Dávid Szabó

Towards the 5G Revolution: A Software Defined Network Architecture Exploiting Network Coding as a Service

Many networking visioners agree that 5G will be much more than the incremental improvement, in terms of data rate, of 4G. Besides the mobile networks, 5G will fundamentally influence the core infrastructure as well. In our vision the realization of the challenging promises of 5G (e.g. extremely fast, low-overhead, low-delay access of mostly cloudified services and content) will require the massive use of multipathing equipped with low overhead transport solutions tailored to fast, reliable and secure data retrieval from cloud architectures. In this demo we present a prototype architecture supporting such services by making use of automatically configured multipath service chains implementing network coding based transport solutions over off-the-shelf software defined networking (SDN) components.

On greedy network formation

Greedy navigability is a central issue in the theory of networks. However, the exogenous nature of network models do not allow for describing how greedy routable-networks emerge in reality. In turn, network formation games focus on the very emergence proess, but the applied shortest-path based cost functions exclude navigational aspects. This paper takes a frst step towards incorporating both emergence (missing in algorithmic network models) and greedy navigability (missing in network formation games) into a single framework, and proposes the Greedy Network Formation Game. Our first contribution is the game definition, where we assume a hidden metric space underneath the network, and, instead of usual shortest path metric, we use the length of greedy paths as the measure of communiation cost between players. Our main finding is that greedy-routable small worlds do not emerge on constant dimensional Eulidean grids. This simply means that the emergence of topologies on which w eunderstood the priniples of greedy forwarding cannot be explained endogenously. We also present a very brief outlook on how the situation hanges in the hyperbolic space.

Notes on the Topological Consequences of BGP Policy Routing on the Internet AS Topology

On the Internet AS level topology, BGP policy routing is in charge of dictating the characteristics of routes which can be used for packet transmission. Furthermore the peculiarities of the BGP policies clearly affect the peering strategies of the ISP-s, hereby influencing the emerging topology. This paper takes a first step towards identifying the topological footprint issued by these policies. For this purpose we modify the framework of network formation games to support the most fundamental BGP policy called valley-free routing. We show the topological properties of the equilibrium topologies of this game in an analytical manner.

Effect of mild alkali/ultrasound treatment on flax and hemp fibres: the different responses of the two substrates

Flax and hemp fibres were treated by various combinations of water/diluted alkaline solution and stirring/ultrasound, respectively. Changes in the microstructure (scanning electron microscopy) and porous structure (low-temperature nitrogen adsorption), removal of non-cellulosic materials (weight loss, FTIR), mean fibre diameter, and adhesion of the polypropylene matrix to the fibres (micro-bond test) were investigated. For both types of fibres, removal of (FTIR) was observed. The fibre diameter of hemp was decreased by several treatments, most of all by stirring in alkali and subsequent sonication in water, while the ultrasound applied in alkali solution did not change the fibre fineness. This can be attributed to the dual effect of ultra-sonication: the swelling effect of alkali combined with ultrasound energy probably served the sticking of inter-fibrillar material rather than their dissolution. Fibre diameter of flax did not change in any circumstances. The porosity of hemp in the mesopore range increased, while that of flax decreased by alkali treatment and subsequent sonication. The reason for this difference might be the dissimilar cell wall structures of the two bast fibres, the high arabinose content of the hemp, and/or the cottonisation of hemp. No treatments altered the fibre-matrix adhesion measured by pulling out the fibre from a micro-droplet of polypropylene.

Monitoring of Actual Thermal Condition of High Voltage Overhead Lines

The main issue of the article is to investigate and improve the usability of existing line rating calculation methods (Cigre, IEEE) in DLR systems, based on years of measured and forecasted weather and conductor data, including the differences of various calculation models (white-box model). In addition to the use on conventional physical model, the application of soft-computation methods is considered (black-box model). The aim is to create a neural network capable of recognizing patterns based on the data of previous years and the actual current values of the wires. In this way, it is not only possible to fine-tune, but also accelerate the applied calculation of maximum load capacity.

Inspection of conductor connectors in the medium voltage grid

There may be many cases when it is necessary to repair broken conductors in the medium voltage grid. There are many types of conductor connectors to do that, but especially their long-term properties may vary in a wide range.

Deductive way of reasoning about the internet AS level topology

Our current understanding about the AS level topology of the Internet is based on measurements and inductive-type models which set up rules describing the behavior (node and edge dynamics) of the individual ASes and generalize the consequences of these individual actions for the complete AS ecosystem using induction. In this paper we suggest a third, deductive approach in which we have premises for the whole AS system and the consequences of these premises are determined through deductive reasoning. We show that such a deductive approach can give complementary insights into the topological properties of the AS graph. While inductive models can mostly reflect high level statistics (e.g. degree distribution, clustering, diameter), deductive reasoning can identify omnipresent subgraphs and peering likelihood. We also propose a model, called YEAS, incorporating our deductive analytical findings that produces topologies contain both traditional and novel metrics for the AS level Internet.

An Information-Theoretic Approach to Routing Scalability

Many of our computer networks, not the least of which the Internet, are built upon hop-by-hop routing. At the moment, it is not clear whether we will be able to scale these networks into the future economically. In this paper, we propose a new information-theoretic model to study routing scalability, we present preliminary analysis suggesting that hop-by-hop routing tolerates network growth surprisingly efficiently, and we sketch the scalability map of the Internet which we then use to make some bold predictions.

Brief announcement: network formation games can give rise to realistic networks

The purpose of network formation games [1] is to give a game-theoretical tool which can effectively explain the topological properties (clustering, degree distribution, small world property) and the emergence of Internet-like complex networks in an incentive centered economical fashion. In the influential book of the subject [2], the development of an incentive-oriented and endogenous model of network formation, that would generate more heterogeneous and realistic networks, is still attributed as an exciting open challenge. Although more recently several studies recovered realistic clustering and degree distribution by encoding these properties into the cost functions of the players, these still qualify as exogeneous models. In this paper, we define a network formation game in which realistic topologies naturally emerge as equilibrium networks, without enforcing topological concerns in the cost functions. Inspired by the wealth of studies concerning greedy search processes in networks, we define a modified game where players are placed in a metric space and, instead of the usual shortest path metric, we use the length of greedy paths as the measure of communication cost between players. We also present some preliminary results.