Arturo Azcorra

University Carlos III de Madrid | UC3M · Department of Telematic Engineering

Network Functions Virtualization (NFV) is a key technology for network automation and has been instrumental to materialize the disruptive view of 5G and beyond mobile networks. In particular, 5G embraces NFV to support the automated and agile provision of telecommunication and vertical services as a composition of versatile virtualized components,...

The purinergic system is one of the oldest cell-to-cell communication mechanisms and exhibits relevant functions in the regulation of the central nervous system (CNS) development. Amongst the components of the purinergic system, the iono-tropic P2X7 receptor (P2X7R) stands out as a potential regulator of brain pathology and physiology. Thus, P2X7R...

5G communications have become an enabler for the creation of new and more complex networking scenarios, bringing together different vertical ecosystems. Such behavior has been fostered by the network function virtualization (NFV) concept, where the orchestration and virtualization capabilities allow the possibility of dynamically supplying network...

Network Function Virtualization (NFV) has been regarded as one of the key enablers for the 5th Generation of mobile networks, or 5G. This paradigm allows to reduce the dependence on specialized hardware to deploy telecommunications and vertical services. To this purpose, it relies on virtualization techniques to softwarize network functions, simpli...

Fog computing has rapidly become a widely accepted computing paradigm to mitigate cloud computing-based infrastructure limitations such as scarcity of bandwidth, large latency, security, and privacy issues. Fog computing resources and applications dynamically vary at run-time, and they are highly distributed, mobile, and appear-disappear rapidly at...

Fog computing has rapidly become a widely accepted computing paradigm to mitigate cloud computing-based infrastructure limitations such as scarcity of bandwidth, large latency, security, and privacy issues. Fog computing resources and applications dynamically vary at run-time, and they are highly distributed, mobile, and appear-disappear rapidly at...

Programmatic advertising operates one of the most sophisticated and efficient service platforms on the Internet. However, the complexity of this ecosystem is a direct cause of one of the most important problems in online advertising, the lack of transparency. This lack of transparency enables subsequent problems such as advertising fraud, which cau...

Programmatic advertising operates one of the most sophisticated and efficient service platforms on the Internet. However, the complexity of this ecosystem is the main cause of one of the most important problems in online advertising, the lack of transparency. This lack of transparency leads to subsequent problems such as advertising fraud, which ca...

5G-DIVE targets end-to-end 5G trials aimed at proving the technical merits and business value proposition of 5G technologies in two vertical pilots, namely (i) Industry 4.0 and (ii) Autonomous Drone Scout. Its design is built around two main pillars, namely (1) end-to-end 5G connectivity including 5G New Radio, Crosshaul transport and 5G Core, and...

Invalid ad traffic is an inherent problem of programmatic advertising that has not been properly addressed so far. Traditionally, it has been considered that invalid ad traffic only harms the interests of advertisers, which pay for the cost of invalid ad impressions while other industry stakeholders earn revenue through commissions regardless of th...

Multi-access edge computing (MEC) technologies bring important improvements in terms of network bandwidth, latency, and use of context information and critical for services like multimedia streaming, augmented, and virtual reality. In future deployments, operators will need to decide how many MEC points of presence (PoPs) are needed and where to de...

Management and orchestration of virtual resources and functions, commonly referred to as MANO, are key functionalities of NFV environments. This article describes the design and deployment of the NFV MANO platform of 5TONIC, the open research and innovation laboratory on 5G technologies founded by Telefonica and IMDEA Networks. This NFV MANO platfo...

The IEEE 802.11aa amendment standardised the Group Addressed Transmission Service (GATS), which extends 802.11 WLANs with a novel set of MAC mechanisms to support an effective and efficient multicast video service. The key challenge with GATS is the selection of the best scheme and its configuration for a given network scenario, as the standard doe...

We claim the strong potential of data-centric communications in Unmanned Aircraft Systems (UAS), as a suitable paradigm to enhance collaborative operations via efficient information sharing, as well as to build systems supporting flexible mission objectives. In particular, this paper analyzes the primary contributions to data dissemination in UAS t...

Cloud or Centralized Radio Access Networks (C-RANs) are expected to be widely deployed under 5G in order to support the anticipated increased traffic demands and reduce costs. Under C-RAN, the radio elements (e.g., eNB or gNB in 5G) are split into a basic radio part (Distributed Unit, DU), and a pool-able base band processing part (Central Unit, CU...

This article dives into the design of the next generation mobile transport networks to simultaneously support the needs of various vertical industries with diverse range of networking and computing requirements. Network slicing has emerged as the most promising approach to address this challenge by enabling per-slice management of virtualized resou...

