Traffic Steering in Radio Level Integration of LTE and Wi-Fi Networks

A smartphone generates approximately 1, 614 MB of data per month which is 48 times of the data generated by a typical basic-feature cell phone. Cisco forecasts that the mobile data traffic growth will remain to increase and reach 49 Exabytes per month by 2021. However, the telecommunication service providers/operators face many challenges in order to improve cellular network capacity to match these ever-increasing data demands due to low, almost flat Average Revenue Per User (ARPU) and low Return on Investment (RoI). Spectrum resource crunch and licensing requirement for operation in cellular bands further complicate the procedure to support and manage the network. In order to deal with the aforementioned challenges, one of the most vital solutions is to leverage the integration benefits of cellular networks with unlicensed operation of Wi-Fi networks. A closer level of cellular and Wi-Fi coupling/interworking improves Quality of Service (QoS) by unified connection management to user devices (UEs). It also offloads a significant portion of user traffic from cellular Base Station (BS) to Wi-Fi Access Point (AP). In this thesis, we have considered the cellular network to be Long Term Evolution (LTE) popularly known as 4G-LTE for interworking with Wi-Fi. Third Generation Partnership Project (3GPP) defined various LTE and Wi-Fi interworking architectures from Rel-8 to Rel-11. Because of the limitations in these legacy LTE Wi-Fi interworking solutions, 3GPP proposed Radio Level Integration (RLI) architectures to enhance flow mobility and to react fast to channel dynamics. RLI node encompasses link level connection between Small cell deployments, (ii) Meeting Guaranteed Bit Rate (GBR) requirements of the users including those experiencing poor Signal to Interference plus Noise Ratio (SINR), and (iii) Dynamic steering of the flows across LTE and Wi-Fi links to maximize the system throughput. The second important problem addressed is the uplink traffic steering. To enable efficient uplink traffic steering in LWIP system, in this thesis, Network Coordination Function (NCF) is proposed. NCF is realized at the LWIP node by implementing various uplink traffic steering algorithms. NCF encompasses four different uplink traffic steering algorithms for efficient utilization of Wi-Fi resources in LWIP system. NCF facilitates the network to take intelligent decisions rather than individual UEs deciding to steer the uplink traffic onto LTE link or Wi-Fi link. The NCF algorithms work by leveraging the availability of LTE as the anchor to improvise the channel utilization of Wi-Fi. The third most important problem is to enable packet level steering in LWIP. When data rates of LTE and Wi-Fi links are incomparable, steering packets across the links create problems for TCP traffic. When the packets are received Out-of-Order (OOO) at the TCP receiver due to variation in delay experienced on each link, it leads to the generation of DUPlicate ACKnowledgements (DUP-ACK). These unnecessary DUP-ACKs adversely affect the TCP congestion window growth and thereby lead to poor TCP performance. This thesis addresses this problem by proposing a virtual congestion control mechanism (VIrtual congeStion control wIth Boost acknowLedgEment -VISIBLE). The proposed mechanism not only improves the throughput of a flow by reducing the number of unnecessary DUPACKs delivered to the TCP sender but also sends Boost ACKs in order to rapidly grow the congestion window to reap in aggregation benefits of heterogeneous links. The fourth problem considered is the placement of LWIP nodes. In this thesis, we have addressed problems pertaining to the dense deployment of LWIP nodes. LWIP deployment can be realized in colocated and non-colocated fashion. The placement of LWIP nodes is done with the following objectives: (i) Minimizing the number of LWIP nodes deployed without any coverage holes, (ii) Maximizing SINR in every sub-region of a building, and (iii) Minimizing the energy spent by UEs and LWIP nodes. Finally, prototypes of RLI architectures are presented (i.e., LWIP and LWA testbeds). The prototypes are developed using open source LTE platform OpenAirInterface (OAI) and commercial-off-the-shelf hardware components. The developed LWIP prototype is made to work with commercial UE (Nexus 5). The LWA prototype requires modification at the UE protocol stack, hence it is realized using OAI-UE. The developed prototypes are coupled with the legacy multipath protocol such as MPTCP to investigate the coupling benefits

Improved planning and resource management in next generation green mobile communication networks

