Software-Defined Networking: A Comprehensive Survey

peer reviewedThe Internet has led to the creation of a digital society, where (almost) everything is connected and is accessible from anywhere. However, despite their widespread adoption, traditional IP networks are complex and very hard to manage. It is both difficult to configure the network according to predefined policies, and to reconfigure it to respond to faults, load, and changes. To make matters even more difficult, current networks are also vertically integrated: the control and data planes are bundled together. Software-defined networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns, introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper, we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound application programming interfaces (APIs), network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this - ew paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms—with a focus on aspects such as resiliency, scalability, performance, security, and dependability—as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment

A Brain-Controlled Exoskeleton with Cascaded Event-Related Desynchronization Classifiers

This paper describes a brain-machine interface for the online control of a powered lower-limb exoskeleton based on electroencephalogram (EEG) signals recorded over the user’s sensorimotor cortical areas. We train a binary decoder that can distinguish two different mental states, which is applied in a cascaded manner to efficiently control the exoskeleton in three different directions: walk front, turn left and turn right. This is realized by first classifying the user’s intention to walk front or change the direction. If the user decides to change the direction, a subsequent classification is performed to decide turn left or right. The user’s mental command is conditionally executed considering the possibility of obstacle collision. All five subjects were able to successfully complete the 3-way navigation task using brain signals while mounted in the exoskeleton. We observed on average 10.2% decrease in overall task completion time compared to the baseline protocol

Study of Multimedia Delivery over Software Defined Networks

[EN] Software Defined Networks (SDN) have become a new way to make dynamic topologies. They have great potential in both the creation and development of new network protocols and the inclusion of distributed artificial intelligence in the network. There are few emulators, like Mininet, that allow emulating a SDN in a single personal computer, but there is lack of works showing its performance and how it performs compared with real cases. This paper shows a performance comparison between Mininet and a real network when multimedia streams are being delivered. We are going to compare them in terms of consumed bandwidth (throughput), delay and jitter. Our study shows that there are some important differences when these parameters are compared. We hope that this research will be the basis to show the difference with real deployments when Mininet is used.This work has been supported by the “Ministerio de Economía y Competitividad”, through the “Convocatoria 2014. Proyectos I+D - Programa Estatal de Investigación Científica y Técnica de Excelencia” in the “Subprograma Estatal de Generación de Conocimiento”, project TIN2014-57991-C3-1-P and the “programa para la Formación de Personal Investigador – (FPI-2015-S2-884)” by the“Universitat Politècnica de València”.Jimenez, JM.; Romero Martínez, JO.; Rego, A.; Dilendra, A.; Lloret, J. (2015). Study of Multimedia Delivery over Software Defined Networks. Network Protocols and Algorithms. 7(4):37-62. https://doi.org/10.5296/npa.v7i4.8794S37627

Context prediction-based prefetching in software-defined wireless networks

In this master thesis we focus on improving in-network caching for mobile users in a large campus WiFi network. First we pinpoint the negative effects of mobility on network conditions and user experience. We propose a method leveraging SDN technology to redirect users' requests to optimally located cache servers, resulting in improved user experience and lowered burden on the backhaul and core network links. Our contribution is a network application that controls the flows in the network via an SDN controller. The application takes user's movement traces as an input, computes the optimal location of cache servers in the network and redirects user's flows accordingly. We tested our solution in a Mininet network simulator. We devised multiple scenarios using real-world movement traces from Dartmouth Campus. We measured requests delay as the main characteristic for user experience and data traffic over core and backhaul links as an indicator of network health. Our experiments show that for mobile users our dynamic redirection approach provides noticeable improvements over traditional, static caching methods

Dual operative radar for vehicle to vehicle and vehicle to infrastructure communication

