News

Talk by Xenofon Vasilakos

08-10-2018
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Xenofon Vasilakos, who is currently postdoctoral fellow at Eurecom graduate school and research centera, France, will give a talk on "Cognitive Network and Slice Management in Virtualized Multi-Tenant 5G Networks" on Tuesday, October 9th, at room 414 of the Trias Str. building

Talk abstract: Fifth Generation (5G) mobile networks pose a major paradigm shift, aimed to improve efficiency and flexibility with a service-oriented architecture that delivers networks as-a-service. The underlying concept is to support multiple services and virtual networks over one or more physical network infrastructure providers, with respect to (wrt) different service definition and agreement requirements, control and management, and performance. This service-oriented 5G vision can address the vast variety of emerging resource-hungry wireless services due to the unprecedented proliferation of smartphone and Internet-of-Things (IoT) devices, via a network composition and resource sharing model that reduces both Capital Expenditure (CAPEX) and operating expenses (OPEX). The later is done by decoupling infrastructure providers (e.g., operators and data center owners), service providers (e.g., operators and verticals) and network function providers (e.g., vendors). Therefore, a 5G service can be built by combining multi-vendor physical network functions and Virtual Network Functions (VNFs), bringing network slicing to the foreground as a key enabler for the envisioned service-oriented 5G. Within this 5G context, a key concept for customizing and offering a slice in a flexible way is to automate its life-cycle management. Following a long period of remaining in obscurity, Machine Learning (ML)-based approaches have created a trend towards this direction in the literature due to breakthroughs made on computational devices (CPUs, GPUs and Tensor Processing Units (TPUs)), which qualify ML as an appropriate option. Nevertheless, Cognitive Network & Slice Management based on ML poses a series of challenges, spanning from the design process of the ML models up to their deployment and their runtime life-cycle, including their cooperation. In addition, another key challenge towards a 5G era is the ever-increasing demand for resource-hungry, content-rich services such as HD video streaming and augmented reality, which require both low latency and high reliability.
This talk will focus on three points of research within the context of Cognitive Network & Slice Management in virtualized multi-tenant 5G networks:
(a) A novel Methodology approach to Cognitive Network & Slice Management based on Machine Learning (ML) models for managing network and slice resources in a way that complies with slice Service Level Agreements (SLAs) and maximizes the revenue of the underlying physical network operator(s). The proposed methodology approach standardizes, orchestrates and automates all the necessary steps and actions for building and deploying efficient ML models as collaborative components of an integrated Cognitive Network & Slice Management system.
(b) LL-MEC, the first open-source Low-Latency Multi-access Edge Computing (MEC) platform enabling coordinated resource programmability in end-to-end slicing scenarios, mobile network monitoring, control, and programmability while retaining compatibility with 3GPP and ETSI specifications.
(c) Ongoing work on coordinated, multi-type resource allocation for E2E slicing.

Presenter's biography: Xenofon Vasilakos is a postdoctoral fellow at Eurecom graduate school and research center, the Communication Systems department. He is funded by the “Investments for the Future” LABEX scholarship programme. Currently, he is working on 5G slicing technologies with a particular focus on Multi-access Edge Computing solutions and cognition approaches inspired by Machine Learning models towards self-managed 5G mobile networks. He has acquired a Ph.D. in Informatics from the Athens University of Economics and Business (AUEB) by working on Information-Centric Networking architectures, protocols and distributed solutions for the Future Internet, with an emphasis on rendezvous networks and seamless mobility support. Before that, he obtained his M.Sc. degree in Parallel and Distributed Computer Systems in 2009 from the Vrije Universiteit Amsterdam and his B.Sc. in Informatics from AUEB in 2007. He has participated in EU funded H2020 ICT projects such as H2020-POINT and, currently, 5GPPP SliceNet and 5GPPP 5G-PICTURE. In the past, he has participated in the EU funded FP7 projects PSIRP and PURSUIT, as well as in the Greek government-funded project I-CAN on clean-slate Information-Centric Networking architectures.

