No abstract

Reducing the power consumed in mobile base stations is an important way to support the effort for energy reduction in communication systems. Mobile base stations are designed for peak load situations, which only occur rarely relative to the overall daily traffic profile. This means, that daily operation of mobile communication networks especially in LTE systems shows a significant amount of time periods without data transmission, leading to reduced average energy efficiency. Sleep modes in base station transceivers, based on the deactivation of components and especially of the power amplifier in time slots of no signal transmission, show a significant potential to reduce the average energy consumption in base stations. This is demonstrated by experimental evaluations, done for different traffic load conditions, on hardware prototypes, dedicated for macro-cell base station. Index Terms -Mobile base stations, power saving, component sleep modes, power amplifiers.

Emisiones de CO 2 ; Producto interior bruto; Consumo de energía; Planes nacionales de asignación Resumen En los últimos años la literatura económica ha prestado especial atención a la relación entre emisiones contaminantes, consumo de energía y actividad económica. Este trabajo pretende profundizar en dicha relación, prestando especial atención al posible efecto que la aplicación de los planes nacionales de asignación ha tenido sobre el comportamiento emisor y energético de los países analizados. En concreto, se estudia si han logrado ser efectivos a la hora de reducir 2 variables clave como son las emisiones de CO 2 y el consumo de energía, incluso cuando se han producido caídas en la actividad económica debido a la crisis de los últimos años. Los países que se han tenido en cuenta para este trabajo son: España, Francia, Alemania, Italia, Portugal y Reino Unido. El periodo considerado es 2000-2010, y se utilizan datos publicados por la Unión Europea relativos a emisiones, asignaciones de derechos, consumo de energía y nivel de producción de los países analizados.

Abstract. Nowadays, energy efficiency has become a major issue in mobile networks operation. Due to the exponential rise in the number of wireless Internet-connected mobile devices reducing electrical energy consumption is not only a matter of showing environmental responsibility, but also of substantially reducing their operational expenditure. However, energy reduction cannot be pursued at any cost and appropriate service has to be supported. Among the diverse hardware and software solutions available, this paper focuses on the dynamic operation of cellular base stations, in which redundant base stations are switched off during periods of low traffic. Besides, we are also describing the use of prediction mechanisms in order to make a proper decision on when to take that action. The proposed schemes are assessed by means simulations using both theoretical and real load models.

After more than ten years of operation of EU-ETS trading, it is time to analyse the results and draw lessons from the experience. Economic research typically considers emission price as the main explanatory variables when measuring the effects of Emission Trading Systems. The novelty of this work is to analyse whether or not trade alone, as an institutional change, is effective in reducing greenhouse gases emissions. The objective of this paper is to analyse to what extent the EU-ETS as a "regulatory" instrument of the supply of allowances is responsible for the effectiveness of the carbon market as a basic tool in the reduction of emissions. The analysis also includes other overlapping policies aimed at fighting climate change, for example, the promotion of renewables. For the empirical analysis, an econometric model is estimated using panel data for the 28 European Union countries between 1990 and 2014. The econometric model include three dummy variables to measure the effectiveness of the three phases of the EU-ETS commerce in reducing emissions. Furthermore, we analyse how effective the phases are when renewables energies are included in the analysis. The results show that the EU-ETS is effective to reduce emissions and each phase has a greater impact on the reduction. Nevertheless, the system should be more flexible to adapt to the fluctuations in the demand for rights.