The research presented in this Thesis deals with the concepts of joint radar and communication system for automotive application. The novel systems developed include a joint radar and communication system based on the fractional Fourier transform (FrFT) and two interference mitigation frameworks. In the joint radar and communication system the FrFT is used to embed the data information into a radar waveform in order to obtain a signal sharing Linear Frequency Modulation (LFM) characteristics while allowing data transmission. Furthermore, in the proposed system multi user operations are allowed by assigning a specific order of the FrFT to each user. In this way, a fractional order division multiplexing can be implemented allowing the allocation of more than one user in the same frequency band with the advantage that the range resolution does not depend on the number of the users that share the same frequency band but only from the assigned of the FrFT. Remarkably, the predicted simulated radar performance of the proposed joint radar and communication system when using Binary Frequency Shift Keying (BFSK) encoding is not significantly affected by the transmitted data. In order to fully describe the proposed waveform design, the signal model when the bits of information are modulated using either BFSK or Binary Phase Shift Keying (BPSK) encoding is derived. This signal model will result also useful in the interference mitigation frameworks. In multi user scenarios to prevent mutual radar interference caused by users that share the same frequency band at the same time, each user has to transmit waveforms that are uncorrelated with those of other users. However, due to spectrum limitations, the uncorrelated property cannot always be satisfied even by using fractional order division multiplexing, thus interference is unavoidable. In order to mitigate the interference, two frameworks are introduced. In a joint radar communication system, the radar also has access to the communication data. With a near-precision reconstruction of the communication signal, this interference can be subtracted. In these two frameworks the interfering signal can be reconstructed using the derived mathematical model of the proposed FrFT waveform. In the first framework the subtraction between the received and reconstructed interference signals is carried out in a coherent manner, where the amplitude and phase of the two signals are taken into account. The performance of this framework is highly depend on the correct estimation of the Doppler frequency of the interfering user. A small error on the Doppler frequency can lead to a lack of synchronization between the received and reconstructed signal. Consequently, the subtraction will not be performed in a correct way and further interference components can be introduced. In order to solve the problem of the lack of the synchronization an alternative framework is developed where the subtraction is carried out in non-coherent manner. In the proposed framework, the subtraction is carried out after that the received radar signal and the reconstructed interference are processed, respectively. The performance is tested on simulated and real signals. The simulated and experimental results show that this framework is capable of mitigating the interference from other users successfully.The research presented in this Thesis deals with the concepts of joint radar and communication system for automotive application. The novel systems developed include a joint radar and communication system based on the fractional Fourier transform (FrFT) and two interference mitigation frameworks. In the joint radar and communication system the FrFT is used to embed the data information into a radar waveform in order to obtain a signal sharing Linear Frequency Modulation (LFM) characteristics while allowing data transmission. Furthermore, in the proposed system multi user operations are allowed by assigning a specific order of the FrFT to each user. In this way, a fractional order division multiplexing can be implemented allowing the allocation of more than one user in the same frequency band with the advantage that the range resolution does not depend on the number of the users that share the same frequency band but only from the assigned of the FrFT. Remarkably, the predicted simulated radar performance of the proposed joint radar and communication system when using Binary Frequency Shift Keying (BFSK) encoding is not significantly affected by the transmitted data. In order to fully describe the proposed waveform design, the signal model when the bits of information are modulated using either BFSK or Binary Phase Shift Keying (BPSK) encoding is derived. This signal model will result also useful in the interference mitigation frameworks. In multi user scenarios to prevent mutual radar interference caused by users that share the same frequency band at the same time, each user has to transmit waveforms that are uncorrelated with those of other users. However, due to spectrum limitations, the uncorrelated property cannot always be satisfied even by using fractional order division multiplexing, thus interference is unavoidable. In order to mitigate the interference, two frameworks are introduced. In a joint radar communication system, the radar also has access to the communication data. With a near-precision reconstruction of the communication signal, this interference can be subtracted. In these two frameworks the interfering signal can be reconstructed using the derived mathematical model of the proposed FrFT waveform. In the first framework the subtraction between the received and reconstructed interference signals is carried out in a coherent manner, where the amplitude and phase of the two signals are taken into account. The performance of this framework is highly depend on the correct estimation of the Doppler frequency of the interfering user. A small error on the Doppler frequency can lead to a lack of synchronization between the received and reconstructed signal. Consequently, the subtraction will not be performed in a correct way and further interference components can be introduced. In order to solve the problem of the lack of the synchronization an alternative framework is developed where the subtraction is carried out in non-coherent manner. In the proposed framework, the subtraction is carried out after that the received radar signal and the reconstructed interference are processed, respectively. The performance is tested on simulated and real signals. The simulated and experimental results show that this framework is capable of mitigating the interference from other users successfully