Ph.D. defense by Yiannis Thomas

19-07-2018
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Yiannis Thomas successfully presented his Ph.D. thesis, with title "Multipath Internet Transport", on Wednesday July 18th

Thesis abstract: The proliferation of smartphones, with their multiple interfaces, and data servers, with their high-performance interconnection networks, has revived interest in multipath transport protocols. Multipath-TCP (MPTCP), the multipath extension of TCP, is currently available in the Apple iOS and Linux operating systems, enabling bandwidth aggregation, load balancing, and resilience to failures and disconnections due to mobility. However, the deployment of multipath transport is challenged by the address-based TCP/IP communication, which does not facilitate the seamless establishment of multiple paths among two end-points, and by the distributed hop-by-hop TCP/IP routing, which does not ensure the disjointness of the paths. Even when multiple paths are deployed, the use of many subflows is both a blessing and a curse for multipath TCP/IP protocols, as they tend to grasp an unfair share of bandwidth, thus becoming unfriendly to single-path TCP flows. The latest congestion control algorithms for MPTCP attempt to equalize the cumulative subflow throughput with the throughput of the fastest single-path flow in the same link, thus exchanging performance for TCP-friendliness. While TCP-friendly in the long run, these approaches exhibit high throughput convergence latency, thus being effective only for long-lived flows.
Our contribution to multipath transport is twofold. First, we introduce the multipath multisource Transport Protocol (mmTP), a transport-layer protocol that offers reliable multipath and multisource content delivery in the Publish-Subscribe Internet (PSI) architecture. mmTP increases the utilization of network processing resources, exploits on-path and off-path caching and does not require additional state at routers, or complex signaling during connection establishment. Second, we propose a novel hybrid multipath congestion control algorithm that enhances resource utilization through greedy friendliness, a design that meets the TCP-friendliness constraint only when is needed. The hybrid congestion control scheme consists of the novel end-to-end Normalized Multiflow Congestion Control (NMCC) algorithm, which offers instant convergence to TCP-Friendliness, and an in-network topology management module, that provides disjoint paths when possible and notifies end-users about shared bottlenecks otherwise. We finally discuss the integration of the proposed designs with the TCP/IP architecture: mmTP through Software Defined Networking (SDN) and NMCC through MPTCP.

Talk by Nikos Vasilakis

25-06-2018
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Nikos Vasilaki who is currently Ph.D. candidate in Computer and Information Science at the University of Pennsylvania, will give a talk on "Retrofitting Security in Applications with Many Third-party Modules" on Tuesday, June 26th, on the 6th floor (606 room) of the Evelpidon Str. building (graduate program building) of the Athens University of Economics and Business (AUEB)

Talk abstract: Developers of large-scale software systems use third-party modules to reduce costs and accelerate release cycles, at a risk to safety and security. I will introduce a set of techniques that exploit module boundaries to automate compartmentalization of systems and enforce security policies, enhancing reliability and security. Our system, BreakApp, transparently spawns modules in protected compartments while preserving their original behavior. Optional high-level policies decouple security assumptions made during development from requirements imposed for module composition and use. These policies allow fine-tuning trade-offs such as security and performance based on changing threat models or load patterns. Evaluation of BreakApp with a prototype implementation for JavaScript -- an environment that is notorioustoday for its high-impact security problems -- demonstrates feasibility by enabling simplified security hardening of existing systems with low performance overhead.

Presenter's biography: Nikos Vasilakis is a Ph.D. candidate in Computer and Information Science at the University of Pennsylvania. Broadly construed, his research focus is large-scale distributed systems, with branches into systems security and programming languages. In the past, he worked as a software engineer in industrial environments that blend engineering with a tablespoon of research (e.g., VMware).

