Anastasios Giovanidis

Anastasios Giovanidis
French National Centre for Scientific Research | CNRS · Laboratoire d'Informatique de Paris 6

Dr.-Ing.

About

64
Publications
3,133
Reads
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785
Citations
Additional affiliations
October 2013 - present
French National Centre for Scientific Research
Position
  • Researcher
September 2011 - August 2013
National Institute for Research in Computer Science and Control
Position
  • PostDoc Position
April 2010 - July 2011
Zuse-Institut Berlin
Position
  • PostDoc Position

Publications

Publications (64)
Article
Full-text available
Cooperation in cellular networks has been recently suggested as a promising scheme to improve system performance, especially for cell-edge users. In this work, we use stochastic geometry to analyze cooperation models where the positions of Base Stations (BSs) follow a Poisson point process distribution and where Voronoi cells define the planar area...
Article
Full-text available
In this work we consider the problem of an optimal geographic placement of content in wireless cellular networks modelled by Poisson point processes. Specifically, for the typical user requesting some particular content and whose popularity follows a given law (e.g. Zipf), we calculate the probability of finding the content cached in one of the bas...
Article
Caching popular content at the wireless edge promises performance benefits as well as business perspectives. In this work we study the following arrangement: a Mobile Network Operator (MNO) pre-installs memory on its wireless equipment, sets a price, and invites a unique Content Provider (CP) to invest. The CP leases memory space and places its con...
Article
We introduce an original mathematical model to analyze the diffusion of posts within a generic online social platform. The main novelty is that each user is not simply considered as a node on the social graph, but is further equipped with his/her own Wall and Newsfeed, and has his/her own individual self-posting and re-posting activity. As a main r...
Preprint
Full-text available
Measuring the influence of users in social networks is key for numerous applications. A recently proposed influence metric, coined as $\psi$-score, allows to go beyond traditional centrality metrics, which only assess structural graph importance, by further incorporating the rich information provided by the posting and re-posting activity of users....
Preprint
Full-text available
Online social platforms have become central in the political debate. In this context, the existence of echo chambers is a problem of primary relevance. These clusters of like-minded individuals tend to reinforce prior beliefs, elicit animosity towards others and aggravate the spread of misinformation. We study this phenomenon on a Twitter dataset r...
Preprint
Future quantum internet aims to enable quantum communication between arbitrary pairs of distant nodes through the sharing of end-to-end entanglement, a universal resource for many quantum applications. As in classical networks, quantum networks also have to resolve problems related to routing and satisfaction of service at a sufficient rate. We dea...
Article
Controlling the network cost by delivering popular content to users, as well as improving streaming quality and overall user experience, have been key goals for content providers in recent years. While proposals to improve performance, through caching or other mechanisms (DASH, multicasting, etc.) abound, recent works have proposed to turn the prob...
Preprint
Full-text available
Network inference is the process of deciding what is the true unknown graph underlying a set of interactions between nodes. There is a vast literature on the subject, but most known methods have an important drawback: the inferred graph is not guaranteed to explain every interaction from the input trace. We consider this an important issue since su...
Preprint
Full-text available
We introduce an original mathematical model to analyse the diffusion of posts within a generic online social platform. The main novelty is that each user is not simply considered as a node on the social graph, but is further equipped with his/her own Wall and Newsfeed, and has his/her own individual self-posting and re-posting activity. As a main r...
Article
Full-text available
As the internet and connected objects gain more and more in popularity, serving the ever-increasing data traffic becomes a challenge for the mobile operators. The traditional cellular radio access network (RAN), where each base station is co-located with its own processing unit and is responsible for a specific geographic area, has evolved first wi...
Preprint
As mobile traffic is dominated by content services (e.g., video), which typically use recommendation systems, the paradigm of network-friendly recommendations (NFR) has been proposed recently to boost the network performance by promoting content that can be efficiently delivered (e.g., cached at the edge). NFR increase the network performance, howe...
Preprint
Full-text available
