Javier Simó | Universidad Rey Juan Carlos (original) (raw)

Papers by Javier Simó

Frontiers in Public Health

Rural areas in developing countries are characterized by lack of resources, low population densit... more Rural areas in developing countries are characterized by lack of resources, low population density, and scarcity of communications infrastructure. These circumstances make it difficult to provide appropriate health-care services. This paper explains research results achieved by Enlace Hispano Americano de Salud - Hispano American Health Link (EHAS) and how they have contributed to improve healthcare in isolated areas of developing countries through the use of information and communication technologies (ICT). As the first step, EHAS always collaborates with public health systems to identify its communication and information needs. Based on the analysis of needs, EHAS does research on appropriate technologies to provide communication in each context and on information systems suited to needs of health personnel. In parallel, EHAS has worked to provide applications that, making use of the communications services installed, could improve the health-care services in these remote areas. I...

WiFi based Long Distance (WiLD) networks have been successfully deployed in rural areas of develo... more WiFi based Long Distance (WiLD) networks have been successfully deployed in rural areas of developing countries, thus providing Internet access and VoIP telephony services to previously isolated regions. However, it is well known that the standard CSMA/CA MAC protocol used by WiFi is not well suited for long distances. To achieve better performance, some researchers have proposed replacing the standard CSMA/CA MAC with a TDMA-based MAC, while others have tried to optimize timing parameters in the IEEE 802.11e EDCA standards. This paper is an experimental comparison of the two approaches for point-to-point links. We measure the throughput and delay in various test scenarios by varying the distance of point-to-point links in a controlled environment created using a wireless channel emulator. As far as we know, this is the first experimental comparison between a TDMA-based MAC solution over 802.11 with the IEEE 802.11e EDCA standard optimized for long distances. Finally, we illustrate ...

El estándar IEEE 802.11, ideado con el propósito de posibilitar las redes locales inalámbricas, s... more El estándar IEEE 802.11, ideado con el propósito de posibilitar las redes locales inalámbricas, se ha empleado en ocasiones realizar enlaces de varios kilómetros y construir redes de cierta extensión, aunque no se adapta bien a esas distancias. No obstante, los estudios formales del MAC de IEEE 802.11 (también llamado WiFi) incluyen simplificaciones que los hacen inaplicables a las largas distancias; poco se sabe del comportamiento que se puede esperar en una determinada instalación con enlaces de ese rango. En este trabajo se va a estudiar el estándar IEEE 802.11 desde la perspectiva de su aplicabilidad a zonas rurales aisladas, y se presentan unas pruebas realizadas con el objeto de conocer el comportamiento de WiFi en enlaces con distancias entre 3 y 88Km.

IEEE Transactions on Wireless Communications

Convex optimization and dual decomposition have been successfully used to design cross-layer reso... more Convex optimization and dual decomposition have been successfully used to design cross-layer resource allocation algorithms for cellular access networks. However, less effort has been devoted to design optimal algorithms for systems equipped with relay stations. Presence of relay stations renders the design of the access schemes more difficult and requires consideration of additional constraints. The present paper relies on a sum-utility constrained maximization framework to design cross-layer algorithms that guarantee diverse quality of service (QoS) and consider different forwarding strategies at the relay stations. One of the main challenges in the design is the joint consideration of both long-term (elastic) and short-term (real-time) constraints. Such constraints account for diverse delay QoS requirements and relay forwarding strategies. A two-step methodology is proposed to efficiently deal with this challenge. Specifically, for each time instant it applies: a) an approximate ...

This paper presents the business context and results of an optimisation exercise for a single-rad... more This paper presents the business context and results of an optimisation exercise for a single-radio mid-range multi-hop wireless mesh network for the provision of VoIP services. Tweaking state of the art technology, this wireless mesh network (WMN) physically covers 30 square kilometres in rural South Africa with a dozen solar-powered nodes. Measurement of a range of values revealed a SlotTime setting that maximises aggregated throughput in this network by 115%. These results have allowed several simultaneous calls in the case study presented. Following the same optimization strategy similar improvements are expected in WMN sharing the same characteristics. We argue that this architecture is comparable yet cheaper and easier to install and maintain than multi-radio systems with directive antennas. We leverage this finding by proposing a win-win business case for a ground up community-based mesh network. Local residents benefit from free internal calls backed up by revenues from low ...

This paper presents the work done thus far towards designing a sustainable business model for rur... more This paper presents the work done thus far towards designing a sustainable business model for ruraltelephony in the community of Mankosi, located in the Eastern Cape province of South Africa. Thepillars of the model are sustainability and community ownership to design both the wireless meshnetwork providing the telephony service and its business model. Given the airtime consumption patternin the community, the model is based only on the provision of calls inside the community and for usingsolar power to charge mobile phones. Some scenarios with different usage of the telephony servicesand different pricing rates are explored in order to find the break even point of the network, or in casethe CAPEX was provided externally, to calculate the revenues expected. These revenues could be usedfor projects that benefit the community at large. Although the project is in its initial phase and thecommunity has some particularities that make it unique, the sustainable business model presented he...

Little is known about how mid-range, or several km, distances affect multipoint-to-multipoint lin... more Little is known about how mid-range, or several km, distances affect multipoint-to-multipoint links when single radio nodes with omnidirectional antennas are used. In this poster, a real network with these characteristics is described and empirical results of its performance are presented. In particular, the effect of increasing the SlotTime value for optimizing the aggregated throughput has been analyzed. Results show the need to increase the SlotTime to considerably bigger values than those oberved for point-to-point and point-to-multipoint long-range links. With the new value of SlotTime, an increase of 115% in aggregated throughput was obtained over the standard Slottime value.