This paper presents an R package to handle and represent measurements with errors in a very simple way. We briefly introduce the main concepts of metrology and propagation of uncertainty, and discuss related R packages. Building upon this, we introduce the 'errors' package, which provides a class for associating uncertainty metadata, automated prop...

Simulation frameworks are important tools for the analysis and design of communication networks and protocols, but they can result extremely costly and/or complex (for the case of very specialized tools), or too naive and lacking proper features and support (for the case of ad-hoc tools). In this paper, we present an analysis of three 5G scenarios...

The impact of the ICT sector in worldwide power consumption is an increasing concern, motivating the research community to devote an important effort to define novel energy efficient networking solutions. Despite file distribution is responsible for a major portion of the current Internet traffic, little effort has been dedicated to address the iss...

Rate adaptation and transmission power control in 802.11 WLANs have received a lot of attention from the research community, with most of the proposals aiming at maximising throughput based on network conditions. Considering energy consumption, an implicit assumption is that optimality in throughput implies optimality in energy efficiency, but this...

In this paper, we revisit the idea of putting interfaces to sleep during 'packet overhearing' (i.e., when there are ongoing transmissions addressed to other stations) from a practical standpoint. To this aim, we perform a robust experimental characterisation of the timing and consumption behaviour of a commercial 802.11 card. We design $\mu$Nap, a...

The simmer package brings discrete-event simulation to R. It is designed as a generic yet powerful process-oriented framework. The architecture encloses a robust and fast simulation core written in C++ with automatic monitoring capabilities. It provides a rich and flexible R API that revolves around the concept of trajectory, a common path in the s...

Rate adaptation in 802.11 WLANs has received a lot of attention from the research community, with most of the proposals aiming at maximising throughput based on network conditions. Considering energy consumption, an implicit assumption is that optimality in throughput implies optimality in energy efficiency, but this assumption has been recently pu...

This paper presents an early exploration and preliminary results on the use of Remotely Piloted Aircrafts (RPA) as 5G points of presence. The use of RPAs in the 5G arena would enable a cost-effective deployment of functions over mobile nodes that could be integrated on demand into the programmable and unified 5G infrastructure, enhancing the capaci...

This paper presents an early exploration and preliminary results on the use of Remotely Piloted Aircrafts (RPA) as 5G points of presence. The use of RPAs in the 5G arena would enable a cost-effective deployment of functions over mobile nodes that could be integrated on demand into the programmable and unified 5G infrastructure, enhancing the capaci...

The CPRI specification has been introduced to enable the communication between radio equipment and radio equipment controllers, and is of particular interest for mobile operators willing to deploy their networks following the novel cloud radio access network approach. In such a case, CPRI provides an interface for the interconnection of remote radi...

Regular works on energy efficiency strategies for wireless communications are based on classical energy models that account for the wireless card only. Nevertheless, there is a non-negligible energy toll called "cross-factor" that encompasses the energy drained while a frame crosses the network stack of an OS. This paper addresses the challenge of...

The Xhaul architecture presented in this article is aimed at developing a 5G integrated backhaul and fronthaul transport network enabling flexible and software-defined reconfiguration of all networking elements in a multi-tenant and service-oriented unified management environment. The Xhaul transport network vision consists of high-capacity switche...

Online social media has recently irrupted as the last major venue for the propagation of news and cultural content, competing with traditional mass media and allowing citizens to access new sources of information. In this paper, we study collectively filtered news and popular content in Twitter, known as Trending Topics (TTs), to quantify the exten...

While substantial effort has been devoted to understand fraudulent activity in traditional online advertising (search and banner), more recent forms such as video ads have received little attention. The understanding and identification of fraudulent activity (i.e., fake views on videos) in video ads for advertisers, is complicated as they rely excl...

This paper describes and evaluates Torii, a layer 2 data centre network fabric protocol. The main features of Torii are being fully distributed, scalable, fault-tolerant and with automatic setup. Torii is based on multiple, tree-based, topological media access control addresses that are used for table-free forwarding over multiple equal-cost paths,...

This paper provides an in-depth understanding of the per-frame energy consumption behavior in 802.11 Wireless LAN devices. Extensive measurements are performed for 7 devices of different types (wireless routers, smart phones, tablets and embedded devices), and for both UDP and TCP traffic. Experimental results unveil that a substantial fraction of...

Low-energy communications is becoming an increasingly relevant research area, due to both economic and environmental reasons. Low-energy is particularly relevant in wireless because of the limited energy available to terminals and the high consumption of the base stations derived from wide geographical coverage. Green wireless aims to formulate a l...

