Low Cost Quality of Service Multicast Routing in High Speed Networks

Many of the services envisaged for high speed networks, such as B-ISDN/ATM, will support real-time applications with large numbers of users. Examples of these types of application range from those used by closed groups, such as private video meetings or conferences, where all participants must be known to the sender, to applications used by open groups, such as video lectures, where partcipants need not be known by the sender. These types of application will require high volumes of network resources in addition to the real-time delay constraints on data delivery. For these reasons, several multicast routing heuristics have been proposed to support both interactive and distribution multimedia services, in high speed networks. The objective of such heuristics is to minimise the multicast tree cost while maintaining a real-time bound on delay. Previous evaluation work has compared the relative average performance of some of these heuristics and concludes that they are generally efficient, although some perform better for small multicast groups and others perform better for larger groups. Firstly, we present a detailed analysis and evaluation of some of these heuristics which illustrates that in some situations their average performance is reversed; a heuristic that in general produces efficient solutions for small multicasts may sometimes produce a more efficient solution for a particular large multicast, in a specific network. Also, in a limited number of cases using Dijkstra's algorithm produces the best result. We conclude that the efficiency of a heuristic solution depends on the topology of both the network and the multicast, and that it is difficult to predict. Because of this unpredictability we propose the integration of two heuristics with Dijkstra's shortest path tree algorithm to produce a hybrid that consistently generates efficient multicast solutions for all possible multicast groups in any network. These heuristics are based on Dijkstra's algorithm which maintains acceptable time complexity for the hybrid, and they rarely produce inefficient solutions for the same network/multicast. The resulting performance attained is generally good and in the rare worst cases is that of the shortest path tree. The performance of our hybrid is supported by our evaluation results. Secondly, we examine the stability of multicast trees where multicast group membership is dynamic. We conclude that, in general, the more efficient the solution of a heuristic is, the less stable the multicast tree will be as multicast group membership changes. For this reason, while the hybrid solution we propose might be suitable for use with closed user group multicasts, which are likely to be stable, we need a different approach for open user group multicasting, where group membership may be highly volatile. We propose an extension to an existing heuristic that ensures multicast tree stability where multicast group membership is dynamic. Although this extension decreases the efficiency of the heuristics solutions, its performance is significantly better than that of the worst case, a shortest path tree. Finally, we consider how we might apply the hybrid and the extended heuristic in current and future multicast routing protocols for the Internet and for ATM Networks.

ActMesh- A Cognitive Resource Management paradigm for dynamic mobile Internet Access with Reliability Guarantees

Wireless Mesh Networks (WMNs) are going increasing attention as a flexible low-cost networking architecture to provide media Internet access over metropolitan areas to mobile clients requiring multimedia services. In WMNs, Mesh Routers (MRs) from the mesh backbone and accomplish the twofold task of traffic forwarding, as well as providing multimedia access to mobile Mesh Clients (MCs). Due to the intensive bandwidth-resource requested for supporting QoS-demanding multimedia services, performance of the current WMNs is mainly limited by spectrum-crowding and traffic-congestion, as only scarce spectrum-resources is currently licensed for the MCs' access. In principle, this problem could be mitigated by exploiting in a media-friendly (e.g., content-aware) way the context-aware capabilities offered by the Cognitive Radio (CR) paradigm. As integrated exploitation of both content and context-aware system's capabilities is at the basis of our proposed Active Mesh (ActMesh) networking paradigm. This last aims at defining a network-wide architecture for realizing media-friendly Cognitive Mesh nets (e.g., context aware Cognitive Mesh nets). Hence, main contribution of this work is four fold: 1. After introducing main functional blocks of our ActMesh architecture, suitable self-adaptive Belief Propagation and Soft Data Fusion algorithms are designed to provide context-awareness. This is done under both cooperative and noncooperative sensing frameworks. 2. The resulting network-wide resource management problem is modelled as a constrained stochastic Network Utility Maximization (NUM) problem, with the dual (contrasting) objective to maximize spectrum efficiency at the network level, while accounting for the perceived quality of the delivered media flows at the client level. 3. A fully distributed, scalable and self-adaptive implementation of the resulting Active Resource Manager (ARM) is deployed, that explicitly accounts for the energy limits of the battery powered MCs and the effects induced by both fading and client mobility. Due to informationally decentralized architecture of the ActMesh net, the complexity of (possibly, optimal) centralized solutions for resource management becomes prohibitive when number of MCs accessing ActMesh net grow. Furthermore, centralized resource management solutions could required large amounts of time to collect and process the required network information, which, in turn, induce delay that can be unacceptable for delay sensitive media applications, e.g., multimedia streaming. Hence, it is important to develop network-wide ARM policies that are both distributed and scalable by exploiting the radio MCs capabilities to sense, adapt and coordinate themselves. We validate our analytical models via simulation based numerical tests, that support actual effectiveness of the overall ActMesh paradigm, both in terms of objective and subjective performance metrics. In particular, the basic tradeoff among backbone traffic-vs-access traffic arising in the ActMesh net from the bandwidth-efficient opportunistic resource allocation policy pursued by the deployed ARM is numerically characterized. The standardization framework we inspire to is the emerging IEEE 802.16h one

