Hugo Coll

Saving Energy in Wireless Local Area Sensor Networks

Many wireless sensor network developers have adopted Bluetooth and Zigbee technologies for sensor communication. However, it has a big problem: the radio coverage is very short; so many sensors are needed to cover wide areas and sensors are expensive. On the other hand, these technologies lack a high bandwidth. IEEE 802.11a/b/g technologies have higher coverage areas and higher bandwidth, but their energy consumption is significantly higher. This paper discusses the energy consumption analytically and gives the considerations that should be taken into account in developing a wireless local area sensor network. Then, we propose a new protocol based on group collaboration to be implemented in these types of networks in order to decrease the energy consumption and save the energy wasted by the whole system. Finally, the protocol proposed is simulated and compared with other protocols available in the Ns2 simulator in order to prove that our solution is better.

Using MANET Protocols in Wireless Sensor and Actor Networks

Although there are several routing protocols for wireless sensor and actor networks (WSAN), none of them have became standard. Now, there are several standard protocols for mobile ad hoc networks (MANET) that have been developed for devices with higher computing features than the sensor nodes. On the other hand, one of the main characteristics of the MANET protocols is their scalability. In this paper, we show the performance of a WSAN, when MANET protocols are used, for several topologies. We will discuss and evaluate which standard protocol is the best one depending on the number of nodes in the topology and depending on their mobility. Finally we will show their comparison. As far as we know, there is not any performance comparison of MANET protocols such as the one presented in this paper.

First Ultra-High-Performance Fibre- Reinforced Concrete Footbridge in Spain: Design and Construction

Abstract Ultra-high-performance fibre-reinforced concrete (UHPFRC) is defined as a cement-based composite material that combines three technical advances in concrete: high compressive strength, presence of steel fibres and flowability. Since UHPFRC is a very expensive material, in order that UHPFRC can be considered as a competitive alternative in structural applications, it is necessary to optimise the design of structural systems. This process leads to UHPFRC lightweight structures that minimise the concrete needs and give solutions more similar to steel than concrete. The innovative design of the 43,5 m span footbridge, constructed only with UHPFRC and placed over the Ovejas ravine in Alicante, Spain, is presented in this paper. The new UHPFRC footbridge has replaced the former design devised in steel due to many factors such as lower construction and maintenance costs, high durability in aggressive environment close to the sea leading to an increase in service life and its aesthetic enhancement. This paper covers several issues about the design and construction of this singular footbridge, such as design justification, structural evaluation, UHPFRC mix design, quality control and construction process at all stages. The static and dynamic load tests performed are also presented. The footbridge over the Ovejas ravine has become the first structure constructed with UHPFRC in Spain, and as far as we know, it is the first truss pedestrian footbridge made only of UHPFRC in the world.

How the Atmospheric Variables Affect to the WLAN Datalink Layer Parameters

There are many issues that affect to WLAN connections (walls, vegetation, rain, objects in the Fresnel zone, etc.). Network designers and telecommunication practitioners must take them into account when they are planning wireless connections between devices. Some studies have demonstrated the implication of the atmospheric variables in the frequency attenuation and in the line of sight of the waves. But, to the extend of our knowledge, there is not any work published that relates the atmospheric variables with the datalink layer parameters of the WLANs. We must take into account that the datalink layer allows us to measure quite more parameters than the physical layer. After a review of the published related works, first, we will show the atmospheric variables measured during two months, and, then we will show the datalink layer parameters that we have been able to measure during those months. Finally, we will discuss the implications of the atmospheric variables in the measured parameters and we will estimate the laws followed by our measurements.

A Multisensor Proposal for Wireless Sensor Networks

Every sensor node in a wireless sensor network (WSN) has a microcontroller, a transmitter/receiver and a sensor. It is able to acquire data from specific point in a real environment and transmit it through the WSN. Sometimes it is useful to gather different type of data from the same place in order to obtain a final result. In the related literature, very few works are about sensing different parameters using a unique sensor. In this paper we propose a Wireless IP multisensor that is able to gather several types of data from the environment and transmit the result of their combination. Our proposal decision has being mainly based on its development costs, its expansion capacity and its flexibility to add more features to the sensor node. We will show all the characteristics of our proposal and its application areas. A comparison with other wireless IP sensors will be also provided.

Does ns2 Really Simulate MPLS Networks

Multi Protocol Label Switching (MPLS) is being used in many corporate networks and public infrastructures and as a backbone technology of many Autonomous Systems. Because of its importance, what is needed is to find out simulators able to simulate MPLS networks whose results reflect the real environment as much as possible. In this article, we will show real measurements from the Railway Infrastructure Administrator (ADIF, the Spanish railway infrastructure manager) MPLS network and we will compare them with the results obtained by the freeware simulator ns2. We will check the level of reliability provided by the simulator and we will know under which parameters its results will be similar with those obtained from the real network. These results could be taken into account later to simulate real-time critical services over MPLS networks.

Aprender de los errores. Una manera de adquirir responsabilidad ética, medioambiental y profesional

En esta comunicacion se presenta el modo en que se ha introducido la competencia transversal “Responsabilidad etica, medioambiental y profesional” en la asignatura “Materiales de Construccion y sus aplicaciones a la ingenieria civil” de segundo curso de grado, para garantizar la adquisicion de un nivel de dominio I. El mayor logro de este trabajo es tener presente la competencia transversal en todas las sesiones de trabajo en el aula a lo largo del curso, por lo que la competencia pasa a formar parte del trabajo diario del alumno. Ademas presente ventajas en cuando a la adquisicion de evidencias y facilita la evaluacion de la misma.

Mixing collaborative learning techniques for practice evaluation in networking

Generally, every higher education subject is based on a unique teaching methodology. So, the skills learned by the students are focused to a unique goal in each subject and it is needed many subjects, using different learning methods, to develop several skills. This paper deals with a learning method that is being used in the practices of a postgraduate course in the Higher Polytechnic School of Gandia. The proposed method is broken down into several stages and each stage is based on the previous one. Every stage tries to enhance a specific skill although all stages use a collaborative method, not only inside groups, but even between groups. The paper will show the results given by a survey, where the students give their feedback anonymously, and we will discuss the measurements taken.