In upcoming years, mobile communication networks will experience a disruptive reinventing process through the deployment of post 5th Generation (5G) mobile networks. Profound impacts are expected on network planning processes, maintenance and operations, on mobile services, subscribers with major changes in their data consumption and generation behaviours, as well as on devices itself, with a myriad of different equipment communicating over such networks. Post 5G will be characterized by a profound transformation of several aspects: processes, technology, economic, social, but also environmental aspects, with energy efficiency and carbon neutrality playing an important role. It will represent a network of networks: where different types of access networks will coexist, an increasing diversity of devices of different nature, massive cloud computing utilization and subscribers with unprecedented data-consuming behaviours. All at greater throughput and quality of service, as unseen in previous generations. The present research work uses 5G new radio (NR) latest release as baseline for developing the research activities, with future networks post 5G NR in focus. Two approaches were followed: i) method re-engineering, to propose new mechanisms and overcome existing or predictably existing limitations and ii) concept design and innovation, to propose and present innovative methods or mechanisms to enhance and improve the design, planning, operation, maintenance and optimization of 5G networks. Four main research areas were addressed, focusing on optimization and enhancement of 5G NR future networks, the usage of edge virtualized functions, subscriber’s behavior towards the generation of data and a carbon sequestering model aiming to achieve carbon neutrality. Several contributions have been made and demonstrated, either through models of methodologies that will, on each of the research areas, provide significant improvements and enhancements from the planning phase to the operational phase, always focusing on optimizing resource management. All the contributions are retro compatible with 5G NR and can also be applied to what starts being foreseen as future mobile networks. From the subscriber’s perspective and the ultimate goal of providing the best quality of experience possible, still considering the mobile network operator’s (MNO) perspective, the different proposed or developed approaches resulted in optimization methods for the numerous problems identified throughout the work. Overall, all of such contributed individually but aggregately as a whole to improve and enhance globally future mobile networks. Therefore, an answer to the main question was provided: how to further optimize a next-generation network - developed with optimization in mind - making it even more efficient while, simultaneously, becoming neutral concerning carbon emissions. The developed model for MNOs which aimed to achieve carbon neutrality through CO2 sequestration together with the subscriber’s behaviour model - topics still not deeply focused nowadays – are two of the main contributions of this thesis and of utmost importance for post-5G networks.Nos próximos anos espera-se que as redes de comunicações móveis se reinventem para lá da 5ª Geração (5G), com impactos profundos ao nível da forma como são planeadas, mantidas e operacionalizadas, ao nível do comportamento dos subscritores de serviços móveis, e através de uma miríade de dispositivos a comunicar através das mesmas. Estas redes serão profundamente transformadoras em termos tecnológicos, económicos, sociais, mas também ambientais, sendo a eficiência energética e a neutralidade carbónica aspetos que sofrem uma profunda melhoria. Paradoxalmente, numa rede em que coexistirão diferentes tipos de redes de acesso, mais dispositivos, utilização massiva de sistema de computação em nuvem, e subscritores com comportamentos de consumo de serviços inéditos nas gerações anteriores. O trabalho desenvolvido utiliza como base a release mais recente das redes 5G NR (New Radio), sendo o principal focus as redes pós-5G. Foi adotada uma abordagem de "reengenharia de métodos” (com o objetivo de propor mecanismos para resolver limitações existentes ou previsíveis) e de “inovação e design de conceitos”, em que são apresentadas técnicas e metodologias inovadoras, com o principal objetivo de contribuir para um desenho e operação otimizadas desta geração de redes celulares. Quatro grandes áreas de investigação foram endereçadas, contribuindo individualmente para um todo: melhorias e otimização generalizada de redes pós-5G, a utilização de virtualização de funções de rede, a análise comportamental dos subscritores no respeitante à geração e consumo de tráfego e finalmente, um modelo de sequestro de carbono com o objetivo de compensar as emissões produzidas por esse tipo de redes que se prevê ser massiva, almejando atingir a neutralidade carbónica. Como resultado deste trabalho, foram feitas e demonstradas várias contribuições, através de modelos ou metodologias, representando em cada área de investigação melhorias e otimizações, que, todas contribuindo para o mesmo objetivo, tiveram em consideração a retro compatibilidade e aplicabilidade ao que se prevê que sejam as futuras redes pós 5G. Focando sempre na perspetiva do subscritor da melhor experiência possível, mas também no lado do operador de serviço móvel – que pretende otimizar as suas redes, reduzir custos e maximizar o nível de qualidade de serviço prestado - as diferentes abordagens que foram desenvolvidas ou propostas, tiveram como resultado a resolução ou otimização dos diferentes problemas identificados, contribuindo de forma agregada para a melhoria do sistema no seu todo, respondendo à questão principal de como otimizar ainda mais uma rede desenvolvida para ser extremamente eficiente, tornando-a, simultaneamente, neutra em termos de emissões de carbono. Das principais contribuições deste trabalho relevam-se precisamente o modelo de compensação das emissões de CO2, com vista à neutralidade carbónica e um modelo de análise comportamental dos subscritores, dois temas ainda pouco explorados e extremamente importantes em contexto de redes futuras pós-5G

Millimetre wave frequency band as a candidate spectrum for 5G network architecture : a survey

In order to meet the huge growth in global mobile data traffic in 2020 and beyond, the development of the 5th Generation (5G) system is required as the current 4G system is expected to fall short of the provision needed for such growth. 5G is anticipated to use a higher carrier frequency in the millimetre wave (mm-wave) band, within the 20 to 90 GHz, due to the availability of a vast amount of unexploited bandwidth. It is a revolutionary step to use these bands because of their different propagation characteristics, severe atmospheric attenuation, and hardware constraints. In this paper, we carry out a survey of 5G research contributions and proposed design architectures based on mm-wave communications. We present and discuss the use of mm-wave as indoor and outdoor mobile access, as a wireless backhaul solution, and as a key enabler for higher order sectorisation. Wireless standards such as IEE802.11ad, which are operating in mm-wave band have been presented. These standards have been designed for short range, ultra high data throughput systems in the 60 GHz band. Furthermore, this survey provides new insights regarding relevant and open issues in adopting mm-wave for 5G networks. This includes increased handoff rate and interference in Ultra-Dense Network (UDN), waveform consideration with higher spectral efficiency, and supporting spatial multiplexing in mm-wave line of sight. This survey also introduces a distributed base station architecture in mm-wave as an approach to address increased handoff rate in UDN, and to provide an alternative way for network densification in a time and cost effective manner

Context-based Resource Management and Slicing for SDN-enabled 5G Smart, Connected Environments

