publications | Luis Sequeira

2021

IEEE
An Edge-Cloud Approach for Video Surveillance in Public Transport Vehicles

Idelkys Quintana-Ramirez, Luis Sequeira, and Jose Ruiz-Mas

IEEE Latin America Transactions, Oct 2021

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A Video Surveillance System VSS is of primary importance in public transport hubs such as airports, train or bus stations but also inside the vehicle itself. In this paper, we present a heuristic architecture model for on-board video surveillance system based on Internet of Video Things IoVT devices which addresses the need for delivering smart video surveillance in public transport vehicles e.g., buses minimizing the impact on network performance. A proof-of-concept was implemented using a public Cloud Service Provider CSP and two Raspberry Pi as edge computing nodes. On the edge nodes, a Machine LearningML application was deployed along with a network-efficient video streaming system. On the other hand, laboratory tests are included to understand the network traffic dynamic, furthermore results are enhanced with a set of simulations in order to analyze the performance of a video streaming application and6differentcongestion control algorithms in terms of packet loss and delay.
@article{ieee9477277, author = {Quintana-Ramirez, Idelkys and Sequeira, Luis and Ruiz-Mas, Jose}, doi = {10.1109/TLA.2021.9477277}, issn = {1548-0992}, journal = {{IEEE Latin America Transactions}}, keywords = {Streaming media; Video surveillance; Quality of service; Throughput; Peer-to-peer computing; Art; 5G mobile communication}, month = oct, number = {10}, pages = {1763--1771}, publisher = {IEEE}, title = {An Edge-Cloud Approach for Video Surveillance in Public Transport Vehicles}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=9477277; https://ieeexplore.ieee.org/document/9477277/}, volume = {19}, x-fetchedfrom = {IEEEXplore}, year = {2021}, }
IEEE
Building a Lane Merge Coordination for Connected Vehicles Using Deep Reinforcement Learning

Omar Nassef, Luis Sequeira, Elias Salam, and Toktam Mahmoodi

IEEE Internet of Things Journal, Feb 2021

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This article presents a data-driven framework for trajectory recommendation in automated and cooperative driving. The considered cooperative driving maneuver is lane-merge coordination, and while the trajectory recommendation can only be communicated to the connected vehicles, in computation of those recommendations both connected and unconnected vehicles are taken into account. The data-driven framework is implemented centrally, comprising of two main components of a traffic orchestrator TO and data fusion DF. The TO predicts the safest trajectories for connected vehicles involved in the lane-merge maneuver. The DF incorporates camera detected vehicles in order to map all vehicles, including connected and unconnected. To this end, the recommendations are built using various state-of-the-art machine learning ML techniques, including deep reinforcement learning and dueling deep Q-network. Our evaluations are conducted using the real-system deployed in the test track, with a mix of connected and unconnected vehicles. The results demonstrate the precision of predicted trajectories, and the percentage of successful lane merge achieved deploying different ML techniques.
@article{ieee9171338, author = {Nassef, Omar and Sequeira, Luis and Salam, Elias and Mahmoodi, Toktam}, doi = {10.1109/JIOT.2020.3017931}, issn = {2372-2541}, journal = {{IEEE Internet of Things Journal}}, keywords = {Merging; Trajectory; Mathematical model; Roads; Connected vehicles; Acceleration; Internet of Things}, month = feb, number = {4}, pages = {2540--2557}, publisher = {IEEE}, title = {Building a Lane Merge Coordination for Connected Vehicles Using Deep Reinforcement Learning}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=9171338; https://ieeexplore.ieee.org/document/9171338/}, volume = {8}, x-fetchedfrom = {IEEEXplore}, year = {2021}, }
Luis Sequeira
El impacto del buffer en la calidad de servicio

Luis Sequeira

Feb 2021

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En este texto se analiza la respuesta de la transmisión de flujos de datos en tiempo real, en escenarios de redes de acceso, en los cuales dichos flujos convergen en un enlace de salida, compitiendo por alcanzar un determinado nivel de calidad de servicio. La concurrencia de este tipo de flujos puede generar ráfagas de paquetes, que en determinadas circunstancias pueden comprometer la capacidad que tienen los buffer para absorber paquetes en períodos de congestión. Además, se presenta un análisis de las características de los buffer en los dispositivos de acceso, especialmente su tamaño y la pérdida de paquetes. En particular, se describe cómo estas características pueden afectar a la calidad de las aplicaciones multimedia cuando estas generan tráfico a ráfagas y sus posibles efectos en el tráfico de otras aplicaciones que comparten un enlace en común.
@book{sequeira2021impacto, author = {Sequeira, Luis}, publisher = {Luis Sequeira}, title = {El impacto del buffer en la calidad de servicio}, x-fetchedfrom = {Google Scholar}, year = {2021}, isbn = {978-9968-49-653-7}, }

2020

IEEE
Deep Reinforcement Learning in Lane Merge Coordination for Connected Vehicles.

Omar Nassef, Luis Sequeira, Elias Salam, and Toktam Mahmoodi

In 2020 IEEE 31st Annual International Symposium on Personal, Indoor and Mobile Radio Communications, Feb 2020

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In this paper, a framework for lane merge coordination is presented utilising a centralised system, for connected vehicles. The delivery of trajectory recommendations to the connected vehicles on the road is based on a Traffic Orchestrator and a Data Fusion as the main components. Deep Reinforcement Learning and data analysis is used to predict trajectory recommendations for connected vehicles, taking into account unconnected vehicles for those suggestions. The results highlight the adaptability of the Traffic Orchestrator, when employing Dueling Deep Q-Network in an unseen real world merging scenario. A performance comparison of different reinforcement learning models and evaluation against Key Performance Indicator (KPI) are also presented.
@inproceedings{journals/corr/abs-2010-10567, added-at = {2020-10-26T00:00:00.000+0100}, author = {Nassef, Omar and Sequeira, Luis and Salam, Elias and Mahmoodi, Toktam}, booktitle = {2020 IEEE 31st Annual International Symposium on Personal, Indoor and Mobile Radio Communications}, biburl = {https://www.bibsonomy.org/bibtex/210d997cabd734f9603940d07b5878b00/dblp}, ee = {https://arxiv.org/abs/2010.10567}, interhash = {00aa71422d69257c816d601bda7b3e38}, intrahash = {10d997cabd734f9603940d07b5878b00}, publisher = {IEEE}, timestamp = {2020-10-27T12:32:51.000+0100}, title = {Deep Reinforcement Learning in Lane Merge Coordination for Connected Vehicles.}, doi = {10.1109/PIMRC48278.2020.9217273}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=9217273}, volume = {abs/2010.10567}, x-fetchedfrom = {Bibsonomy}, year = {2020}, }
ACM
The role of machine learning for trajectory prediction in cooperative driving.