Talk by Michalis Faloutsos

02-04-2018
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Michalis Faloutsos who is currently a faculty member at the Computer Science Dpt and Director of Entrepreneurship in the University of California Riverside, will give a talk on "Can we reduce the first-mover-advantage of cyber-hackers?" on Tuesday, April 4th, on the 6th floor (606 room) of the Evelpidon Str. building (graduate program building) of the Athens University of Economics and Business (AUEB)

Talk abstract: Can we do better than just waiting for the next attack to happen? We aruge that security should become more proactive in order to minimize the damage that an attack, such as a DDoS or a virus, can have. This is a very ambitious goal, but we believe that we are making significant first steps towards it. Specifically, our work focuses on the following questions: a) Can we improve network security by mining social media? b)Can we analyze malware to detect artifacts that can help us block or even eliminate them? We present our efforts that attempt to address the above questions. First, we develop a systematic approach to extract actionable information from social media, focusing on security forums. Specifically, we develop RIPEx, a hands-free method to extract IP addresses, that are reported as malicious in the forums. The results are very encouraging: a handful of such forums can provide 4 times more malicious IP addresses compared to the well-known VirusTotal repository. Second, we present the value of the information that we can extract by analyzing malware binaries that target routers and IoT devices. To automate the study of such malware, we develop, RARE, a systematic and comprehensive system to extract patterns and communication artifacts that can help detect and contain malware, and also point us to the communication and control points of botnets.

Presenter's biography: Michalis Faloutsos is a faculty member at the Computer Science Dpt and Director of Entrepreneurship in the University of California Riverside. He got his bachelor's degree at the National Technical University of Athens and his M.Sc. and Ph.D. at the University of Toronto. His interests include, network and systems security, online social networks analytics, and network measurements. With his two brothers, he co-authored the paper "On powerlaws of the Internet topology" (SIGCOMM'99), which received the "Test of Time" award from ACM SIGCOMM. His research has resulted in more than 18K citations, an h-index greater than 56, and an i10-index greater than 120. His work has been supported by many NSF, DHS, ARL, and DAPRA grants, for a cumulative amount of more than $12M. He is the co-founder of stopthehacker.com, a web-security start-up, which got acquired by Cloudflare in November 2013. In Aug 2014, he co-founded programize.com, which provides product development as a service and grew to 55 people by its third year.

Talk by Salil Kanhere

21-03-2018
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Salil Kanhere who is currently an Associate Professor in the School of Computer Science and Engineering at UNSW Sydney, Australia, will give a talk on "A Lightweight Scalable Blockchain for Internet of Things" on Tuesday, March 22nd, on the 6th floor (606 room) of the Evelpidon Str. building (graduate program building) of the Athens University of Economics and Business (AUEB)

Talk abstract: BlockChain (BC) has attracted tremendous attention due to its immutable nature and the associated security and privacy benefits. In this talk, we argue that BC has the potential to overcome security and privacy challenges of Internet of Things (IoT). However, traditional instantiations of BC are computationally expensive, have limited scalability and incur significant bandwidth overheads and delays which are not suited to the IoT context. We propose a tiered Lightweight Scalable BC (LSB) that is optimized for IoT requirements. We explore LSB in a smart home setting as a representative example for broader IoT applications. Low resource devices in a smart home benefit from a centralized manager that establishes shared keys for communication and processes all incoming and outgoing requests. LSB achieves decentralization by forming an overlay network where high resource devices jointly manage a public BC that ensures end-to-end privacy and security. The overlay is organized as distinct clusters to reduce overheads and the cluster heads are responsible for managing the public BC. LSB incorporates several optimizations which include algorithms for lightweight consensus, distributed trust and throughput management. Qualitative arguments demonstrate that LSB is resilient to several security attacks. Extensive simulations show that LSB decreases packet overhead and delay and increases BC scalability compared to relevant baselines.