We formulate and analyze a generic sequential resource access problem arising in a variety of engineering fields, where a user disposes a number of heterogeneous computing, communication, or storage resources, each characterized by the probability of successfully executing the user's task and the related access delay and cost, and seeks an optimal...
Preprint
Full-text available
Caching content over CDNs or at the network edge has been solidified as a means to improve network cost and offer better streaming experience to users. Furthermore, nudging the users towards low-cost content has recently gained momentum as a strategy to boost network performance. We focus on the problem of optimal policy design for Network Friendly...
Preprint
We introduce an original mathematical model to analyze the diffusion of posts within a generic online social platform. Each user of such a platform has his own Wall and Newsfeed, as well as his own self-posting and re-posting activity. As a main result, using our developed model, we derive in closed form the probabilities that posts originating fro...
Book
This book constitutes the refereed proceedings of the 8th EAI International Conference on Game Theory for Networks, GameNets 2019, held in Paris, France, in April 2019. The 8 full and 3 short papers presented were carefully reviewed and selected from 17 submissions. They are organized in the following topical sections: Game Theory for Wireless Netw...
Article
A device-to-device (D2D) wireless network is considered, where user devices also have the ability to cache content. In such networks, users are mobile and communication links can be spontaneously activated and dropped depending on the users’ relative position. Receivers request files from transmitters, these files having a certain popularity and fi...
Conference Paper
Caching popular content at the wireless edge is recently proposed as a means to reduce congestion at the backbone of cellular networks. The two main actors involved are Mobile Network Operators (MNOs) and Content Providers (CPs). In this work, we consider the following arrangement: an MNO pre-installs memory on its wireless equipment (e.g. Base Sta...
Article
Full-text available
Caching popular content at the wireless edge is recently proposed as a means to reduce congestion at the backbone of cellular networks. The two main actors involved are Mobile Network Operators (MNOs) and Content Providers (CPs). In this work, we consider the following arrangement: an MNO pre-installs memory on its wireless equipment (e.g. Base Sta...
Article
Full-text available
Base station cooperation is a promising scheme to improve network performance for next generation cellular networks. Up to this point research has focused on station grouping criteria based solely on geographic proximity. However, for the cooperation to be meaningful, each station participating in a group should have sufficient available resources...
Article
Full-text available
This article introduces a novel family of decentralised caching policies, applicable to wireless networks with finite storage at the edge-nodes (stations). These policies, that are based on the Least-Recently-Used replacement principle, are here referred to as spatial multi-LRU. They update cache inventories in a way that provides content diversity...
Article
Full-text available
Cooperation in cellular networks is a promising scheme to improve system performance. Existing works consider that a user dynamically chooses the stations that cooperate for his/her service, but such assumption often has practical limitations. Instead, cooperation groups can be predefined and static, with nodes linked by fixed infrastructure. To an...
Article
Full-text available
Caching of popular content on wireless nodes is recently proposed as a means to reduce congestion in the backbone of cellular networks and to improve Quality of Service. From a network point of view, the goal is to offload as many users as possible from the backbone network to the wireless caches. However, if not done appropriately, this can lead t...
Conference Paper
In this work a novel family of decentralised caching policies for wireless networks is introduced, referred to as spatial multi-LRU. These improve cache-hit probability by exploiting multi-coverage. Two variations are proposed, the multi-LRU-One and -All, which differ in the number of replicas inserted in the covering edge-caches. The evaluation is...
Article
Full-text available
In this work a novel family of decentralised caching policies for wireless networks is introduced, referred to as spatial multi-LRU. These improve cache-hit probability by exploiting multi-coverage. Two variations are proposed, the multi-LRU-One and -All, which differ in the number of replicas inserted in the covering edge-caches. The evaluation is...
Conference Paper
This article introduces a novel family of decentralised caching policies for wireless networks, referred to as spatial multi-LRU. Based on these, cache inventories are updated in a way that provides content diversity to users that are covered by, and thus have access to, more than one station. Two variations are proposed, the multi-LRU-One and -All...
Article
Full-text available