ActMesh- A Cognitive Resource Management paradigm for dynamic mobile Internet Access with Reliability Guarantees

Wireless Mesh Networks (WMNs) are going increasing attention as a flexible low-cost networking architecture to provide media Internet access over metropolitan areas to mobile clients requiring multimedia services. In WMNs, Mesh Routers (MRs) from the mesh backbone and accomplish the twofold task of traffic forwarding, as well as providing multimedia access to mobile Mesh Clients (MCs). Due to the intensive bandwidth-resource requested for supporting QoS-demanding multimedia services, performance of the current WMNs is mainly limited by spectrum-crowding and traffic-congestion, as only scarce spectrum-resources is currently licensed for the MCs' access. In principle, this problem could be mitigated by exploiting in a media-friendly (e.g., content-aware) way the context-aware capabilities offered by the Cognitive Radio (CR) paradigm. As integrated exploitation of both content and context-aware system's capabilities is at the basis of our proposed Active Mesh (ActMesh) networking paradigm. This last aims at defining a network-wide architecture for realizing media-friendly Cognitive Mesh nets (e.g., context aware Cognitive Mesh nets). Hence, main contribution of this work is four fold: 1. After introducing main functional blocks of our ActMesh architecture, suitable self-adaptive Belief Propagation and Soft Data Fusion algorithms are designed to provide context-awareness. This is done under both cooperative and noncooperative sensing frameworks. 2. The resulting network-wide resource management problem is modelled as a constrained stochastic Network Utility Maximization (NUM) problem, with the dual (contrasting) objective to maximize spectrum efficiency at the network level, while accounting for the perceived quality of the delivered media flows at the client level. 3. A fully distributed, scalable and self-adaptive implementation of the resulting Active Resource Manager (ARM) is deployed, that explicitly accounts for the energy limits of the battery powered MCs and the effects induced by both fading and client mobility. Due to informationally decentralized architecture of the ActMesh net, the complexity of (possibly, optimal) centralized solutions for resource management becomes prohibitive when number of MCs accessing ActMesh net grow. Furthermore, centralized resource management solutions could required large amounts of time to collect and process the required network information, which, in turn, induce delay that can be unacceptable for delay sensitive media applications, e.g., multimedia streaming. Hence, it is important to develop network-wide ARM policies that are both distributed and scalable by exploiting the radio MCs capabilities to sense, adapt and coordinate themselves. We validate our analytical models via simulation based numerical tests, that support actual effectiveness of the overall ActMesh paradigm, both in terms of objective and subjective performance metrics. In particular, the basic tradeoff among backbone traffic-vs-access traffic arising in the ActMesh net from the bandwidth-efficient opportunistic resource allocation policy pursued by the deployed ARM is numerically characterized. The standardization framework we inspire to is the emerging IEEE 802.16h one

Self-Evolving Integrated Vertical Heterogeneous Networks

6G and beyond networks tend towards fully intelligent and adaptive design in order to provide better operational agility in maintaining universal wireless access and supporting a wide range of services and use cases while dealing with network complexity efficiently. Such enhanced network agility will require developing a self-evolving capability in designing both the network architecture and resource management to intelligently utilize resources, reduce operational costs, and achieve the coveted quality of service (QoS). To enable this capability, the necessity of considering an integrated vertical heterogeneous network (VHetNet) architecture appears to be inevitable due to its high inherent agility. Moreover, employing an intelligent framework is another crucial requirement for self-evolving networks to deal with real-time network optimization problems. Hence, in this work, to provide a better insight on network architecture design in support of self-evolving networks, we highlight the merits of integrated VHetNet architecture while proposing an intelligent framework for self-evolving integrated vertical heterogeneous networks (SEI-VHetNets). The impact of the challenges associated with SEI-VHetNet architecture, on network management is also studied considering a generalized network model. Furthermore, the current literature on network management of integrated VHetNets along with the recent advancements in artificial intelligence (AI)/machine learning (ML) solutions are discussed. Accordingly, the core challenges of integrating AI/ML in SEI-VHetNets are identified. Finally, the potential future research directions for advancing the autonomous and self-evolving capabilities of SEI-VHetNets are discussed.Comment: 25 pages, 5 figures, 2 table