Luis Sequeira, and Toktam Mahmoodi

In Proceedings of the Twenty-First International Symposium on Theory, Algorithmic Foundations, and Protocol Design for Mobile Networks and Mobile Computing, Feb 2020

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In this paper, we study the role that machine learning can play in cooperative driving. Given the increasing rate of connectivity in modern vehicles, and road infrastructure, cooperative driving is a promising first step in automated driving. The example scenario we explored in this paper, is coordinated lane merge, with data collection, test and evaluation all conducted in an automotive test track. The assumption is that vehicles are a mix of those equipped with communication units on board, i.e. connected vehicles, and those that are not connected. However, roadside cameras are connected and can capture all vehicles including those without connectivity. We develop a Traffic Orchestrator that suggests trajectories based on these two sources of information, i.e. connected vehicles, and connected roadside cameras. Recommended trajectories are built, which are then communicated back to the connected vehicles. We explore the use of different machine learning techniques in accurately and timely prediction of trajectories.
@inproceedings{conf/mobihoc/SequeiraM20, added-at = {2020-10-16T00:00:00.000+0200}, author = {Sequeira, Luis and Mahmoodi, Toktam}, biburl = {https://www.bibsonomy.org/bibtex/29c97aca264051814e1d84194f410e7a1/dblp}, booktitle = {Proceedings of the Twenty-First International Symposium on Theory, Algorithmic Foundations, and Protocol Design for Mobile Networks and Mobile Computing}, editor = {Melodia, Tommaso and Ekici, Eylem and Abouzeid, Alhussein and Chen, Minghua}, ee = {https://doi.org/10.1145/3397166.3413470}, interhash = {49158cd3813197ee98765801aea7e2d9}, intrahash = {9c97aca264051814e1d84194f410e7a1}, isbn = {978-1-4503-8015-7}, doi = {10.1145/3397166.3413470}, pages = {368--373}, publisher = {Association for Computing Machinery}, timestamp = {2020-10-17T11:34:22.000+0200}, address = {New York, NY, USA}, title = {The role of machine learning for trajectory prediction in cooperative driving.}, url = {https://doi.org/10.1145/3397166.3413470}, x-fetchedfrom = {Bibsonomy}, year = {2020}, series = {Mobihoc '20}, }

2019

IEEE
A Lane Merge Coordination Model for a V2X Scenario

Luis Sequeira, Adam Szefer, Jamie Slome, and Toktam Mahmoodi

In 2019 European Conference on Networks and Communications EuCNC, Jun 2019

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Cooperative driving using connectivity services has been a promising avenue for autonomous vehicles, with the low latency and further reliability support provided by 5th Generation Mobile Network 5G. In this paper, we present an application for lane merge coordination based on a centralised system, for connected cars. This application delivers trajectory recommendations to the connected vehicles on the road. The application comprises of a Traffic Orchestrator as the main component. We apply machine learning and data analysis to predict whether a connected vehicle can successfully complete the cooperative manoeuvre of a lane merge. Furthermore, the acceleration and heading parameters that are necessary for the completion of a safe merge are elaborated. The results demonstrate the performance of several existing algorithms and how their main parameters were selected to avoid over-fitting.
@inproceedings{ieee8801987, author = {Sequeira, Luis and Szefer, Adam and Slome, Jamie and Mahmoodi, Toktam}, booktitle = {2019 European Conference on Networks and Communications EuCNC}, doi = {10.1109/EuCNC.2019.8801987}, isbn = {978-1-7281-0547-5}, issn = {2475-6490}, month = jun, pages = {198--203}, publisher = {IEEE}, title = {A Lane Merge Coordination Model for a V2X Scenario}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=8801987; https://ieeexplore.ieee.org/document/8801987/}, x-fetchedfrom = {IEEEXplore}, year = {2019}, }
IEEE
Minimizing the Impact of P2P-TV Applications in Access Links

I. Quintana, Luis Sequeira, J. Fernandez, J. Ruiz, and J. Saldana

IEEE Latin America Transactions, Jun 2019

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Many studies are concentrated on provisioning certain levels of Quality of Service (QoS) employing different approaches related to different areas (control congestion algorithms, transport protocols, etc). This paper is focused on the improvement of the QoS of peer-to-peer TV (P2P-TV), and in particular, it proposes a methodology to minimise the impact of bursty traffic in the buffer of access devices using a traffic shaping technique. This paper shows how QoS can be improved by means of traffic shaping, specifically by using smoothing techniques. Some parameters such as packet loss, delay and throughput of a popular P2PTV application are analysed. The competition for the available bandwidth between the P2P-TV and some Transport Control Protocol (TCP) traffic flows is also studied. The results show a reduction in terms of loss percentage when the traffic of the P2P-TV application is smoothed, introducing small delays as a counterpart.
@article{8863163, author = {Quintana, I. and Sequeira, Luis and Fernandez, J. and Ruiz, J. and Saldana, J.}, doi = {10.1109/TLA.2019.8863163}, journal = {IEEE Latin America Transactions}, number = {02}, pages = {183--192}, title = {Minimizing the Impact of P2P-TV Applications in Access Links}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=8863163}, volume = {17}, publisher = {IEEE}, year = {2019}, }
Wiley-IEEE
Haptic networking supporting vertical industries

Luis Sequeira, Konstantinos Antonakoglou, Maliheh Mahlouji, and Toktam Mahmoodi

Jun 2019

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Touch is seen as the modality that will complement hearing and vision as a third media stream over the Internet in a variety of future haptic applications. This chapter introduces the basics for haptic communication and discusses its quality of service and quality of experience requirements as well as the main key performance indicators (KPIs) for the Tactile Internet. In addition, it reviews and evaluates notable methodologies and technologies of bilateral teleoperation stability control and haptic data reduction, necessary components of the haptic communication infrastructure. Furthermore, the chapter takes into account the 5th Generation architecture, KPIs and some 3rd Generation Partnership Project components as well as the European Telecommunications Standards Institute Network Function Virtualisation management and orchestration capabilities that will allow haptic applications to take life, in combination with the haptic data communication protocols, bilateral teleoperation control schemes and haptic data processing needed.
@book{sequeira2019haptic, author = {Sequeira, Luis and Antonakoglou, Konstantinos and Mahlouji, Maliheh and Mahmoodi, Toktam}, booktitle = {Enabling 5G Communication Systems to Support Vertical Industries}, pages = {41--73}, publisher = {John Wiley \& Sons - IEEE Press}, title = {Haptic networking supporting vertical industries}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=8786853}, year = {2019}, }

2018

IEEE
The Making of 5G: Building an End-to-End 5G-Enabled System

Idelkys Quintana-Ramirez, Anthony Tsiopoulos, Maria A. Lema, Fragkiskos Sardis, Luis Sequeira, James Arias, Aravindh Raman, Ali Azam, and Mischa Dohler

IEEE Communications Standards Magazine, Dec 2018

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This article documents one of the world’s first standards-compliant pre-commercial end-to-end fifth generation 5G systems. Focus is on a standardized 5G architecture that includes the underlying 3GPP components but also the ETSI network functions virtualization management and orchestration capabilities. The truly innovative character of 5G enabling fundamental changes to architecture and implementation is discussed, as well as details of monitoring and orchestration approaches that are deemed instrumental in unlocking the full potential of 5G. Finally, it is important to us to share the lessons learned, which we hope are of use to industry and academia alike when building, deploying, and testing emerging 5G systems.
@article{ieee8636843, author = {Quintana-Ramirez, Idelkys and Tsiopoulos, Anthony and Lema, Maria A. and Sardis, Fragkiskos and Sequeira, Luis and Arias, James and Raman, Aravindh and Azam, Ali and Dohler, Mischa}, doi = {10.1109/MCOMSTD.2018.1800024}, issn = {2471-2833}, keywords = {5G mobile communication; Cloud computing; Software; 3GPP; Computer architecture; Monitoring}, month = dec, number = {4}, pages = {88--96}, journal = {IEEE Communications Standards Magazine}, publisher = {IEEE}, title = {The Making of 5G: Building an End-to-End 5G-Enabled System}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=8636843; https://ieeexplore.ieee.org/document/8636843/}, volume = {2}, x-fetchedfrom = {IEEEXplore}, year = {2018}, }

