George Xylomenos
Athens University of Economics and Business
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Featured researches published by George Xylomenos.
IEEE Communications Surveys and Tutorials | 2014
George Xylomenos; Christopher N. Ververidis; Vasilios A. Siris; Nikos Fotiou; Christos Tsilopoulos; Xenofon Vasilakos; Konstantinos V. Katsaros; George C. Polyzos
The current Internet architecture was founded upon a host-centric communication model, which was appropriate for coping with the needs of the early Internet users. Internet usage has evolved however, with most users mainly interested in accessing (vast amounts of) information, irrespective of its physical location. This paradigm shift in the usage model of the Internet, along with the pressing needs for, among others, better security and mobility support, has led researchers into considering a radical change to the Internet architecture. In this direction, we have witnessed many research efforts investigating Information-Centric Networking (ICN) as a foundation upon which the Future Internet can be built. Our main aims in this survey are: (a) to identify the core functionalities of ICN architectures, (b) to describe the key ICN proposals in a tutorial manner, highlighting the similarities and differences among them with respect to those core functionalities, and (c) to identify the key weaknesses of ICN proposals and to outline the main unresolved research challenges in this area of networking research.
IEEE Communications Magazine | 2001
George Xylomenos; George C. Polyzos; Petri Mähönen; Mika Saaranen
This article discusses the problems arising when the TCP/IP protocol suite is used to provide Internet connectivity over existing and emerging wireless links. Due to the strong drive toward wireless Internet access through mobile terminals, these problems must be carefully studied in order to build improved systems. We review wireless link characteristics using wireless LANs and cellular communications systems as examples. We then outline the performance problems of the TCP/IP protocol suite when employed over those links, such as degraded TCP performance due to mistaking wireless errors for congestion. We present various proposals for solving these problems and examine their benefits and limitations. Finally, we consider the future evolution of wireless systems and the challenges that emerging systems will impose on the Internet protocol suite.
international conference on computer communications | 1999
George Xylomenos; George C. Polyzos
We present a comprehensive set of measurements of a 2.4 GHz DSSS wireless LAN and analyze its behavior. We examine issues such as host and interface heterogeneity, bidirectional (TCP) traffic and error modeling, that have not been previously analyzed. We uncover multiple problems with TCP and UDP performance in this system. We investigate the causes of these problems (radio hardware, device drivers, network protocols) and discuss the effectiveness of proposed improvements.
IEEE Communications Magazine | 1997
George Xylomenos; George C. Polyzos
We present alternative designs for efficiently supporting multicast for mobile hosts on the Internet. Methods for separately supporting multicasting and mobility along with their possible interactions are briefly described, and then various solutions to the combined problem are explored. We examine three different multicast delivery mechanisms and compare them based on their efficiency and impact on host protocol software. We describe proposals for integrating multicasting and mobility in the Internet architecture. We first present IP extensions for host mobility and other extensions for multicasting. We then examine local multicasting mechanisms, focusing on a group membership protocol that is optimized for wireless point-to-point links. Next, we examine the problems of sending and receiving multicast datagrams in a wide area network. For multicast reception, we describe three alternative proposals and compare them by examining both their applicability and their performance, as well as possible tradeoffs among the two.
Computer Networks | 2011
Konstantinos V. Katsaros; George Xylomenos; George C. Polyzos
It has become apparent for quite some time that the Internet has evolved from a network connecting pairs of end-hosts to a substrate for information dissemination. While this shift towards information centric networking has been clearly demonstrated by the proliferation of file sharing and content delivery applications, it has not been reflected in a corresponding shift in network architecture. To address this issue, we designed MultiCache, an information-centric architecture aiming at the efficient use of network resources. MultiCache is based on two primitives: multicast and caching. It exploits overlay multicast as a means for content delivery and takes advantage of multicast forwarding information to locate, in an anycast fashion, nearby caches that have been themselves fed via multicast. We evaluate MultiCache against a widespread file sharing application (BitTorrent) with respect to both network resource consumption and end-user experience.
