Róbert Szabó

Participatory sensing based real-time public transport information service

Modern cities continuously struggle with infrastructural problems especially when the population is massively growing. One affected area is public transportation. In default of offering convenient and reliable service the passengers tend to consider other transport alternatives. However, even a relatively simple functional enhancement, such as providing real-time timetable information, requires considerable investment and effort following traditional means, e.g. deploying sensors and building a background communication and processing infrastructure. Using the power of crowd to gather the required data, share information and send feedback is a viable and cost effective alternative. In this demonstration, we present TrafficInfo, our prototype smart phone application to implement a participatory sensing based live public transport information service. TrafficInfo visualizes the actual position of public transport vehicles with live updates on a map, and gives support to crowd sourced data collection and passenger feedback.

Self organizing ambient control space: an ambient network architecture for dynamic network interconnection

One of the major challenges in ambient networking is to provide interworking between heterogeneous and dynamically changing networks. This paper presents a novel network and system architecture enabling network self-organization and dynamic network composition. The proposed network architecture is based on a hierarchical overlay network model, where components of the overlays can also be overlays themselves. This introduces a self-contained network architecture argued to suit ambient networking. The network architecture is discussed together with the rules or composition principles that enforce an attracting tree structure to the hierarchical overlays. Besides the network architecture the major components of the system architecture is also presented involving the naming and addressing scheme and handling of network management data1.

Novel Enhancements to Load Control - A Soft-State, Lightweight Admission Control Protocol

In this paper we present enhancements to a load control algorithm, which was proposed to perform resource reservations in a differentiated services domain. The basic load control algorithm performs distributed admission control decision, uses only aggregated network states (one per perhop-behavior - PHB) and soft state approach with periodic refreshes to account for resource usage. It is enhanced by several means to adapt it to recent networking requirements. Our proposals include solution to multi-rate reservation, enhancements in network utilization adapting the protocol to transient periods, and handling of possible quality of service violations. We also demonstrate through prototype implementation and extensive performance analysis to what extent the former objectives are fulfilled by our proposals. We claim that most of the enclosed proposals in this article could be reused in other lightweight resource reservation protocols.

OSPF for Implementing Self-adaptive Routing in Autonomic Networks: A Case Study

Autonomicity, realized through control-loop structures operating within network devices and the network as a whole, is an enabler for advanced and enriched self-manageability of network devices and networks. In this paper, we argue that the degree of self-management and self-adaptation embedded by design into existing protocols needs to be well understood before one can enhance or integrate such protocols into self-managing network architectures that exhibit more advanced autonomic behaviors. We justify this claim through an illustrative case study: we show that the well-known and extensively used intra-domain IP routing protocol, OSPF, is itself a quite capable self-managing entity, complete with all the basic components of an autonomic networking element like embedded control-loops, decision-making modules, distributed knowledge repositories, etc. We describe these components in detail, concentrating on the numerous control-loops inherent to OSPF, and discuss how some of the control-loops can be enriched with external decision making logics to implement a truly self-adapting routing functionality.

Towards distributed hash tables (De)composition in ambient networks

When different wireless networks come in close proximity there is often a need for them to logically combine, or compose. We focus on a known research problem particularly in Ambient Networks (ANs), where hetero-geneous Distributed Hash Tables (DHTs) contained in these wireless networks need to merge or divide as a result of these dynamic (de)composition processes, respectively. We present two novel DHT (de)composition models for ANs, known as absorption and gatewaying, that are designed to handle (de)composition of DHTs in different AN network environments, with minimal disturbance to existing member nodes.

Ambient Networks Management Challenges and Approaches

System management addresses the provision of functions required for controlling, planning, allocating, monitoring, and deploying the resources of a network and of its services in order to optimize its efficiency and productivity and to safeguard its operation. It is also an enabler for the creation and sustenance of new business models and value chains, reflecting the different roles the service providers and users of a network can assume. Ambient Network represents a new networking approach and it aims to enable the cooperation of heterogeneous networks, on demand and transparently, to the potential users, without the need for pre-configuration or offline negotiation between network operators. To achieve these goals, ambient network management systems have to become dynamic, adaptive, autonomic and responsive to the network and its ambience. This paper discusses relationships between the concepts of autonomous and self-manageability and those of ambient networking, and the challenges and benefits that arise from their employment.

