Mariano Molina Garcia - Academia.edu (original) (raw)

Papers by Mariano Molina Garcia

A software tool for planning and sizing wireless networks based on standard 802.16 is presented i... more A software tool for planning and sizing wireless networks based on standard 802.16 is presented in this paper. Due to the deployment of communication systems based on this standard, it is necessary a tool which allows an easy implementation and sizing of this type of networks. With this tool the user will be able to define technical specifications of transmitters

In enterprise scenarios, multi-femtocell deployments can be carried out to improve indoor service... more In enterprise scenarios, multi-femtocell deployments can be carried out to improve indoor services performance. In this environment, a detailed cell planning can be made in order to optimize network performance. To solve optimization problems in wireless networks, many techniques have been proposed, typically taking the number of base stations to be deployed as an input to the automatic planning process or including them as a fixed cost to assess fitness value. In this paper, a novel genetic algorithm for computer aided optimization of multi-femtocell deployments is presented, assuming that the optimal number of femtocells to fulfill design constraints is unknown. This novel genetic approach is demonstrated using a multi-objective multi-femtocell deployment in a typical enterprise scenario.

Although networks based on IEEE802.11 were originally intended to transport best-effort data traf... more Although networks based on IEEE802.11 were originally intended to transport best-effort data traffic, the appearance of IEEE802.11e has brought about the opportunity of supplying real time voice and conversational video communications with strict requirements of quality of service. The success of these services will depend on the quality achieved in the multicell wireless indoor scenarios, dependent on delay, jitter and packet loss rate in the network deployed. This paper analyzes the concept of user-perceived QoS in audio and video conversational services, and a simple method to predict the impact on speech and conversational video performance of packet loss rate has been proposed. Finally, the paper presents a new procedure to optimize a WLAN network oriented to guarantee perceived quality in real time voice and conversational video services.

2012 42nd European Microwave Conference

ABSTRACT Emerging femtocell networks are conceived to extend radio coverage indoors, giving suppo... more ABSTRACT Emerging femtocell networks are conceived to extend radio coverage indoors, giving support to a high variety of services. In enterprise scenarios, the demand of reliable and accurate indoor Location Based Services (LBS) is gaining momentum. The femtocell network infrastructure can be used to provide location services based on Received Signal Strength Index (RSSI) and fingerprint location techniques. In this paper, an analysis of different propagation models has been carried out to evaluate their suitability for reducing calibration efforts during fingerprint calibration stage. For that purpose, a procedure including both a simulation process and a measurement campaign has been defined. Results obtained will allow adjusting indoor propagation models parameters and evaluating their applicability for reducing calibration effort while improving accuracy in location fingerprint techniques.

Xxv Simposium Nacional De La Union Cientifica Internacional De Radio Xxv Simposium Nacional De La Union Cientifica Internacional De Radio 15 09 2010 17 09 2010 Bilbao Espana, 2010

Long Term Evolution (LTE) has appeared with the aim of improving the performance of 3G networks, ... more Long Term Evolution (LTE) has appeared with the aim of improving the performance of 3G networks, increasing spectral efficiency and peak rates both at downlink and uplink, reducing latency and increasing flexibility of frequency allocation. Therefore, LTE is expected to have a key role in the development of wireless networks and services in the next years, and, of course, in specific dedicated in-building solutions. Due to that fact, an analysis of LTE performance in indoor scenarios in terms of capacity and grade of service is essential, as well as its comparison with other indoor solutions, pointing out the technical challenges derived, and describing and proposing performance assessment rules to be used in LTE deployments.