Τα συστήματα κινητής επικοινωνίας πέμπτης γενιάς (5G) τα οποία αναμένονται τα αμέσως επόμενα χρόνια, θα αντιμετωπίσουν πρωτοφανείς απαιτήσεις όσον αφορά τον όγκο και το ρυθμό μεταδόσης δεδομένων, τις καθυστερήσεις του δικτύου, καθώς και τον αριθμό των συνδεδεμένων συσκευών. Τα μελλοντικά δικτυακά οικοσυστήματα θα περιλαμβάνουν μια πληθώρα τεχνολογιών ασύρματης επικοινωνίας (είτε τεχνολογιών 3GPP, είτε μη-3GPP) όπως το Wi-Fi, το 3G, το 4G ή LTE, το Bluetooth, κτλ. Τα σενάρια ανάπτυξης του 5G προβλέπουν έναν πολυεπίπεδο συνδυασμό μακρο- και μικρο-κυψελών, όπου πολυλειτουργικές συσκευές –οι οποίες μπορούν να υποστηρίξουν ποικιλία διαφορετικών εφαρμογών και υπηρεσιών- εξυπηρετούνται από διαφορετικές τεχνολογίες. Οι περιορισμοί που υπήρξαν στα παλιότερα συστήματα κινητών επικοινωνιών πρέπει να εξαλειφθούν, ανοίγοντας το δρόμο για ένα νέο κύμα υπηρεσιών και συνολική εμπειρία χρήστη. Ως εκ τούτου, η διαχείριση των ασύρματων πόρων μέσω της χαρτογράφησης και διανομής τους στις κινητές συσκευές, μέσω της πλέον κατάλληλης τεχνολογίας πρόσβασης, η οποία εξυπηρετεί τις ανάγκες των συγκεκριμένων υπηρεσιών/εφαρμογών αποκτά πρωταρχική σημασία. Οι κύριοι μηχανισμοί διαχείρισης πόρων δικτύου πρόσβασης δηλαδή η επιλογή κυψέλης (cell selection/reselection), η παράδοση υπηρεσίας από τη μία κυψέλη στην άλλη (handover), καθώς και ο έλεγχος εισαγωγής κλήσεων/υπηρεσιών (call/service admission control), είναι αυτοί που τελικώς θα μπορέσουν να προσφέρουν στους χρήστες εξαιρετικά υψηλή ποιότητα υπηρεσιών (Quality of Service - QoS) και εμπειρίας (Quality of Experience - QoE) προς τις πολύ απαιτητικές περιπτώσεις χρήσης του 5G. Αυτό θα γίνει εφικτό μέσω της βελτιστοποίησης του συσχετισμού-χαρτογράφησης μεταξύ των διαφορετικών (τελικών) κινητών συσκευών και των συνυπαρχόντων ασύρματων δικτύων πρόσβασης. Επιπλέον της οπτικής του χρήστη, οι Πάροχοι Δικτύων Κινητής θα είναι σε θέση να εκμεταλλευτούν τη μέγιστη αποδοτικότητα και χρήση των –ήδη δυσεύρετων- ασύρματων πόρων. Ευφυείς βελτιστοποιήσεις και αποδοτικές λύσεις όσον αφορά το κόστος και την κατανάλωση ενέργειας πρέπει επίσης να εισαχθούν στα δίκτυα 5ης γενιάς με σκοπό να προάγουν ένα συνεκτικό, στοχευμένο στο χρήστη και πολυδιάστατο οικοσύστημα πληροφοριών. Η παρούσα διατριβή αυτή εστιάζει στη Διαχείριση Ασύρματων Δικτυακών Πόρων (ΔΑΔΠ - RRM) από την οπτική των κύριων διαδικασιών που σχετίζονται με την επιλογή ασύρματης τεχνολογίας πρόσβασης και στρώματος κυψέλης (μικρο-, μάκρο κυψέλη, κτλ.), δηλαδή η επιλογή κυψέλης, η παράδοση υπηρεσίας και ο έλεγχος εισαγωγής κλήσεων/υπηρεσιών. Έπειτα, η διατριβή προχωρά ένα βήμα παραπέρα, με σκοπό να συνδέσει τη ΔΑΔΠ με μία από τις πιο πρόσφατες προσεγγίσεις διαχείρισης δικτυακών πόρων, δηλαδή τον «τεμαχισμό δικτύου» (network slicing), όπως αυτή εισάγεται σε περιβάλλοντα που χρησιμοποιούν τη μέθοδος της Δικτύωσης Βασισμένης στο Λογισμικό (Software Defined Networking), η οποία δημιουργεί μικρότερα, εικονικά τμήματα του δικτύου, προσαρμοσμένα και βελτιστοποιημένα για συκεκριμένες υπηρεσίες και αντίστοιχες απαιτήσεις. Σαν πρώτο βήμα, πραγματοποιήθηκε μια ολοκληρωμένη ανάλυση για τις υπάρχουσες λύσεις – όπως αυτές προδιαγράφονται στα πρότυπα της 3GPP, στη βιβλιογραφία, καθώς και τις σχετικές πατέντες-. Η διατριβή αυτή αρχικά εντοπίζει τους δεσμούς μεταξύ των προσπαθειών της ερευνητικής κοινότητας, των υλοποιήσεων της βιομηχανίας, καθώς και των δράσεων προτυποποίησης, σε μια προσπάθεια να επισημανθούν ρεαλιστικές λύσεις εφαρμογής, να προσδιοριστούν οι κύριοι στόχοι, τα πλεονεκτήματα, αλλά και οι ελλείψεις αυτών των προσπαθειών. Όπως θα δειχθεί, οι υπάρχουσες λύσεις προσπαθούν να εξισορροπήσουν σε ένα σημείο μεταξύ της βέλτιστης λύσης και μιας απλής υλοποίησης. Έτσι, οι λύσεις που έχουν προταθεί είτε είναι απλοποιημένες σε τέτοιο βαθμό που απομακρύνονται από μια ρεαλιστική πρόταση, και επιτυγχάνουν υπο-βέλτιστες λύσεις ή από την άλλη παρέχουν πολύ σημαντικές βελτιώσεις, αλλά η πολυπλοκότητά τους και η επιβάρυνση που επιβάλλουν στο δίκτυο (όσον αφορά για παράδειγμα κόστος σηματοδοσίας, ή επεξεργαστικής ισχύος) τις καθιστούν ελκυστικές για μια πραγματική ανάπτυξη. Προς αυτή την κατεύθυνση, η παρούσα διατριβή εισαγωγή ένα σύνολο μηχανισμών επίγνωσης πλαισίου για τη διαχείριση δικτυακών πόρων, που αποτελείται από τρεις επιμέρους μηχανισμούς με διακριτό ρόλο: Δύο από τους μηχανισμούς χρησιμοποιούν πληροφορία πλαισίου με σκοπό τη βελτίωση τη διαχείριση πόρων και και τη χαρτογράφηση μεταξύ ροών δεδομένων κινητών συσκευών και κυψέλης/τεχνολογίας δικτύου. Ο τρίτος μηχανισμός δρα με έναν ενισχυτικό ρόλο στους δύο προηγούμενους, μέσω μιας προ-επεξεργασίας που πραγματοποιεί πάνω σε πληροφορία πλαισίου, με σκοπό τον περιορισμό του κόστους της επιπλέον σηματοδοσίας που απαιτείται για την μεταφορά της πληροφορίας πλαισίου μεταξύ των διαφόρων ενδιαφερόμενων δικτυακών οντοτήτων. Εκτός από τους τρεις μηχανισμούς αυτούς, πραγματοποιήθηκαν εκτενείς μελέτες σε σχέση με αρχιτεκτονικά ζητήματα και πτυχές, στο πλαίσιο της επικείμενης αρχιτεκτονικής δικτύου 5G και χαρτογράφηση των προτεινόμενων μηχανισμών στα συστατικά στοιχεία του δικτύου 5G -όπως αυτά εισήχθησαν στα τελευταίο κείμενα προτυποποίησης της 3GPP-. Η πρώτη κύρια συμβολή της παρούσας διατριβής είναι το COmpAsS, ένας μηχανισμός επιλογής Τεχνολογίας Ασύρματης Πρόσβασης πολλαπλών κριτηρίων, με γνώμονα το περιβάλλον, το κύριο μέρος του οποίου λειτουργεί στην πλευρά του Εξοπλισμού Χρήστη (UE), ελαχιστοποιώντας με αυτό τον τρόπο τις επιβαρύνσεις σηματοδότησης στη διεπαφή αέρα και το φορτίο υπολογισμού στους σταθμούς βάσης. Ο μηχανισμός COmpAsS εκτελεί παρακολούθηση σε πραγματικό χρόνο, υιοθετώντας την Ασαφή Λογική (Fuzzy Logic -FL) ως μία από τις βασικές προσεγγίσεις αντίληψης και ανάλυσης της κατάστασης του δικτύου. Σε συνδυασμό με ένα σύνολο προκαθορισμένων κανόνων, υπολογίζει μια λίστα με τις καταλληλότερες διαθέσιμες επιλογές πρόσβασης