Multimedia Systems | 1998
Joseph Pasquale; George C. Polyzos; George Xylomenos
Abstract. This paper explores the problems associated with the multicasting of continuous media to support multimedia group applications. The interaction between multicasting and the delivery of multiple time-correlated continuous-media streams with real-time delay requirements poses various new and interesting problems in research on communication protocols and architectures. We describe these problems, and identify where the opportunities are for effective solutions, all in the context of providing an overview of the current state of research in multimedia multicasting. The issues we discuss include quality of service, resource reservations, routing, error and traffic control, heterogeneity, and the use of hierarchical coding and open-loop control techniques.
IEEE Communications Magazine | 2012
George Xylomenos; Xenofon Vasilakos; Christos Tsilopoulos; Vasilios A. Siris; George C. Polyzos
The Internet is straining to meet demands that its design never anticipated, such as supporting billions of mobile devices and transporting huge amounts of multimedia content. The publish-subscribe Internet (PSI) architecture, a clean slate information-centric networking approach to the future Internet, was designed to satisfy the current and emerging user demands for pervasive content delivery, which the Internet can no longer handle. This article provides an overview of the PSI architecture, explaining its operation from bootstrapping to information delivery, focusing on its support for network layer caching and seamless mobility, which make PSI an excellent platform for ubiquitous information delivery.
IEEE Network | 1999
George Xylomenos; George C. Polyzos
This article discusses the problems that arise when standard Internet protocols such as TCP are used over wireless links. We review wireless link characteristics with case studies drawn from commercial wireless LANs and cellular telephony systems. We discuss problems with Internet protocols when employed over these systems, such as degraded TCP performance when wireless errors are interpreted as congestion losses. We survey various proposed approaches to mitigating such problems and examine their applicability. Finally, we look at the future of wireless systems and the new challenges that they will create for Internet protocols, and state some goals for further protocol enhancement and evolution, pointing out the need for better protocol integration across layers.
acm special interest group on data communication | 2011
Christos Tsilopoulos; George Xylomenos
In this paper we focus on the issue of transferring diverse kinds of information through information-centric networks (ICNs). We argue that the one request per packet mode of operation suggested in the early development of ICN applications is not a good fit for some types of traffic, such as media streams and real-time notifications. To efficiently deliver all kinds of information, we argue that an ICN should not only identify information by its name, it should also be aware of the nature of its traffic. We classify information traffic types based on two characteristics: a) reliable vs. unreliable transfer and b) real-time vs. on-demand delivery. The combination of these two characteristics leads to three broad categories: a) channels, b) on-demand documents and c) real-time documents. To handle all traffic types, we propose two extensions to the CCN architecture: Persistent Interests and Reliable Notifications. We describe how these additions, together with a careful selection of information names, can efficiently support these three categories of information traffic types.
IFIP'12 Proceedings of the 11th international IFIP TC 6 conference on Networking - Volume Part I | 2012
Konstantinos V. Katsaros; Nikos Fotiou; Xenofon Vasilakos; Christopher N. Ververidis; Christos Tsilopoulos; George Xylomenos; George C. Polyzos
Information-centric networking (ICN) is a paradigm that aims to better reflect current Internet usage patterns by focusing on information, rather than on hosts. One of the most critical ICN functionalities is the efficient resolution/location of information objects i.e., name resolution. The vast size of the information object namespace calls for a highly scalable and efficient name resolution approach. Currently proposed solutions either rely on a DHT structure, thus ensuring load balancing and scalability at the cost of inefficient routing, or on hierarchical structures, thus preserving routing efficiency at the cost of limited scalability. In this paper, we study in detail the tradeoff between state/signaling overhead versus routing efficiency for a generic name-resolution system based on a novel DHT scheme with enhanced routing properties, and compare it to DONA, an ICN architecture based on hierarchical resolution and routing.