A Hybrid Approach to Quality of Service Multicast Routing in High Speed Networks

Multimedia services envisaged for high speed networks may have large numbers of users, require high volumes of network resources and have real-time delay constraints. For these reasons, several multicast routing heuristics that use two link metrics have been proposed with the objective of minimising multicast tree cost while maintaining a bound on delay. Previous evaluation work has compared the relative average performance of some of these heuristics and concludes that they are generally efficient. This thesis presents a detailed analysis and evaluation of these heuristics which illustrate that in some situations their average performance is prone to wide variance for a particular multicast in a specific network. It concludes that the efficiency of an heuristic solution depends on the topology of both the network and the multicast, which is difficult to predict. The integration of two heuristics with Dijkstras shortest path tree algorithm is proposed, to produce a hybrid that consistently generates efficient multicast solutions for all possible multicast groups in any network. The evaluation results show good performance over a wide range of networks (flat and hierarchical) and multicast groups, within differing delay bounds. The more efficient the multicast tree is, the less stable it will be as multicast group membership changes. An efficient heuristic is extended to ensure multicast tree stability where multicast group membership is dynamic. This extension decreases the efficiency of the heuristics solutions, although they remain significantly cheaper than the worst case, a shortest delay path tree. This thesis also discusses how the hybrid and the extended heuristic might be applied to multicast routing protocols for the Internet and ATM Networks. Additionally, the behaviour of the heuristics is examined in networks that use a single link metric to calculate multicast trees and concludes one of the heuristics may be of benefit in such networks

PEER-TO-PEER VIDEO CONTENT DELIVERY OPTIMIZATION SERVICE IN A DISTRIBUTED NETWORK

Η δυναμικά προσαρμοζόμενη ροή βίντεο μέσω HTTP (DASH) παρέχει βελτιώσεις στην ποιότητα της εμπειρίας χρήσης (QoE) κατά την αναπαραγωγή βίντεο σε δίκτυα παλαιότερα των δικτύων 5ης γενιάς (5G). Ωστόσο, οι εφαρμογές τύπου νέφους τις οποίες μπορεί να παρέχει η αρχιτεκτονική δικτύων 5ης γενιάς, σε συνδυασμό με την υλοποίηση υπολογιστικών υποδομών νέφους στο άκρο του δικτύου και κοντά στους τελικούς χρήστες, μπορεί να βελτιώσει σημαντικά τόσο την ποιότητα της προσφερόμενης υπηρεσίας (QoS) όσο και την εμπειρία χρήσης λόγω της δυνατότητας προσωρινής αποθήκευσης περιεχομένου βίντεο στο άκρο του δικτύου, λόγω της δυνατότητας παροχής προσωρινής αποθήκευσης μέρους του βίντεο στο άκρο του δικτύου. Επιπροσθέτως, εκτός της αποθήκευσης στο και διανομής βίντεο από το άκρο του δικτύου προς τους τελικούς χρήστες, οι νέες υποδομές βίντεο θα παρέχουν τη δυνατότητα διανομής περιεχομένου βίντεο απευθείας από συσκευή σε συσκευή (D2D). Αξιοποιώντας τις τεχνολογίες αυτές, μπορούν να υλοποιηθούν καινοτόμες υπηρεσίες ροής βίντεο, οι οποίες μπορούν όχι μόνο να βελτιώσουν την εμπειρία χρήσης των τελικών χρηστών κατά την αναπαραγωγή βίντεο, αλλά και να μειώσουν το συνολικό κόστος διανομής βίντεο καθώς και την συμφόρηση των δικτύων, άρα και την καθυστέρηση από άκρο σε άκρο και τη συμφόρηση στα δίκτυα διανομής περιεχομένου (CDN) των παρόχων υπηρεσιών διανομής και ροής βίντεο. Στην παρούσα διπλωματική εργασία μελετούμε την επίπτωση που έχουν διάφοροι συνδυασμοί τεχνικών προσωρινής αποθήκευσης, διανομής, καθώς και επιλογής ανάλυσης, σε περιεχόμενο βίντεο, πάνω στην ποιότητα της προσφερόμενης υπηρεσίας και στην εμπειρία των τελικών χρηστών που βρίσκονται στο άκρο του δικτύου, οι οποίες μπορούν να αξιοποιηθούν στη δημιουργία μιας καινοτόμας υπηρεσίας που βελτιστοποιεί τη διανομή περιεχομένου βίντεο μεταξύ ομότιμων κόμβων (P2P) σε ένα κατανεμημένο δίκτυο.Dynamtic Adaptive Streaming over HTTP (DASH) has yield several improvements in the video playback Quality of Experimence (QoE) for the end users in pre-fifth generation (5G) networks. However, cloud applications that 5G networks enable, combined with cloud infrastructures at the edge of the network and in close vicinity to the end users, can offer significant improvements in both the offered Quality of Service (QoS) and QoE because of the video content caching capabilities at the edge of the network that the edge cloud can offer. Furthermore, in addition to edge caching and edge video streaming to the end users, new video infrastructures can offer Device-to-Device (D2D) video content exchange and delivery. Taking advantage of these technologies, innovative video streaming services can be developed which not only improve the video playback QoE for the end users but also reduce the video delivery costs and generated network traffic, which also means reduced end-to-end latency and reduced overhead in video content providers’ Content Delivery Network (CDN). In this thesis we study the impact of using different combinations of distinct video caching techniques, video segment request and streaming algorithms and video resolution selection logics on the QoS and the QoE of end users at the network edge, which can be used in developing an innovative Peer-to-Peer (P2P) video content delivery optimization service in a distributed network

