18 research outputs found
DCU 250 Arabic dependency bank: an LFG gold standard resource for the Arabic Penn treebank
This paper describes the construction of a dependency bank gold standard for Arabic, DCU 250 Arabic Dependency Bank (DCU 250), based on the Arabic Penn Treebank Corpus (ATB) (Bies and Maamouri, 2003; Maamouri and Bies, 2004) within the theoretical framework of Lexical Functional Grammar (LFG). For parsing and automatically extracting grammatical and lexical resources from treebanks, it is necessary to evaluate against established gold standard resources. Gold standards for various languages have been developed, but to our knowledge, such a resource has not yet been constructed for Arabic. The construction of the DCU 250 marks the first step
towards the creation of an automatic LFG f-structure annotation algorithm for the ATB,
and for the extraction of Arabic grammatical and lexical resources
Continual Learning-Based MIMO Channel Estimation: A Benchmarking Study
With the proliferation of deep learning techniques for wireless
communication, several works have adopted learning-based approaches to solve
the channel estimation problem. While these methods are usually promoted for
their computational efficiency at inference time, their use is restricted to
specific stationary training settings in terms of communication system
parameters, e.g., signal-to-noise ratio (SNR) and coherence time. Therefore,
the performance of these learning-based solutions will degrade when the models
are tested on different settings than the ones used for training. This
motivates our work in which we investigate continual supervised learning (CL)
to mitigate the shortcomings of the current approaches. In particular, we
design a set of channel estimation tasks wherein we vary different parameters
of the channel model. We focus on Gauss-Markov Rayleigh fading channel
estimation to assess the impact of non-stationarity on performance in terms of
the mean square error (MSE) criterion. We study a selection of state-of-the-art
CL methods and we showcase empirically the importance of catastrophic
forgetting in continuously evolving channel settings. Our results demonstrate
that the CL algorithms can improve the interference performance in two channel
estimation tasks governed by changes in the SNR level and coherence time
Domain Generalization in Machine Learning Models for Wireless Communications: Concepts, State-of-the-Art, and Open Issues
Data-driven machine learning (ML) is promoted as one potential technology to
be used in next-generations wireless systems. This led to a large body of
research work that applies ML techniques to solve problems in different layers
of the wireless transmission link. However, most of these applications rely on
supervised learning which assumes that the source (training) and target (test)
data are independent and identically distributed (i.i.d). This assumption is
often violated in the real world due to domain or distribution shifts between
the source and the target data. Thus, it is important to ensure that these
algorithms generalize to out-of-distribution (OOD) data. In this context,
domain generalization (DG) tackles the OOD-related issues by learning models on
different and distinct source domains/datasets with generalization capabilities
to unseen new domains without additional finetuning. Motivated by the
importance of DG requirements for wireless applications, we present a
comprehensive overview of the recent developments in DG and the different
sources of domain shift. We also summarize the existing DG methods and review
their applications in selected wireless communication problems, and conclude
with insights and open questions
Super-Wideband Massive MIMO
We present a unified model for connected antenna arrays with a massive (but
finite) number of tightly integrated (i.e., coupled) antennas in a compact
space within the context of massive multiple-input multiple-output (MIMO)
communication. We refer to this system as tightly-coupled massive MIMO. From an
information-theoretic perspective, scaling the design of tightly-coupled
massive MIMO systems in terms of the number of antennas, the operational
bandwidth, and form factor was not addressed in prior art and hence not clearly
understood. We investigate this open research problem using a physically
consistent modeling approach for far-field (FF) MIMO communication based on
multi-port circuit theory. In doing so, we turn mutual coupling (MC) from a foe
to a friend of MIMO systems design, thereby challenging a basic percept in
antenna systems engineering that promotes MC mitigation/compensation. We show
that tight MC widens the operational bandwidth of antenna arrays thereby
unleashing a missing MIMO gain that we coin "bandwidth gain". Furthermore, we
derive analytically the asymptotically optimum spacing-to-antenna-size ratio by
establishing a condition for tight coupling in the limit of large-size antenna
arrays with quasi-continuous apertures. We also optimize the antenna array size
while maximizing the achievable rate under fixed transmit power and
inter-element spacing. Then, we study the impact of MC on the achievable rate
of MIMO systems under light-of-sight (LoS) and Rayleigh fading channels. These
results reveal new insights into the design of tightly-coupled massive antenna
arrays as opposed to the widely-adopted "disconnected" designs that disregard
MC by putting faith in the half-wavelength spacing rule
From Multilayer Perceptron to GPT: A Reflection on Deep Learning Research for Wireless Physical Layer
Most research studies on deep learning (DL) applied to the physical layer of
wireless communication do not put forward the critical role of the
accuracy-generalization trade-off in developing and evaluating practical
algorithms. To highlight the disadvantage of this common practice, we revisit a
data decoding example from one of the first papers introducing DL-based
end-to-end wireless communication systems to the research community and
promoting the use of artificial intelligence (AI)/DL for the wireless physical
layer. We then put forward two key trade-offs in designing DL models for
communication, namely, accuracy versus generalization and compression versus
latency. We discuss their relevance in the context of wireless communications
use cases using emerging DL models including large language models (LLMs).
