Pablo Serrano

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

The Industry 4.0 paradigm aims to bring real-time production data analytics, cloud computing, and cyber–physical inter-connectivity to today’s industries. This evolution fosters network-based use cases, such as remote-controlled mobile robots with stringent network latency requirements. 5G networks have become a promising technology for such use ca...

Fifth generation (5G) and beyond systems require flexible and efficient monitoring platforms to guarantee optimal key performance indicators (KPIs) in various scenarios. Their applicability in Edge computing environments requires lightweight monitoring solutions. This work evaluates different candidate technologies to implement a monitoring platfor...

The Google's Loon (TM) initiative aims at covering rural or underdeveloped areas via fleets of high-altitude balloons supporting LTE connectivity. But how effective and stable can be the coverage provided by a network deployed via propulsion-free balloons, floating in the sky, and only loosely controllable through altitude variations To provide som...

The arrival of 5G paves the way for the deployment of the so-called Industry 4.0, which is a new paradigm devoted to the digital transformation of manufacturing and factory production. Because of the resources required to perform this transformation, the importance of field trials and experimentation cannot be overstated, both to support the design...

The fifth generation (5G) of mobile networks is designed to accommodate different types of use cases, each of them with different and stringent requirements and key performance indicators (KPIs). To support the optimization of the network performance and validation of the KPIs, there exist the necessity of a flexible and efficient monitoring system...

The Fifth-Generation (5G) of mobile networks is designed to accommodate different types of use cases, each of them with different and stringent requirements and Key Performance Indicators (KPIs). To support the optimization of the network performance and validation of the KPIs, there exists the necessity of a flexible and efficient monitoring syste...

With network slicing, operators can acquire and manage virtual instances of a mobile network, tailored to a given service, in this way maximizing flexibility while increasing the overall resource utilization. However, the currently used tunnelling protocol, i.e., GTP, might not be the most appropriate choice for the envisioned scenarios, given its...

Document Sections I. Introduction II. Evolution of Cloud and Mobile Networking III. Serverless Mobile Architectures IV. Challenges To Address V. Summary Authors Figures References Keywords Metrics Abstract: The softwarization of communication networks provides notable benefits, such as flexibility, improved resource efficiency, and commoditization....

Network Function Virtualization enables network slicing as a novel paradigm for service provisioning. With network slicing, Virtual Network Functions (VNFs) can be instantiated at different locations of the infrastructure, choosing their optimal placement based on parameters such as the requirements of the service or the resources available. One li...

Anonymous communication tools, such as Tor, are extensively employed by users who want to keep their web activity private. But recent works have shown that when a local, passive adversary observes nothing more than the timestamp, size and direction (incoming or outgoing) of the packets, it can still identify with high accuracy the website accessed...

With network slicing, the infrastructure is divided into separate networks, each one customized to provide a specific service. Network slicing is a key technology to efficiently support services with very diverse requirements, such as the ones that should support 5G networks. While the architectural work for 5G is well advanced, and many theoretica...

The novel network slicing paradigm represents an effective turning point to operate future wireless networks. Available networking and computational resources may be shared across different (instantiations of) services tailored onto specific vertical needs, envisioned as the main infrastructure tenants. While such customization enables meeting adva...

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...

While the work on architectural and algorithmic solutions for 5G has reached a good maturity level, the experimental work lags behind, in particular on the development of open source solutions. In this paper, we describe our implementation experiences when deploying a small-scale multi-service network prototype, used to demonstrate some selected ad...

Given the urgency of standardizing the fifth generation (5G) mobile systems to meet the ever more stringent demands of new applications, the importance of field trials and experimentation cannot be overstated. Practical experimentation with cellular networks has been historically reserved exclusively to operators, primarily due to equipment costs a...

Network slicing represents a new paradigm to operate mobile networks. With network slicing, the underlying infrastructure is "sliced" into logically separate networks that can be customized to the specific needs of their tenant. Hands-on experiments on this technology are essential to understand its benefits and limits, and to validate the design a...

5G networks will have to offer extremely high volumes of content, compared to today’s. Moreover, they will have to support heterogeneous traffics, including Machine-to-machine, generated by a massive volume of Internet-of-Things devices. Traffic demands will be variable in time and space. In this work, we argue that all this can be achieved in a co...