Contributing to the pathway towards 5G experimentation with an SDN-controlled network box

Καθώς η απαίτηση σε ευρυζωνικές υπηρεσίες κινητών επικοινωνιών αυξάνεται ραγδαία, τα υπάρχοντα δίκτυα κινητών επικοινωνιών πλησιάζουν τα όριά τους κάνοντας επιτακτική την ανάγκη εξέλιξής τους η οποία θα επέλθει με την τεχνολογική άφιξη της επόμενης γενιάς κινητών επικοινωνιών, ευρέως γνωστής ως 5G. Το 5G μεταφέρει όλες εκείνες τις δυνατότητες οι οποίες είναι απαραίτητες για να καλυφθούν οι συνεχώς αυξανόμενες ανάγκες σε ευρυζωνικές υπηρεσίες, να υποστηρίξουν το Internet of Things καθώς και να ενοποιήσουν ετερογενείς υπηρεσίες σε διαφορετικές βιομηχανίες. Η παρούσα διπλωματική εργασία στοχεύει να παρουσιάσει το “Network in a box”, ένα καινοτόμο εργαλείο που αναπτύξαμε στο εργαστήριο, το οποίο βασίζεται επάνω στους θεμέλιους λίθους του 5G, το SDN και το NFV. Με το SDN να είναι η νέα προσέγγιση στα δίκτυα κινητών επικοινωνιών, ο έλεγχος διαχωρίζεται από τα δεδομένα παρέχοντας τη δυνατότητα οποιεσδήποτε αποφάσεις ελέγχου, να λαμβάνονται κεντρικά, μετατρέποντας έτσι τις κλασικές δικτυακές συσκευές σε απλά προωθητικά στοιχεία του δικτύου. Η συγκεκριμένη διάταξη μιμείται ένα πραγματικό δίκτυο, το οποίο διαθέτει δυνατότητες αυτο-οργάνωσης και αυτο-βελτίωσης, προσομοιώνοντας τη λειτουργία του 5G δικτύου. Το συγκεκριμένο εργαλείο είναι επίσης ικανό να παράσχει KPI μετρικές του 5G δικτύου κάτω από πραγματικές συνθήκες ενόσω αληθινές δικτυακές συσκευές είναι συνδεδεμένες σε αυτό. Η δομή της παρούσας διπλωματικής εργασίας αναλύεται σε πέντε κεφάλαια. Το πρώτο κεφάλαιο παρουσιάζει τις προκλήσεις που σύντομα θα κληθούν να αντιμετωπίσουν τα δίκτυα κινητών επικοινωνιών και πώς αυτές μπορούν να καλυφθούν με την τεχνολογία του 5G. Το δεύτερο κεφάλαιο εισάγει την τάση στην αγορά των κινητών επικοινωνιών που διαφένεται πίσω από την επερχόμενη άφιξη του 5G, αποκαλύπτοντας το επιχειρηματικό πλαίσιο για επιχειρήσεις, καταναλωτές και συνεργασίες όπως επίσης και κάποιες περιπτώσεις χρήσης που αντικατοπτρίζουν την διαρκή εξέλιξη στις ευρυζωνικές υπηρεσίες κινητών επικοινωνιών. Το τρίτο κεφάλαιο εμπεριέχει μια μικρή επισκόπηση των τρέχοντων έργων πάνω στο 5G, τα οποία ξεκίνησαν υπό την αιγίδα της Ευρωπαϊκής Επιτροπής με τη συνεργασία προμηθευτών τεχνολογίας επικοινωνιών, παρόχων υπηρεσιών, μικρομεσαίων επιχειρήσεων και πανεπιστημίων. Γίνεται επίσης αναφορά στις βασικές τεχνολογίες του 5G και στις δραστηριότητες προτυποποίησής του. Προχωρώντας στο τέταρτο κεφάλαιο, περιγράφουμε σε βάθος την αρχιτεκτονική του 5G δικτύου, αναλύοντας τα SDN, NFV, MANO και εξετάζουμε πώς αυτά συνεισφέρουν στη βιωσιμότητα του δικτύου. Τέλος, στο πέμπτο κεφάλαιο εισάγουμε μια καινοτόμο ιδέα που αναπτύξαμε στο εργαστήριο δικτύων του πανεπιστημίου μας, ένα πλήρως αυτόνομο δικτυακό εργαλείο, το “Network in a box”. Παρουσιάζουμε σε βάθος πώς αυτός ο server μπορεί να εγκατασταθεί και να λειτουργήσει καθώς και τις δυνατότητές του κάτω από πραγματικές συνθήκες λειτουργίας του δικτύου, ενώ λαμβάνουν χώρα υποβάθμιση ποιότητας ή μη-διαθεσιμότητα στις δικτυακές ζεύξεις, παρέχοντας επίσης μετρικές από