δικτύου, για κάθε μία από τις ροές δεδομένων/υπηρεσίας που είναι ενεργές εκείνη τη στιγμή. Τα πλεονεκτήματα του COmpAsS παρουσιάζονται μέσω μιας εκτεταμένης σειράς σεναρίων προσομοίωσης, ως μέρος των περιπτώσεων χρήσης εξαιρετικά πυκνών δικτύων (UDN) 5G. Τα αποτελέσματα αποδεικνύουν τον τρόπο με τον οποίο ο προτεινόμενος μηχανισμός βελτιστοποιεί τους βασικούς δείκτες επιδόσεων (Key Performance Indicators - KPIs), όταν αντιπαρατίθεται σε έναν από τους καθιερωμένους LTE αλγορίθμους. Η δεύτερη σημαντική συμβολή της παρούσας διατριβής είναι η Μηχανή Εξόρυξης Πλαισίου και Δημιουργίας Προφίλ (Context Extraction and Profiling Engine – CEPE), ένας μηχανισμός διαχείρισης πόρων, ο οποίος αναλύει συμπεριφορικά πρότυπα των χρηστών/κινητών συσκευών, εξάγει ουσιώδη γνώση και δημιουργεί αντίστοιχα προφίλ/πρότυπα συμπεριφοράς, με σκοπό να τα χρησιμοποιήσει για βέλτιστο προγραμματισμό πόρων, καθώς επίσης και για την μελλοντική πρόβλεψη απαιτήσεων πόρων. Το CEPE συλλέγει πληροφορίες σχετικά με τους χρήστες, τις υπηρεσίες, τις κινητές συσκευές, καθώς και τις συνθήκες δικτύου, και μέσω επεξεργασίας -χωρίς σύνδεση, ετεροχρονισμένα- αποκτά ένα μοντέλο γνώσης, το οποίο στη συνέχεια χρησιμοποιείται για τη βελτιστοποίηση των κύριων μηχανισμών ΔΑΔΠ (RRM). Το προαναφερθέν μοντέλο γνώσης μεταφράζεται έπειτα σε προφίλ χρηστών/κινητών συσκευών, τα οποία εφαρμόζονται ως είσοδος κατά τις διαδικασίες ΔΑΔΠ. Η βιωσιμότητα και η εγκυρότητα του CEPE επιδεικνύεται μέσω εκτεταμένων σεναρίων προσομοίωσης. Η τρίτη σημαντική συμβολή είναι το CIP (Context Information Preprocessor), ένας μηχανισμός προεπεξεργασίας πληροφοριών πλαισίου, με στόχο τον εντοπισμό και την απόρριψη περιττών δεδομένων κατά τη σηματοδοσία πριν από την εξαγωγή της γνώσης. Το CIP θα μπορούσε να θεωρηθεί ως αναπόσπαστο μέρος των προαναφερθέντων σχημάτων σχεδίασης, δηλαδή των COmpAsS και CEPE. Ο προτεινόμενος μηχανισμός περιλαμβάνει τη συγκέντρωση και συμπίεση πληροφοριών πλαισίου σχετικά με το δίκτυο ανά μοναδικό αναγνωριστικό κινητής συσκευής/χρήστη, -όπως η διεθνής ταυτότητα συνδρομητή κινητού (IMSI)-, καθώς και τεχνικές που σχετίζονται με την αναγνώριση και την απόρριψη δεδομένων πλαισίου που δε συμβάλλουν στην βελτίωση ή διόρθωση του πρόφιλ χρήστη, πριν από οποιαδήποτε μετάδοση προς το CEPE (ή άλλο μηχανισμό ΔΑΔΠ). Οι βελτιώσεις και τα κέρδη του CIP στη διαδικασία της σηματοδοσίας απεικονίζονται μέσω λεπτομερούς αναλυτικής προσέγγισης, η οποία καθορίζεται από τις καθιερωμένες απαιτήσεις περί χρήσης 5G. Ως τελική σημαντική συμβολή αυτής της διατριβής, διεξάγεται μια εκτεταμένη ανάλυση όσον αφορά τη διασύνδεση των CEPE-COmpAsS, στο πλαίσιο της επικείμενης αρχιτεκτονικής δικτύου 5G και της χαρτογράφησης αυτών με τα τελευταία συστατικά στοιχεία του δικτύου 5G –όπως αυτά παρουσιάστηκαν στις τελευταίες δημοσιεύσεις προτυποποίησης της 3GPP -. Το έργο σε αυτή την ενότητα δείχνει πώς μπορεί να παρουσιαστεί το προτεινόμενο πλαίσιο ως μέρος των συνιστωσών του δικτύου 5G και των λειτουργιών που εισάγονται σε περιβάλλοντα με δυνατότητα SDN, όπως η προσέγγιση του «Τεμαχισμού Δικτύου», ο Μηχανισμός Ανάλυσης Δικτυακών Δεδομένων (Network Data Analytics Function – NWDAF), η λειτουργία επιλογής βέλτιστου τεμαχίου δικτύου (Network Slice Selection Function) - προς περαιτέρω βελτιστοποίηση της διανομής και της διαχείρισης των διαθέσιμων πόρων δικτύου μεταξύ των συσκευών-, καθώς και το ATSSS – Access Traffic Steering, Switching and Splitting, μια οντότητα υπεύθυνη για τη διαχείριση των ροών δεδομένων των UE –με δυνατότητες επαναδρομολόγησης, διαχωρισμού και σύνδεσης της κάθε ροής με την αντίστοιχη βέλτιστη, διαθέσιμη τεχνολογία πρόσβασης. Δύο συμπληρωματικές μελέτες περιλαμβάνονται –τέλος- σε αυτή τη διατριβή: μια αρχική ανάλυση των πολιτικών μηχανικής κυκλοφορίας (Traffic Engineering) που βασίζονται σε προφίλ χρηστών που προκύπτουν από το CEPE, καθώς και μία περίπτωση χρήσης 5G που σχετίζεται με τον τομέα του Διαδικτύου των Πραγμάτων - και πιο συγκεκριμένα την «Καλλιέργεια Ακριβείας» (Precision Farming), με σκοπό να δοθεί έμφαση σε ρητές απαιτήσεις των περιπτώσεων χρήσης 5G, όπως η επικοινωνία τύπου μηχανής κρίσιμης σημασίας (Mission-Critical Machine Type Communication).The fifth-generation (5G) mobile communication systems, which are expected to emerge in the forthcoming years, will address unprecedented demands in terms of system capacity, service latency and number of connected devices. Future 5G network ecosystems will comprise a plethora of 3GPP and non-3GGP Radio Access Technologies (RATs), such as Wi-Fi, 3G, 4G or LTE, Bluetooth, etc. Deployment scenarios envision a multi-layer combination of macro, micro and femto cells where multi-mode end devices, supporting diverse applications, are served by different technologies. Limitations previously posed by legacy generation systems need to be eliminated, paving the way to a new wave of services and overall experience for the user. As a result, the management of radio resources via mapping the end devices to the most appropriate access network becomes of paramount importance; the primary Radio Resource Management (RRM) mechanisms, i.e. cell selection/reselection, handover and call admission control will be able to offer extremely high Quality of Service (QoS) and Experience (QoE) to the users, towards the very demanding 5G use case requirements; this will be realised via an optimal association between the diverse end devices and the coexisting available access networks. Besides the user’s perspective, the Mobile Network Operators (MNOs) will be able to take advantage of the maximum efficiency and utilization over the –already scarce- wireless resources. Intelligent optimizations, as well as cost and energy efficient solutions need to be introduced in 5G networks in order to promote a consistent, user-centred and all-dimensional information ecosystem. This thesis focuses on