527 research outputs found
Siting Foreign Law: How Derrida Can Help
Secondary spectrum access to TV white spaces is considered as a promising solution to relieve the spectrum shortage. In Europe, SE43 working group in CEPT is leading the discussion on the technical requirements for exploiting TV white spaces through the recent ECC report 159. Its analytical approach for determining the maximum permissible power for the secondary user, however, overestimates the power level, and leads to significant violation of the interference limit for TV reception. In this letter, we address the problem by proposing a new approach for determining the secondary user transmit power based on the framework established in ECC report 159. Monte Carlo simulation shows that our method keeps the interference lose to the target.QC 20121113QUASA
Assessment of the economic development of Latvia and Ukraine
The global financial crisis and the ensuing global recession not only adversely affected global growth
and poverty, but also presented constraints and challenges to public policy. Even though the world economy is slowly
returning to growth, the recovery was difficult and lasted for almost 10 years. Preparing for the future requires an
assessment of the consequences of the crisis and future challenges. Since 2010 economic growth in Latvia has been
one of the fastest in the EU (from 2011-2018, GDP, on average, increased by 3.5% annually), however in 2019
economic growth has moderated. Growth opportunities are limited both by the uncertainty in the external environment
(“trade wars” on the global economy, the outcome of Brexit, slower growth in EU countries, etc.), and the existing
economic structure, which also negatively affects the competitiveness of Latvian producers. In the competitiveness
rankings regularly published by the World Economic Forum (WEF), Latvia lags far behind other new EU member
states, incl. other Baltic States.
The economy of Ukraine currently is in very difficult environment: carrying out the Anti-terrorism activity in the
eastern part, occupation of Crimea, the uncertainty in the system of political processes, the economic instability and
other factors slow down its development. The deepening of the political and economic crisis in Ukraine, on the one
hand, and transformational processes towards expanding European integration, on the other hand, daily create new
challenges that domestic economic entities have not encountered before, and which are difficult to predict.
The aim of the research is to carry out a comprehensive assessment of the dynamics of macroeconomic indicators
of the social and economic development of the national economies of Latvia and Ukraine over the past 10 years (from
2010 to 2019) and identify the factors influencing it, to improve the forecasting of further trends and the planning of
anti-crisis measures.
As a result of the study, possible directions of economic policy were identified to improve the economic structure
of Latvia and Ukraine in order to promote their sustainable development and competitiveness in the world market
IDEF method-based simulation model design and development
The purpose of this study is to provide an IDEF method-based integrated
framework for a business process simulation model to reduce the model development time
by increasing the communication and knowledge reusability during a simulation project. In
this framework, simulation requirements are collected by a function modeling method
(IDEF0) and a process modeling method (IDEF3). Based on these requirements, a
common data model is constructed using the IDEF1X method. From this reusable data
model, multiple simulation models are automatically generated using a database-driven
simulation model development approach. The framework is claimed to help both
requirement collection and experimentation phases during a simulation project by
improving system knowledge, model reusability, and maintainability through the systematic
use of three descriptive IDEF methods and the features of the relational database
technologies. A complex semiconductor fabrication case study was used as a testbed to
evaluate and illustrate the concepts and the framework. Two different simulation software
products were used to develop and control the semiconductor model from the same
knowledge base. The case study empirically showed that this framework could help
improve the simulation project processes by using IDEF-based descriptive models and the
relational database technology. Authors also concluded that this framework could be easily
applied to other analytical model generation by separating the logic from the dataPeer Reviewe
CellTV - on the Benefit of TV Distribution over Cellular Networks A Case Study
As mobile IP-access is becoming the dominant technology for providing
wireless services, the demand for more spectrum for this type of access is
increasing rapidly. Since IP-access can be used for all types of services,
instead of a plethora of dedicated, single-service systems, there is a
significant potential to make spectrum use more efficient. In this paper, the
feasibility and potential benefit of replacing the current terrestrial UHF TV
broadcasting system with a mobile, cellular data (IP-) network is analyzed. In
the cellular network, TV content would be provided as {one} of the services,
here referred to as CellTV. In the investigation we consider typical Swedish
rural and urban environments. We use different models for TV viewing patterns
and cellular technologies as expected in the year 2020. Results of the
quantitative analysis indicate that CellTV distribution can be beneficial if
the TV consumption trend goes towards more specialized programming, more local
contents, and more on-demand requests. Mobile cellular systems, with their
flexible unicast capabilities, will be an ideal platform to provide these
services. However, the results also demonstrate that CellTV is not a
spectrum-efficient replacement for terrestrial TV broadcasting with current
viewing patterns (i.e. a moderate number of channels with each a high numbers
of viewers). In this case, it is doubtful whether the expected spectrum savings
can motivate the necessary investments in upgrading cellular sites and
developing advanced TV receiver required for the success of CellTV
distribution.Comment: To appear on Trans. Broadcasting 201
A Time Series Based Study of Correlation, Channel Power Imbalance and Diversity Gain in Indoor Distributed Antenna Systems at 60 GHz
In this article, we investigate the potential enhancements in signal reliability which can be achieved using a millimeter-wave distributed antenna system (DAS) within an indoor environment. To achieve this, we measured the signal power simultaneously received at nine ceiling-mounted access point (AP) locations likely to be used in future indoor DAS deployments while a mobile user imitated making a voice call on a hypothetical user equipment. Key metrics, associated with the performance of multiple antenna systems, such as the cross correlation coefficient (CCC) and channel power imbalance (CPI) are determined. It was found that line-of-sight (LOS) and quasi-LOS (QLOS) links with the APs typically led to higher CCC values than the non-LOS (NLOS) cases. Similarly, LOS and QLOS links typically produced higher CPI values between APs than the NLOS case. To enable the reproduction of our results, we have successfully applied autoregressive moving average and autoregressive integrated moving average modeling to the CCC and CPI time series. The performance improvement that can be achieved using a DAS instead of a single AP was evaluated using three commonly deployed diversity combining schemes, namely, selection combining, equal gain combining, and maximal ratio combining along with three AP selection mechanisms, namely, per-sample random AP selection, one-shot AP selection, and per-sample optimal AP selection. Finally, we have provided some useful insight into the influence of differing AP numbers on the diversity gain when considering the aforementioned AP selection methods
Dynamic Resource Management in CDRT Systems through Adaptive NOMA
This paper introduces a novel adaptive transmission scheme to amplify the
prowess of coordinated direct and relay transmission (CDRT) systems rooted in
non-orthogonal multiple access principles. Leveraging the maximum ratio
transmission scheme, we seamlessly meet the prerequisites of CDRT while
harnessing the potential of dynamic power allocation and directional antennas
to elevate the system's operational efficiency. Through meticulous derivations,
we unveil closed-form expressions depicting the exact effective sum throughput.
Our simulation results adeptly validate the theoretical analysis and vividly
showcase the effectiveness of the proposed scheme.Comment: 11 pages, 7 figures, submitted to IEEE journal for revie
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