τη λειτουργία του δικτύου σε πραγματικό χρόνο.As the demand in mobile broadband is tremendously increased and the heterogeneity of the services to be covered is growing rapidly, current mobile networks are close to their limits imposing the need of an evolution which is going to be introduced by the next generation technology, the ITU IMT-2020, well known as 5G. 5G brings all those capabilities required to cover the increased mobile broadband needs, support the Internet of Things and bind heterogeneous services in different industries. This diploma thesis aims at presenting the “Network in a box”, an innovative tool we developed which is based on the key 5G principles, SDN and NFV. With Software Defined Networking (SDN) being the new approach in mobile networks, control and data plane are decoupled providing the ability to make any control related decisions centrally and transform legacy network devices to simple forwarding elements. This testbed is a portable emulated network device which is self-managed and self-optimised and can be connected between any real network devices, emulating how the 5G network will perform. This plug & play black-box testbed is also capable of providing KPI metrics of the 5G network under real circumstances when real network devices are connected to it. The structure of this diploma thesis is decomposed in five chapters. Chapter 1 presents the challenges mobile networks will shortly face due to the growing heterogeneous demands in communications towards the year 2020 and beyond and how these can be met with the upcoming 5G technology. Chapter 2 introduces the market trend behind the new era of 5G, revealing the business context for enterprises, consumers, verticals and partnerships as well as some use cases which reflect the continuous mobile broadband evolution. Chapter 3 includes a short overview of the ongoing 5G projects, initiated under the umbrella of the European Commission, with the collaboration of communications technology vendors, telecommunications operators, service providers, small and medium-sized enterprises (SMEs) and universities. There is also a reference in 5G key enabling technologies and standardisation activities as we move towards the next generation mobile networks technology. Moving forward, chapter 4 describes in detail the technological components of 5G network architecture such as SDN, NFV, MANO and examines how these 5G key enabling technologies contribute to the overall networks’ sustainability. Finally, in chapter 5 we introduce an innovative idea developed in our university’s communications network research laboratory, an autonomous emulated portable network testbed, the “Network in a box”. We present in-depth how this portable server is deployed, operates and demonstrate the way it can be connected to real network elements emulating a real 5G end-to-end customer network. Moreover, in this last chapter we present “Network in a box” capabilities under real network circumstances when link degradations or failures take place, providing also real-time network metrics