Routing in Large Scale tactical mobile ad hoc Networks

The current Transformation of the military networks adopts the MANET as a main component of the tactical domain. Indeed, a MANET is the right solution to enable highly mobile, highly reactive and quickly deployable tactical networks. Many applications such as the Situational Awareness rely on group communications, underlying the need for a multicast service within the tactical environment where the MANET is employed as a transit network. The purpose of this thesis is to study the setting up of an optimal multicast service within this tactical environment. We firstly focus on defining the protocol architecture to carry out within the tactical network paying particular attention to the MANET. This network is interconnected with different types of networks based on IP technologies and implementing potentially heterogeneous multicast protocols. The tactical MANET is supposed to be made of several hundred of mobile nodes, which implies that the scalability is crucial in the multicast protocol architecture choice. Since the concept of clustering proposes interesting scalability features, we consider that the MANET is a clustered network. Thereby, we define two multicast routing protocols adapted to the MANET: firstly STAMP that is in charge of the multicast communications within each cluster and secondly SAFIR that handles multicast flows between the clusters. These two protocols that can be implemented independently, act in concert to provide an efficient and scalable multicast service for the tactical MANET. Then, we study the interoperability of these multicast protocols employed within the MANET with those employed in the heterogeneous networks that it is interconnected with in order to guarantee end-to-end seamless multicast services to users. Finally, since the multicast protocols proposed in this thesis rely on underlying unicast routing protocols, we propose, in the last chapter, a scalable unicast routing protocol based on OLS

Image steganography applications for secure communication

To securely communicate information between parties or locations is not an easy task considering the possible attacks or unintentional changes that can occur during communication. Encryption is often used to protect secret information from unauthorised access. Encryption, however, is not inconspicuous and the observable exchange of encrypted information between two parties can provide a potential attacker with information on the sender and receiver(s). The presence of encrypted information can also entice a potential attacker to launch an attack on the secure communication. This dissertation investigates and discusses the use of image steganography, a technology for hiding information in other information, to facilitate secure communication. Secure communication is divided into three categories: self-communication, one-to-one communication and one-to-many communication, depending on the number of receivers. In this dissertation, applications that make use of image steganography are implemented for each of the secure communication categories. For self-communication, image steganography is used to hide one-time passwords (OTPs) in images that are stored on a mobile device. For one-to-one communication, a decryptor program that forms part of an encryption protocol is embedded in an image using image steganography and for one-to-many communication, a secret message is divided into pieces and different pieces are embedded in different images. The image steganography applications for each of the secure communication categories are discussed along with the advantages and disadvantages that the applications have over more conventional secure communication technologies. An additional image steganography application is proposed that determines whether information is modified during communication. CopyrightDissertation (MSc)--University of Pretoria, 2012.Computer Scienceunrestricte

The model of interoperable electronic business of payments systems founded on ontologies