Presenter's biography: Salil Kanhere is an Associate Professor in the School of Computer Science and Engineering at UNSW Sydney, Australia. His research interests include Internet of Things, blockchain, pervasive and mobile computing, crowdsourcing, privacy and security. He has published 175 peer-reviewed articles and delivered over 20 keynote talks and technical tutorials on these topics. Salil regularly serves on the organizing committee of a number of IEEE and ACM international conferences. He currently serves as the Area Editor for Pervasive and Mobile Computing and Computer Communications. Salil is a Senior Member of both the IEEE and the ACM. He is a recipient of the Humboldt Research Fellowship.

UMObile project presentation

05-03-2018
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Christos-Alexandros Sarros, Ph.D student at the Democritus University of Thrace, Greece, and Vassilis Tsaoussidis, professor at the Democritus University of Thrace, Greece and adjunct professor at Athena RC, will give a talk on "A Universal, Mobile-Centric and Opportunistic Communications Architecture" on Tuesday, March 6th, on the 6th floor (606 room) of the Evelpidon Str. building (graduate program building) of the Athens University of Economics and Business (AUEB)

Talk abstract: The Future Internet architecture is expected to incorporate disruptive environments, new applications and information-centric services. Unlike the traditional host-centric access paradigm, where access to a desired content is mapped to its location, UMOBILE architecture relies on the information-centric communication model to enable the association of access to a desired content with the content itself and on the DTN technology to meet the requirements of opportunistic communications; the two approaches are integrated into a single architecture. Furthermore, our approach to push services near the edge of the network but also to interpret connectivity as a time-tolerant aspect, allows for the development of innovative applications that access data independent of the level of end-to-end connectivity availability. In this talk, we will highlight the design features of the UMOBILE architecture. Prior to that, a brief introduction to our group activities and relevant recent project results will be presented.

Presenters' biography: Christos-Alexandros Sarros obtained his diploma in electrical and computer engineering from Democritus University of Thrace, Greece, in 2016. Currently, he is pursuing a Ph.D. at the same university under the supervision of Prof. Vassilis Tsaoussidis, and is working as research assistant at the Athena Research and Innovation Center. His research interests lie in the area of information-centric networking and delay-/disruption-tolerant networking.
Vassilis Tsaoussidis is a professor at DUTH and adjunct professor at Athena RC, holding degrees in applied mathematics (Aristotle University) and computer science (Ph.D. in computer science, Humboldt University, Berlin). He joined the research community of Rutgers in 1996 and later the faculty communities of Stony Brook and Northeastern. He also joined MIT as a visiting professor in 2009. He was scientific leader for ESA, FP-7, and HORIZON 2020 projects, including the UMOBILE project. Vassilis was an active member of the Democritus University Board and had a vital role in redefining ethics in University administration.

SOFIE kickoff

26-01-2018
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On January 23-25, SOFIE's project kickoff meeting took place

MMLab members participated in the SOFIE project's kick-off meeting which took place on Janaury 23-25 in Athens, Greece. The meeting was hosted by Optimum SA. MMLab will be in charge of the evaluation of the SOFIE's platfrom and it will actively participate in all project's activities
For more information about the SOFIE project, visit the project's page

Achilles Project second review

19-01-2018
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Achilles Project second review took place on Januray 19, in Valencia, Spain

Achilles' team presented the project's initial results on January 19, Valencia, Spain. The review took place at the Universitat Politechica de Valencia, and the team demonstrated how Achilles can be used to provide access control for the Inter-IoT gateway.
For more information about Achilles visit the project's page

Talk by Vasilis Kemerlis

08-01-2018
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Vasilis Kemerlis who is currently assistant professor of Computer Science at Brown University, will give a talk on "Secure Operating Systems" on Tuesday, January 9, on the 6th floor (606 room) of the Evelpidon Str. building (graduate program building) of the Athens University of Economics and Business (AUEB)

