This paper analyzes the channel dispersion of quasi-static multiple-input multiple-output fading channels with no channel state information at the transmitter. We show that the channel dispersion is zero under mild conditions on the fading distribution. The proof of our result is based on Stokes' theorem, which deals with the integration of differential forms on manifolds with boundary. ; Seventh Framework Programme (FP7) (Grant 333680) ; Spanish Government (TEC2009-14504-C02-01) ; Spanish Government (CSD2008-00010) ; Spanish Government (TEC2012-38800-C03-01) ; National Science Foundation (U.S.) (CAREER Award Grant Agreement CCF-1253205)
The material in this paper was presented in part at the 2011 IEEE International Symposium on Information Theory (ISIT), Saint Petersburg, Russia, 31 July-5 August 2011 and the 49th Annual Allerton Conference on Communication, Control and Computing, Monticello, IL, USA, 28-30 September 2011. ; We study the information rates of noncoherent, stationary, Gaussian, and multiple-input multiple-output (MIMO) flat-fading channels that are achievable with nearest neighbor decoding and pilot-aided channel estimation. In particular, we investigate the behavior of these achievable rates in the limit as the signal-to-noise ratio (SNR) tends to infinity by analyzing the capacity pre-log, which is defined as the limiting ratio of the capacity to the logarithm of the SNR as the SNR tends to infinity. We demonstrate that a scheme estimating the channel using pilot symbols and detecting the message using nearest neighbor decoding (while assuming that the channel estimation is perfect) essentially achieves the capacity pre-log of noncoherent multiple-input single-output flat-fading channels, and it essentially achieves the best so far known lower bound on the capacity pre-log of noncoherent MIMO flat-fading channels. Extending the analysis to fading multiple-access channels reveals interesting relationships between the number of antennas and Doppler bandwidth in the comparative performance of joint transmission and time division multiple-access. ; The work of A.T.A was supported in part by the Yousef Jameel Scholarship at the University of Cambridge. T. K. received funding from the European's Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 252663, from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement number 714161), and from the Spanish Ministerio de Economía y Competitividad under grant RYC-2014-16332. The work of A.G.i.F. has been funded by the European Research Council under ERC grant agreements 259663 and 725411.
Background: Data from the Programme for the International Assessment of Adult Competencies (PIAAC) revealed that countries systematically differ in their respondents' literacy, numeracy, and problem solving in technology-rich environments skills; skill levels also vary by gender, age, level of education or migration background. Similarly, systematic differences have been documented with respect to adults' participation in education, which can be considered as a means to develop and maintain skills. From a psychological perspective, motivation to learn is considered a key factor associated with both skill development and participation in (further) education. In order to account for motivation when analyzing PIAAC data, four items from the PIAAC background questionnaire were recently compiled into a motivation-to-learn scale. This scale has been found to be invariant (i.e., showing full weak and partial strong measurement invariance) across 21 countries. Methods: This paper presents further analyses using multiple-group graded response models to scrutinize the validity of the motivation-to-learn scale for group comparisons. Results: Results indicate at least partial strong measurement invariance across gender, age groups, level of education, and migration background in most countries under study (all CFI > .95, all RMSEA < .08). Thus, the scale is suitable for comparing both means and associations across these groups. Conclusions: Results are discussed in light of country characteristics, challenges of measurement invariance testing, and potential future research using PIAAC data.
Background: Despite the importance of lifelong learning as a key to individual and societal prosperity, we know little about adult motivation to engage in learning across the lifespan. Building on educational psychological approaches, this article presents a measure of Motivation-to-Learn using four items from the background questionnaire of the Programme for the International Assessment of Adult Competencies (PIAAC). Methods: We used multiple-group confirmatory factor analyses for ordered categorical data to investigate the scale's dimensionality and measurement invariance across countries. Regression analyses were used to investigate the scale's criterion validity. Results: Results show that the proposed four-item scale fits the data considerably better than the original six-item scale labeled Readiness-to-Learn. Further analyses support the scale's configural, metric (weak) and partial scalar (strong) measurement invariance across 21 countries. As expected, Motivation-to-Learn has significant relations to the working population's engagement in learning in terms of participation in non-formal education over the last 12 months. These relations remain relevant after taking literacy as an indicator of level of education into account. Conclusion: The Motivation-to-Learn scale presented here may be used to indicate adult motivation in cross-country comparisons. The potential of using the scale in future PIAAC analyses and research on adult learning is discussed.
