώς συχνά παρουσιάζονται προβλήματα που σχετίζονται με την εφαρμογή και την ερμηνεία τους. Οι κλασσικές στατιστικές μέθοδοι εκτίμησης παρουσιάζουν περιορισμένες δυνατότητες μοντελοποίησης δεδομένων της Τεχνολογίας Λογισμικού καθώς δεν επιτρέπουν την ερμηνεία των αποτελεσμάτων και τον συνυπολογισμό της αβεβαιότητας εκτίμησης. Οι τυπικές μέθοδοι εκτίμησης, στην αποτελεσματική εφαρμογή των οποίων εστιάζει η παρούσα διατριβή, μπορούν να επιλύσουν σε μεγάλο βαθμό τα παραπάνω προβλήματα. Πιο συγκεκριμένα η διατριβή αυτή χωρίζεται σε τρία μέρη: 1) Σύγκριση μεθόδων Αρχικά πραγματοποιείται μια σειρά από συγκρίσεις των τυπικών μεθόδων εκτίμησης, σε διάφορα ζητήματα που σχετίζονται με το κόστος ανάπτυξης λογισμικού και την ποιότητά του. Οι μέθοδοι που εφαρμόζονται είναι οι Κανόνες Συσχέτισης (ΚΣ), οι οποίοι εφαρμόζονται για πρώτη φορά σε αυτό το επιστημονικό πεδίο, τα Δέντρα Απόφασης (ΔΑ), τα Δίκτυα Bayes (ΔΒ) και η εκτίμηση βασισμένη στις Αναλογίες (ΕβΑ). Οι συγκρίσεις που πραγματοποιήθηκαν ανέδειξαν τα πλεονεκτήματα και τα μειονεκτήματα των μεθόδων βάσει των οποίων προτείνεται η επιλογή της καταλληλότερης μεθόδου ανάλογα με το καθεστώς εκτίμησης. 2) Προτάσεις βελτίωσης Στη συνέχεια με βάση τα αποτελέσματα των συγκρίσεων που πραγματοποιήθηκαν προτείνονται τρόποι για την βελτίωση της απόδοσης των τυπικών μεθόδων εκτίμησης παραμέτρων ανάπτυξης λογισμικού. Προτείνεται α) ο συνδυασμός ΚΣ και ΔΑ για τη δημιουργία μοντέλων εκτίμησης με δυνατότητες περιγραφής και πρόβλεψης β) η Παλινδρόμηση μέσω Κατηγοριοποίησης για την αυτοματοποιημένη εφαρμογή τυπικών μεθόδων γ) η παραμετροποίηση ΕβΑ με Κανόνες Απόφασης για την αύξηση της ακρίβειας της μεθόδου, επίσης προτείνεται δ) η αναπαράσταση διαφόρων προβλημάτων ανάπτυξης λογισμικού με τη χρήση ΔΒ με στόχο την δημιουργία μοντέλων τα οποία διαχειρίζονται την αβεβαιότητα και συνυπολογίζουν την υποκειμενική κρίση του τελικού εκτιμητή. 3) Πρακτική εφαρμογή Τέλος προτείνεται ένα σύνολο από εξειδικευμένα μοντέλα εκτίμησης που αφορούν την πρόβλεψη παραμέτρων ανάπτυξης Συστημάτων Στήριξης Απόφασης και Συστημάτων Βάσης Γνώσης, Τηλεπικοινωνιακών Εφαρμογών και εφαρμογών Ελεύθερου Λογισμικού/ Λογισμικού Ανοιχτού Κώδικα. Η δημιουργία εξειδικευμένων μοντέλων έχει ως στόχο τον συνυπολογισμό των ιδιαιτεροτήτων ανάπτυξης του εκάστοτε τύπου εφαρμογής αλλά και την αύξηση της ακρίβειας πρόβλεψης λόγω ομοιογένειας των ιστορικών δεδομένων

Examining the reuse potentials of IoT application frameworks

The major challenge that a developer confronts when building IoT systems is the management of a plethora of technologies implemented with various constraints, from different manufacturers, that at the end need to cooperate. In this paper we argue that developers can benefit from IoT frameworks by reusing their components so as to build in less time and effort IoT systems that can easily integrate new technologies. In order to explore the reuse opportunities offered by IoT frameworks we have performed a case study and analyzed 503 components reused by 35 IoT projects. We examined (a) the types of functionality that are most facilitated for reuse (b) the reuse strategy that is most adopted (c) thequality of the reused components. The results of the case study suggest that the main functionality reused is the one related to the Device Management layer and that Black-box reuse is the main type. Moreover, the quality of the reused components is improved compared to the rest of the components built from scratch

A Bayesian Belief Network for Modeling Open Source Software Maintenance Productivity

Part 1: Full PapersInternational audienceMaintenance is one of the most effort consuming activities in the software development lifecycle. Efficient maintenance within short release cycles depends highly on the underlying source code structure, in the sense that complex modules are more difficult to maintain. In this paper we attempt to unveil and discuss relationships between maintenance productivity, the structural quality of the source code and process metrics like the type of a release and the number of downloads. To achieve this goal, we developed a Bayesian Belief Network (BBN) involving several maintainability predictors and three managerial indices for maintenance (i.e., duration, production, and productivity) on 20 open source software projects. The results suggest that maintenance duration depends on inheritance, coupling, and process metrics. On the other hand maintenance production and productivity depend mostly on code quality metrics

Precision Agriculture: A Remote Sensing Monitoring System Architecture

Smart Farming is a development that emphasizes on the use of modern technologies in the cyber-physical field management cycle. Technologies such as the Internet of Things (IoT) and Cloud Computing have accelerated the digital transformation of the conventional agricultural practices promising increased production rate and product quality. The adoption of smart farming though is hampered because of the lack of models providing guidance to practitioners regarding the necessary components that constitute IoT-based monitoring systems. To guide the process of designing and implementing Smart farming monitoring systems, in this paper we propose a generic reference architecture model, taking also into consideration a very important non-functional requirement, the energy consumption restriction. Moreover, we present and discuss the technologies that incorporate the seven layers of the architecture model that are the Sensor Layer, the Link Layer, the Encapsulation Layer, the Middleware Layer, the Configuration Layer, the Management Layer and the Application Layer. Furthermore, the proposed Reference Architecture model is exemplified in a real-world application for surveying Saffron agriculture in Kozani, Greece