the radio resource management (RRM) from the perspective of the primary RAT and cell layer selection processes (i.e., cell (re)selection, handover, admission control); afterwards, it goes one step beyond, in order to link the RRM with one of the latest RRM optimization approaches, i.e. the Network Slicing, as introduced in Software Defined Networking (SDN)-enabled environments, which creates smaller, virtual “portions” of the network, adapted and optimized for specific services/requirements. As a first step, a comprehensive analysis for the existing solutions -as these are specified in 3GPP standards, research papers, and patents has taken place. This thesis initially identifies the links between the research community efforts, the industry implementations, as well as the standardization efforts, in an attempt to highlight realistic solution implementations, identify the main goals, advantages and shortcomings of these efforts. As will be shown, existing solutions attempt to balance between implementation simplicity and solution optimality. Thus, solutions are either simple to implement but achieve sub-optimal solutions or provide significant improvements but their complexity and the burden placed on the network components renders them unattractive for a real-life deployment. Towards this end, this thesis introduces a context-based radio resource management (RRM) framework, comprised of three distinct mechanisms: Two out of the three mechanisms exploit contextual information with the aim of optimising the resource management and UE-RAT mapping, while the third mechanism acts with an augmenting role to the former two, by pre-processing the contextual information required by such, context-based mechanisms and –thus- by limiting the signalling cost required for communicating this contextual information among network entities. In addition to the three mechanisms, comprehensive analysis has taken place in relation to architectural aspects, in the context of the forthcoming 5G network architecture and by mapping them with the latest 5G network components –as these were introduced in the latest 3GPP work-. The first major contribution of this thesis is COmpAsS, a context-aware, multi-criteria RAT selection mechanism, the main part of which operates on the User Equipment (UE) side, minimizing signalling overhead over the air interface and computation load on the base stations. COmpAsS mechanism performs real-time monitoring and adopts Fuzzy Logic (FL) as one the core logic modules, responsible for the perception of the network situation and, in combination with a set of pre-defined rules, calculates a list of the most suitable available access network options. The merits of COmpAsS are showcased via an extensive series of simulation scenarios, as part of 5G ultra dense networks (UDN) use cases. The results prove how the proposed mechanism optimises Key Performance Indicators (KPIs), when juxtaposed to a well-established LTE handover algorithm. The second major contribution of the current thesis the Context Extraction and Profiling Engine (CEPE), a resource management framework, which analyzes user behavioral patterns, extracts meaningful knowledge and performs user profiling in order to apply it for optimal resource planning, as well as prediction of resource requirements. CEPE collects information about users, services, terminals and network conditions and –based on offline processing– derives a knowledge model, which is subsequently used for the optimization of the primary RRM mechanisms. Then, the extracted context information is translated into user profiles and is finally applied as input for enhanced cell (re)selection, handover or admission control. The viability and validity of CEPE is demonstrated via an extensive set of simulation scenarios. The third major contribution is CIP, a Context Information Pre-processing scheme, aiming to identify and discard redundant or unnecessary data during network signalling and before knowledge extraction. CIP could be considered as an integral part of the afore described profiling schemes, i.e. COmpAsS and CEPE. The module comprises aggregating and compressing mobile network-related context information per unique identifier, such as the end device’s International Mobile Subscriber Identity (IMSI), as well as techniques related to identifying and discarding user profile-redundant or unnecessary context data, before any transmission to CEPE. CIP gains are illustrated via a detailed analytical approach, guided by well-established 5G use case requirements. As a final major contribution of this thesis, a comprehensive analysis takes place with regard to the CEPE-COmpAsS interworking, in the context of the forthcoming 5G network architecture and by mapping them with the latest 5G network components –as these were introduced in the latest 3GPP work-. The work in this section shows how the proposed framework can be instantiated as part of the 5G network components and functions introduced in SDN-enabled environments, such as the Network Slicing approach, the Network Data Analytics and the Network Slice Selection Functions, towards further optimising the distribution and management of the available infrastructure and network resources among the UEs, as well as the Access Traffic Steering, Switching and Splitting (ATSSS), responsible for managing the UE data flows and mapping each single UE flow with the optimal available access technology.. Two supplementary studies are finally included in this dissertation: a preliminary analysis on traffic engineering policies based on user profiling realised by CEPE, as well as a 5G use case related to the Internet of Things domain -and more specifically, Precision Farming-, aiming to highlight explicit requirements such as mission-critical machine type communication

