Luis Sequeira

Bio: Luis Sequeira is an academic researcher from King's College London. The author has contributed to research in topics: Network packet & Packet loss. The author has an hindex of 8, co-authored 38 publications receiving 224 citations. Previous affiliations of Luis Sequeira include University of Zaragoza & University of Lisbon.

Building an SDN Enterprise WLAN Based on Virtual APs

Abstract: 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.

Virtual Archaeology in Second Life and OpenSimulator

Abstract: Traditional approaches to virtual archaeology include dealing with research methods to capture information from heritage sites, creating models out of that information and how to present them to the public; these are intense technical procedures which might be too costly for some types of history or heritage-based projects. Virtual worlds allowed new types of models of/for heritage sites to be produced and disseminated at a fraction of the cost. Second Life®, and its open source counterpart, OpenSimulator, are virtual world platforms with user-generated content. 3D models are created in real time and instantly rendered for all visitors. This allows amateurs and researchers create their own virtual archaeology projects easily and with few costs, and to have the resulting models immediately available to a vast community of users. This article presents an overview of four different approaches to virtual archaeology projects that are present in these platforms and that have been publicly discussed and analyzed; in particular, the last type shows a novel approach to virtual archaeology which is not found in other platforms, and explains how researchers have managed to extend the concept to new areas and develop methodologies to incorporate the validation of historical accuracy to encompass these areas.

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

Abstract: 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.

Building a Lane Merge Coordination for Connected Vehicles Using Deep Reinforcement Learning

Abstract: 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.

Video Conferences through the Internet: How to Survive in a Hostile Environment

Abstract: 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.

OpenSDWN: Programmatic Control overHome and Enterprise WiFi

Abstract: The quickly growing demand for wireless networks and the numerous application-specific requirements stand in stark contrast to today’s inflexible management and operation of WiFi networks. In this paper, we present and evaluate OPENSDWN, a novel WiFi architecture based on an SDN/NFV approach. OPENSDWN exploits datapath programmability to enable service differentiation and fine-grained transmission control, facilitating the prioritization of critical applications. OPENSDWN implements per-client virtual access points and per-client virtual middleboxes, to render network functions more flexible and support mobility and seamless migration. OPENSDWN can also be used to out-source the control over the home network to a participatory interface or to an Internet Service Provider.

Peer-to-Peer Networking and Applications

Abstract: Aims & Scope Peer-to-Peer Networking and Applications (P2PNA) has received significant attention from both academia and industry in recent years. The aim of the Peer-to-Peer Networking and Applications journal is to disseminate state-of-the-art research and development results in this rapidly growing research area, to facilitate the deployment of P2P networking and applications, and to bring together the academic and industry communities, with the goal of fostering interaction to promote further research interests and activities, thus enabling new P2P applications and services. The journal not only will address research topics related to networking and communications theory, but will also consider the standardization, economic, and engineering aspects of P2P technologies, and their impacts on software engineering, computer engineering, networked communication, and security.

Virtual World as a Resource for Hybrid Education

Abstract: The virtual worlds in the educational environment, have opened new possibilities to innovation in the teaching-learning process, where the flexibility of access to information inside or outside the classroom through an avatar, tends to a paradigm shift in education traditional, in terms of the way of transmitting and acquiring knowledge through technological means. In this sense, an investigation was carried out on the design, development and use of a metaverse as a digital tool of didactic support to students of the Faculty of Systems Engineering of the University of Cundinamarca, with a view to establishing its viability to be implemented in a course of mathematics and demonstrate the possibilities offered by this type of resource to motivate the student in his training. The metaverse design included various ICT tools, thereby promoting self-learning and collaborative learning. Finally, it was evaluated what was the appreciation of a group of students against their interaction with the metaverse, which validated its usefulness and functionality inside and outside the classroom.

Perception of medical students and residents about virtual interviews for residency applications in the United States

Abstract: Introduction Residency applications via virtual-interview could potentially mitigate the extensive cost and time required for customary in-person interviews. We outline the perception of medical students and residents on the use of virtual-interview for residency applications in lieu of in-person interviews. Methods We obtained 1824 responses from medical students and residents through an online questionnaire between March2019-Feb2020 in Texas-United States. The survey had 11 statements (five in favor of in-person interviews and 6 in favor of virtual interviews) that respondents could rank on a 5-point Likert scale. All statements’ scores were summed based on the response given by each participant to create a total score between 11 and 55. The perception of the two groups was analyzed using an independent sample T-test and ANOVA. Results We received a total of 1711 responses from medical students and 113 from medical residents. Respondents were more female (82.2% of medical students and 47.8% of residents), with a mean age of 22.87±3.42 years old for medical students and 28.72±4.35 years old for residents. Both groups preferred in-person interviews; however, the residents were significantly more in favor (P = 0.03). Both groups agree that virtual-interviews should be as an option, though this was considerably higher in the medical students (P = 0.001). In the multivariate analysis, “travel distance” and “type of medical school” had a significant impact on choosing the virtual-interviews in both groups (p<0.01). Conclusions In-person interviews are favored by both medical students and residents compared to virtual-interview services in normal circumstances. However, both groups agree that programs should offer the option of having virtual-interviews as an available choice. Distance to an interview location and the type of medical school were the factors that had a significant impact on perception of using virtual-interviews. Knowing about the applicants’ attitude toward residency interviews and the national circumstances are essential when preparing the interview guides. Our findings are limited by the small sample size and the low response rate. Further extensive studies are warranted to better understand the perception of residency applicants toward virtual-interviews to improve the interview process in the United States.