This paper investigates the maximal achievable rate for a given blocklength and error probability over quasi-static multiple-input multiple-output fading channels, with and without channel state information at the transmitter and/or the receiver. The principal finding is that outage capacity, despite being an asymptotic quantity, is a sharp proxy for the finite-blocklength fundamental limits of slow-fading channels. Specifically, the channel dispersion is shown to be zero regardless of whether the fading realizations are available at both transmitter and receiver, at only one of them, or at neither of them. These results follow from analytically tractable converse and achievability bounds. Numerical evaluation of these bounds verifies that zero dispersion may indeed imply fast convergence to the outage capacity as the blocklength increases. In the example of a particular 1 × 2 single-input multiple-output Rician fading channel, the blocklength required to achieve 90% of capacity is about an order of magnitude smaller compared with the blocklength required for an AWGN channel with the same capacity. For this specific scenario, the coding/decoding schemes adopted in the LTE-Advanced standard are benchmarked against the finite-blocklength achievability and converse bounds. ; This work was supported in part by the Swedish Research Council under grant 2012-4571, by the Ericsson Research Foundation under grant FOSTIFT- 12:022, by a Marie Curie FP7 Integration Grant within the 7th European Union Framework Programme under Grant 333680, by the Spanish government (TEC2009-14504-C02-01, CSD2008-00010, and TEC2012-38800-C03-01), and by the National Science Foundation under Grant CCF-1253205. The material of this paper was presented in part at the 2013 and 2014 IEEE International Symposium on Information Theory.
The idea of a general working model of attachment suggests a high consistency among the attachments to different attachment figures. However, many empirical results show that attachments to different attachment figures differ substantially. In this study, 512 emerging adults rated their attachment quality to one parent, the romantic partner, and several friends over three measurement occasions. We used a multilevel structural equation model to examine the degree of consistency and different aspects of specificity. Attachment to parents was strongly associated with the attachment to friends (around r = .4) and less strongly with the attachment to romantic partners (around r = .3). However, most of the variance was specific to the different attachment figures. Attachments to different friends were more strongly correlated with each other than with the attachments to figures of other domains. The results hint at the existence of specific attachment patterns for every domain of attachment figures.
Proceeding of: 2020 IEEE International Symposium on Information Theory (ISIT), Los Angeles, CA, USA, 21-26 June 2020 ; The channel capacity of wireless networks Is often studied under the assumption that the communicating nodes have perfect channel-state information and that interference is always present. In this paper, we study the channel capacity of a wireless network without these assumptions, i.e., a bursty noncoherent wireless network where the users are grouped in cells and the base-station features several receive antennas. We demonstrate that the channel capacity is bounded in the signal-to-noise ratio (SNR) when the number of receive antennas is finite and the probability of presence of interference is strictly positive. ; This work has been supported in part by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant No. 714161), and by the Spanish Ministerio de Economía y Competitividad under Grants RYC-2014-16332 and TEC2016-78434-C3-3-R (AEI/FEDER, EU).
We conducted this realist evaluation study of an organizational health intervention involving 421 low-skilled workers (50% female), half of whom were immigrants, in three companies over six months. Non-profit agencies implemented peer-mentoring and taught peer-mentors and line managers how to enhance social support in order to improve workers' work situation in a participative way. We formulated five mechanisms of change: the company management encouragement mechanism, the role model mechanism, the peer-mentor support mechanism, the line manager support mechanism, and the participative work improvement mechanism. We combined realist evaluation with a quasi-experimental design and process evaluation in a multi-methods approach. Results of multiple group latent change models and qualitative research showed that intervention-group workers perceived increases in peer-mentor support but not in line manager support. Peer-mentors managed to initiate high-quality improvements at work. Intervention-group workers showed significant reductions in blood pressure. Control-group workers experienced more psychosomatic complaints over time in significant contrast to intervention-group workers. Our results suggest that peer-mentoring offers an effective way for low-skilled workers and immigrants to achieve better health. To improve such health effects, a greater focus on line managers' work situations is needed to help them provide support.