On three use cases of multi-connectivity paradigm in emerging wireless networks

As envisioned by global network operators, the increasing trend of data traffic demand is expected to continue with exponential growth in the coming years. To cope with this rapid increase, significant efforts from the research community, industry and even regulators have been focused towards improving two main aspects of the wireless spectrum: (i) spectrum capacity and (ii) spectral efficiency. Concerning the spectrum capacity enhancement, the multi-connectivity paradigm has been seen to be fundamentally important to solve the capacity problem in the next generation networks. Multi-connectivity is a feature that allows wireless devices to establish and maintain multiple simultaneous connections across homogeneous or heterogeneous technologies. In this thesis, we focus on identifying the core issues in applying the multi-connectivity paradigm for different use cases and propose novel solutions to address them. Specifically, this thesis studies three use cases of the multi-connectivity paradigm. First, we study the uplink/downlink decoupling problem in 4G networks. More specifically, we focus on the user association problem in the decoupling context, which is considered challenging due to the conflicting objectives of different entities (e.g., mobile users and base stations) in the system. We use a combination of matching theory and stochastic geometry to reconcile competing objectives between users in the uplink/downlink directions and also from the perspective of base stations. Second, we tackle the spectrum aggregation problem for wireless backhauling links in unlicensed opportunistic shared spectrum bands, specifically, TV White Space (TVWS) spectrum. In relation to this, we present a DIY mobile network deployment model to accelerate the roll-out of high-end mobile services in rural and developing regions. As part of this model, we highlight the importance of low-cost and high-capacity backhaul infrastructure for which TVWS spectrum can be exploited. Building on that, we conduct a thorough analytical study to identify the characteristics of TVWS in rural areas. Our study sheds light on the nature of TVWS spectrum fragmentation for the backhauling use case, which in turn poses requirements for the design of spectrum aggregation systems for TVWS backhaul. Motivated by these findings, we design and implement WhiteHaul, a flexible platform for spectrum aggregation in TVWS. Three challenges have been tackled in this work. First, TVWS spectrum is fragmented in that the spectrum is available in non-contiguous manner. To fully utilize the available spectrum, multiple radios should be enabled to work simultaneously. However, all the radios have to share only a single antenna. The key challenge is to design a system architecture that is capable of achieving different aggregation configurations while avoiding the interference. Second, the heterogeneous nature of the available spectrum (i.e., in terms of bandwidth and link characteristics) requires a design of efficient traffic distribution algorithm that takes into account these factors. Third, TVWS is unlicensed opportunistic shared spectrum. Thus, the coordination mechanism between the two nodes of backhauling link is essential to enable seamless channel switching. Third, we study the integration of multiple radio access technologies (RATs) in the context of 4G/5G networks. More specifically, we study the potential gain of enabling the Multi-RAT integration at the Packet Data Convergence Protocol (PDCP) layer compared with doing it at the transport layer. In this work, we consider ultra-reliable low-latency communication (URLLC) as one of the motivating services. This work tackles the different challenges that arise from enabling the Multi-RAT integration at the PDCP layer, including, packet reordering and traffic scheduling

View on 5G Architecture: Version 2.0

The 5G Architecture Working Group as part of the 5GPPP Initiative is looking at capturing novel trends and key technological enablers for the realization of the 5G architecture. It also targets at presenting in a harmonized way the architectural concepts developed in various projects and initiatives (not limited to 5GPPP projects only) so as to provide a consolidated view on the technical directions for the architecture design in the 5G era. The first version of the white paper was released in July 2016, which captured novel trends and key technological enablers for the realization of the 5G architecture vision along with harmonized architectural concepts from 5GPPP Phase 1 projects and initiatives. Capitalizing on the architectural vision and framework set by the first version of the white paper, this Version 2.0 of the white paper presents the latest findings and analyses with a particular focus on the concept evaluations, and accordingly it presents the consolidated overall architecture design

Analytical Performance Evaluation of Cooperative and Multi-Radio Concepts in Emerging Wireless Networks

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Networking Solutions for Integrated Heterogeneous Wireless Ecosystem

This work targets at applying computer networking techniques to address challenges in modern wireless networks and in various environments built around these networks. The main focus of the work is on designing and implementing prototypes and demonstrators to support research in domains of heterogeneous networks (HetNets). These research domains include centralized radio resource management in emerging cellular network architectures, network assistance role in device-to-device (D2D) communications, and studying prospective services in these networks. Within the research group the author was tasked with designing network architectures and demonstrating certain connectivity and functionality interesting for the research. The author was responsible for modifying commercial off-the-shelf equipment to become suitable for target research scenarios, selecting network technologies to achieve connectivity requirements, deploying network architecture entities within the research group's cloud platform. For HetNet track, the primary goal was to design a platform that would mimic a device connected through a heterogeneous network, allowing researchers to experiment with traffic flow optimization in an environment close to the envisioned next-generation network architecture. Prototype solution and testbed were designed building on software defined network principles of automation, abstraction and software based flow switching, and were implemented using overlay networks and virtual network functions. Within D2D communications research, the task was to design architecture demonstrating feasibility of traffic offloading from infrastructure network to direct links. Prototype was implemented with automated routing control in overlay network. To demonstrate novel services enabled by advanced security frameworks, D2D platform was augmented and a new network application has been implemented, also suitable for wearable electronics

