Interplay of spectral efficiency, power and doppler spectrum for reference-signal-assisted wireless communication

Expressions relating spectral efficiency, power, and Doppler spectrum, are derived for Rayleigh-faded wireless channels with Gaussian signal transmission. No side information on the state of the channel is assumed at the receiver. Rather, periodic reference signals are postulated in accordance with the functioning of most wireless systems. The analysis relies on a well-established lower bound, generally tight and asymptotically exact at low SNR. In contrast with most previous studies, which relied on block-fading channel models, a continuous-fading model is adopted. This embeds the Doppler spectrum directly in the derived expressions, imbuing them with practical significance. Closed-form relationships are obtained for the popular Clarke-Jakes spectrum and informative expansions, valid for arbitrary spectra, are found for the low- and high-power regimes. While the paper focuses on scalar channels, the extension to multiantenna settings is also discussed.

High-SNR power offset in multiantenna communication

The analysis of the multiantenna capacity in the high-SNR regime has hitherto focused on the high-SNR slope (or maximum multiplexing gain), which quantifies the multiplicative increase as function of the number of antennas. This traditional characterization is unable to assess the impact of prominent channel features since, for a majority of channels, the slope equals the minimum of the number of transmit and receive antennas. Furthermore, a characterization based solely on the slope captures only the scaling but it has no notion of the power required for a certain capacity. This paper advocates a more refined characterization whereby, as function of SNRjdB, the high-SNR capacity is expanded as an affine function where the impact of channel features such as antenna correlation, unfaded components, etc, resides in the zero-order term or power offset. The power offset, for which we find insightful closed-form expressions, is shown to play a chief role for SNR levels of practical interest.

Spectral efficiency in reference-signal-assisted low-power wireless communication

Expressions relating spectral efficiency, power and Doppler spectrum are derived for low-power Rayleighfaded wireless channels with proper complex signaling. Noside information on the state of the channel is assumed at the receiver. Rather, periodic reference signals are postulated inaccordance with the functioning of most wireless systems. In contrast with most previous studies, which relied on block-fading channel models, a continuous-fading model is adopted. This embeds the Doppler spectrum directly in thederived expressions thereby imbuing them with practical significance.

Optimum pilot overhead in wireless communication: a unified treatment of continuous and block-fading channels

The optimization of the pilot overhead in wireless fading channels is investigated, and the dependence of this overhead on various system parameters of interest (e.g., fading rate, signal-to-noise ratio) is quantified. The achievable pilot-based spectral efficiency is expanded with respect to the fading rate about the no-fading point, which leads to an accurate order expansion for the pilot overhead. This expansion identifies that the pilot overhead, as well as the spectral efficiency penalty with respect to a reference system with genie-aided CSI (channel state information) at the receiver, depend on the square root of the normalized Doppler frequency. It is also shown that the widely-usedblock fading model is a special case of more accurate continuous fading models in terms of the achievable pilot-based spectral efficiency. Furthermore, it is established that the overhead optimization for multiantenna systems is effectively the same as for single-antenna systems with thenormalized Doppler frequency multiplied by the number of transmit antennas.

La campaña institucional “rumanos en Europa”, como fenómeno integrador ante la inmigración en España e Italia

La inmigración rumana en España e Italia ha constituido un fenómeno único, tanto por su magnitud como por el corto espacio de tiempo en el que se ha producido. Sin embargo, existe una evidente percepción negativa de los españoles e italianos hacia los rumanos, que se debe en una medida considerable al discurso mediático. Dadas las situaciones, el Gobierno rumano llevó a cabo una campaña institucional, para corregir la imagen generalizada hacia los ciudadanos rumanos, que tuvo dos propósitos: la integración y la aceptación. El presente trabajo representa un proyecto de investigación de los efectos de dicha campaña entre los inmigrantes rumanos y las comunidades autóctonas de los dos países: Italia y España. El diseño de la investigación se centra en dos ciudades con un número elevado de inmigrantes rumanos, como son Barcelona y Milano. Se utiliza el análisis cualitativo, representado por los grupos de discusión, para indagar las opiniones, los sentimientos de afinidad, indiferencia o rechazo del público objeto hacia la campaña.

La evolución de la teoría de los efectos de los medios de comunicación de masas: la teoría de la espiral del silencio a partir de la construcción de la realidad social por parte de los medios de comunicación de masas

Este trabajo estudia la evolución de la teoría de los efectos de los medios decomunicación de masas desde su origen, a principios del siglo XX en el contextonorteamericano de la Mass Communication Research, hasta la fecha. Para ello, repasalos diferentes paradigmas en el análisis de la comunicación y sus teorías, haciendo unespecial énfasis en el contexto histórico en que se dan, así como los paradigmassociológicos y psicológicos simultáneos. El trabajo se centra en la teoría de la espiraldel silencio de Noelle-Neumann, como consecuencia de la construcción social de larealidad a partir de los medios de comunicación, y analiza los efectos psicosociales de dicha teoría, principalmente el miedo al aislamiento, la percepción del clima de opinióny la voluntad de expresar opiniones en público.