Predmet ove disertacije je razvoj i primena modela interoperabilnog elektronskog poslovanja platnih sistema zasnovanog na ontologijama i Resource-Event-Agent - REA (ISO/IEC 15944-4:2007) ontološkoj objektnoj strukturi sistema. Istraživanje je bazirano na globalnim poslovnim standardima finansijske industrije - referentnim modelima za razmenu informacija. Saznanja iz implementacije sistema za kliring čekova i sistema za direktno zaduženje u Udruženju banaka Srbije koji su realizovani korišćenjem obrazaca za poslovnu integraciju (EIP - Enterprise Integration Patterns) i standardizovanih sistema poruka primenjena su u istraživanju. Istraživanje je prilagođeno i za implementaciju interoperabilnih platnih sistema u Srbiji. Različiti platni sistemi u procesu elektronskog poslovanja su u interakciji sa različitim poslovnim sistemima učesnika. Poslovni sistemi učesnika podržavaju veliki broj korisnika i poslovnih procesa sa specifičnim zahtevima. Osnovni problem je heterogenost između poslovnih procesa, podataka i korišćenih IT tehnologija. Iz tog razloga vreme, finansijska sredstva i informatički resursi se troše na prevođenje podataka iz jednog sistema u drugi. Razmena finansijskih transakcija elektronskim putem postala je prevladavajuća. Time nastaje potreba za razvojem modela interoperabilnog elektronskog poslovanja platnog sistema za razmenu finansijskih transakcija i njihovu obradu. Standardizacija u domenu modeliranja platnih sistema, koja će biti razmatrana, treba da doprinese i većoj efikasnosti ostalih sistema elektronskog poslovanja i interoperabilnosti elektronskog poslovanja učesnika. U svakoj državi platni sistem se sastoji od skupa platnih instrumenata, bankarskih procedura i sistema za prenos sredstava između finansijskih institucija u cilju obezbeđivanja cirkulacije novca. Centralna banka neposredno definiše, reguliše i usmerava tokove novca i ispunjava svoju osnovnu funkciju regulatora finansijskih tokova putem kontrole platnih sistema. Najvažniji je Real Time Gross Settlement System - RTGS, sa kojim su hijerarhijski povezani sistemi banaka i drugih finansijskih institucija, pravnih i fizičkih lica. Među njima su klirinške kuće, agenti, procesorske kuće i zakonom definisane institucije koje se bave izvršenjem, procesiranjem,akvizicijom ili distribucijom informacija o finansijskim transakcijama, ali i drugi sistemi elektronskog poslovanja. Platni sistemi, na način opisan u ovom radu, objedinjuju elemente koji figurišu u svakom sistemu baziranom na porukama, tehnološke elemente nadređenih institucija koji su implicirani standardnim formatom poruka, ambijentalne uslove zadate mestom na kome se platni sistem ostvaruje (mesto u finansijskoj vertikali, vrsti procesiranja za koje je opredeljen, geopolitičkoj topologiji i drugim mogućim elementima), potrebnoj komunikacionoj interakciji, neophodnim informacionim tehnologijama za realizaciju pojedinačnih i opštih zadataka...The subject of this dissertation is development and application of the model of interoperable e-Business of payment systems based on ontologies and Resource-Event-Agent - REA (ISO/IEC 15944-4:2007) ontological object system structure. Referential models in the information exchange upon global business standards of financial industry are basis for this investigation. It will apply the experience and knowledge from the implementation of the Check Clearing and Direct Debit systems within the Association of Serbian Banks, created by the use of Enterprise Integration Patterns (EIP) and the standardized systems of messages. The investigation will be adjusted to the implementation of interoperable payment systems in Serbia. Various payment systems in the process of electronic transaction interact with various participants′ business systems. Participants’ business systems support a great number of users and business processes with specific requirements. In this, the basic problem is dissimilarity between business processes, data and IT technologies. From that reason, time, financial, and informatics resources are wasted on the data transfer from one to another system. Today, the exchange of financial transactions electronically became predominant. This calls for the development of models of interoperable e-Business of payment systems for the exchange of financial transactions and their processing. The standardization in the domain of payment system modeling, considered in this study should contribute to greater efficiency of other electronic business systems and to interoperability of participants’ electronic businesses. In every country payment system comprises a number of payment instruments, banking procedures, and the systems for the fund transfer between financial institutions. That alowws the circulation of money in the country. The Central Bank directly defines, regulates and directs the money flow, and fulfills the function of the regulator of financial flows through the control of the payment systems. The most important is Real Time Gross Settlement System - RTGS, which for the mentioned reasons, is mainly under the supervision of Central Bank. Banks′ systems and the systems of other financial institutions are connecting by RTGS System. Among them there are institutions like clearing houses, payment agents, processing houses, and other. They are defined by law, deals with implementation, processing, information acquisition, or distribution regarding financial transactions, as well as other systems of electronic business. Payment systems, on the wyu described in this work, unify the elements, existent in every system based on messages, technological elements of supervising institutions, implicated by the standard message format, ambient conditions imposed by the place with the implemented payment system (in financial vertical, with kind of processing for which it is committed, geo-political typology, and other possible elements), required communicational interaction, information technologies necessary for realization of general and specific tasks..