Laboratorio de Redes

Nuestra misión es la investigación y desarrollo de tecnología para las redes de comunicaciones

Principales publicaciones

Abstract—In this paper, we address the optimization of the energy efficiency of underlay multicast device-to-device (D2MD) communications on cellular networks. In particular, we maximize the energy efficiency of both the global network and the individual users considering various fairness factors such as maximum power and minimum rate constraints. For this, we employ a canonical mixed-integer non-linear formulation of the joint power control and resource allocation problem. To cope with its NP-hard nature, we propose a two-stage semi-distributed solution. In the first stage, we find a stable, yet sub-optimal, channel allocation for D2MD groups using a cooperative coalitional game framework, allowing co-channel transmission over a set of shared resource blocks and/or transmission over several different channels per D2MD group. In the second stage, a central entity determines the optimal transmission power for each user in the system via fractional programming. We performed extensive simulations to analyze the resulting energy efficiency and attainable transmission rates. The results show that the performance of our semi-distributed approach is very close to that obtained with a pure optimal centralized one.
In IEEE Trans. Mobile Computing, 2020

The low power idle mode implemented by Energy Efficient Ethernet (EEE) allows network interfaces to save up to 90% of their nominal energy consumption when idling. There is an ample body of research that recommends the use of frame coalescing algorithms—that enter the low power mode as soon as there is no more traffic waiting to be sent, and delay the exit from this mode until there is an acceptable amount of traffic queued—to minimize energy usage while maintaining an acceptable performance. However, EEE capable hardware from several manufactures delays the entrance to the low power mode for a considerable amount of time (hysteresis). In this paper we augment existing EEE energy models to account for the hysteresis delay and show that, using the configuration ranges provided by manufacturers, most existing EEE networking devices are unable to obtain significant energy savings. To improve their energy efficiency, we propose to implement frame coalescing directly at traffic sources, before reaching the network interface. We also derive the optimum coalescing parameters to obtain a given target energy consumption at the EEE device when its configuration parameters are known in advance.
In Journal of Network and Computer Applications, 2020

Sunlight is one of the most frequently used ambient energy sources for energy harvesting in wireless sensor networks. Although virtually unlimited, solar radiation experiences significant variations depending on the weather, the season, and the time of day, so solar-powered nodes commonly employ solar prediction models to effectively adapt their energy demands to harvesting dynamics. We present in this paper a novel energy prediction model that makes use of the altitude angle of the sun at different times of day to predict future solar energy availability. Unlike most of the state-of-the-art predictors that use past energy observations to make predictions, our model does not require one to maintain local energy harvesting patterns of past days. Performance evaluation shows that our scheme is able to provide accurate predictions for arbitrary forecasting horizons by performing just a few low complexity operations. Moreover, our proposal is extremely simple to set up since it does not require any particular tuning for each different scenario or location.
En Sensors, 2020

In this paper, we optimize the energy efficiency of device-to-multi-device (D2MD) communications. While point-to-point has been extensively studied to improve the spectral efficiency in cellular networks, the introduction of multicast communications brings, in addition, the possibility of reusing the spectrum resources also inside the groups. We formulate the energy efficiency problem in this context, and show that a decomposition approach which first uses matching theory to allocate the channels to each group, and then optimizes to find the unique transmission power vectors in each group gives good performance results for the optimization both of the system’s energy efficiency and of the max-min individual energy efficiency. This is achieved for a desired minimum transmission rate. Numerical results are presented to confirm the usefulness of the proposed framework for optimizing the planning and deployment of D2MD networks with energy efficiency as a primary performance goal.
En IEEE Transactions Communications, 2019

Frame coalescing is one of the most efficient techniques to manage the low power idle (LPI) mode supported by Energy Efficient Ethernet (EEE) interfaces. This technique enables EEE interfaces to remain in the LPI mode for a certain amount of time upon the arrival of the first frame (time-based coalescing) or until a predefined amount of traffic accumulates in the transmission buffer (size-based coalescing). This paper provides new insights on the practical efficiency limits of both coalescing techniques. In particular, we derive the fundamental limits on the maximum energy savings considering a target average frame delay. Additionally, we present new open-loop adaptive variants of both time-based and size-based coalescing techniques. These proposals dynamically adjust the length of the sleeping periods in accordance with actual traffic conditions to reduce energy consumption while keeping the average delay near a predefined value simultaneously. Analytical and simulation results show that the energy consumption of both proposals is comparable to the fundamental limits. Consequently, we recommend the usage of the time-based algorithm in most scenarios because of its simplicity as well as its ability to bound the maximum frame delay at the same time.
En IEEE Transactions on Green Communications and Networking, 2019