This article introduces a novel family of decentralised caching policies for wireless networks, referred to as spatial multi-LRU. Based on these, cache inventories are updated in a way that provides content diversity to users that are covered by, and thus have access to, more than one station. Two variations are proposed, the multi-LRU-One and -All...
Conference Paper
A device-to-device (D2D) wireless network is considered, where user devices also have the ability to cache content. In such networks, users are mobile and communication links can be spontaneously activated and dropped depending on the users’ relative position. Receivers request files from transmitters, these files having a certain popularity and fi...
Article
Full-text available
Cooperation in cellular networks has been recently suggested as a promising scheme to improve system performance. In this work, clusters are formed based on the Mutually Nearest Neighbour relation, which defines which stations cooperate in pair and which do not. When node positions follow a Poisson Point Process (PPP) the performance of the origina...
Article
Full-text available
A device-to-device (D2D) wireless network is considered, where user devices also have the ability to cache content. In such networks, users are mobile and communication links can be spontaneously activated and dropped depending on the users' relative position. Receivers request files from transmitters, these files having a certain popularity and fi...
Article
Full-text available
This report presents a survey on how to group together in a static way planar nodes, that may belong to a wireless network (ad hoc or cellular). The aim is to identify appropriate methods that could also be applied for Point Processes. Specifically matching pairs and algorithms are initially discussed. Next, specifically for Point Processes, the Ne...
Technical Report
Full-text available
This report presents a survey on how to group together in a static way planar nodes, that may belong to a wireless network (ad hoc or cellular). The aim is to identify appropriate methods that could also be applied for Point Processes. Specifically matching pairs and algorithms are initially discussed. Next, specifically for Point Processes, the Ne...
Article
Full-text available
The problem of base station cooperation has recently been set within the framework of Stochastic Geometry. Existing works consider that a user dynamically chooses the set of stations that cooperate for his/her service. However, this assumption often does not hold. Cooperation groups could be predefined and static, with nodes connected by fixed infr...
Article
Full-text available
This work considers a single-cell random access channel (RACH) in cellular wireless networks. Communications over RACH take place when users try to connect to a base station during a handover or when establishing a new connection. We approach the problem of optimal coordination of user actions, taking into account a dynamic environment (channel fad...
Article
Full-text available
We study a cooperation model where the positions of base stations follow a Poisson point process distribution and where Voronoi cells define the planar areas associated with them. For the service of each user, either one or two base stations are involved. If two, these cooperate by exchange of user data and reduced channel information (channel phas...
Article
Full-text available
Base station cooperation in the downlink of cellular systems has been recently suggested as a promising concept towards a better exploitation of the communication system's physical resources. It may offer a high gain in capacity through interference mitigation. This however, comes at a cost of high information exchange between cooperating entities...
Article
Full-text available
Within a cellular wireless network the unbalanced user load among cells, together with Inter-Cell-Interference (ICI), constitute major factors responsible for poor overall performance. In the current work, a novel decentralized algorithm for Load Balancing in the downlink is suggested.
Conference Paper
Full-text available
Within a cellular wireless network the unbalanced user load among cells, together with Inter-Cell-Interference (ICI), constitute major factors responsible for poor overall performance. In the current work, a novel decentralized algorithm for Load Balancing in the downlink is suggested. Two are the major novelties in the analysis. (A) The algorithm...
Article
Full-text available
This work considers a single-cell random access channel in cellular wireless networks and provides an algorithmic approach to the problem of optimal coordination of user actions. In the scenario considered, an access effort is successful if (a) the signal is detected at the receiver and (b) no collision occurs. The first event is controlled by the...
Article
Full-text available
In the current work the effects of hop-by-hop packet loss and retransmissions via ARQ protocols are investigated within a Mobile Ad-hoc NET-work (MANET). A success probability function is related to each link, which can be controlled by power and rate allocation. The expression for the network's stability region is initially derived where the succe...
Article
Full-text available