Horizon 2020

5GCAR Demonstration guidelines

N Brahmi, T Frye, D Martinan, P Dafonte, X Abad, M Sáez, B Cellarius, S Gangakhedkar, H Cao, Luis Sequeira, and others

Dec 2018

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@techreport{brahmi20185gcar,
  author = {Brahmi, N and Frye, T and Martinan, D and Dafonte, P and Abad, X and S{\'a}ez, M and Cellarius, B and Gangakhedkar, S and Cao, H and Sequeira, Luis and others},
  title = {5GCAR Demonstration guidelines},
  publisher = {Horizon 2020},
  url = {https://cordis.europa.eu/project/id/761510},
  year = {2018},
}

IEEE
Unsticking the Wi-Fi Client: Smarter Decisions Using a Software Defined Wireless Solution

Jose Saldana, Rubén Munilla, Salim Eryigit, Omer Topal, José Ruiz-Mas, Julián Fernández-Navajas, and Luis Sequeira

IEEE Access, Dec 2018

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This paper presents a novel software-defined wireless network architecture that integrates coordination mechanisms to enhance the capabilities of a set of central managed Wi-Fi access points APs. The global architecture is presented in detail, where the handoff mechanism is integrated with a set of active and passive monitoring tools and other functionalities, resulting in a solution that is able to provide smart functionalities using low-cost commercial APs. The framework includes a central controller that has all the information available, and is therefore able to make smart decisions about the assignment of clients to APs. This avoids the problem of the “sticky client”that remains connected to the original AP it is associated with, rather than moving to a nearby AP, which would be a better choice. Two different test scenarios are used to compare a proactive and a reactive handoff mechanism in realistic conditions, with different walking speeds. The results illustrate the advantage of the proactive handoff, as it is more scalable and allows a better integration with other functionalities such as load balancing. The delay incurred by the handoff between APs in different channels is measured with three wireless devices, using five values for the inter-beacon time, proving that fast and seamless handoffs are possible in the scenario. The paper shows that these advanced functionalities, usually available in proprietary solutions, can also be achieved using off-the-shelf equipment.
@article{ieee8371599, author = {Saldana, Jose and Munilla, Rub{\'e}n and Eryigit, Salim and Topal, Omer and Ruiz-Mas, Jos{\'e} and Fern{\'a}ndez-Navajas, Juli{\'a}n and Sequeira, Luis}, doi = {10.1109/ACCESS.2018.2844088}, issn = {2169-3536}, journal = {{IEEE Access}}, keywords = {Wireless networks; Wireless fidelity; Delays; Proposals; IEEE 802.11 Standard; Computer architecture}, pages = {30917--30931}, publisher = {IEEE}, title = {Unsticking the Wi-Fi Client: Smarter Decisions Using a Software Defined Wireless Solution}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=8371599; https://ieeexplore.ieee.org/document/8371599/}, volume = {6}, x-fetchedfrom = {IEEEXplore}, year = {2018}, }

2017

IEEE

Building an SDN Enterprise WLAN Based on Virtual APs

Luis Sequeira, Juan Luis Cruz, José Ruiz-Mas, Jose Saldana, Julián Fernandez-Navajas, and José Almodovar

IEEE Communications Letters, Feb 2017

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In this letter, the development and testing of an open enterprise Wi-Fi solution based on virtual access points APs, managed by a central WLAN controller is presented. It allows seamless handovers between APs in different channels, maintaining the QoS of real-time services. The potential scalability issues associated to the beacon generation and channel assignment have been addressed. A battery of tests has been run in a real environment, and the results are reported in terms of packet loss and delay.

@article{ieee7727996,
  author = {Sequeira, Luis and de la Cruz, Juan Luis and Ruiz-Mas, Jos{\'e} and Saldana, Jose and Fernandez-Navajas, Juli{\'a}n and Almodovar, Jos{\'e}},
  doi = {10.1109/LCOMM.2016.2623602},
  issn = {2373-7891},
  journal = {{IEEE Communications Letters}},
  keywords = {IEEE 802.11 Standard; Real-time systems; Wireless LAN; Scalability; Wireless networks; Handover},
  month = feb,
  number = {2},
  pages = {374--377},
  publisher = {IEEE},
  title = {Building an SDN Enterprise WLAN Based on Virtual APs},
  url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7727996; https://ieeexplore.ieee.org/document/7727996/},
  volume = {21},
  x-fetchedfrom = {IEEEXplore},
  year = {2017},
}

UPV
Mejora de la Calidad en Redes WLAN Coordinadas a través de SDWN

Julián Fernández Navajas, Luis Sequeira, José Ruiz Mas, and José Marı́a Saldaña Medina

In XIII Jornadas de Ingenierı́a telemática JITEL 2017, Sep 2017

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En el presente trabajo se propone una arquitectura capaz de mejorar la calidad de las comunicaciones multimedia en redes WLAN coordinadas, mediante la utilización de SDN Software Defined Networks. Para esto se requiere que dichas soluciones SDN sean adaptadas para poder identificar los parámetros propios de las redes Wi-Fi, tales como interferencias, movilidad, selección de canales, etc. y sean capaces de abordar los problemas derivados de los requerimientos de calidad de las estaciones que comparten la misma red inalámbrica.
@inproceedings{fernandez2018mejora, author = {{Fern{\'a}ndez Navajas}, Juli{\'a}n and {Sequeira}, Luis and {Ruiz Mas}, Jos{\'e} and {Salda{\~n}a Medina}, Jos{\'e} Mar{\'\i}a}, booktitle = {XIII Jornadas de Ingenier{\'\i}a telem{\'a}tica JITEL 2017}, pages = {148--151}, publisher = {Editorial Universitat Polit{\`e}cnica de Val{\`e}ncia}, title = {Mejora de la Calidad en Redes WLAN Coordinadas a trav{\'e}s de SDWN}, doi = {10.4995/JITEL2017.2017.6564}, url = {https://riunet.upv.es/handle/10251/102988}, year = {2017}, month = sep, }

2016

Horizon 2020

Specification of Smart AP solutions

Jose Saldana, Luis Sequeira, and Jose Ruiz-Mas

Dec 2016

Bib HTML PDF

@techreport{New2,
  author = {Saldana, Jose and Sequeira, Luis and Ruiz-Mas, Jose},
  month = dec,
  title = {Specification of Smart AP solutions},
  publisher = {Horizon 2020},
  year = {2016},
  url = {https://cordis.europa.eu/project/id/644262},
}

Horizon 2020

Definition of the performance monitoring mechanisms

Jose Saldana, Luis Sequeira, Jose Ruiz-Mas, Julian Fernadez-Navajas, and Ali Arsal

Dec 2016

Bib HTML PDF

@techreport{New3,
  author = {Saldana, Jose and Sequeira, Luis and Ruiz-Mas, Jose and Fernadez-Navajas, Julian and Arsal, Ali},
  month = dec,
  title = {Definition of the performance monitoring mechanisms},
  publisher = {Horizon 2020},
  year = {2016},
  url = {https://cordis.europa.eu/project/id/644262},
}

UFBS
Demo: Can a Wi-Fi WLAN Support a Real-Time Services During Handoff?