Trending Topics seem to be a powerful tool to be used in marketing and advertisement contexts, however there is not any rigorous analysis that demonstrates this. In this paper we present a first effort in this direction. We use a dataset including more than 110K Trending Topics from 35 countries collected over a period of 3 months as basis to chara...

BitTorrent is one of the most important applications in the current Internet. Despite of its interest, we still have little knowledge regarding the connectivity properties of real BitTorrent swarms. In this paper we leverage a dataset including the connectivity information of 250 real torrents and more than 150k peers to carefully study the connect...

Despite file distribution applications are responsible for a major portion of the current Internet traffic, so far little effort has been dedicated to study file distribution from the point of view of energy efficiency. In this paper, we present the first extensive and detailed theoretical study for the problem of energy efficiency in file distribu...

The current Online Social Networks' infrastructure is com-posed by thousands of servers distributed across data-centers spread over several geographical locations. These servers store all the users' information (profile, contacts, contents, etc). Such an infrastructure incurs high operational and maintenance costs. Furthermore, this may threaten th...

Despite file-distribution applications are responsible for a major portion of the current Internet traffic, so far little effort has been dedicated to study file distribution from the point of view of energy efficiency. In this paper, we present a first approach at the problem of energy efficiency for file distribution. Specifically, we first demon...

BitTorrent is one of the most popular application in the current Internet. However, we still have little knowledge about the topology of real BitTorrent swarms and how the traffic is actually exchanged among peers. This paper addresses fundamental questions regarding the topology of live BitTorrent swarms. For this purpose we have collected the evo...

BitTorrent is the most successful peer-to-peer application. In the last years the research community has studied the BitTorrent ecosystem by collecting data from real BitTorrent swarms using different measurement techniques. In this article we present the first survey of these techniques that constitutes a first step in the design of future measure...

In this paper we conduct a large scale measurement study in order to analyse the fake content publishing phenomenon in the BitTorrent Ecosystem. Our results reveal that fake content represents an important portion (35%) of those files shared in BitTorrent and just a few tens of users are responsible for 90% of this content. Furthermore, more than 9...

Already a popular application in the Internet, IPTV is becoming, among the service providers, a preferred alternative to conventional broadcasting technologies. Since many of the existing deployments have been done within the safe harbor of telco-owned networks, IP multicast has been the desired streaming solution. However, previous studies showed...

The enhanced distributed channel access (EDCA) mechanism of the IEEE 802.11e standard provides quality-of-service (QoS) support through service differentiation by using different medium-access-control (MAC) parameters for different stations. The configuration of these parameters, however, is still an open research challenge, as the standard provide...

Normal TCP/IP operation is for the routing system to select a best path that remains stable for some time, and for TCP to adjust to the properties of this path to optimize throughput. By executing TCP's congestion control algorithms on multiple paths at the same time, a multipath TCP can shift its traffic to a less congested path, thus maximizing b...

In this paper we propose Fast Path Ethernet, an evolution of the transparent bridges learning mechanisms to increase infrastructure utilization for campus and datacenter networks in a simple way. Fast Path Ethernet Switches reuse standard ARP Request and Reply packets to set up fast on-demand paths between hosts. This architecture uses the standard...

We claim that the slow deployment of IPv6 seen so far is related with the complete decoupling with IPv4 regarding to routing and addressing. In this paper we propose Integrated Routing and Addressing (InRA), a new solution to allow IPv6 to integrate with IPv4 routing and addressing in order to decrease management cost during the coexistence period,...

This paper characterizes analytically the performance of REAchability Protocol (REAP), a network layer end-to-end recovery protocol for IPv6. REAP was developed by the IETF SHIM6 Working Group as part of its multihoming solution. The behavior of REAP is governed by a small number of parameters: three timers, a simple characterization of the applica...

Ethernet switched networks do not scale appropriately due to limitations inherent to the spanning tree protocol. Ethernet architectures based on routing over a virtual topology in which turns are prohibited offer improved performance over spanning tree, although in some cases suffer from excessive computational complexity. Up/Down routing is a turn...

Home networks and home environments are developing so fast that a new generation of residential gateways is needed in order to allow emerging services and the huge amount of available bandwidth to take advantage of this evolution. New protocols, applications, devices and services are appearing day after day and in order to properly cope with them,...

Tree-based Routing (TRE) revisits Tree-based Routing Architecture for Irregular Networks (TRAIN)—a forwarding scheme based on a spanning tree that was extended to use some shortcut links.We propose its adaptation to Ethernet, using a new type of hierarchical Ethernet addresses and a procedure to assign them to bridges. We show that compared to RSTP...