En los ultimos tiempos, el trafico generado por los usuarios de redes moviles ha crecido de maner... more En los ultimos tiempos, el trafico generado por los usuarios de redes moviles ha crecido de manera muy notable, y se preve que dicho crecimiento se mantenga de manera continuada a lo largo de los proximos anos. El trafico gestionado por redes moviles se ha multiplicado por cinco entre los anos 2010 y 2013, y las predicciones senalan un aumento de diez veces entre 2013 y 2019. De este trafico que deben gestionar las redes moviles, una gran parte se genera en el interior de edificios. En la actualidad, este oscila entre el 70% y el 80% del trafico movil total, y este porcentaje se preve que aumente hasta cerca del 95% en los proximos anos. En esta situacion, con el trafico movil aumentando de manera exponencial, especialmente en interiores, el despliegue de soluciones especificas para estos entornos se antoja imprescindible para evitar situaciones de saturacion constante de las redes moviles. Desde el punto de vista de los operadores moviles, estas soluciones permitiran limitar los problemas de cobertura, mejorar la eficiencia del uso de recursos radio y reducir el coste de las infraestructuras. Asimismo, desde el punto de vista de los usuarios, estos despliegues especificos en interiores permitiran suministrar de manera continua altas tasas de transferencia y satisfacer los altos requisitos de calidad de servicio que demandan los servicios en tiempo real. La complejidad de las actuaciones a realizar para llevar a cabo el despliegue de soluciones especificas en interiores varia considerablemente segun el tipo de entorno al que estan destinadas. Por un lado, las soluciones en escenarios de tipo residencial se caracterizan por despliegues masivos de transmisores realizados por los propios usuarios. De esta manera, no hay posibilidad de realizar ningun tipo de planificacion previa que permita la optimizacion del rendimiento y solo se puede recurrir, para la mejora de este, a metodos de autoconfiguracion y autooptimizacion. Por otro lado, las soluciones en entornos empresariales se caracterizan por la necesidad de realizar una labor de diseno y planificacion previa, cuya dificultad estara asociada a las dimensiones del escenario de despliegue y al numero de transmisores necesarias. De esta labor de diseno y de la configuracion de los elementos involucrados en la solucion desplegada dependera el funcionamiento adecuado de la red, el rendimiento conseguido y la calidad del servicio que se podra suministrar a traves de esta. En esta Tesis Doctoral se abordan dos de los problemas principales en el ambito del despliegue de soluciones especificas de interiores. El primero de ellos es la dificultad para estimar la capacidad y el rendimiento que puede garantizarse mediante soluciones autodesplegadas, y el segundo es la complejidad de disenar y configurar despliegues de soluciones especificas de interiores en entornos empresariales que requieran un numero de transmisores considerable. En el ambito de los autodespliegues en escenarios residenciales, las principales contribuciones originales de esta Tesis Doctoral se centran en el diseno, desarrollo e implementacion de procedimientos que permitan de manera sencilla y precisa la estimacion de la capacidad y el rendimiento en autodespliegues. Por otro lado, en el ambito de los despliegues en escenarios empresariales, las aportaciones originales de esta Tesis consisten en el desarrollo de nuevas tecnicas que permitan el diseno automatico de soluciones especificas de interiores en estos entornos. Los resultados obtenidos han permitido la creacion de herramientas especificas para el analisis del rendimiento de autodespliegues en escenarios residenciales reales y para el diseno y configuracion de despliegues en escenarios empresariales. Estas herramientas permiten sistematizar la aplicacion practica de las contribuciones de la presente Tesis Doctoral. ABSTRACT In recent times, the traffic generated by users of mobile networks has grown very significantly, and this increase is expected to continue steadily over the next few years. Traffic carried by mobile networks has increased fivefold between 2010 and 2013, and forecasts indicate a tenfold increase between 2013 and 2019. Furthermore, a great part of this traffic is generated inside buildings. Currently, between 70% and 80% of mobile traffic occurs inside buildings, and this percentage is expected to increase to about 95% in the coming years. In this situation, with mobile traffic growing exponentially, especially indoors, the deployment of specific solutions for these environments can be essential to avoid a constant saturation of mobile networks. On the one hand, from the point of view of mobile operators, these solutions will help to reduce the problems of coverage, improve the efficiency of radio resource usage and reduce the cost of infrastructures. Also, from the point of view of users, these specific indoor deployments can both guarantee high data transfer rates and meet the high quality of service requirements…

Xvi Jornadas Telecom I D Xvi Jornadas Telecom I D 29 11 2006 01 12 2006 Madrid Espana, 2006

2015 IEEE 81st Vehicular Technology Conference (VTC Spring), 2015

Railway scenarios present several specific features that complicate the deployment of a radio com... more Railway scenarios present several specific features that complicate the deployment of a radio communication network, especially for high speed trains. Nowadays, railway operators are evaluating the migration process from GSM-R to a new broadband system, like Long Term Evolution (LTE). In this paper, system-level simulations are carried out in order to evaluate overall network performance with Mobile Relay Node architecture for LTE uplink access in High Speed Railway scenarios. This implies developing specific tools for accurate characterization of such propagation environments.

2008 IEEE Radio and Wireless Symposium, 2008

In indoor mobile radio environments, the signal strength received in a mobile terminal vary due t... more In indoor mobile radio environments, the signal strength received in a mobile terminal vary due to amplitude fading that can be modelled by several distributions, such as Lognormal, Rayleigh, Rice, Nakagami, Suzuki or Weibull. Unfortunately, the application of these models does not allow to obtain analytical expressions that relate a signal strength value with mean value and typical deviation of

Computers in Railways XIII, 2012

Railway environments cannot be away from the current evolution of public communication systems. T... more Railway environments cannot be away from the current evolution of public communication systems. The Long Term Evolution (LTE) mobile communication system is considered to be the natural evolution for current Global System for Mobile Communications Railways (GSM-R). LTE all IP networking technology plays a key role for the integration and convergence of heterogeneous networks and services, both the specific for the railway operative and the commercial broadband ones for passengers. The adoption of a new generation standard for railway communication must be based on an exhaustive feasibility study of the new system to become the railway mobile communication system. In this paper, LTE's top challenges to address the specific requirements and features of railway communication services are evaluated. Under this scope, LTE features to implement the required railway functionalities, LTE technical challenges, spectrum harmonization, network deployment considerations and LTE capabilities to meet the railway service Reliability, Availability, Maintainability and Safety (RAMS) requirements, are assessed.