D6.6 Final report on the METIS 5G system concept and technology roadmap

This deliverable presents the METIS 5G system concept which was developed to fulfil the requirements of the beyond-2020 connected information society and to extend today’s wireless communication systems to include new usage scenarios. The METIS 5G system concept consists of three generic 5G services and four main enablers. The three generic 5G services are Extreme Mobile BroadBand (xMBB), Massive Machine- Type Communications (mMTC), and Ultra-reliable Machine-Type Communication (uMTC). The four main enablers are Lean System Control Plane (LSCP), Dynamic RAN, Localized Contents and Traffic Flows, and Spectrum Toolbox. An overview of the METIS 5G architecture is given, as well as spectrum requirements and considerations. System-level evaluation of the METIS 5G system concept has been conducted, and we conclude that the METIS technical objectives are met. A technology roadmap outlining further 5G development, including a timeline and recommended future work is given.Popovski, P.; Mange, G.; Gozalvez -Serrano, D.; Rosowski, T.; Zimmermann, G.; Agyapong, P.; Fallgren, M.... (2014). D6.6 Final report on the METIS 5G system concept and technology roadmap. http://hdl.handle.net/10251/7676

Enhanced connectivity in wireless mobile programmable networks

Mención Interancional en el título de doctorThe architecture of current operator infrastructures is being challenged by the non-stop growing demand of data hungry services appearing every day. While currently deployed operator networks have been able to cope with traffic demands so far, the architectures for the 5th generation of mobile networks (5G) are expected to support unprecedented traffic loads while decreasing costs associated with the network deployment and operations. Indeed, the forthcoming set of 5G standards will bring programmability and flexibility to levels never seen before. This has required introducing changes in the architecture of mobile networks, enabling different features such as the split of control and data planes, as required to support rapid programming of heterogeneous data planes. Network softwarisation is hence seen as a key enabler to cope with such network evolution, as it permits controlling all networking functions through (re)programming, thus providing higher flexibility to meet heterogeneous requirements while keeping deployment and operational costs low. A great diversity in terms of traffic patterns, multi-tenancy, heterogeneous and stringent traffic requirements is therefore expected in 5G networks. Software Defined Networking (SDN) and Network Function Virtualisation (NFV) have emerged as a basic tool-set for operators to manage their infrastructure with increased flexibility and reduced costs. As a result, new 5G services can now be envisioned and quickly programmed and provisioned in response to user and market necessities, imposing a paradigm shift in the services design. However, such flexibility requires the 5G transport network to undergo a profound transformation, evolving from a static connectivity substrate into a service-oriented infrastructure capable of accommodating the various 5G services, including Ultra-Reliable and Low Latency Communications (URLLC). Moreover, to achieve the desired flexibility and cost reduction, one promising approach is to leverage virtualisation technologies to dynamically host contents, services, and applications closer to the users so as to offload the core network and reduce the communication delay. This thesis tackles the above challengeswhicharedetailedinthefollowing. A common characteristic of the 5G servicesistheubiquityandthealmostpermanent connection that is required from the mobile network. This really imposes a challenge in thesignallingproceduresprovidedtogettrack of the users and to guarantee session continuity. The mobility management mechanisms will hence play a central role in the 5G networks because of the always-on connectivity demand. Distributed Mobility Management (DMM) helps going towards this direction, by flattening the network, hence improving its scalability,andenablinglocalaccesstotheInternet and other communication services, like mobile-edge clouds. Simultaneously, SDN opens up the possibility of running a multitude of intelligent and advanced applications for network optimisation purposes in a centralised network controller. The combination of DMM architectural principles with SDN management appears as a powerful tool for operators to cope with the management and data burden expected in 5G networks. To meet the future mobile user demand at a reduced cost, operators are also looking at solutions such as C-RAN and different functional splits to decrease the cost of deploying and maintaining cell sites. The increasing stress on mobile radio access performance in a context of declining revenues for operators is hence requiring the evolution of backhaul and fronthaul transport networks, which currently work decoupled. The heterogeneity of the nodes and transmisión technologies inter-connecting the fronthaul and backhaul segments makes the network quite complex, costly and inefficient to manage flexibly and dynamically. Indeed, the use of heterogeneous technologies forces operators to manage two physically separated networks, one for backhaul and one forfronthaul. In order to meet 5G requirements in a costeffective manner, a unified 5G transport network that unifies the data, control, and management planes is hence required. Such an integrated fronthaul/backhaul transport network, denoted as crosshaul, will hence carry both fronthaul and backhaul traffic operating over heterogeneous data plane technologies, which are software-controlled so as to adapt to the fluctuating capacity demand of the 5G air interfaces. Moreover, 5G transport networks will need to accommodate a wide spectrum of services on top of the same physical infrastructure. To that end, network slicing is seen as a suitable candidate for providing the necessary Quality of Service (QoS). Traffic differentiation is usually enforced at the border of the network in order to ensure a proper forwarding of the traffic according to its class through the backbone. With network slicing, the traffic may now traverse many slice edges where the traffic policy needs to be enforced, discriminated and ensured, according to the service and tenants needs. However, the very basic nature that makes this efficient management and operation possible in a flexible way – the logical centralisation – poses important challenges due to the lack of proper monitoring tools, suited for SDN-based architectures. In order to take timely and right decisions while operating a network, centralised intelligence applications need to be fed with a continuous stream of up-to-date network statistics. However, this is not feasible with current SDN solutions due to scalability and accuracy issues. Therefore, an adaptive telemetry system is required so as to support the diversity of 5G services and their stringent traffic requirements. The path towards 5G wireless networks alsopresentsacleartrendofcarryingoutcomputations close to end users. Indeed, pushing contents, applications, and network functios closer to end users is necessary to cope with thehugedatavolumeandlowlatencyrequired in future 5G networks. Edge and fog frameworks have emerged recently to address this challenge. Whilst the edge framework was more infrastructure-focused and more mobile operator-oriented, the fog was more pervasive and included any node (stationary or mobile), including terminal devices. By further utilising pervasive computational resources in proximity to users, edge and