One person in the battlefield is not a warrior: Self-construal, perceived ability to make a difference, and socially responsible behavior

We suggest that cultivating an individual's connectedness to others promotes sociallyresponsible behavior both directly and indirectly through increased perceived abilityto make a difference. Individuals whose interdependent self is more prominent feel theyhave more of an impact on larger scale societal outcomes and, therefore, engage more insocially responsible behaviors than do individuals whose independent self is moreprominent. We test these hypotheses in two experiments in which participants makefinancial contributions or exert an effort for a social cause. In a survey, we find thatperceived effectiveness mediates the effect of self-construal on socially responsibleconsumption.

Social security, retirement, and the single-mindedness of the electorate

We propose a positive theory that is consistent with two important featuresof social security programs around the world: (1) they redistributeincome from young to old and (2) they induce retirement. We construct avoting model that includes a political campaign or debate prior to theelection. The model incorporates single-mindedness of the groups that donot work: while the workers divide their political capital between their age concerns and occupational concerns , the retired concentrate alltheir political capital to support their age group. In our model, theelderly end up getting transfers from the government (paid by the young)and distortionary labor income taxes induce the retirement of the elderly.In addition, our model predicts that occupational groups that work morewill tend to have more political power. The opposite is true fornon-occupational groups (such as the elderly). We provide some evidencethat supports these additional predictions.

The intra-generational redistributive effects of social security

This paper provides a quantitative evaluation of the intra--cohortredistributive elements of the United States social security system in thecontext of a computable general equilibrium model. I determine how thewell--being of individuals that differ across {\sl gender, race} and {\sl education}is affected by government social security policy. I find that females, whitesand non--college graduates stand less to gain (lose) from reductions(increases) in the size of social security than males, non--whites andcollege graduates, respectively. Differences in mortality risk and laborproductivity translate into differences in the magnitudes of capitalaccumulation and labor supply distortions, that are responsible for theobserved welfare difference between types. Results imply that the currentprogram is lifetime progressive across gender and education, yet lifetimeregressive across race.

A reflection about the social and technological aspects in flood risk management - the case of the Italian Civil Protection

The right of a person to be protected from natural hazards is a characteristic of the social and economical development of the society. This paper is a contribution to the reflection about the role of Civil Protection organizations in a modern society. The paper is based in the inaugural conference made by the authors on the 9th Plinius Conference on Mediterranean Storms. Two major issues are considered. The first one is sociological; the Civil Protection organizations and the responsible administration of the land use planning should be perceived as reliable as possible, in order to get consensus on the restrictions they pose, temporary or definitely, on the individual free use of the territory as well as in the entire warning system. The second one is technological: in order to be reliable they have to issue timely alert and warning to the population at large, but such alarms should be as "true" as possible. With this aim, the paper summarizes the historical evolution of the risk assessment, starting from the original concept of "hazard", introducing the concepts of "scenario of event" and "scenario of risk" and ending with a discussion about the uncertainties and limits of the most advanced and efficient tools to predict, to forecast and to observe the ground effects affecting people and their properties. The discussion is centred in the case of heavy rains and flood events in the North-West of Mediterranean Region.

Qüestionari de trajectòria educativa i capital social acadèmic

Projecte de recerca (EDU2011-25960) Ministerio de Economía y Competitividad

Qüestionari de percepció de recolzament social. Context comunitari, educatiu i familiar

Projecte de recerca (EDU2011-25960) Ministerio de Ciencia e Innovación.

Qüestionari de percepció de recolzament social. Context comunitari, educatiu i familiar

Projecte de recerca (EDU2011-25960) Ministerio de Ciencia e Innovación.

Qüestionari de trajectòria educativa i capital social acadèmic

Projecte de recerca (EDU2011-25960) Ministerio de Economía y Competitividad

Conflictivitat comunicativa en episodis d'emergència: aproximació a la cobertura informativa i la gestió institucional de l'esfondrament d'un túnel del metro al barri del Carmel de Barcelona

En aquesta investigació s’estudien els processos de producció de la informacióper part dels mitjans de comunicació i la gestió comunicativa institucional en episodis d’emergència. En concret, s’analitzen les negociacions entre els actors, les fonts informatives i el respecte deontològic en la divulgacióde les notícies. Per tal de conèixer específicament aquesta conflictivitat,s’ha escollit per a l’estudi de cas l’esfondrament d’un túnel del metro albarri del Carmel de Barcelona el gener de 2005. Per a realitzar aquesta investigació,s’ha utilitzat una perspectiva teòrica multidisciplinària. S’han pres en consideració els postulats teòrics de la sociologia, a partir del diàleg queestableixen diferents autors (Beck, Giddens, Lash i Luhmann) entre el conceptede modernitat i el nou paradigma que Beck (1998) denomina la societat del risc. També s’han tingut en compte els camps de la teoria i la sociologia de la comunicació i, més específicament, el marc teòric del periodisme i de les relacions públiques.