Nuestros investigadores

Javier Añorga Benito

Publicaciones científicas más recientes (desde 2010)

Autores: Valdivia, L. J., (Autor de correspondencia); Adin, Íñigo; Añorga, Javier; et al.
ISSN 0748-8017  Vol. 35  Nº 2  2019  págs. 561 - 571
A malicious attack on a safety-critical system can derive in an undesired behavior of the system that may result in a failure. In this case, the reliability of the device is decreased, and it might affect directly to safety. Therefore, the security is also an essential issue to consider in the design of safety-critical systems. The main problem when safety and security are considered is to make them work together without interfering each other. A safety-critical device needs to be certified following standards like IEC-61508, and any security mechanisms must not affect this certification. This paper describes a system that integrates safety and security mechanisms to improve reliability without affecting safety certification. With the aim of reaching the required safety level, a redundant system is considered. This system is an n out of m distributed and synchronized voter. The synchronization method is based on the precision time protocol (IEEE-1588) allowing that all devices on a local network have the same time.
Autores: Añorga, Javier, (Autor de correspondencia); Arrizabalaga, Saioa; Sedano, Beatriz; et al.
ISSN 1380-7501  Vol. 77  Nº 7  2018  págs. 7977 - 8000
The popular Internet service, YouTube, has adopted by default the HyperText Markup Language version 5 (HTML5). With this adoption, YouTube has moved to Dynamic Adaptive Streaming over HTTP (DASH) as Adaptive BitRate (ABR) video streaming technology. Furthermore, rate adaptation in DASH is solely receiver-driven. This issue motivates this work to make a deep analysis of YouTube's particular DASH implementation. Firstly, this article provides a state of the art about DASH and adaptive streaming technology, and also YouTube traffic characterization related work. Secondly, this paper describes a new methodology and test-bed for YouTube's DASH implementation traffic characterization and performance measurement. This methodology and test-bed do not make use of proxies and, moreover, they are able to cope with YouTube traffic redirections. Finally, a set of experimental results are provided, involving a dataset of 310 YouTube's videos. The depicted results show a YouTube's traffic pattern characterization and a discussion about allowed download bandwidth, YouTube's consumed bitrate and quality of the video. Moreover, the obtained results are cross-validated with the analysis of HTTP requests performed by YouTube's video player. The outcomes of this article are applicable in the field of Quality of Service (QoS) and Quality of Experience (QoE) management. This is valuable information for Internet Service Providers (ISPs), because QoS management based on assured download bandwidth can be used in order to provide a target end-user's QoE when YouTube service is being consumed.
Autores: Valdivia, Leonardo Jesús, (Autor de correspondencia); Adin, Íñigo; Arrizabalaga, Saioa; et al.
ISSN 1556-6072  Vol. 13  Nº 1  2018  págs. 48 - 55
Most critical applications today depend on computers, so a computer failure can cause financial disaster, serious injury, or even death. In this context, railways are considered a critical application, so they must meet the highest standards of availability and safety. Availability ensures continuous operation of the system, while a safe system must behave correctly in all operating and environmental conditions.