Generic multipath routing concept for dynamic traffic engineering

This letter presents a generic adaptive multipath routing solution. The method, called Core-State-Limited Load Sharing (CSLLS), has two parameters. One determines the adaptation time to load changes and the other one controls how long the path of a flow is unchanged. With these two parameters CSLLS is capable of modelling previous multipath routing concepts like ECMP, OMP and QoSPF. CSLLS overcomes the limitations of earlier approaches by being adaptive (opposed to ECMP), by ensuring path integrity for a flow (opposed to OMP), and by relying on only a few stored states in core routers (opposed to QoSPF)

UNIFYing Cloud and Carrier Network Resources: An Architectural View

Cloud networks provide various services on top of virtualized compute and storage resources. The flexible operation and optimal usage of the underlying infrastructure are realized by resource orchestration methods and virtualization techniques developed during the recent years. In contrast, service deployment and service provisioning in carrier networks have several limitations in terms of flexibility, scalability or optimal resource usage as the built-in mechanisms are strongly coupled to the physical topology and special purpose hardware elements. Network Function Virtualization (NFV) opens the door between cloud and carrier networks by providing software-based telecommunication services which can run in virtualized environment on general purpose hardwares. Our main goal is to unify software and network resources in a common framework. In this paper, we propose a novel architecture supporting automated, dynamic service creation based on a fine-granular service chaining model, SDN and cloud virtualization techniques. First, we introduce the architecture with the main components. Second, the most important benefits are highlighted and compared to other state-of-the-art approaches. Finally, preliminary experiences with our proof-of-concept prototypes are presented.

Towards ambient networks management

Ambient Networks (AN) are under development and they are based on novel networking concepts and systems that will enable a wide range of user and business communication scenarios beyond todays fixed, 3rd generation mobile and IP standards. Central to this project is the concept of Ambient Control Space (ACS) and the Domain Manager control function, which manages the underlying data transfer capabilities and presents a set of interfaces towards the supported services and applications. Network Management Systems of Ambient Networks must work in an environment where heterogeneous networks compose and cooperate, on demand and transparently, without the need for manual (pre or re)-configuration or offline negotiations between network operators. To achieve these goals, ambient network management systems must become dynamic, distributed, self-managing and responsive to the network and its ambience. This paper describes the different management research challenges and four complementary solution approaches (i.e. Pattern-based Management, Peer-to-Peer Management, (Un)PnP Management, Traffic Engineering Management Application Approaches) that enable efficient management of ambient networks, and the relationships between them, and presents the main results achieved so far.

Stochastic maintenance of overlays in structured P2P systems

Peer-to-peer networks have widespread and got commonly used in our every day life. The maintenance strategy of overlays is a key factor in structured peer-to-peer networks. Most of these routing overlays scale well even for a very large number of nodes in static and quasi-static networks. However, providing good performance in dynamic network environments is still an open question. We analyse maintenance of routing overlays in structured P2P systems under churn. We exploit the inherent difference in the role of local (short-range) and long-range connections. We propose a dual strategy for the routing overlays: (i) we reuse strict, proactive and self-stabilizing short-range connection maintenance and (ii) we define a novel, loose and stochastic long-range connection maintenance mechanism, which can significantly reduce maintenance overhead in large networks with high churn rates without affecting routing performance. We use Kleinbergs small worlds model to describe and (re)construct long-range connections. We formally describe the evolution of our proposed system under churn by a Markov chain model and we derive its steady state maintenance traffic (overhead). We formally show that our maintenance method scales logarithmically with the systems size, which is the theoretical lower bound for maintenance traffic to ensure connectivity of the network. Finally, we numerically analyse overlay and maintenance behaviour using various protocol parameter settings and conclude that an overlay with our maintenance method is stable at very high levels of churn.