Luis Sequeira, Juan Luis Cruz, José Almodovar, Jose Saldana, Julian Fernandez-Navajas, and Jose Ruiz-Mas

In , Jun 2016

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Online games with tight real-time constraints are becoming ubiquitous: they are no longer exclusive of high-end PCs, but many of them have been ported to tablets or even smartphones. The Wi-5 (What to do With the Wi-Fi Wild West) Project is exploring a set of functionalities to be included in a pool of coordinated smart Wi-Fi APs, including resource management algorithms that take into account the nature of each flow. In addition, seamless handovers between APs are required for supporting user mobility. Can this Wi-Fi WLAN support seamless handovers between different APs? In this case, “seamless” means that the player of a First Person Shooter must experience a good quality.
@inproceedings{New4, author = {Sequeira, Luis and de la Cruz, Juan Luis and Almodovar, Jos{\'e} and Saldana, Jose and Fernandez-Navajas, Julian and Ruiz-Mas, Jose}, journal = {Ultra-fast Broadband Seminar}, publisher = {Ultra-fast Broadband Seminar}, location = {The Hague, Netherlands}, month = jun, pages = {27--30}, title = {Demo: Can a Wi-Fi WLAN Support a Real-Time Services During Handoff?}, year = {2016}, }

2015

IEEE
Can a Wi-Fi WLAN support a first person shooter?

Jose Saldana, Juan Luis Cruz, Luis Sequeira, Julián Fernández-Navajas, and José Ruiz-Mas

In 2015 International Workshop on Network and Systems Support for Games NetGames, Dec 2015

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In corporate and commercial environments, the deployment of a set of coordinated Wi-Fi APs is becoming a common solution to provide Internet coverage to moving users. In these scenarios, real-time services as online games can also be present. This paper presents a set of experiments developed in a test scenario where an end device moves between different APs while generating game traffic. A WLAN solution based on virtual APs is used, in order to make the handoffs transparent for Layer 3. The results show that it is possible to maintain an acceptable level of subjective quality during the handoff. At the same time, it is set clear that the fact of having a gamer in an AP could be taken into account by radio resource management algorithms, in order to provide a better quality.
@inproceedings{ieee7383001, author = {Saldana, Jose and de la Cruz, Juan Luis and Sequeira, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Ruiz-Mas, Jos{\'e}}, booktitle = {2015 International Workshop on Network and Systems Support for Games NetGames}, doi = {10.1109/NetGames.2015.7383001}, isbn = {978-1-5090-0067-8}, issn = {2156-8146}, keywords = {Delays; Games; IEEE 802.11 Standard; Real-time systems; Wireless LAN; Handover}, month = dec, pages = {1--3}, publisher = {IEEE}, title = {Can a Wi-Fi WLAN support a first person shooter?}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7383001; https://ieeexplore.ieee.org/document/7383001/}, x-fetchedfrom = {IEEEXplore}, year = {2015}, }
Unizar
Técnicas de estimación de buffer, centradas en las redes de acceso, para la transmisión de flujos ip en tiempo real

Luis Sequeira

Universidad de Zaragoza, Dec 2015

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Esta tesis doctoral presenta una serie de estudios que analizan la respuesta de la transmisión de flujos IP en tiempo real, en escenarios de redes de acceso, en los cuales dichos flujos convergen en un enlace de salida, compitiendo por alcanzar un determinado nivel de calidad de servicio. La concurrencia de este tipo de flujos puede generar ráfagas de paquetes, que en determinadas circunstancias pueden comprometer la capacidad que tienen los buffer para absorber paquetes en períodos de congestión.
@phdthesis{villarreal2015tecnicas, author = {Sequeira, Luis}, school = {Universidad de Zaragoza}, title = {T{\'e}cnicas de estimaci{\'o}n de buffer, centradas en las redes de acceso, para la transmisi{\'o}n de flujos ip en tiempo real}, x-fetchedfrom = {Google Scholar}, url = {https://search.ebscohost.com/login.aspx?direct=true&AuthType=sso&db=cat09079a&AN=cbu.oai.edge.unizar.folio.ebsco.com.fs00001047.25fdd9b9.98a4.4147.991e.e51d9a1bbc18&lang=es&site=eds-live&scope=site&custid=s1132340}, year = {2015}, }

2014

IARIA
Characterization of Real Internet Paths by Means of Packet Loss Analysis

Luis Sequeira, Julián Fernández-Navajas, and Jose Saldana

In The Eighth International Conference on Digital Society ICDS 2014, Mar 2014

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The behaviour of the routers’ buffer may affect the Quality of Service (QoS) of network services under certain conditions, since it may modify some traffic characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of the buffer is interesting, especially when multimedia flows are transmitted and even more if they transport information with real-time requirements. This work presents a packet loss analysis with the aim of determining the technical and functional characteristics of the real buffers (as, e.g., behaviour, size, limits, input and output rate) of a network path. An improved methodology is considered in which two different buffers are concatenated. It permits the estimation of some parameters of the intermediate buffers (size, input and output rate) in a network path including different devices across the Internet. The method presented in this paper permits the characterization of commercial router buffer by means of the analysis of the dropped packets in the buffer.
@inproceedings{sequeira2014characterization, author = {Sequeira, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Saldana, Jose}, title = {Characterization of Real Internet Paths by Means of Packet Loss Analysis}, booktitle = {The Eighth International Conference on Digital Society ICDS 2014}, publisher = {IARIA}, isbn = {978-1-61208-324-7}, location = {Barcelona, Spain}, month = mar, year = {2014}, url = {http://www.thinkmind.org/index.php?view=article&articleid=icds_2014_4_10_10153}, }
Hindawi
Video conferences through the internet: how to survive in a hostile environment

Carlos Fernández, Jose Saldana, Julián Fernández-Navajas, Luis Sequeira, Luis Casadesus, and others

The Scientific World Journal, Mar 2014

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This paper analyzes and compares two different video conference solutions, widely used in corporate and home environments, with a special focus on the mechanisms used for adapting the traffic to the network status. The results show how these mechanisms are able to provide a good quality in the hostile environment of the public Internet, a best effort network without delay or delivery guarantees. Both solutions are evaluated in a laboratory, where different network impairments (bandwidth limit, delay, and packet loss) are set, in both the uplink and the downlink, and the reaction of the applications is measured. The tests show how these solutions modify their packet size and interpacket time, in order to increase or reduce the sent data. One of the solutions also uses a scalable video codec, able to adapt the traffic to the network status and to the end devices.
@article{fernandez2014video, author = {Fern{\'a}ndez, Carlos and Saldana, Jose and Fern{\'a}ndez-Navajas, Juli{\'a}n and Sequeira, Luis and Casadesus, Luis and others}, journal = {The Scientific World Journal}, publisher = {Hindawi}, title = {Video conferences through the internet: how to survive in a hostile environment}, volume = {2014}, year = {2014}, doi = {10.1155/2014/860170}, url = {https://www.hindawi.com/journals/tswj/2014/860170/}, }
Hindawi
Describing the access network by means of router buffer modelling: a new methodology