2009 IEEE Radio and Wireless Symposium, 2009

Although networks based on IEEE 802.11 was originally intended to transport best-effort data traf... more Although networks based on IEEE 802.11 was originally intended to transport best-effort data traffic, the appearance of IEEE 802.11e has brought about the opportunity of supplying real time voice communications with strict requirements of quality of service. In WLAN IEEE 802.11 networks, the handover process follow a ldquobreak-before-makerdquo mechanism, provoking discontinuities in the communication, which have associated a variation of the packet loss rate, and, therefore, changes in the subjective quality of voice perceived by the user along the communication. It will be necessary to take into account this effect in the planning and sizing process of WLAN networks which have to deal with conversational services. With this purpose, in this paper is illustrated the influence of the horizontal handover events on the evolution of the MOS value for different VoIP codecs and several handover decision algorithms and durations.

IEICE Transactions on Communications, 2014

This paper assesses the main challenges associated with the propagation and channel modeling of b... more This paper assesses the main challenges associated with the propagation and channel modeling of broadband radio systems in a complex environment of high speed and metropolitan railways. These challenges comprise practical simulation, modeling interferences, radio planning, test trials and performance evaluation in different railway scenarios using Long Term Evolution (LTE) as test case. This approach requires several steps; the first is the use of a radio propagation simulator based on ray-tracing techniques to accurately predict propagation. Besides the radio propagation simulator, a complete test bed has been constructed to assess LTE performance, channel propagation conditions and interference with other systems in real-world environments by means of standard-compliant LTE transmissions. Such measurement results allowed us to evaluate the propagation and performance of broadband signals and to test the suitability of LTE radio technology for complex railway scenarios.

2014 44th European Microwave Conference, 2014

Nowadays, the increased use of smartphones, laptops and tablets, has led to an exponential increm... more Nowadays, the increased use of smartphones, laptops and tablets, has led to an exponential increment of mobile data services in high speed mobility scenarios. Under this scope, the 3GPP working group for LTE standardization, is paying more attention to communication in railways environments. This standardization group is promoting the usage of mobile relay nodes for improving performance in high speed railways scenario. In this paper, the authors investigate the issue of mobile relay capacity improvement for on-board train users and its impact on the overall network performance.

2014 28th International Conference on Advanced Information Networking and Applications Workshops, 2014

ABSTRACT Nowadays the number of vehicular users demanding mobile data services greatly increases ... more ABSTRACT Nowadays the number of vehicular users demanding mobile data services greatly increases due to the high penetration rate of smart phones, laptops and tablets. Under this scope, the 3GPP working group for LTE standardization, is paying more attention on vehicular scenarios, like railways environments. The proposed solution for improving performance in high speed railways scenario, is the mobile relay node. The authors focus on Type-1 in-band relays, which have been proposed for LTE-Advanced. In this work, authors investigate the issue of mobile relay capacity improvement for on-board train users and its impact on the overall network performance. Besides, the impact of several key configuration parameters of MRN, like the number of MBSFN sub frames, will be assessed.

2007 IEEE Radio and Wireless Symposium, 2007

IEEE Radio and Wireless Symposium formerly, 2008

En las redes convergentes inalámbricas, el traspaso horizontal entre distintos puntos de acceso d... more En las redes convergentes inalámbricas, el traspaso horizontal entre distintos puntos de acceso de la red WLAN es una gran fuente de degradación de la calidad de la VoIP y otros servicios conversacionales en tiempo real. Esto es debido a que este tipo de redes no fueron concebidas originalmente para soportar este tipo de servicios, y los traspasos siguen un protocolo "cortar antes de realizar", produciéndose interrupciones en la comunicación motivadas por el tiempo que necesitan los terminales en volver a asociarse a la red. En este artículo se estudia el efecto que tienen el tamaño de la ventana de promediado de la señal, la histéresis variable y el retardo del handover por parecido entre potencia de puntos de acceso de destino sobre el número de traspasos y las caídas de la potencia de señal por debajo del valor de sensibilidad del terminal, causantes principales de las interrupciones en la comunicación, y, con ello, de la degradación de la calidad de las comunicaciones.