Luis Bellido

A rig booking system for on-line laboratories

Recently, many educational institutions have acknowledged the importance of making laboratories available on-line, allowing their students to run experiments from a remote computer. While usage of virtual laboratories scales well, remote experiments, based on scarce and expensive rigs, i.e. physical resources, do not and typically can only be used by one person or cooperating group at a time. It is therefore necessary to administer the access to rigs, where we distinguish between three different roles: content providers, teachers and students. This paper reports on a conceptual model and technical design of a rig booking system that provides mechanisms for content providers and teachers to control and grant access to on-line remote laboratories. The design of the booking system is based on a requirements analysis carried out by the EC funded LiLa project in cooperation with international partners from the Global Online Lab Consortium, GoLC.

A virtualized platform for analyzing LTE broadcast services

Nowadays, users are demanding access to video content anytime and anywhere. LTE broadcast services and video streaming services can reduce the resources used by telecommunication companies to give access to video content and open up new business opportunities. In this context, testbeds and simulation tools can help in the analysis of the different parameters that need to be considered in the deployment of video services based on LTE. In this paper, we describe the design and implementation of an open-source virtualized platform that supports both LTE broadcast services and video streaming services. The testbed is being used both over real LTE networks and LTE network emulations to analyze the performance of video streaming services and to validate new proposals.

A model to evaluate MBSFN and AL-FEC techniques in a multicast video streaming service

In a multicast video streaming service over a cellular network, the same content is sent to a mass audience using a common channel. However, users belonging to the same multicast channel perceive different characteristics of the radio channel. Moreover, in wireless environments, the radio interface introduces an important level of interference and noise, resulting in a high rate of transmission errors. Therefore, a protection of the information is needed at each receiver using Forward Error Correction (FEC) schemes, which allow the recovery of the lost packets sending redundancy together with the payload. FEC solutions can be used in combination with other techniques to overcome the existing limitations of the mobile network, in particular, the use of a single-frequency network to prevent the effect of destructive signal interference. This paper analyzes the performance of a video streaming service comparing different FEC schemes, Raptor and RaptorQ codes, where some system parameters can be tuned in a single-frecuency network.

Reducing Latency for Multimedia Broadcast Services Over Mobile Networks

Multimedia services over mobile networks pose several challenges, such as the efficient management of radio resources or the latency induced by network delays and buffering requirements on the multimedia players. In Long Term Evolution (LTE) networks, the definition of multimedia broadcast services over a common radio channel addresses the shortage of radio resources but introduces the problem of network error recovery. In order to address network errors on LTE multimedia broadcast services, the current standards propose the combined use of forward error correction and unicast recovery techniques at the application level. This paper shows how to efficiently synchronize the broadcasting server and the multimedia players and how to reduce service latency by limiting the multimedia player buffer length. This is accomplished by analyzing the relation between the different parameters of the LTE multimedia broadcast service, the multimedia player buffer length, and service interruptions. A case study is simulated to confirm how the quality of the multimedia service is improved by applying our proposals.

Analysis of the impact of FEC techniques on a multicast video streaming service over LTE

In a multicast video streaming service the same multimedia content is sent to a mass audience using only one multicast stream. In multicast video streaming over a cellular network, due to the nature of the multicast communication, from a source to multiple recipients, and due to the characteristics of the radio channel, different for each receiver, transmission errors are addressed at the application level by using Forward Error Correction (FEC) techniques. However, in order to protect the communication over the radio channel, FEC techniques are also applied at the physical layer. Another important technique to improve the communication of the radio channel is the use of a single-frequency network. This paper analyzes the performance of a video streaming service over a cellular network taking into account the combined impact of different factors that affect the transmission, both the physical deployment of the service and the two levels of FEC.

Experiences with middleware and mobile agents in an e-commerce European project

This paper presents several experiences and conclusions about the usage of the J2EE middleware platform in an e-commerce mediation framework, and introduces mobile agent possibilities within the same environment. The main conclusions are taken from the Smart-EC project, where J2EE and mobility are considered as a value added in its architecture. Other advanced technologies such as XML based multi-device publishing and the utilisation of e-commerce ontologies to handle static and dynamic aspects of complex services or to control their transactional properties, are also considered in the project.

Remote access to computer networking laboratories

This paper discusses the requirements to provide controlled remote access to computer networking experiments and assignments and how these requirements can be fulfilled by an existing framework based on the use of “Lab Learning Objects” (LLOs) that are accessed through a Learning Management System (LMS).

New strategies for learning computer networks

This paper describes experiences in computer networking education with a large number of students based on two kinds of learning activities: personalized exercises and hands-on experiments using virtualization tools. Using an example of each kind of activity the paper explains the process of creating the activity, the software tools that have been developed to support them in the context of a Learning Management System and the impact of the activities in the learning process.

Federated authentication and authorization for reusable learning objects

The LiLa (Library of Labs) project goal is to combine virtual laboratories and remote experiments spread out over Europe, which will be shared and exchanged among educational institutions in the form of reusable learning objects. This work addresses the needs of authentication and authorization when reusable learning objects are exported from an experiment provider organization to an experiment user Learning Management System. The paper discusses possible solutions based on using the SCORM run-time environment specification as a framework for learning objects and Shibboleth as a framework for a federated authentication and authorization.

NFV-based QoS provision for Software Defined Optical Access and residential networks

The promises of SDN and NFV technologies to boost innovation and to reduce the time-to-market of new services is changing the way in which residential networks will be deployed, managed and maintained in the near future. New user-centric management models for residential networks combining SDN-based residential gateways and cloud technologies have already been proposed, providing flexibility and ease of deployment. Extending the scope of SDN technologies to optical access networks and bringing cloud technologies to the edge of the network enable the creation of advanced residential networks in which complex service function chains can be established to provide traffic differentiation. In this context, this paper defines a novel network management model based on a user-centric approach that allows residential users to define and control access network resources and the dynamic provision of traffic differentiation to fulfill QoS requirements.