China has had an enormous growth of energy and electricity consumption during the last decades. This has been fuelled primarily by using domestic coal resources. Until 1997, annual construction of power stations averaged around 15 GW which was not sufficient to alleviate the demand surplus. Forecasts envisaged continuation of this growth. The majority of power stations is small scale and reather inefficient. Local air pollution is becoming very strong and is increasingly seen as a politi-cal issue. Foreign investment in the power sector has been hampered by bureaucracy and unclear competencies. On the demand side, energy efficiency has improved markedly in the last two dec-ades, albeit from a very low basis. Due to the economic transformation, many proven incentives for efficiency improvement cannot be used any more. The Clean Development Mechanism (CDM) opens a host of possibilities to link foreign investment in the energy supply and demand sectors with projects that enhance efficiency and reduce greenhouse gas emissions. All big industrial countries have been very keen on climate policy coop-eration with China. While the official Chinese negotiation position towards the CDM and climate policy in general has been extremely cautious, many government bodies show great interest. The Asian financial crisis, which led to an electricity oversupply in 1998, gives the possibility to retire the most inefficient power plants. ; China wies in den letzten Jahrzehnten ein enormes Wachstum des Energie- und Stromverbrauchs auf. Es wurde hauptsächlich durch heimische Kohleressourcen gespeist. Bis 1997 belief sich der jährliche Zubau an Kraftwerksleistung auf ca. 15 GW, aber selbst das reichte nicht aus, um den Nachfrageüberhang abzubauen. Die Mehrzahl der Kraftwerke ist klein und ziemlich ineffizient. Die lokale Luftverschmutzung wird sehr stark und zusehends als politisches Problem angesehen. Ausländische Investitionen im Energiesektor sind durch bürokratische Hürden und unklare Kompetenzverteilung behindert worden. Auf der Nachfrageseite ist die Energieeffizienz in den letzten Jahrzehnten stark verbessert worden, allerdings von einer sehr niedrigen Ausgangslage. Aufgrund der ökonomischen Transformation können viele bewährte Anreize zur Effizienzsteigerung nicht mehr eingesetzt werden. Der CDM eröffnet vielfältige Möglichkeiten zur Verbindung von Direktinvestitionen in Energieangebot und - nachfrage. CDM-Projekte erhöhen die Effizienz und verringern Treibhaus-Gasemissionen. Alle großen Industrieländer sind sehr an Klimaschutzkooperation mit China interessiert. Während die offizielle chinesische Verhandlungsposition bezüglich des CDM und Klima-Politik im allgemeinen sehr zurückhaltend ist, sind viele Regierungsinstitutionen sehr stark am CDM interessiert. Die Asienkrise, die 1998 zu einem Angebotsüberhang im Stromsektor führte, ermöglicht die Abschaltung der ineffizientesten Kraftwerke.
Das Werk stellt komprimiert und verständlich die einzelnen Bereiche des universitären Schwerpunkts im Informations- und Kommunikationsrecht dar. Hierbei wird Wert darauf gelegt, die unterschiedlichen Facetten der universitären Ausbildung vollständig zu erfassen. Der Leser kann in diesem Zusammenhang von der reichhaltigen Erfahrung der Autoren profitieren, die allesamt bestens mit der universitären Prüfungspraxis vertraut sind. Neben der Darstellung der einzelnen Teilrechtsgebiete finden Studierende wertvolle Klausurtipps und Hinweise auf Vertiefungsmöglichkeiten. Die Autoren greifen aktuelle Gerichtsentscheidungen sowie Streitstände auf und weisen auf die mögliche Prüfungsrelevanz der Fragestellungen hin.