fog can be merged to construct a computing platform, which can also be used as a common stage for multiple radio access technologies (RATs) to share their information, hence opening a new dimension of multi-RAT integration.La arquitectura de las infraestructuras actuales de los operadores está siendo desafiada por la demanda creciente e incesante de servicios con un elevado consumo de datos que aparecen todos los días. Mientras que las redes de operadores implementadas actualmente han sido capaces de lidiar con las demandas de tráfico hasta ahora, se espera que las arquitecturas de la quinta generación de redes móviles (5G) soporten cargas de tráfico sin precedentes a la vez que disminuyen los costes asociados a la implementación y operaciones de la red. De hecho, el próximo conjunto de estándares 5G traerá la programabilidad y flexibilidad a niveles nunca antes vistos. Esto ha requerido la introducción de cambios en la arquitectura de las redes móviles, lo que permite diferentes funciones, como la división de los planos de control y de datos, según sea necesario para soportar una programación rápida de planos de datos heterogéneos. La softwarisación de red se considera una herramienta clave para hacer frente a dicha evolución de red, ya que proporciona la capacidad de controlar todas las funciones de red mediante (re)programación, proporcionando así una mayor flexibilidad para cumplir requisitos heterogéneos mientras se mantienen bajos los costes operativos y de implementación. Por lo tanto, se espera una gran diversidad en términos de patrones de tráfico, multi-tenancy, requisitos de tráfico heterogéneos y estrictos en las redes 5G. Software Defined Networking (SDN) y Network Function Virtualisation (NFV) se han convertido en un conjunto de herramientas básicas para que los operadores administren su infraestructura con mayor flexibilidad y menores costes. Como resultado, los nuevos servicios 5G ahora pueden planificarse, programarse y aprovisionarse rápidamente en respuesta a las necesidades de los usuarios y del mercado, imponiendo un cambio de paradigma en el diseño de los servicios. Sin embargo, dicha flexibilidad requiere que la red de transporte 5G experimente una transformación profunda, que evoluciona de un sustrato de conectividad estática a una infraestructura orientada a servicios capaz de acomodar los diversos servicios 5G, incluso Ultra-Reliable and Low Latency Communications (URLLC). Además, para lograr la flexibilidad y la reducción de costes deseadas, un enfoque prometedores aprovechar las tecnologías de virtualización para alojar dinámicamente los contenidos, servicios y aplicaciones más cerca de los usuarios para descargar la red central y reducir la latencia. Esta tesis aborda los desafíos anteriores que se detallan a continuación. Una característica común de los servicios 5G es la ubicuidad y la conexión casi permanente que se requiere para la red móvil. Esto impone un desafío en los procedimientos de señalización proporcionados para hacer un seguimiento de los usuarios y garantizar la continuidad de la sesión. Por lo tanto, los mecanismos de gestión de la movilidad desempeñarán un papel central en las redes 5G debido a la demanda de conectividad siempre activa. Distributed Mobility Management (DMM) ayuda a ir en esta dirección, al aplanar la red, lo que mejora su escalabilidad y permite el acceso local a Internet y a otros servicios de comunicaciones, como recursos en “nubes” situadas en el borde de la red móvil. Al mismo tiempo, SDN abre la posibilidad de ejecutar una multitud de aplicaciones inteligentes y avanzadas para optimizar la red en un controlador de red centralizado. La combinación de los principios arquitectónicos DMM con SDN aparece como una poderosa herramienta para que los operadores puedan hacer frente a la carga de administración y datos que se espera en las redes 5G. Para satisfacer la demanda futura de usuarios móviles a un coste reducido, los operadores también están buscando soluciones tales como C-RAN y diferentes divisiones funcionales para disminuir el coste de implementación y mantenimiento de emplazamientos celulares. El creciente estrés en el rendimiento del acceso a la radio móvil en un contexto de menores ingresos para los operadores requiere, por lo tanto, la evolución de las redes de transporte de backhaul y fronthaul, que actualmente funcionan disociadas. La heterogeneidad de los nodos y las tecnologías de transmisión que interconectan los segmentos de fronthaul y backhaul hacen que la red sea bastante compleja, costosa e ineficiente para gestionar de manera flexible y dinámica. De hecho, el uso de tecnologías heterogéneas obliga a los operadores a gestionar dos redes separadas físicamente, una para la red de backhaul y otra para el fronthaul. Para cumplir con los requisitos de 5G de manera rentable, se requiere una red de transporte única 5G que unifique los planos de control, datos y de gestión. Dicha red de transporte fronthaul/backhaul integrada, denominada “crosshaul”, transportará tráfico de fronthaul y backhaul operando sobre tecnologías heterogéneas de plano de datos, que están controladas por software para adaptarse a la demanda de capacidad fluctuante de las interfaces radio 5G. Además, las redes de transporte 5G necesitarán acomodar un amplio espectro de servicios sobre la misma infraestructura física y el network slicing se considera un candidato adecuado para proporcionar la calidad de servicio necesario. La diferenciación del tráfico generalmente se aplica en el borde de la red para garantizar un reenvío adecuado del tráfico según su clase a través de la red troncal. Con el networkslicing, el tráfico ahora puede atravesar muchos fronteras entre “network slices” donde la política de tráfico debe aplicarse, discriminarse y garantizarse, de acuerdo con las necesidades del servicio y de los usuarios. Sin embargo, el principio básico que hace posible esta gestión y operación eficientes de forma flexible – la centralización lógica – plantea importantes desafíos debido a la falta de herramientas de supervisión necesarias para las arquitecturas basadas en SDN. Para tomar decisiones oportunas y correctas mientras se opera una red, las aplicaciones de inteligencia centralizada necesitan alimentarse con un flujo continuo de estadísticas de red actualizadas. Sin embargo, esto no es factible con las soluciones SDN actuales debido a problemas de escalabilidad y falta de precisión. Por lo tanto, se requiere un sistema de telemetría adaptable para respaldar la diversidad de los servicios 5G y sus estrictos requisitos de tráfico. El camino hacia las redes inalámbricas 5G también presenta una tendencia clara de realizar acciones cerca de los usuarios finales. De hecho, acercar los contenidos, las aplicaciones y las funciones de red a los usuarios finales es necesario para hacer frente al enorme volumen de datos y la baja latencia requerida en las futuras redes 5G. Los paradigmas de “edge” y “fog” han surgido recientemente para abordar este desafío. Mientras que el edge está más centrado en la infraestructura y más orientado al operador móvil, el fog es más ubicuo e incluye cualquier nodo (fijo o móvil), incluidos los dispositivos finales. Al utilizar recursos de computación de propósito general en las proximidades de los usuarios, el edge y el fog pueden combinarse para construir una plataforma de computación, que también se puede utilizar para compartir información entre múltiples tecnologías de acceso radio (RAT) y, por lo tanto, abre una nueva dimensión de la integración multi-RAT.Programa Oficial de Doctorado en Ingeniería TelemáticaPresidente: Carla Fabiana Chiasserini.- Secretario: Vincenzo Mancuso.- Vocal: Diego Rafael López Garcí