Finally, we summarize our proposed evaluation guidelines to enhance the
research impact of DL on wireless communications. These guidelines are an
attempt to reconcile the empirical nature of DL research with the rigorous
requirement metrics of wireless communications systems
Optimization of a cationic dye desorption from a loaded-lignocellulosic biomass: factorial design experiments and investigation of mechanisms
The sustainable management of loaded adsorbents with organic pollutants represents an important environmental challenge. The current research work investigates the regeneration process optimization of raw orange tree sawdust (ROS) loaded with methylene blue (MB) by using NaCl solutions as eluent. The MB desorption was assessed in static mode under different process variables, notably the desorbing NaCl solutionâs pH and concentration and the MB-loaded biomass dose. A full factorial design composed of 24 experiments was employed to apprehend the statistical significance of each followed parameter. Experimental results showed that the maximum desorption yield was estimated to be about 82.4% for the following parameterâs values: aqueous pH 3, [NaCl] 0.2 M and MB-loaded-ROS dosage in the desorbing solution 1Â gL. The statistical study confirmed the good fit of the experimental data with the statistical model used as well as regression and adjusted regression coefficients of about 99.0% and 96.6%, respectively. Moreover, the ranking of the effect of each studied parameter in terms of standardized effect on the desorption efficiency of MB from ROS was assessed through ANOVA test. The desorption mechanisms involved were explored by using multiple analysis techniques. It appears that the MB moleculesâ desorption from ROSâs particles is mainly driven by a counter chemisorption process based on cationic exchange with the sodium and hydronium ions present in the desorbing solutions
Optimization of a cationic dye desorption from a loaded-lignocellulosic biomass: factorial design experiments and investigation of mechanisms
The sustainable management of loaded adsorbents with organic pollutants represents an important environmental challenge. The current research work investigates the regeneration process optimization of raw orange tree sawdust (ROS) loaded with methylene blue (MB) by using NaCl solutions as eluent. The MB desorption was assessed in static mode under different process variables, notably the desorbing NaCl solutionâs pH and concentration and the MB-loaded biomass dose. A full factorial design composed of 24 experiments was employed to apprehend the statistical significance of each followed parameter. Experimental results showed that the maximum desorption yield was estimated to be about 82.4% for the following parameterâs values: aqueous pH 3, [NaCl] 0.2 M and MB-loaded-ROS dosage in the desorbing solution 1Â gL. The statistical study confirmed the good fit of the experimental data with the statistical model used as well as regression and adjusted regression coefficients of about 99.0% and 96.6%, respectively. Moreover, the ranking of the effect of each studied parameter in terms of standardized effect on the desorption efficiency of MB from ROS was assessed through ANOVA test. The desorption mechanisms involved were explored by using multiple analysis techniques. It appears that the MB moleculesâ desorption from ROSâs particles is mainly driven by a counter chemisorption process based on cationic exchange with the sodium and hydronium ions present in the desorbing solutions