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Proceeding of: 53rd Asilomar Conference on Signals, Systems, and Computers (ACSSC 2019), 3-6 Nov. 2019, Pacific Grove, CA, USA ; Several emerging wireless communication services and applications have stringent latency requirements, necessitating the transmission of short packets. To obtain performance benchmarks for short-packet wireless communications, it is crucial to study the maximum coding rate as a function of the blocklength, commonly called finite-blocklength analysis. A finiteblocklength analysis can be performed via nonasymptotic bounds or via refined asymptotic approximations. This paper reviews finite-blocklength approximations for the noncoherent Rayleigh block-fading channel. These approximations have negligible computational cost compared to the nonasymptotic bounds and are shown to be accurate for error probabilities as small as 10-8 [super index] and SNRs down to 0 dB. ; A. Lancho has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement number 714161) and from the Swedish Research Council under grant 2016-03293. J. O¨ stman has been supported by the Swedish Research Council under grants 2014-6066 and 2016-03293. T. Koch has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement number 714161) and from the Spanish Ministerio de Economía y Competitividad under grants RYC-2014-16332 and TEC2016-78434-C3-3-R (AEI/FEDER, EU). G. Vazquez-Vilar has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement number 714161) and from the Spanish Ministerio de Economía y Competitividad under grant TEC2016- 78434-C3-3-R (AEI/FEDER, EU).
Proceeding of: IEEE International Symposium on Information Theory (ISIT 2018) ; The capacity-achieving input distribution of the complex Gaussian channel with both average- and peak-power constraint is known to have a discrete amplitude and a continuous, uniformly-distributed, phase. Practical considerations, however, render the continuous phase inapplicable. This work studies the backoff from capacity induced by discretizing the phase of the input signal. A sufficient condition on the total number of quantization points that guarantees an arbitrarily small backoff is derived, and constellations that attain this guaranteed performance are proposed. ; The work of W. Huleihel was supported by the MIT - Technion Postdoctoral Fellowship. The work of Z. Goldfeld was supported by the Rothchild postdoctoral fellowship. The work of T. Koch has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement number 714161), from the Spanish Ministerio de Economíıa y Competitividad under Grants TEC2013-41718-R, RYC-2014-16332, and TEC2016-78434-C3-3-R (AEI/FEDER, EU), and from the Comunidad de Madrid under Grant S2103/ICE-2845. The work of M. Mokshay was supported by NSF grant #1409504.
This article was presented in part at the 2019 IEEE International Symposium on Information Theory, Paris, France, July 2019, and in part at the 2019 53rd Annual Asilomar Conference on Signals, Systems, and Computers, Pacific Grove, CA, USA, November 2019. ; In recent years, the derivation of nonasymptotic converse and achievability bounds on the maximum coding rate as a function of the error probability and blocklength has gained attention in the information theory literature. While these bounds are accurate for many scenarios of interest, they need to be evaluated numerically for most wireless channels of practical interest, and their evaluation is computationally demanding. This paper presents saddlepoint approximations of state-of-the-art converse and achievability bounds for noncoherent, single-antenna, Rayleigh block-fading channels. These approximations can be calculated efficiently and are shown to be accurate for SNR values as small as 0 dB and blocklengths of 168 channel uses or more. ; The work of Alejandro Lancho was supported in part by European Research Council (ERC) through the European Union's Horizon 2020 Research and Innovation Programme under Grant 714161, and in part by the Wallenberg AI, Autonomous Systems, and Software Program. The work of Johan Östman and Giuseppe Durisi was supported by the Swedish Research Council under Grant 2014-6066 and Grant 2016-03293. The work of Tobias Koch was supported in part by the European Research Council (ERC) through the European Union's Horizon 2020 Research and Innovation Programme under Grant 714161 and in part by the Spanish Ministerio de Economía y Competitividad (AEI/FEDER, EU) under Grant RYC-2014-16332 and Grant TEC2016-78434-C3-3-R. The work of Gonzalo Vazquez-Vilar was supported in part by the European Research Council (ERC) through the European Union's Horizon 2020 Research and Innovation Programme Under Grant 71416 and in part by the Spanish Ministerio de Economía y Competitividad (AEI/FEDER, EU) under Grant TEC2016-78434-C3-3-R.