Journal of Telemedicine and Telecare

A systematic review of telemedicine projects in Colombia was conducted. We searched electronic da... more A systematic review of telemedicine projects in Colombia was conducted. We searched electronic databases, and also searched for relevant Internet websites. Each project manager was contacted by telephone to identify projects which had not actually been carried out. They were interviewed to request information about the projects they were managing, and whether they knew of other projects in Colombia. The search process identified 43 different projects, which were classified into two groups: telemedicine research initiatives and projects for providing health-care services via telemedicine. There were 32 projects which provided telemedicine services, of which 14 had been finished, 11 remained active, 4 were being implemented and no data were available about the state of the other 3. Health-care services had been provided using telemedicine to at least 550,000 patients. The projects had connected more than 650 health-care institutions, mainly in deprived areas of the country. Unfortunat...

IEEE Technology and Society Magazine

In general terms, technology is born as the indirect consequence of social demands that are ident... more In general terms, technology is born as the indirect consequence of social demands that are identified by researchers as interesting problems to solve; in solving the problem, they produce new knowledge. If they think they will obtain benefits, manufacturers and service providers take those results and produce products and services that satisfy that demand. Undoubtedly, there exist social needs that cannot be covered while obtaining benefit. If a society considers covering those needs to be a social priority, then complementary measurements should be taken to adequately promote innovation.

BioMedical Engineering OnLine

BACKGROUND: Acute respiratory infections are the leading cause of childhood mortality. The lack o... more BACKGROUND: Acute respiratory infections are the leading cause of childhood mortality. The lack of physicians in rural areas of developing countries makes difficult their correct diagnosis and treatment. The staff of rural health facilities (health-care technicians) may not be qualified to distinguish respiratory diseases by auscultation. For this reason, the goal of this project is the development of a tele-stethoscopy system that allows a physician to receive real-time cardio-respiratory sounds from a remote auscultation, as well as video images showing where the technician is placing the stethoscope on the patient's body. METHODS: A real-time wireless stethoscopy system was designed. The initial requirements were: 1) The system must send audio and video synchronously over IP networks, not requiring an Internet connection; 2) It must preserve the quality of cardiorespiratory sounds, allowing to adapt the binaural pieces and the chestpiece of standard stethoscopes, and; 3) Card...

Advances in Intelligent Systems and Computing, 2015

4th IET Seminar on Appropriate Healthcare Technologies for Developing Countries, 2006

Isolated rural areas often lack for any terrestrial telecommunication networks, specially in deve... more Isolated rural areas often lack for any terrestrial telecommunication networks, specially in developing countries, which supposes an important obstacle for offering health assistance of acceptable quality. On the other hand, low density and low concentration of population, lack of electricity in many points and accessibility problems make difficult to propose realistic solutions based on conventional technologies. This work presents the development of an autonomous solarpowered wireless node for lowcost static mesh networks. IEEE 802.11 is used for communications among nodes. The network is QoSaware at the IP level providing reliable VoIP services, and nodes contain a software PBX so that any two nodes in the network can establish a multihop VoIP communication.

quaderns internacionals] de tecnologia per al desenvolupament humà 001_ Software lliure en països... more quaderns internacionals] de tecnologia per al desenvolupament humà 001_ Software lliure en països en vies de desenvolupament de l'Àfrica Subsahariana: el cas de Benín Francisco Javier Simó Reigadas

IFIP International Federation for Information Processing, 2006

Ad-hoc wireless networks are constituted by routers enabled to establish wireless links among the... more Ad-hoc wireless networks are constituted by routers enabled to establish wireless links among them in a mesh topology. This kind of networks are becoming very popular because of their potential, low cost and ease of deployment, specially when IEEE 802.11b wireless technology is used. There has been a lot of research in the design of protocols and algorithms for improving the performance of this kind of networks, and there have also been many efforts in studying the particular characteristics of their behavior for packet switching, specially when realtime traffic is a concern. However, real implementations and testbeds are scarce, and even those few well known interesting experiences are not QoS-aware and their implementation details are not consistent. This paper presents the design of a 802.11b multi-hop QoS-aware mesh network specifically designed for isolated rural environments by means of adapting the most appropriated software implementations available for IP auto-configuration, QoS-aware traffic control and dynamic multi-hop routing. This proposed network is used as a testbed for driving some initial experiments that aim to measure its performance when supporting both elastic and real-time traffic. The evaluation includes guidelines for a QoS-aware deployment of the network and recommendations for further work that can improve these results.

Proceedings of the 3rd Extreme Conference on Communication The Amazon Expedition - ExtremeCom '11, 2011

Isolated rural areas of developing countries often lack of any kind of communications infrastruct... more Isolated rural areas of developing countries often lack of any kind of communications infrastructure. There are some WiFi for Long Distances (WiLD) networks that have been deployed successfully in forests and mountainous regions of countries such as India, Colombia and Peru, for providing Voice over IP and Internet support to health centers. In this work a real telemedicine WiFi network deployed in the Amazonian jungle of Peru is introduced. Technical and social considerations taken into account and devices used for its deployment in such a difficult context are described together with the services provided. Furthermore, performance of this multihop network is analyzed in order to provide a better insight of its behavior. As a conclusion, we describe future and present works related to the improvement of the network.