1,634 research outputs found
MIMO precoding for filter bank modulation systems based on PSVD
In this paper we consider the design of a linearly precoded MIMO transceiver based on filter bank (FB) modulation for transmission over broadband frequency selective fading channels. The modulation FB is capable of lowering the channel dispersion at sub-channel level. Nevertheless, the sub-channels experience some level of inter-symbol interference. Therefore, the pre-coder and the equalizer are designed exploiting the polynomial singular value decomposition (PSVD). In particular, we consider two types of FB system. The first system deploys maximal frequency confined pulses and it is referred to as filtered multitone (FMT) modulation, while the second uses maximal time confined pulses with rectangular impulse response, i.e., it corresponds to the conventional orthogonal frequency division multiplexing (OFDM) system. We compare the performance of the considered systems in terms of capacity over typical WLAN channels, showing that PSVD precoding with FMT can outperform the performance of precoded OFDM in the two-bytwo antenna case especially for moderate to low SNRs
Evaluating the Effects of Farm Programs: Results from Propensity Score Matching
The paper applies a non-parametric propensity score matching approach to evaluate the effects of two types of farm programs (agri-environment (AE) programs and the less favoured area (LFA) scheme) on input use and farm output of individual farms in Germany. The analysis reveals a positive and significant treatment effect of the LFA scheme for farm sales and the area under cultivation. Participants in AE schemes are found to significantly increase the area under cultivation (in particular grassland), resulting in a decrease of livestock densities. Furthermore, participation in AE programs significantly reduced the purchase of farm chemicals (fertilizer, pesticide). We also find substantial differences in the treatment effect between individual farms (heterogeneous treatment effects). Farms which can generate the largest benefit from the program are most likely to participate.evaluation, farm programs, propensity score matching, Agricultural and Food Policy,
Farm Structure and the Effects of Agri-Environmental Programs: Results from a Matching Analysis for European Countries
This paper extends previous research (Pufahl and Weiss, 2009) and applies a semi-parametric propensity score matching approach to evaluate the effects of agrienvironment (AE) programs on input use and farm output of individual farms in eight Member States of the European Union. We find substantial differences in treatment effects between countries. The analysis reveals significant effects of AE participation on production (Germany, France) and farm profits (France, Ireland, United Kingdom). AE participation sporadically reduces the intensity of land use as measured by the purchase of farm chemicals (fertilizer, pesticide) and grazing livestock densities. We also find differences in the treatment effect among farms with different farm size (heterogeneous treatment effects).evaluation, agri-environment programs, propensity score matching, Germany, Italy, Spain, France, Portugal, United Kingdom, The Netherlands, EU-15, Agribusiness, Agricultural and Food Policy,
Dynamical symmetry breaking in transport through molecules
We analyze the interplay between vibrational and electronic degrees of
freedom in charge transport across a molecular single-electron transistor. We
focus on the wide class of molecules which possess quasi-degenerate vibrational
eigenstates, while no degeneracy occurs for their anionic configuration. We
show that the combined effect of a thermal environment and coupling to leads,
involving tunneling events charging and discharging the molecule, leads to a
dynamical symmetry breaking where quasi-degenerate eigenstates acquire
different occupations. This imbalance gives rise to a characteristic asymmetry
of the current versus an applied gate voltage.Comment: 4 pages, 2 figures, revised final published versio
PLC for the smart grid: state-of-the-art and challenges
This paper aims to review systems and applications for power line communications (PLC) in the context of the smart grid. We discuss the main applications and summarise state-of-the-art PLC systems and standards. We report efforts and challenges in channel and noise modelling, as well as in state-of-the-art transmission technology approaches
The Role of Iranian Azeris, Armenians and Georgians in Iran's Economic Relations with the Countries of the South Caucasus
This contribution examines Iran’s economic relations with the South Caucasus through the (admittedly marginal)
roles of Iranian Azeris, Armenians and Georgians. In quantitative terms, such as the movement of
goods, economic interdependency between Iran and the South Caucasus is rather low and the ties are weak.
Because the prevailing understanding of nationality in Iran is primarily of a civic nature, and not least due
to their low numbers, these Iranian minority populations do not form the strong links to the Caucasus that
one might expect
Turkish Georgians: The Forgotten Diaspora, Religion and Social Ties
Turkey is home to a Georgian diaspora of historical origins and of the Laz, a Kartvelian speaking population. This article outlines the historical origins of these transboundary diasporic populations and their importance for contemporary Georgian-Turkish relations in three spheres of societal ties: cultural, religious and business
Initial results on an MMSE precoding and equalisation approach to MIMO PLC channels
This paper addresses some initial experiments using polynomial matrix decompositions to construct MMSE precoders and equalisers for MIMO power line communications (PLC) channels. The proposed scheme is based on a Wiener formulation based on polynomial matrices, and recent results to design and implement such systems with polynomial matrix tools. Applied to the MIMO PLC channel, the strong spectral dynamics of the PLC system together with the long impulse responses contained in the MIMO system result in problems, such that diagonlisation and spectral majorisation is mostly achieved in bands of high energy, while low-energy bands can resist any diagonalisation efforts. We introduce the subband approach in order to deal with this problem. A representative example using a simulated MIMO PLC channel is presented
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