Flexibility and energy efficiency are considered two principal requirements of future fifth generation (5G) systems. From an architectural point of view, centralized processing and a dense deployment of small cells will play a vital role in enabling the efficient and dynamic operation of 5G networks. In this context, reconfigurable hotspots will pr...

5G networks will be characterized by their diversity in terms of traffic patterns, multi-tenancy and heterogeneous and stringent traffic requirements. Network softwarization is a key enabler to cope with such management burden, as it provides the ability to control all networking functions through (re)programming, thus providing higher flexibility...

Vertical markets and industries are addressing alarge diversity of heterogeneous services, use cases, and ap-plications in 5G. It is currently common understanding thatfor networks to be able able to satisfy those needs, a flexible,adaptable, and programmable architecture based on networkslicing is required. Moreover, a softwarization and cloudifi-...

This chapter addresses implementation challenges and a complexity analysis of 5th generation (5G) hardware (HW) and software (SW) platforms. It focuses on analog and mixed signal HW, and addresses digital HW. The chapter explains the link between the HW and SW domains, and describes a set of functional requirements for SW platforms. The cognitive a...

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...

We are currently observing the softwarization of communication networks, where network functions are translated from monolithic pieces of equipment to programs running over a shared pool of computational, storage, and communication resources. While it is clear that almost any softwarization improves flexibility (eg, the ability to instantiate more...

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...

Cloud-based radio access networks (C-RAN) are expected to face important challenges in the forthcoming fifth generation (5G) communication systems. For this reason, more flexible C-RAN architectures have recently been proposed in the literature, where the radio communication stack is partitioned and placed across different RAN nodes to tackle the 5...

The need for massive content delivery is a consolidated trend in mobile communications, and will even increase for next years. Moreover, while 4G maturity and evolution is driven by video contents, next generation (5G) networks will be dominated by heterogeneous data and additional massive diffusion of Internet of Things (IoT). The current network...

Increasing the density of access points is one of the most effective mechanisms to cope with the growing traffic demand in wireless networks. To prevent energy wastage at low loads, a resource-on-demand (RoD) scheme is required to opportunistically (de)activate access points as network traffic varies. While previous publications have analytically m...

Testbeds are essential for experimental evaluation as well as for product development. In the context of LTE networks, existing testbed platforms are limited either in functionality and/or extensibility or are too complex to modify and customise. In this work we present srsLTE, an open-source platform for LTE experimentation designed for maximum mo...

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 the Flex5Gware project, whose goal is to deliver highly reconfigurable hardware (HW) platforms and HW-agnostic software (SW) platforms for 5G network elements and terminal devices. Flex5Gware will enable 5G HW/SW platforms to meet the requirements imposed by the growth in mobile traffic and the diversity of applications by incre...

We study the fair coexistence of scheduled and random access transmitters sharing the same frequency channel. Interest in coexistence is topical due to the need for emerging unlicensed LTE technologies to coexist fairly with WiFi. However, this interest is not confined to LTE/WiFi as coexistence is likely to become increasingly commonplace in IoT n...

Resource on Demand in 802.11 Wireless LANs is receiving an increasing attention, with its feasibility already proved in practice and some initial analytical models available. However, while these models have assumed that access points (APs) start up in zero time, experimentation has showed that this is hardly the case. In this work, we provide a ne...

Testbeds are essential for experimental evaluation as well as for product development. In the context of LTE networks, existing testbed platforms are limited either in functionality and/or extensibility or are too complex to modify and customise. In this work we present srsLTE, an open-source platform for LTE experimentation designed for maximum mo...

To cope with the growing traffic demand, future mobile networks will be denser and integrate heterogeneous technologies. However, if not properly engineered, such networks may incur huge energy waste when there is little traffic, and may suffer from an unbearable management burden caused by the variety of technologies integrated. In this article, w...

Resource on Demand in 802.11 Wireless LANs is receiving an increasing attention, with its feasibility already proved in practice and some initial analytical models available. However, while these models have assumed that access points (APs) start up in zero time, experimentation has showed that this is hardly the case. In this work, we provide a ne...