Talk abstract: Modern operating systems consist of large, monolithic blobs of complex code, and are plagued with vulnerabilities that allow perpetrators to exploit them for profit. This, coupled with the sophistication of modern adversaries, makes the need for effective and targeted defenses more critical than ever. In this talk, I will present our work on developing novel protection mechanisms and exploit prevention techniques that improve the security posture of commodity operating system kernels. In particular, I will discuss kR^X and XPFO, two projects whose goal is to harden contemporary OSes, against attacks that exploit memory safety vulnerabilities in kernel code, without entailing super-privileged software (e.g., a hypervisor or VMM). In addition, I will talk about ret2dir, a new kernel exploitation technique that we developed, which unveils how standard OS design approaches can significantly weaken the effectiveness of deployed, state of-the-art kernel defenses.

Presenter's biography: Vasileios (Vasilis) Kemerlis is an Assistant Professor of Computer Science at Brown University. His research interests are in the areas of systems and software security, with a focus on OS kernel protection, automated software hardening, and information-flow tracking. His work on kernel security has been profiled by press and social media outlets, including LWN.net, the Linux Journal, Dark Reading, and Hacker News, won the first prize in the Applied Security Research Paper competition, at the Cyber Security Awareness Week (CSAW) 2014, and led to the adoption of kernel hardening techniques from OpenBSD and Qualcomm's MSM Android. In addition, Vasilis has contributed to the design and implementation of Microsoft's primary solution for automatically triaging crash dumps, which is now part of the Windows Error Reporting Platform. In the past, he was a member of the Solaris Core Kernel team at Oracle, where he worked on adding support for full Address Space Layout Randomization (ASLR) in the Solaris OS. Lastly, Vasilis has co-invented the first cache-based side channel attack that can be entirely executed from JavaScript context, which resulted in Apple and Mozilla limiting the time resolution of JavaScript's performance API (as a mitigation to the proposed attack), and the Tor Project decreasing the time precision of JavaScript entirely. Vasilis holds a PhD (2015), MPhil (2013), and MS (2010) in Computer Science from Columbia University, and a BS (2006) in Computer Science from Athens University of Economics and Business.

Workshop on blockhain technologies

19-12-2017
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On of December 1, 2017 we had our first internal workshop on blockchain technologies. The goal of the workshop was to introduce blockhains and smart contracts and to discuss their applications in the domain of the Internet of Things.

Program and presentations
The agenda of the workshop follows:

Talk by Stratis Ioannidis

18-12-2017
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Stratis Ioannidis who is currently assistant professor in the Electrical and Computer Engineering Department of Northeastern University, in Boston, MA will give a talk on "Adaptive Caching Networks with Optimality Guarantees" on Tuesday, December 19st, on the 6th floor (606 room) of the Evelpidon Str. building (graduate program building) of the Athens University of Economics and Business (AUEB)

Talk abstract: Optimally placing content over a network of arises in many networking applications. Given the content demand, described by content requests and paths they follow, we wish to determine the content placement that maximizes the expected caching gain, i.e., the reduction of routing costs due to intermediate caching. The offline version of this problem is NP-hard. To make matters worse, in most cases, both the demand and the network topology may be a priori unknown; hence, distributed, adaptive content placement algorithms that yield constant approximation guarantees are desired. We show that path replication, an algorithm encountered often in both networking literature and in practice, can be arbitrarily suboptimal when combined with traditional cache eviction policies, like LRU, LFU, or FIFO. We propose a distributed, adaptive algorithm that provably constructs a probabilistic content placement within 1−1/e factor from the optimal, in expectation. Finally, we extend these results to optimizing caching and routing decisions jointly.