Luis Sequeira, Julián Fernández-Navajas, Jose Saldana, José Ramón Gállego, Marı́a Canales, and others

The Scientific World Journal, Mar 2014

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The behaviour of the routers’ buffer may affect the quality of service (QoS) of network services under certain conditions, since it may modify some traffic characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of the buffer is interesting, especially when multimedia flows are transmitted and even more if they transport information with real-time requirements. This work presents a new methodology with the aim of determining the technical and functional characteristics of real buffers (i.e., behaviour, size, limits, and input and output rate) of a network path. It permits the characterization of intermediate buffers of different devices in a network path across the Internet.
@article{sequeira2014describing, author = {Sequeira, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Saldana, Jose and G{\'a}llego, Jos{\'e} Ram{\'o}n and Canales, Mar{\'\i}a and others}, journal = {The Scientific World Journal}, publisher = {Hindawi}, title = {Describing the access network by means of router buffer modelling: a new methodology}, volume = {2014}, year = {2014}, doi = {10.1155/2014/238682}, url = {https://www.hindawi.com/journals/tswj/2014/238682/}, }
TIIS
The Effect of the Buffer Size in QoS for Multimedia and bursty Traffic: When an Upgrade Becomes a Downgrade

Luis Sequeira, Julián Fernández-Navajas, and Jose Saldana

KSII Transactions on Internet and Information Systems, Sep 2014

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This work presents an analysis of the buffer features of an access router, especially the size, the impact on delay and the packet loss rate. In particular, we study how these features can affect the Quality of Service (QoS) of multimedia applications when generating traffic bursts in local networks. First, we show how in a typical SME (Small and Medium Enterprise) network in which several multimedia flows (VoIP, videoconferencing and video surveillance) share access, the upgrade of the bandwidth of the internal network may cause the appearance of a significant amount of packet loss caused by buffer overflow. Secondly, the study shows that the bursty nature of the traffic in some applications traffic (video surveillance) may impair their QoS and that of other services (VoIP and videoconferencing), especially when a certain number of bursts overlap. Various tests have been developed with the aim of characterizing the problems that may appear when network capacity is increased in these scenarios. In some cases, especially when applications generating bursty traffic are present, increasing the network speed may lead to a deterioration in the quality. It has been found that the cause of this quality degradation is buffer overflow, which depends on the bandwidth relationship between the access and the internal networks. Besides, it has been necessary to describe the packet loss distribution by means of a histogram since, although most of the communications present good QoS results, a few of them have worse outcomes. Finally, in order to complete the study we present the MOS results for VoIP calculated from the delay and packet loss rate.
@article{sequeira2014effect, author = {Sequeira, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Saldana, Jose}, journal = {KSII Transactions on Internet and Information Systems}, number = {9}, pages = {3159-3176}, title = {The Effect of the Buffer Size in QoS for Multimedia and bursty Traffic: When an Upgrade Becomes a Downgrade}, volume = {8}, year = {2014}, month = sep, doi = {10.3837/tiis.2014.09.012}, url = {https://itiis.org/digital-library/manuscript/834}, }

2013

IEEE
The influence of the buffer size in packet loss for competing multimedia and bursty traffic

Luis Sequeira, Julián Fernández-Navajas, Luis Casadesus, Jose Saldana, Idelkys Quintana, and José Ruiz-Mas

In 2013 International Symposium on Performance Evaluation of Computer and Telecommunication Systems SPECTS, Jul 2013

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This work presents an analysis of the effect of the access router buffer size on packet loss rate and how it can affect the QoS of multimedia services when bursty traffic is present. VoIP traffic, real traces of videoconferencing and videosurvellance are used in two different scenarios with medium link utilization. The study shows that the bursty nature of some applications may impair the MOS of voice calls especially when a certain number of bursts overlap. When link utilization is above 70% good values of VoIP QoS cannot be obtained.
@inproceedings{ieee6595753, author = {Sequeira, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Casadesus, Luis and Saldana, Jose and Quintana, Idelkys and Ruiz-Mas, Jos{\'e}}, booktitle = {2013 International Symposium on Performance Evaluation of Computer and Telecommunication Systems SPECTS}, isbn = {978-1-56555-352-1}, keywords = {Packet loss; Cameras; Teleconferencing; Streaming media; Bandwidth; Multimedia communication}, month = jul, pages = {134--141}, publisher = {IEEE}, title = {The influence of the buffer size in packet loss for competing multimedia and bursty traffic}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6595753; https://ieeexplore.ieee.org/document/6595753/}, x-fetchedfrom = {IEEEXplore}, year = {2013}, }
IEEE
Optimization of P2P-TV traffic by means of header compression and multiplexing

Idelkys Quintana-Ramirez, Jose Saldana, Jose Ruiz-Mas, Luis Sequeira, Julian Fernandez-Navajas, and Luis Casadesus

In 2013 21st International Conference on Software, Telecommunications and Computer Networks - SoftCOM 2013, Sep 2013

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This paper studies the optimization of the traffic of a P2P-TV application SOPCast. First, a traffic characterization is deployed, and it is observed that the service generates a high rate of small UDP packet bursts between peers. Then, an optimization method based on header compression and multiplexing is used for sending together the packets with the same destination. Two multiplexing policies are defined and tested. The first one is based on a fixed multiplexing period, and the other one defines an inter-packet time threshold, with the aim of multiplexing together a whole traffic burst. Simulations using real traffic traces of SOPCast are performed in order to estimate the expected savings for both policies. The results show that the efficiency is improved, achieving uplink bandwidth savings between 26% and 33% for the period-based policy, and roughly 35% for the policy based on a threshold. The amount of packets per second is also reduced by a factor of 10 in both cases. As a counterpart, the addition of a small retention delay is necessary, but the tests show that it does not impair user’s experience.
@inproceedings{ieee6671891, author = {Quintana-Ramirez, Idelkys and Saldana, Jose and Ruiz-Mas, Jose and Sequeira, Luis and Fernandez-Navajas, Julian and Casadesus, Luis}, booktitle = {2013 21st International Conference on Software, Telecommunications and Computer Networks - SoftCOM 2013}, doi = {10.1109/SoftCOM.2013.6671891}, isbn = {978-953-290-040-8}, keywords = {Multiplexing; Streaming media; Bandwidth; Delays; Optimization; Peer-to-peer computing; Games}, month = sep, pages = {1--5}, publisher = {IEEE}, title = {Optimization of P2P-TV traffic by means of header compression and multiplexing}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6671891; https://ieeexplore.ieee.org/document/6671891/}, x-fetchedfrom = {IEEEXplore}, year = {2013}, }
IEEE
Characterization of the buffers in real Internet paths

Luis Sequeira, Julián Fernández-Navajas, and Jose Saldana

In 2013 International Symposium on Performance Evaluation of Computer and Telecommunication Systems SPECTS, Jul 2013