Adaptive Multi-Functional Space Systems for Micro-Climate Control

This report summarizes the work done during the Adaptive Multifunctional Systems for Microclimate Control Study held at the Caltech Keck Institute for Space Studies (KISS) in 2014-2015. Dr. Marco Quadrelli (JPL), Dr. James Lyke (AFRL), and Prof. Sergio Pellegrino (Caltech) led the Study, which included two workshops: the first in May of 2014, and another in February of 2015. The Final Report of the Study presented here describes the potential relevance of adaptive multifunctional systems for microclimate control to the missions outlined in the 2010 NRC Decadal Survey. The objective of the Study was to adapt the most recent advances in multifunctional reconfigurable and adaptive structures to enable a microenvironment control to support space exploration in extreme environments (EE). The technical goal was to identify the most efficient materials, architectures, structures and means of deployment/reconfiguration, system autonomy and energy management solutions needed to optimally project/generate a micro-environment around space assets. For example, compact packed thin-layer reflective structures unfolding to large areas can reflect solar energy, warming and illuminating assets such as exploration rovers on Mars or human habitats on the Moon. This novel solution is called an energy-projecting multifunctional system (EPMFS), which are composed of Multifunctional Systems (MFS) and Energy-Projecting Systems (EPS)

An SDN QoE Monitoring Framework for VoIP and video applications

Τα τελευταία χρόνια έχει σημειωθεί ραγδαία άνοδος του κλάδου των κινητών επικοινωνιών, αφού η χρήση των κινητών συσκευών εξαπλώνεται με ταχύτατους ρυθμούς και αναμένεται να συνεχίσει τη διείσδυσή της στην καθημερινότητα των καταναλωτών. Το γεγονός αυτό, σε συνδυασμό με τους περιορισμούς που θέτει η τρέχουσα δομή των δικτύων επικοινωνιών, καθιστά αναγκαία την ανάπτυξη νέων δικτύων με αυξημένες δυνατότητες, ώστε να είναι δυνατή η εξυπηρέτηση των χρηστών με την καλύτερη δυνατή ποιότητα εμπειρίας και ταυτόχρονα τη βέλτιστη αξιοποίηση των πόρων του δικτύου. Μία νέα δικτυακή προσέγγιση αποτελεί η δικτύωση βασισμένη στο λογισμικό (Software Defined Networking - SDN), η οποία αφαιρεί τον έλεγχο από τις συσκευές προώθησης του δικτύου, και οι αποφάσεις λαμβάνονται σε κεντρικό σημείο. Η ποιότητα υπηρεσίας που αντιλαμβάνεται ο χρήστης, ή αλλιώς ποιότητα εμπειρίας, κρίνεται ζήτημα υψηλής σημασίας στα δίκτυα SDN. Η παρούσα διπλωματική εργασία έχει ως στόχο την παρουσίαση της τεχνολογίας SDN, την επισκόπηση της υπάρχουσας έρευνας στο πεδίο της ποιότητας εμπειρίας σε SDN δίκτυα και στη συνέχεια την ανάπτυξη μίας SDN εφαρμογής η οποία παρακολουθεί και διατηρεί την ποιότητας εμπειρίας σε υψηλά επίπεδα για εφαρμογές VoIP και video. Πιο συγκεκριμένα, η εφαρμογή SQMF (SDN QoE Monitoring Framework) παρακολουθεί περιοδικά στο μονοπάτι μετάδοσης των πακέτων διάφορες παραμέτρους του δικτύου, με βάση τις οποίες υπολογίζει την ποιότητα εμπειρίας. Εάν διαπιστωθεί ότι το αποτέλεσμα είναι μικρότερο από ένα προσδιορισμένο κατώφλι, η εφαρμογή αλλάζει το μονοπάτι μετάδοσης, και έτσι η ποιότητα εμπειρίας ανακάμπτει. Η δομή της παρούσας διπλωματικής εργασίας είναι η εξής: Στο κεφάλαιο 1 παρουσιάζεται η σημερινή εικόνα των δικτύων επικοινωνιών και οι προβλέψεις για τη μελλοντική εικόνα, καθώς και οι προκλήσεις στις οποίες τα σημερινά δίκτυα δε θα μπορούν να αντεπεξέλθουν. Στη συνέχεια στο κεφάλαιο 2 περιγράφεται αναλυτικά η τεχνολογία SDN ως προς την αρχιτεκτονική, το κύριο πρωτόκολλο που χρησιμοποιεί, τα σενάρια χρήσης της, την προτυποποίηση, τα πλεονεκτήματα και