Presenter's biography: Stratis Ioannidis is an assistant professor in the Electrical and Computer Engineering Department of Northeastern University, in Boston, MA, where he also holds a courtesy appointment with the College of Computer and Information Science. He received his B.Sc. (2002) in Electrical and Computer Engineering from the National Technical University of Athens, Greece, and his M.Sc. (2004) and Ph.D. (2009) in Computer Science from the University of Toronto, Canada. Prior to joining Northeastern, he was a research scientist at the Technicolor research centers in Paris, France, and Palo Alto, CA, as well as at Yahoo Labs in Sunnyvale, CA. He is the recipient of a Google Faculty Research Award and a best paper award at ICN 2017

Talk by Pekka Nikander

21-11-2017
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Pekka Nikander who is currently professor of Industrial Internet at Aalto University, Finland, will present the SOFIE project on Tuesday, November 21st, on the 6th floor (606 room) of the Evelpidon Str. building (graduate program building) of the Athens University of Economics and Business (AUEB)

Title: SOFIE — architecture, modelling and analysis

Talk abstract: SOFIE is an EU H2020 IoT project starting in January 2018, with both AUEB and Aalto as partners. In his talk, Pekka will first very briefly introduce the SOFIE project, assuming that most of the audience already have some background and may have read the white paper draft (https://mm.aueb.gr/tr/Sofie.pdf). After that, he will dive a little bit deeper in describing his current thoughts about the SOFIE architecture and what Aalto is currently planning there. In the end of his talk, Pekka will try to entice some discussion about the expected modelling and analysis needs in SOFIE.

Presenter's biography: Pekka Nikander is a professor of Industrial Internet at Aalto University, Finland. He is a serial entrepreneur, lead programmer, and security researcher with over 30 years of experience. He has founded 6 startups (one listed at Nasdaq OMX) and published over 100 peer reviewed papers. Among other things, he is a past member of the Internet Architecture Board, an internet user since 1987, and the author of the TCP/IP support in Tcl/Tk.

Talk by Dimitrios Koutsonikolas

30-10-2017
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Dimitrios Koutsonikolas who is currently Associate Professor of Computer Science and Engineering at the University at Buffalo, The State University of New York, will present part of his work on Tuesday, October 31st , on the 6th floor (606 room) of the Evelpidon Str. building (graduate program building) of the Athens University of Economics and Business (AUEB)

Title: Enabling Motion Detection on Commodity WiFi Devices using PHY Layer Information

Talk abstract: Client motion detection in WLANs has the potential to both improve protocol performance and enable a number of novel applications. In this talk, I will discuss our work on leveraging wireless signals to enable human motion detection at different granularities on commodity WiFi devices. In the first part of the talk, I will present a scheme for detecting and classifying client mobility on the access point side by leveraging Channel State Information (CSI) and Time-of-Flight (ToF), and I will demonstrate how mobility-awareness can improve the performance of a number of wireless protocols. In the second part of the talk, I will introduce WiDraw, the first hand motion tracking system based on commodity WiFi cards. WiDraw harnesses the Angle-of-Arrival (AoA) values of incoming wireless signals at the mobile device to track the user’s hand trajectory without requiring the user to touch the device or use any external hardware. Using WiDraw, a user can draw arbitrary lines, curves, or even alphabetical characters, simply by hand motion in the air. I will also give an overview of other research projects in UB WiNS Lab.

Presenter's biography: Dimitrios Koutsonikolas received his Ph.D. in Electrical and Computer Engineering from Purdue University in August 2010 and he worked as a Postdoctoral Researcher at Purdue University from September to December 2010. He is currently an Associate Professor of Computer Science and Engineering at the University at Buffalo, The State University of New York. Dimitrios’ research interests lie broadly in experimental wireless networking and mobile computing, with a current focus on millimeter wave WLANs, LTE in unlicensed spectrum, smartphone energy consumption, and motion detection using wireless signals. He has published over 60 papers in top venues including MobiCom, CoNEXT, INFOCOM, ICDCS, HotNets, Transactions on Networking, Transactions on Mobile Computing, and Transactions on Wireless Communications. He has been regularly serving on the TPC of a number of networking conferences including MobiCom, INFOCOM, CoNEXT, ICDCS, and he has been on the Editorial Board of IEEE Transactions on Mobile Computing since February 2017. He is the general Co-Chair of EWSN 2018, and he has co-chaired a number of workshops in wireless networking. Dimitrios is a senior member of IEEE and a member of ACM and USENIX. He received the NSF CAREER Award in 2016, the CSE Early Career Faculty Teaching Award and the School of Engineering and Applied Sciences Early Career Researcher of the Year Award in 2015, and best paper awards in WCNC 2017 and SENSORCOMM 2007.