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The behaviour of the routers’ buffer is of primary importance when studying network traffic, since it may modify some of this characteristics, as delay or jitter, and may also drop packets affecting the Quality of Service QoS of different services. As a consequence, the characterization of this buffer is interesting, especially when real-time flows are being transmitted. This work presents a preliminary study of how to determine the technical and functional characteristics of buffers as e.g., behaviour, size, limits, input and output rate of a network path. Two different methodologies are considered on two test scenarios; real measurements permit the estimation of some parameters of the intermediate buffers as size, input and output rates, in a network path including different devices across the Internet.
@inproceedings{ieee6595756, author = {Sequeira, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Saldana, Jose}, booktitle = {2013 International Symposium on Performance Evaluation of Computer and Telecommunication Systems SPECTS}, isbn = {978-1-56555-352-1}, keywords = {Packet loss; Internet; Delays; Quality of service; Buffer storage; Size measurement}, month = jul, pages = {155--160}, publisher = {IEEE}, title = {Characterization of the buffers in real Internet paths}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6595756; https://ieeexplore.ieee.org/document/6595756/}, x-fetchedfrom = {IEEEXplore}, year = {2013}, }
JITEL
Optimizacion del Tráfico P2P-TV mediante el uso de Técnicas de Compresion y Multiplexion

Idelkys Quintana-Ramirez, Jose Saldana, Jose Ruiz-Mas, Luis Sequeira, Julian Fernandez-Navajas, and Luis Casadesus

In XI Jornadas de Ingeniería Telemática (JITEL 2013), Oct 2013

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En este trabajo se presenta un estudio sobre la optimización del tráfico P2P-TV, específicamente de SOPCast, una de las aplicaciones más utilizadas por los usuarios a día de hoy. En primer lugar se presenta una caracterización del tráfico, obserándose que genera altas tasas de paquetes UDP de pequeño tamaño entre diferentes peer, presentando por tanto una eficiencia baja. Posteriormente se propone el uso de un método de optimización de ancho de banda basado en la compresión de las cabeceras y en la multiplexión de los paquetes originales. Se emplean dos políticas de multiplexión, la primera se basa en un período fijo y en la segunda se define un umbral para el tiempo entre paquetes. En las simulaciones se emplea una traza real del tráfico SOPCast, mostrándose para ambas políticas, una mejora en la eficiencia y valores significativos de ahorro de ancho de banda para el enlace de subida de un usuario (aproximadamente entre un 26% y un 35%). La cantidad de paquetes por segundo se reduce en un factor de 10 en ambos casos. Como contrapartida, se añade un retardo a los paquetes nativos, pero las pruebas muestran que no empeora la experiencia del usuario ni la calidad del vídeo percibido.
@inproceedings{quintanaoptimizacion, author = {Quintana-Ramirez, Idelkys and Saldana, Jose and Ruiz-Mas, Jose and Sequeira, Luis and Fernandez-Navajas, Julian and Casadesus, Luis}, title = {Optimizacion del Tr{\'a}fico P2P-TV mediante el uso de T{\'e}cnicas de Compresion y Multiplexion}, booktitle = {XI Jornadas de Ingeniería Telemática (JITEL 2013)}, publisher = {Jornadas de Ingeniería Telemática}, isbn = {978-84-616-5597-7}, pages = {345--350}, month = oct, location = {Granada, Spain}, year = {2013}, url = {https://dialnet.unirioja.es/servlet/articulo?codigo=8630912}, }

2012

Jornadas Sarteco
Comparison of Multiplexing Policies for FPS Games in terms of Subjective Quality

Jose Saldana, Julian Fernandez Navajas, Jose Ruiz Mas, Luis Sequeira, and Luis Casadesus

In Proc. II Workshop on Multimedia Data Coding and Transmission 2012, Jul 2012

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This paper compares two policies which can be used for multiplexing the traffic of a number of players of a First Person Shooter game. A network scenario in which a number of players share an access network has been simulated, in order to compare the policies in terms of a subjective quality estimator. The first policy, namely timeout, achieves higher bandwidth savings, while the second one, period, introduces less delay and jitter. The results show that the difference in terms of QoE is only significant when the number of players is small. Thus, in order to make the correct decision, the concrete network scenario and the characteristics of the router would have to be considered in each case, taking into account the estimation of the subjective quality that can be expected.
@inproceedings{2007.15096v1, archiveprefix = {arXiv}, author = {Saldana, Jose and Navajas, Julian Fernandez and Mas, Jose Ruiz and Sequeira, Luis and Casadesus, Luis}, booktitle = {Proc. II Workshop on Multimedia Data Coding and Transmission 2012}, publisher = {Jornadas Sarteco}, location = {Elche, Spain}, isbn = {978-84-695-4472-3}, comment = {published=2020-07-29T20:32:45Z, updated=2020-07-29T20:32:45Z}, eprint = {2007.15096v1}, month = jul, pages = {978--84}, primaryclass = {cs.NI}, title = {Comparison of Multiplexing Policies for FPS Games in terms of Subjective Quality}, url = {http://arxiv.org/abs/2007.15096v1; http://arxiv.org/pdf/2007.15096v1}, x-fetchedfrom = {arXiv.org}, year = {2012}, }
IEEE
Empirically characterizing the buffer behaviour of real devices

Luis Sequeira, Julián Fernández-Navajas, Jose Saldana, and Luis Casadesus

In 2012 International Symposium on Performance Evaluation of Computer & Telecommunication Systems SPECTS, Jul 2012

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All the routers include a buffer in order to enqueue packets waiting to be transmitted. The behaviour of the routers’ buffer is of primary importance when studying network traffic, since it may modify some characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of this buffer is interesting, especially when real-time flows are being transmitted: if the buffer characteristics are known, then different techniques can be used so as to adapt the traffic: multiplexing a number of small packets into a big one, fragmentation, etc. This work presents a preliminary study of how to determine the technical and functional characteristics of the buffer of a certain device as e.g. behaviour, size, limits, input and output rate, or even in a remote Internet network node. Two different methodologies are considered, and tested on two real scenarios which have been implemented; real measurements permit the estimation of the buffer size, and the input and output rates, when there is physical or remote access to the “System Under Test”. In case of having physical access, the maximum number of packets in the queue can be determined by counting. In contrast, if the node is remote, its buffer size has to be estimated. We have obtained accurate results in wired and wireless networks.
@inproceedings{ieee6267042, author = {Sequeira, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Saldana, Jose and Casadesus, Luis}, booktitle = {2012 International Symposium on Performance Evaluation of Computer \& Telecommunication Systems SPECTS}, isbn = {978-1-56555-346-0}, keywords = {Delay; Bandwidth; Internet; Size measurement; Multiplexing; Estimation; Wireless networks}, month = jul, pages = {1--6}, publisher = {IEEE}, title = {Empirically characterizing the buffer behaviour of real devices}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6267042}, x-fetchedfrom = {IEEEXplore}, year = {2012}, }
URSI
Influencia del Buffer del Router en la Distribucı́on de Video P2P-TV.