This work considers a single-cell random access channel in cellular wireless networks and provides an algorithmic approach to the problem of optimal coordination of user actions. In the scenario considered, an access effort is successful if (a) the signal is detected at the receiver and (b) no collision occurs. The first event is controlled by the...
Article
Full-text available
The focus of the current thesis is on the modeling, analysis and control of Automatic Retransmission reQuest (ARQ) protocols as part of a wireless communications system. The function of these protocols is the detection and correction of errors. To achieve this the receiver informs the transmitter over the result of packet decoding using a binary co...
Article
In the current work the effects of hop-by-hop packet loss and retransmissions via ARQ protocols are investigated within a Mobile Ad-hoc NET-work (MANET). Errors occur due to outages and a success probability function is related to each link, which can be controlled by power and rate allocation. We first derive the expression for the network's capac...
Conference Paper
Full-text available
In the current work the effects of hop-by-hop packet loss and retransmissions via ARQ protocols are investigated within a Mobile Ad-hoc NET-work (MANET). Errors occur due to outages and a success probability function is related to each link, which can be controlled by power and rate allocation. We first derive the expression for the network's capac...
Article
Full-text available
A single queue incorporating a retransmission protocol is investigated, assuming that the sequence of per effort success probabilities in the Automatic Retransmission reQuest (ARQ) chain is a priori defined and no channel state information at the transmitter is available. A Markov Decision Problem with an average cost criterion is formulated where...
Conference Paper
Full-text available
We consider ARQ protocols which vary the error probabilities per retransmission, having no channel state information at the transmitter. Such protocols can be described by irreducible and aperiodic discrete time Markov chains with countably infinite states of a specific form. Ergodicity of such chains guarantees finite expected delay until correct...
Conference Paper
Full-text available
We derive the optimal power allocation policy for the transmission of a single packet of information via stop-and-wait ARQ (automatic retransmission request). Using finite-horizon Markov decision processes, we show that the optimal policy is monotone, that it is asymptotically constant, and that there are only finitely many optimal policies. For th...
Conference Paper
Full-text available
In the current work a downlink scenario is studied where packets for each user are buffered at the base station waiting for service. The service rates are considered constant and determined by QoS requirements. Errors due to outages occur and are reported to the base station via a reliable binary feedback link. Erroneous packets are held in the que...
Conference Paper
Full-text available
The renewal-reward theorem has been widely used in the literature to provide the expected throughput of ARQ systems when the inter-arrival intervals between consecutive message acknowledgements (ACKs) are iid random variables. In cases however when the channel error probability may be allowed to vary with time the above approach cannot accurately e...
Conference Paper
In this paper, strategies for dynamic user grouping and shared frequency resource assignments for OFDMA systems are proposed. The users are grouped based on their modulation type and a metric for this purpose is introduced which considers tradeoffs between maximum rate and minimum allocated resources per user. The available resources are distribute...
Conference Paper
The problem of optimal power allocation for a single user in an OFDMA system is considered for uplink, under the assumption that the total power is divided equally to a selected subset of subcarriers. This scenario suggests reduced feedback information for power control from base station to the user since only the information over modulation on eac...
Article
Full-text available
In the current work the conceptual framework of optimally stopping a stochastic process is used to determine the optimal maximum number of retransmissions in an ARQ chain. The process sequentially observed is the binary ARQ feedback after each packet (re)transmission (ACK/NAK). A reward-cost process Y C n is constructed as a function of the observe...
Conference Paper
In this paper the problem of optimal subcarrier and power allocation for sum rate maximization in the uplink of an OFDMA system is considered, under the assumption that each user allocates equal transmit power to an assigned subset of subcarriers. Such On-Off power allocation requires very limited feedback from the base station to the users. Furthe...

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Projects

Projects (3)
Project
Problems related to content placement and user routing given a fixed infrastructure. Additional aspects of user routing to caches. Practical implementation aspects of suggested cache protocols. Interplay of Network operators and Content providers.