τα μειονεκτήματά της. Το κεφάλαιο 3 εισάγει την έννοια της ποιότητας εμπειρίας του χρήστη και παραθέτει ευρέως γνωστά μοντέλα υπολογισμού της για διάφορους τύπους εφαρμογών, που χρησιμοποιούνται στην παρούσα εργασία. Σχετικές υπάρχουσες μελέτες στο πεδίο της ποιότητας εμπειρίας σε δίκτυα SDN αλλά και συγκριτικός πίνακας μπορούν να βρεθούν στο κεφάλαιο 4. Τα επόμενα κεφάλαια αφορούν στην εφαρμογή SQMF που υλοποιήθηκε στα πλαίσια της παρούσας διπλωματικής εργασίας: το κεφάλαιο 5 περιγράφει αναλυτικά όλα τα προαπαιτούμενα εργαλεία και οδηγίες για την ανάπτυξη του SQMF, ενώ το κεφάλαιο 6 παρουσιάζει παραδείγματα όπου η ποιότητα εμπειρίας ενός δικτύου μπορεί να υποστεί μείωση. Τέλος, το κεφάλαιο 7 αναλύει σε βάθος τις σχεδιαστικές προδιαγραφές, τη λογική και τον κώδικα του SQMF και παρέχει επίδειξη της λειτουργίας του και αξιολόγησή του, ενώ το κεφάλαιο 8 συνοψίζει επιγραμματικά τα συμπεράσματα της παρούσας εργασίας και ανοιχτά θέματα για μελλοντική έρευνα.Lately, there has been a rapid rise of the mobile communications industry, since the use of mobile devices is spreading at a fast pace and is expected to continue its penetration into the daily routine of consumers. This fact, combined with the limitations of the current communications networks’ structure, necessitates the development of new networks with increased capabilities, so that users can be served with the best possible quality of service and at the same time with the optimal network resources utilization. A new networking approach is Software Defined Networking (SDN) which decouples the control from the data plane, transforming the network elements to simple forwarding devices and making decisions centrally. The quality of service perceived by the user, or quality of experience (QoE), is considered to be a matter of great importance in software defined networks. This diploma thesis aims at presenting SDN technology, reviewing existing research in the field of QoE on SDN networks and then developing an SDN application that monitors and preserves the QoE for VoIP and video applications. More specifically, the developed SDN QoE Monitoring Framework (SQMF) periodically monitors various network parameters on the VoIP/video packets transmission path, based on which it calculates the QoE. If it is found that the result is less than a predefined threshold, the framework changes the transmission path, and thus the QoE recovers. The structure of this diploma thesis is the following: Chapter 1 presents the current state of communications networks and predictions for the future state, as well as the challenges that current networks will not be able to cope with. Chapter 2 then describes in detail the SDN technology in terms of architecture, main control-data plane communication protocol, use cases, standardization, advantages and disadvantages. Chapter 3 introduces the concept of QoE and lists well-known QoE estimation models for various applications types, some of which were used in this thesis. Relevant existing studies in the field of QoE on SDN networks as well as a comparative table can be found in chapter 4. The following chapters concern the framework implemented in the context of this diploma thesis: Chapter 5 describes in detail all the required tools and instructions for the development of SQMF, while Chapter 6 presents examples where the QoE in a network can face degradation. Finally, Chapter 7 analyzes in depth SQMF's design principles, logic and code files, provides a demonstration of its operation and evaluates it, whereas Chapter 8 briefly summarizes the conclusions and of this thesis and future work points