Idelkys Quintana Ramı́rez, Jose Saldana, José Ruı́z-Mas, Julián Fernández-Navajas, Luis A. Casadesus Pazos, and Luis Sequeira

In Actas del XXVII Simposium Nacional de la Union Científica Internacional de Radio, Sep 2012

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This work presents a study of the behaviour of the router buffer when managing the traffic of P2P-TV applications, where a number of peers exchange video content. First, a summary of the characteristics of SOPCast is presented. Then, the results obtained in simulation tests using different buffer policies are presented. Real traces of the application, obtained from a research project, have been used for the tests, sharing the Internet access with different amounts of background traffic. The results show that a similar buffer behaviour for all the access technologies. In addition, the big amount of small packets generated may impair the video traffic, thus avoiding the retransmission of the contents by the application.
@inproceedings{journals/corr/abs-2007-15366, author = {Ram{\'\i}rez, Idelkys Quintana and Saldana, Jose and Ru{\'\i}z-Mas, Jos{\'e} and Fern{\'a}ndez-Navajas, Juli{\'a}n and Pazos, Luis A. Casadesus and Sequeira, Luis}, booktitle = {Actas del XXVII Simposium Nacional de la Union Científica Internacional de Radio}, biburl = {https://www.bibsonomy.org/bibtex/29cb200bc8a22cfaa6cca0e334775b6c2/dblp}, interhash = {d84c426b411eb86e4f7cdf073a843080}, intrahash = {9cb200bc8a22cfaa6cca0e334775b6c2}, timestamp = {2020-08-04T11:40:57.000+0200}, title = {Influencia del Buffer del Router en la Distribuc{\'\i}on de Video P2P-TV.}, url = {http://dblp.uni-trier.de/db/journals/corr/corr2007.html#abs-2007-15366}, volume = {abs/2007.15366}, x-fetchedfrom = {Bibsonomy}, year = {2012}, month = sep, }
URSI
Herramienta para Automatizar la Caracterizacion de Entornos de Red: Análisis y Medidas de Calidad

Elisa Santos, Julián Fernádez Navajas, Luis Sequeira, and Luis Casadesus

In Actas del XXVII Simposium Nacional de la Union Cientı́fica Internacional de Radio URSI, Sep 2012

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In the last few years, IP networks and multimedia real-time applications running on them have experienced an amazing development. These applications require plenty of network resources for a correct performance. As a consequence, the characterization of network environment is interesting for research center even companies. This work presents a tool to automate traffic analysis for different applications and services and it permits to determinate technical and functional characteristics of real device or network. Three different methods are considered and tested on real scenarios which have been implemented; real measurements permit traffic modeling and quality measures
@inproceedings{santos2012herramienta, author = {Santos, Elisa and Navajas, Juli{\'a}n Fern{\'a}dez and Sequeira, Luis and Casadesus, Luis}, booktitle = {Actas del XXVII Simposium Nacional de la Union Cient{\'\i}fica Internacional de Radio URSI}, title = {Herramienta para Automatizar la Caracterizacion de Entornos de Red: An{\'a}lisis y Medidas de Calidad}, publisher = {Union Cient{\'\i}fica Internacional de Radio}, location = {Elche, Spain}, x-fetchedfrom = {Google Scholar}, year = {2012}, url = {https://ursi.es/actas-de-congresos-celebrados/}, }
URSI
Caracterización de Tecnologı́as y Dispositivos de Red: Comportamiento de los Buffer

Luis Sequeira, Julian Fernández Navajas, Jose Saldana, and Luis A. Casadesus Pazos

In Actas del XXVII Simposium Nacional de la Union Cientı́fica Internacional de Radio URSI 2012, Sep 2012

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Buffers are included in routers in order to enqueue packets waiting to be transmitted. The behaviour of the routers’ buffer is of primary importance when studying network traffic, since it may modify some characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of this buffer is interesting, especially when real-time flows are being transmitted: if the buffer characteristics are known, then different techniques can be used so as to adapt the traffic. This work presents a study of how to determine the technical and functional characteristics of the buffer of a certain device, or even in a remote Internet network node. Two different methodologies are considered and tested on two real scenarios which have been implemented; real measurements permit the estimation of the buffer size, and the input and output rates, when there is physical or remote access to the system under test. We have obtained accurate results in wired and wireless networks.
@inproceedings{New1, author = {Sequeira, Luis and Navajas, Julian Fern{\'a}ndez and Saldana, Jose and Pazos, Luis A. Casadesus}, booktitle = {Actas del XXVII Simposium Nacional de la Union Cient{\'\i}fica Internacional de Radio URSI 2012}, isbn = {978-84-695-4327-6}, month = sep, title = {Caracterizaci{\'o}n de Tecnolog{\'\i}as y Dispositivos de Red: Comportamiento de los Buffer}, publisher = {Union Cient{\'\i}fica Internacional de Radio}, year = {2012}, url = {https://ursi.es/actas-de-congresos-celebrados/}, }
IEEE
Empirically characterizing the buffer behaviour of real devices

Luis Sequeira, Julián Fernández-Navajas, Jose Saldana, and Luis Casadesus

In 2012 International Symposium on Performance Evaluation of Computer & Telecommunication Systems SPECTS, Jul 2012

Abs arXiv Bib HTML

All the routers include a buffer in order to enqueue packets waiting to be transmitted. The behaviour of the routers’ buffer is of primary importance when studying network traffic, since it may modify some characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of this buffer is interesting, especially when real-time flows are being transmitted: if the buffer characteristics are known, then different techniques can be used so as to adapt the traffic: multiplexing a number of small packets into a big one, fragmentation, etc. This work presents a preliminary study of how to determine the technical and functional characteristics of the buffer of a certain device as e.g. behaviour, size, limits, input and output rate, or even in a remote Internet network node. Two different methodologies are considered, and tested on two real scenarios which have been implemented; real measurements permit the estimation of the buffer size, and the input and output rates, when there is physical or remote access to the “System Under Test”. In case of having physical access, the maximum number of packets in the queue can be determined by counting. In contrast, if the node is remote, its buffer size has to be estimated. We have obtained accurate results in wired and wireless networks.
@inproceedings{ieee6267042_2, author = {Sequeira, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Saldana, Jose and Casadesus, Luis}, booktitle = {2012 International Symposium on Performance Evaluation of Computer \& Telecommunication Systems SPECTS}, isbn = {978-1-56555-346-0}, keywords = {Delay; Bandwidth; Internet; Size measurement; Multiplexing; Estimation; Wireless networks}, month = jul, pages = {1--6}, publisher = {IEEE}, title = {Empirically characterizing the buffer behaviour of real devices}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6267042; https://ieeexplore.ieee.org/document/6267042/}, x-fetchedfrom = {IEEEXplore}, year = {2012}, }
IEEE
Traffic optimization for TCP-based Massive Multiplayer Online Games

Jose Saldana, Luis Sequeira, Julián Fernández-Navajas, and José Ruiz-Mas

In 2012 International Symposium on Performance Evaluation of Computer & Telecommunication Systems SPECTS, Jul 2012