Both economic and environmental costs are driving much research in the area of energy efficiency of networking equipment. This research has produced a great amount of proposals. However, the majority of them remain unimplemented due to the lack of flexibility of current hardware devices and a certain lack of enthusiasm from commercial vendors. At the same time, Software-Defined Networking (SDN) has allowed customers to control switching decisions with a flexibility and precision previously unheard of. This paper explores the potential convergence between the two aforementioned trends and presents a promising power saving algorithm that can be implemented using standard SDN capabilities of current switches, reducing operation costs on both data centers and wired access networks. In particular, we focus on minimizing the energy consumption in bundles of Energy Efficient Ethernet links leveraging SDN. For this, we build on an existing theoretical algorithm and adapt it for implementing with an SDN solution. We study several approaches and compare the resulting algorithms not only according to their energy eficiency, but also taking into account additional QoS metrics. The results show that the resulting algorithm is able to closely match the theoretical results, even when taking into account the requirements of delay sensitive traffic.
In Sensors, 2018, 2018

Energy efficiency of cellular networks can be greatly improve if base stations (BSs) can be put into a low power operation mode during low load periods. In this paper, we present a new dynamic scheme to manage the sleep mode of energy-aware BSs that can be autonomously governed. This kind of BSs, such as those operating in heterogeneous or hyper-cellular networks, can be put to sleep without causing undesired coverage holes, thus preserving the cellular service over the whole coverage area. With the proposed mechanism, energy-aware BSs enter the sleep mode as soon as they have no traffic to send and then apply a coalescing algorithm that dynamically adjusts the length of the sleeping periods to maximize the energy savings while maintaining the average service delay around a target value at the same time.
In Journal of Network and Computer Applications, 2018

The energy demands of Ethernet links have been an active focus of research in the recent years. This work has enabled a new generation of energy-efficient Ethernet (EEE) interfaces able to adapt their power consumption to the actual traffic demands, thus yielding significant energy savings. With the energy consumption of single network connections being a olved problem, in this paper, we focus on the energy demands of linkaggregates that are commonly used to increase the capacity of a network connection. We build on known energy models of single EEE links to derive the energy demands of the whole aggregate as a function on how the traffic load is spread among its powered links. We then provide a practical method to share the load that minimizes overall energy consumption with controlled packet delay and prove that it is valid for a wide range of EEE links. Finally, we validate our method with both synthetic and real traffic traces captured inInternet backbones.
In IEEE Systems Journal, 2018

Networking operational costs and environmental concerns have lately driven the quest for energy efficient equipment. In wired networks, energy efficient Ethernet (EEE) interfaces can greatly reduce power demands when compared to regular Ethernet interfaces. Their power saving capabilities have been studied and modeled in many research articles in the last few years, together with their effects on traffic delay. However, to this date, all articles have considered them in isolation instead of as part of a network of EEE interfaces. In this paper we develop a model for the traffic delay on a network of EEE interfaces. We prove that, whatever the network topology, the per interface delay increment due to the power savings capabilities is bounded and, in most scenarios, negligible. This confirms that EEE interfaces can be used in all but the most delay constrained scenarios to save considerable amounts of power.
In IEEE Communications Letters, 2017

This paper presents a new frame coalescing mechanism that dynamically adjusts the coalescing queue threshold in order to minimize the energy consumption of dual-mode EEE interfaces and maintains, at the same time, the average frame delay close to a target value.
In IEEE Trans. Commun., 2017

This paper presents a promising mechanism that reduces energy consumption of user equipments using the DRX mechanism while simultaneously maintaining average packet delay around a desired target. In addition, our proposal is able to achieve significant power savings without either increasing signaling overhead or requiring any changes to deployed wireless protocols.
In IEEE J. Sel. Areas Commun., 2015

Rising energy consumption of IT infrastructure concerns have spurred the development of more power efficient networking equipment and algorithms. When old equipment just drew an almost constant amount of power regardless of the traffic load, there were some efforts to minimize the total energy usage by modifying routing decisions to aggregate traffic in a minimal set of links, creating the opportunity to power off some unused equipment during low traffic periods. New equipment, with power profile functions depending on the offered load, presents new challenges for optimal routing. The goal now is not just to power some links down, but to aggregate and/or spread the traffic so that devices operate in their sweet spot in regards to network usage. In this paper we present an algorithm that, making use of the ant colonization algorithm, computes, in a decentralized manner, the routing tables so as to minimize global energy consumption. Moreover, the resulting algorithm is also able to track changes in the offered loadand react to them in real time.
In Journal of Network and Computer Applications, 2015