Ph.D. positions available

12-10-2017
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Our lab is opening two positions for Ph.D. students in the following areas:

  • Cloud-assisted cognitive self-organizing networks
  • Federated architecture for secure interoperability across heterogeneous Internet of Things platforms

For more information contact Prof. George C. Polyzos

Best demo award

22-09-2017
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Our demo prensented in the 4th ACM Conference on Information-Centric Networking (ACM-ICN 2017), Berlin, Germany, won the Best demo award.

Our demo, entitled "ICN enabling CoAP Extensions for IP based IoT devices", presented how Information-Centric Networking can benefit the Internet of Things. This is a joint work by N. Fotiou, G. Xylomenos, and G. C. Polyzos from AUEB/MMlab, H. Islam and D. Lagutin, from Aalto University, Finland, and T. Hakala and E. Hakala, from e-lli, Finalnd.

You can find more details in our paper in this link.

The President of the Hellenic Republic visits our lab

27-05-2017
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On 23 May 2017 the President of the Hellenic Republic, Prokopis Pavlopoulos, inaugurated the new building of our university. After the ceremony he visited our lab.

Prof. George C. Polyzos presented to the President the activities and the facilities of our lab.

Talk by Georgios Kollias

06-03-2017
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Georgios Kollias who is currently a PhD candidate at the Technical University of Catalonia (UPC) will present part of his work on Tuesday, March 7th , on the 9th floor (901 room) of the Evelpidon Str. building (graduate program building) of the Athens University of Economics and Business (AUEB).

Title: Self-Organized Solutions in Future Heterogeneous Cellular Networks

Abstract: The ever increasing demands of cellular users for seamless connectivity anytime and anywhere forced network operators to search for solutions that would increase their capacity, expand the coverage of their networks, improve the offered quality of theirs services and simultaneously ensure high profits for them. The answer is the large scale deployment of low power nodes (i.e small cells), that can offer high rates in limited areas and therefore boost networks' capacity by covering areas with increased traffic, or areas with limited macro coverage. The result will be the transformation of traditional macro only networks to heterogeneous (HetNets) due to the existence of multiple tiers consisting of cells with different characteristics (e.g micro, pico, metro, femto, etc.).
The need for more efficient and flexible management of future HetNets as well as the necessity for continuous monitoring of the performance and optimization of their operation, is the reason for the integration of Self-Organized solutions under the Self-Organized Network (SON) concept. The aim of SONs is to replace the human factor with functions that will have the ability to handle dynamics, meaning variations in traffic or in network conditions, immediately.
Motivated by the aforementioned changes in cellular networks, the aim of this presentation is to propose novel schemes and algorithms under the SON umbrella and is divided in three parts:

Ph.D. defense by Xenofon Vasilakos

27-02-2017
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Xenofon Vasilakos will present his Ph.D. thesis on Wednesday, March 1st, 11:00AM EET, at Teleconference & e-learning room, 4th floor, Antoniadou section, central building complex of the Athens University of Economics and Business. Title and abstract follow.