This article surveys the major existing approaches and proposes a novel architecture to support mobile networks in network-based, localized mobility domains. Our architecture enables conventional terminals without mobility support to obtain connectivity either from fixed locations or mobile platforms (e.g., vehicles) and move between them, while ke...

CARMEN is a three-year Specific Targeted Research Project (STREP) funded by the European Commission within the 7th Framework Program. The CARMEN access network will complement existing access technologies by exploiting low cost mesh networking techniques, thus minimizing deployment and maintenance costs. The CARMEN architecture introduces an abstra...

Wireless technologies are rapidly evolving and the users are demanding the possibility of changing their point of attachment to the Internet (i.e. Access Routers) without breaking the IP communications. This can be achieved by using Mobile IP or NEMO. However, mobile clients must forward their data packets through its Home Agent (HA) to communicate...

CARMEN is a three-year Specific Targeted Research Project (STREP) funded by the European Commission within the 7th Framework Program. The CARMEN access network will complement existing access technologies by exploiting low cost mesh networking techniques, thus minimizing deployment and maintenance costs. The CARMEN architecture introduces an abstra...

This article describes a scalable, self-configuring architecture for campus networks, the ABridges architecture. It is a two-tiered hierarchy of layer two switches in which network islands running independent rapid spanning tree protocols communicate through a core formed by island root bridges (ABridges). ABridges use AMSTP, a simplified and self...

It is sometimes believed that a "broadband access" network, providing ample transmission capacity to residential environments, is enough so as to allow a flawless delivery of advanced services. However, the provisioning of a combination of multiple services with guaranteed quality up to the end-user terminal requires a carefully designed architectu...

Fourth-generation mobile devices incorporate multiple interfaces with diverse access technologies. The current Mobile IPv6 protocol fails to support the enhanced fault tolerance capabilities that are enabled by the availability of multiple interfaces. In particular, established MIPv6 communications cannot be preserved through outages affecting the...

In this paper, we present a model to analyze the throughput and delay performance of the EDCA mechanism under non saturation conditions. The main strength of our model is that it can be used to analyze generic source models, as it neither makes any assumption on the source’s arrival process nor requires all packets be of the same length. Simulation...

We present an architecture for the provision of network layer privacy based on the SHIM6 multihoming protocol. In its basic form, the architecture prevents on-path eavesdroppers from using SHIM6 network layer information to correlate packets that belong to the same communication but use different locators. To achieve this, several extensions to the...

The three papers in this special section were originally presented at the IEEE INFOCOM 2006 conference in Barcelona. The augmented papers, which address issues in wireless networks and mobile computing, represent the high quality of research presented at the conference.

The standardization process of the UMTS technology has led to the development of the IP Multimedia Subsystem (IMS). IMS provides a framework that supports the negotiation of the next generation multimedia services with QoS requirements that are envisioned for 3G networks. But even though many of these services involve the participation of multiple...

To date, broadcasting traffic data represents a low percentage of the total traffic in the Internet when compared to other kinds of information. This may be caused by difficulties with multicast transmissions (i.e filtering by ISPs), low bandwidth rates in the last mile access, quality of service (QoS) and the use of Network Address Translation (NA...

In this paper, we analyse the provision of enhanced communications between vehicles. It is expected that vehicles will have several communication devices, and that a specialised node will provide external connectivity to these devices, i.e., the devices in the vehicle form a Mobile Network. We propose the use of Network Mobility communication solut...

The TISPAN group from ETSI is currently working on the specification a Next Generation Network (NGN), based on the IP Multimedia Subsystem (IMS) as the service control architecture. This NGN provide a extensible platform that supports the delivering of next generation multimedia services with QoS requirements over multiple access network technologi...

The development of specifications for next generation networks has introduced a new network paradigm that has features and capabilities to ensure the provisioning of new value-added multimedia services over the broadband access technologies that are currently being deployed in the market. In this respect, the TISPAN group from ETSI is working in th...

Internet access has been, until now, the main driver for the generalization of broadband connections in the residential market. Simple IP based services like email and web browsing were, during many years, the typical services provided to residential customers. Today the telecommunications market is changing and operators are looking for ways to pr...

It is sometimes believed that a “broadband access” network, providing ample transmission capacity to residential environments, is enough so as to allow a flawless delivery of advanced services. However, the provisioning of a combination of multiple services with guaranteed quality up to the end-user terminal requires a carefully designed architectu...