This paper evaluates through simulation the potential power savings that can be obtained in ONUs using the low power mode known as doze mode. In particular, the impact of the DBA algorithm and the doze mode governor on both energy efficiency and frame delay are analyzed.
In Journal of Lightwave Technology, 2014

This paper provides a general GI/G/1 model for the energy consumption and the traffic delay obtained with a 10 Gb/s EEE interface using both frame and burst transmission algorithms. Specializations of the general model for Poisson and deterministic traffic are also provided.
In IEEE Trans. Commun., 2012

This paper provides mathematical models for the expected energy savings and the average packet delay obtained in EEE interfaces using the most well known sleeping algorithms. These models are then used to derive the optimum configuration parameters for the sleeping algorithms given some efficiency constraints.
In Computer Networks, 2012

This paper provides an accurate analytical model for the power savings achievable in EEE devices using the burst transmission algorithm to govern the low power mode.
In IEEE Commun. Lett., 2011

Traditional TCP-Reno like congestion control protocols exhibit poor performance when deployed in fast or very large network paths. Delay based congestion avoidance mechanisms (DCA), like FAST-TCP, get much higher performance, in the same circumstances. However, when mixed with TCP-Reno or alike traffic they are unable to attain their fair share of bandwidth. In this paper we present a new mechanism that can indirectly detect the present of non DCA-friendly traffic that can be used by new DCA algorithms to auto-tune themselves with more aggressive parameters to achieve their fair share.
In NET COOP’ 2008, 2008

Delay-based congestion control algorithms provide higher throughput and stability than traditional loss-based AIMD algorithms, but they are inherently unfair against older connections when the queuing and the propagation delay cannot be measured accurately and independently. This paper presents a novel measurement algorithm whereby fairness between old and new connections is preserved. The algorithm does not modify the dynamics of congestion control, and runs entirely in the server host using locally available information.
In IEEE Communications Letters, 2008

Charlas y conferencias

Distributed Resource Allocation Approach For Device-to-Device Multicast Communications
Oct 16, 2018 11:00
Matching-Theory-Based Resource Allocation for Underlay Device to Multi-Device Communications
Oct 15, 2018 09:00
QoS-aware Energy-Efficient Algorithms for Ethernet Link Aggregation in Software Defined Networks
Sep 15, 2018 09:30
Implementing Energy Saving Algorithms for Ethernet Link Aggregates with ONOS
Feb 24, 2018 16:00


Tecnologías de comunicación avanzadas para redes densas energéticamente óptimas.

Resource pooling and virtualization for the future Internet.

Escalabilidad en redes ópticas IPv6 con calidad de servicio.

Provisión óptima de servicios a redes vehiculares en movimiento.

Modelado, Análisis y Simulación de los Servicios y la Arquitectura de Internet.


Las personas de nuestra red


Resto del equipo

Antiguos compañeros

  • Manuel Fernández Veiga (Ph.D.)
  • Miguel Á. González Ortega (Ph.D.)
  • Christian A. Lazo Ramírez (Ph.D.)
  • Pablo J. Argibay Losada (Ph.D.)


Además de la docencia de grado y máster, los profesores del Laboratorio de Redes imparten cursos especializados sobre tecnologías y productos IP.

Cursos de especialización

  1. Sistemas de almacenamiento

    • Descripción: Redes de ordenadores: elementos básicos, protocolos y aplicaciones
  2. Ingeniería de redes IP

    • Descripción: Redes de ordenadores elementos básicos, protocolos y aplicaciones
  3. Curso básico de redes e Internet

    • Descripción: Redes de ordenadores: elementos básicos, protocolos y aplicaciones
  4. Curso de audio en Internet

    • Descripción: Codificación, transmisión y almacenamiento de audio digital; multimedia en Internet
  5. Sistemas avanzados de audio y vídeo

    • Descripción: Redes de ordenadores: elementos básicos, protocolos y aplicaciones
  6. Administración de laboratorios docentes
    Descripción: Formación del profesorado, laboratorios informáticos

  7. Operaciones y mantenimiento de redes IP

    • Descripción: Redes de ordenadores: elementos básicos, protocolos y aplicaciones
  8. Curso de redes e Internet

    • Descripción: Redes de ordenadores: elementos básicos, protocolos y aplicaciones