The huge adoption of 802.11 technologies has triggered a vast amount of experimentally-driven research works. These works range from performance analysis to protocol enhancements, including the proposal of novel applications and services. Due to the affordability of the technology, this experimental research is typically based on commercial off-the...

Distributed Opportunistic Scheduling (DOS) techniques have been recently proposed to improve the throughput performance of wireless networks. With DOS, each station contends for the channel with a certain access probability. If a contention is successful, the station measures the channel conditions and transmits in case the channel quality is above...

Legacy IEEE 802.11 does not efficiently support multicast transmissions. To cope with the increasing demand for multicast, which is mainly required to deliver multimedia traffic, the IEEE 802.11aa Task Group has recently standardized new mechanisms for allowing efficient and robust transmission of multicast flows in wireless local area networks (WL...

Handling voice traffic in existing WLANs is extremely inefficient, due to the large overhead of the protocol operation as well as the time spent in contention. In this paper, we propose a simple scheme (VoIPiggy) to improve the efficiency of WLANs with voice traffic. The key idea of the mechanism is to piggyback voice frames onto the MAC layer ackn...

Software defined networking, characterized by a clear separation of the control and data planes, is being adopted as a novel paradigm for wired networking. With SDN, network operators can run their infrastructure more efficiently, supporting faster deployment of new services while enabling key features such as virtualization. In this article, we ad...

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...

Current IEEE 802.11 WLANs suffer from the well-known rate anomaly problem, which can drastically reduce network performance. Opportunistic relaying can address this problem, but three major considerations, typically considered separately by prior work, need to be taken into account for an efficient deployment in real-world systems: 1) relaying coul...

Distributed Opportunistic Scheduling (DOS) exploits multiuser diversity in wireless networks without the requirement of a central scheduler. With DOS, users take their own scheduling decisions based on a local observation of the channel to maximize performance. While DOS has been used in the past to optimize throughput-related figures, in this pape...

In this paper, we propose to provide throughput guarantees in heterogeneous wireless mesh networks by jointly optimizing routing and Medium Access Control configuration. Our solution is based on the notion of linearized capacity region, which provides a technology‐independent way of representing the capacity of a wireless link (thereby hiding the t...

The IEEE 802.11aa Task Group has recently standardized a set of mechanisms to efficiently support video multicasting, namely, the Group Addressed Transmission Service (GATS). In this article, we report the implementation of these mechanisms over commodity hardware, which we make publicly available, and conduct a study to assess their performance un...

The 802.11e standard enables user configuration of several MAC parameters, making WLANs vulnerable to users that selfishly configure these parameters to gain throughput. In this paper we propose a novel distributed algorithm to thwart such selfish behavior. The key idea of the algorithm is for honest stations to react, upon detecting a selfish stat...

Current trends on mobile traffic show an exponential grow of the traffic consumed by users from smartphones and other portable devices. The explosion of traffic in cellular networks has forced operators to start deploying solutions to alleviate the congestion on their capacity-limited and expensive radio access networks. One of the solutions being...

Nowadays, it is common to find multiple WLAN deployments coexisting in shared spaces. The resulting interference between transmissions represents an important source of performance degradation, specially those originating from hidden traffic. This note explores the relation between hidden traffic and packet losses, using renewal theory to show that...

Wi-Fi Direct is a new technology defined by the Wi-Fi Alliance aimed at enhancing direct device to device communications in Wi-Fi. Thus, given the wide base of devices with Wi-Fi capabilities, and the fact that it can be entirely implemented in software over traditional Wi- Fi radios, this technology is expected to have a significant impact. In this...

Video traffic is foreseen to account for the majority of the Internet traffic in the near future. While the demand of video transmission keeps growing, the vast majority of wireless equipment deployed in the home environment, based on IEEE 802.11, cannot satisfy the amount of bandwidth that the video applications require. In order to cope with the...

In this paper, we present a modular Layer 2 architecture which makes wireless access in IEEE 802.11 networks programmable and thus opens the door for broader range of enhancements. We show the power of the proposed architecture by presenting a number of innovative solutions for infrastructure, direct links and mesh cases. Early prototyping results...