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This paper studies the use of a traffic optimization technique named TCM Tunneling, Compressing and Multiplexing to reduce the bandwidth of MMORPGs Massively Multiplayer Online Role-Playing Games, which employ TCP to provide a soft real-time service. In order to optimize the traffic and to improve bandwidth efficiency, TCM can be applied when the packets of a number of players share the same link, which occurs in some scenarios, as e.g. the traffic between proxies and servers of game-supporting infrastructures. First, TCP/IP headers are compressed using standard algorithms that avoid sending repeated fields; next, a number of packets are blended into a bigger one and finally, they are sent using a tunnel. The expected compressed header size has been obtained using traffic traces of a real game. Next, simulations using a traffic model of a popular MMORPG have been performed in order to estimate the expected bandwidth savings and the reduction in packets per second. The obtained bandwidth saving is about 60 percent. Packets per second are also significantly reduced. In addition, the added delays are shown to be small enough so as not to impair players’ experienced quality.
@inproceedings{ieee6267019, author = {Saldana, Jose and Sequeira, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Ruiz-Mas, Jos{\'e}}, booktitle = {2012 International Symposium on Performance Evaluation of Computer \& Telecommunication Systems SPECTS}, isbn = {978-1-56555-346-0}, keywords = {Multiplexing; Games; Servers; IP networks; Bandwidth; Protocols; Context}, month = jul, pages = {1--8}, publisher = {IEEE}, title = {Traffic optimization for TCP-based Massive Multiplayer Online Games}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6267019; https://ieeexplore.ieee.org/document/6267019/}, x-fetchedfrom = {IEEEXplore}, year = {2012}, }
IEEE
The Effect of TCP Variants on the Coexistence of MMORPG and Best-Effort Traffic

Jose Saldana, Mirko Suznjevic, Luis Sequeira, Julian Fernandez-Navajas, Maja Matijasevic, and Jose Ruiz-Mas

In 2012 21st International Conference on Computer Communications and Networks ICCCN, Jul 2012

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Massive Multiplayer Online Role Playing Games MMORPGs have been reported as real-time applications using TCP. This surprising fact makes it interesting to study their behavior when sharing a link with other TCP flows. In this paper the coexistence of an MMORPG flow and an FTP background application is studied. A network scenario which fits an access network is simulated with NS2, using synthetic traffic of a game, generated according to a statistical model. The FTP background application uses different TCP variants. The results show that TCP Vegas is able to maintain a constant rate while competing with the traffic of the game, since it prevents packet loss and high queuing delays by avoiding the increase of the sending window size. In contrast, TCP SACK and TCP New Reno tend to indefinitely increase their window size, thus causing packet loss and adding undesired delays to the game traffic. Finally, small buffers have been proved to be more convenient when dealing with real-time applications, since big ones add higher delays.
@inproceedings{ieee6289245, author = {Saldana, Jose and Suznjevic, Mirko and Sequeira, Luis and Fernandez-Navajas, Julian and Matijasevic, Maja and Ruiz-Mas, Jose}, booktitle = {2012 21st International Conference on Computer Communications and Networks ICCCN}, doi = {10.1109/ICCCN.2012.6289245}, isbn = {978-1-4673-1542-5}, issn = {1095-2055}, keywords = {Games; Delay; Servers; Protocols}, month = jul, pages = {1--5}, publisher = {IEEE}, title = {The Effect of TCP Variants on the Coexistence of MMORPG and Best-Effort Traffic}, url = {https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6289245; https://ieeexplore.ieee.org/document/6289245/}, x-fetchedfrom = {IEEEXplore}, year = {2012}, }
ACM
The utility of characterizing the buffer of network devices in order to improve real-time interactive services

Luis Sequeira, Idelkys Quintana, Jose Saldana, Luis Casadesus, Julián Fernández-Navajas, and José Ruiz-Mas

In Proceedings of the 7th Latin American Networking Conference, Oct 2012

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The behaviour of the routers’ buffer is of primary importance when studying network traffic, since it may modify some characteristics, as delay or jitter, and may also drop packets. As a consequence, the characterization of this buffer is interesting, especially when real-time flows of interactive services are being transmitted. If the buffer characteristics are known, then different techniques can be used so as to adapt the traffic: multiplexing a number of small packets into a big one or fragmentation. This work presents a study of how to determine the technical and functional characteristics of the buffer of a certain device (e.g. size, input and output rate and others characteristics related to its behaviour), or even in a remote node. Two different methodologies are considered, and tested on two real scenarios which have been implemented; real measurements permit the estimation of the buffer size, and the input and output rates, when we have physical or remote access to the "System Under Test". In case of having physical access, the maximum number of packets in the queue can be determined by counting. In contrast, if the node is remote, its buffer size can be estimated. We have obtained accurate results in wired and wireless networks.
@inproceedings{ACM-10.1145/2382016.2382020, address = {New York, NY, USA}, author = {Sequeira, Luis and Quintana, Idelkys and Saldana, Jose and Casadesus, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Ruiz-Mas, Jos{\'e}}, booktitle = {Proceedings of the 7th Latin American Networking Conference}, doi = {10.1145/2382016.2382020}, isbn = {9781450317504}, keywords = {buffer size; streaming; queueing; unattended measurements; P2P-TV}, location = {Medell{\'\i}n, Columbia}, month = oct, numpages = {9}, pages = {19--27}, publisher = {Association for Computing Machinery}, series = {LANC '12}, title = {The utility of characterizing the buffer of network devices in order to improve real-time interactive services}, x-fetchedfrom = {ACM Digital Library}, year = {2012}, url = {https://dl.acm.org/doi/10.1145/2382016.2382020}, }
ACM
IPTV quality assessment system

Luis Casadesus, Julián Fernández-Navajas, Luis Sequeira, Idelkys Quintana, Jose Saldana, and José Ruiz-Mas

In Proceedings of the 7th Latin American Networking Conference, Oct 2012

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Due to the Increasing deployment of real-time multimedia services like IPTV and videoconferencing, the Internet has new Challenges. These new real-time Applications require a reliable performance of the network so as to provide a good Quality of Service (QoS) so it is important for the services providers to estimate the quality offered; and regardless of the transport network to know the quality perceived by the user. For this it is important to have tools to evaluate the quality of service provided. This paper presents a system for IPTV quality assessment. This will allow us to study the user’s perceived quality for different codecs, bit rates, frame rates and video resolutions, and the impact of the network packet loss rate, in order to determine the objective and subjective quality. We propose an application simulating packet loss as a function of network parameters, which can be used to obtain the received video with different network impairments, without the need for transmitting it. It has two main advantages: first, it avoids the need of transmitting the video a number of times; second, it allows test repeatability.
@inproceedings{ACM-10.1145/2382016.2382026, address = {New York, NY, USA}, author = {Casadesus, Luis and Fern{\'a}ndez-Navajas, Juli{\'a}n and Sequeira, Luis and Quintana, Idelkys and Saldana, Jose and Ruiz-Mas, Jos{\'e}}, booktitle = {Proceedings of the 7th Latin American Networking Conference}, doi = {10.1145/2382016.2382026}, isbn = {9781450317504}, keywords = {Quality of Experience QoE; metrics; IPTV; video streaming; quality assessment; Quality of Service QoS}, location = {Medell{\'\i}n, Columbia}, month = oct, numpages = {7}, pages = {52--58}, publisher = {Association for Computing Machinery}, series = {LANC '12}, title = {IPTV quality assessment system}, x-fetchedfrom = {ACM Digital Library}, year = {2012}, url = {https://dl.acm.org/doi/10.1145/2382016.2382026}, }