Title: Mobility-based Proactive Caching Models for Addressing Niche Mobile Demand and Scalable ICN Name Resolution Designs

Abstract: Since its original conception, the Internet has undergone a series of radical technological breakthroughs and usage expansions. From the perspective of its users, it is a global framework for sharing information among millions of fixed and mobile users. However, its legacy architecture poses serious functionality limitations or inefficiencies to information sharing & retrieval. At the same time, the patched mobility support over the legacy architecture and even the intrinsic mobility support of Future Internet architectures that adapt the Information-Centric Networking (ICN) paradigm are not enough to sufficiently address the Quality-of-Service (QoS) requirements and the desired user-perceived Quality-of-Experience (QoE) levels in contemporary mobile application scenarios. The former problems get further aggravated by the unprecedented and continuously increasing numbers of the different Information Objects (IOs) and mobile devices in the Internet, as well as the corresponding high content resolution traffic and mobile traffic volumes.
The main contribution of this thesis lies in the design of efficient proactive caching models for enhancing seamless mobility that run at the application layer of any underlying network architecture or within the network layer of ICN architectures. Our main model regards an Efficient Mobility-based Caching (EMC) scheme for addressing niche mobile demand along with popularity-based and legacy caching model extensions.
Opposite to other proactive solutions, which focus exclusively on popular content, our proposed distributed design targets less popular or personalised content requests by prefetching and caching the desired information locally in small cells based on aggregated user mobility prediction information and a local cache congestion pricing scheme. Such niche demand, particularly for video content, represents a significant 20–40% of demand in the Internet and follows a growing trend. Due to its novel design, EMC can directly address niche demand and get easily extended to make a joint use of content popularity information with the novelty of dynamically balancing the influence of mobility prediction and content popularity information on local cache actions. Based on thorough performance evaluation simulations for exploring different demand levels, video catalogues and mobility scenarios, including human walking and automobile mobility, we show that the gains from mobility prediction can be high and able to adapt well to temporal locality due to the localised and short timescale character of the exploited mobility prediction measurements, exceeding cache gains from popularity-only caching. Moreover, the performance of our model can be further improved by adapting cache replacements at the cost of an added computational overhead.
Additionally, this thesis makes a contribution towards a feasible and globally scalable ICN Name Resolution System (NRS) to facilitate information sharing & retrieval in ICN. The contribution lies in certain design and performance aspects related to the structure of the underlying inter-domain topology in the Internet and specifically to a) the design of the hierarchical overlay routing mechanism that underlies the Distributed Hash Table-based Name Resolution System (DHT-NRS) and b) a thorough performance quantification study of DHT-NRS and other cutting-edge ICN NRSs with respect to load distribution and routing policy compliance across the Internet topology.

Vaggelis Douros will visit MMLab

01-02-2017
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Dr. Vaggelis Douros, a post-doctoral researcher of the Institute for Networked Systems, RWTH Aachen University (and a Ph.D. alumnus of MMLab), will visit us from 03 February till 07 February. He will give us a seminar on Tuesday 07 February, room: 901, time: 9:30-11:00. The title and the abstract of the seminar follows:

Caching Games between Content Providers and Internet Service Providers

Abstract
We consider a scenario where an Internet Service Provider (ISP) serves users that choose digital content among M Content Providers (CP). In the status quo, these users pay both access fees to the ISP and content fees to each chosen CP; however, neither the ISP nor the CPs share their profit. We revisit this model by introducing a different business model where the ISP and the CP may have motivation to collaborate in the framework of caching. The key idea is that the ISP deploys a cache for a CP provided that they share both the deployment cost and the additional profit that arises due to caching. Under the prism of coalitional games, our contributions include the application of the Shapley value for a fair splitting of the profit, the stability analysis of the coalition and the derivation of closed-form formulas for the optimal caching policy. Our model captures not only the case of non-overlapping contents among the CPs, but also the more challenging case of overlapping contents; for the latter case, a non-cooperative game among the CPs is introduced and analyzed to capture the negative externality on the demand of a particular CP when caches for other CPs are deployed
This is a joint work with S. Elayoubi, E. Altman, and Y. Hayel.