Taufik Abrao
Universidade Estadual de Londrina, Electrical Engineering, Faculty Member
- Electrical Engineering, Wireless Communications, Convex Optimization, Non-convex optimization, Cognitive Radio Networks, Wireless Relay Networks, and 9 moreAd Hoc Networks, Sensor networks, Cellular Networks, Cooperative Communication, Multi-User MIMO Communication, Wireless Sensor Networks, Wireless Computing, Wireless MAC protocols, and Wireless networksedit
- Taufik ABRAO (IEEE-M’97–SM’12, PQ-1D CNPq) received the B.S., M.Sc., and Ph.D. degrees in electrical engineering from... moreTaufik ABRAO (IEEE-M’97–SM’12, PQ-1D CNPq) received the B.S., M.Sc., and Ph.D. degrees in electrical engineering from the Polytechnic School, University of São Paulo, São Paulo, Brazil, in 1992, 1996, and 2001, respectively. Since 1997, he has been with the Communications Group, Department of Electrical Engineering, Londrina State University (UEL), Paraná, Brazil, where he is currently an Associate Professor in telecommunications and the Head of the Telecommunicationedit
This work investigates issues concerning the computational complexity of multiuser receivers in direct sequence code division multiple access (DS/CDMA) systems based on heuristic techniques and implemented on commercial platform for... more
This work investigates issues concerning the computational complexity of multiuser receivers in direct sequence code division multiple access (DS/CDMA) systems based on heuristic techniques and implemented on commercial platform for digital signal processing (DSP) (Texas TMS320C6713). The multiuser detection (MuD) algorithms which were implemented in baseband are based on the heuristic local search (LS) and simulated annealing (SA) approaches. Figures of merit regarding the bit error rate (BER) performance versus computational complexity trade-off are evaluated as a function of the system loading increasing (number of active users per processing gain); as a result, a methodology for the design and implementation of a baseband multiuser receiver structure using DSP platform is developed as well. Key–Words: DSP, DS/CDMA, MuD, heuristic algorithms, computational complexity, performance-complexity tradeoff.
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The cellular internet-of-things wireless network is a promising solution to provide massive connectivity for machine- type devices. However, designing grant-free random access (GF- RA) protocols to manage such connections is challenging,... more
The cellular internet-of-things wireless network is a promising solution to provide massive connectivity for machine- type devices. However, designing grant-free random access (GF- RA) protocols to manage such connections is challenging, since they must operate in interference-aware scenarios with sporadic device activation patterns and a shortage of mutually orthogonal resources. Supervised machine learning models have provided efficient solutions for activity detection, non-coherent data detection, and non-orthogonal preamble design in scenarios with massive connectivity. Considering these promising results, in this paper, we develop two deep learning (DL) sparse support recovery algorithms to detect active devices in mMTC random access. The DL algorithms, developed to deploy GF-RA protocols, are based on the deep multilayer perceptron and the convolutional neural network models. Unlike previous works, we investigate the impact of the type of sequences for preamble design on the a...
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In cognitive radio (CR), the sensed aggregate bandwidth could be as large as several GHz. This is especially challenging if the bandwidths and central frequencies of the sensed signals are unknown and need to be estimated. This work... more
In cognitive radio (CR), the sensed aggregate bandwidth could be as large as several GHz. This is especially challenging if the bandwidths and central frequencies of the sensed signals are unknown and need to be estimated. This work discusses a new improved method for MB spectrum sensing (iMB-SS) based on edge detection and using Wavelet Spectrum Filtering. The proposed iMB-SS method uses a Welch power spectrum density (PSD) estimate and a multi-scale Wavelet approach to reveal the spectrum transition (edges), which is deployed to characterize the spectrum occupancy in CR scenarios where the operation frequencies of the primary users (PUs) are unknown. The focus of this work lies in improving the performance of the MB spectrum sensor, particularly by refining the spectral edge location and reducing misleading detection. A comprehensive analytical description and numerical analysis have been carried out by focusing on orthogonal-frequency-division-multiplexing (OFDM) signal applicati...
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This work presents a comparative framework for different multiuser detectors (MUD) applied to single input multiple output (SIMO) multicarrier-code division multiple access (MC-CDMA) system. The Optimum MUD (OMUD), Parallel Interference... more
This work presents a comparative framework for different multiuser detectors (MUD) applied to single input multiple output (SIMO) multicarrier-code division multiple access (MC-CDMA) system. The Optimum MUD (OMUD), Parallel Interference Cancelling (PIC), Linear MUDs and the 1-optimum Local Search (1-LS) algorithms are analyzed and compared as performance against complexity trade-off. Performance evaluation is carried out in terms of symbol error
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Neste trabalho, o modelo de Verhulst e o teorema de Perron-Frobenius são aplicados ao problema de controle de potência em redes de comunicação de múltiplo acesso móveis limitadas por interferência. Analisa-se o compromisso... more
Neste trabalho, o modelo de Verhulst e o teorema de Perron-Frobenius são aplicados ao problema de controle de potência em redes de comunicação de múltiplo acesso móveis limitadas por interferência. Analisa-se o compromisso desempenho-complexidade de ambos os algoritmos de alocação de potência (PCA - power control algorithm), bem como são enfatizados aspectos relativos aos custos computacionais inerentes à possibilidade de implementação desses dois métodos no modo distribuído (DPCA - distributed PCA). Como prova-de-conceito, a implementação dos algoritmos é realizada em uma plataforma DSP comercial de ponto flutuante e os resultados em termos de número de ciclos e tempo de processamento indicam a) viabilidade de implementação do PCA-Verhulst em sistemas celulares 2G e 3G; b) elevado custo computacional para o PCA-Perron-Frobenius.
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Abstract This chapter discusses the nature-inspired metaheuristic firefly algorithm (FA) applied in telecommunications. FA has been developed based on the behavior of the fireflies and the light emitted, where the brightest firefly... more
Abstract This chapter discusses the nature-inspired metaheuristic firefly algorithm (FA) applied in telecommunications. FA has been developed based on the behavior of the fireflies and the light emitted, where the brightest firefly attracts the others in his direction. Besides combining stochastic behavior and a population-based multimodal characteristic, the FA approach is able to solve optimization problems in different areas of knowledge such as engineering, robotics, combinatorial optimization, and so on. This chapter aims to show the FA performance in two distinct network optimization problems: traffic characterization and energy-efficient cooperative networks. In the first optimization problem, FA is applied as a clustering algorithm to create a network traffic pattern called Digital Signature of Network Segment using Flow analysis (DSNSF); in the second, FA has been applied to the energy-efficiency maximization problem in multicarrier direct sequence code division multiple access (MC-DS/CDMA) cooperative networks.
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Research Interests: Computer Science and SBRT
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This paper addresses the optimization problem on subcarrier and power allocation of orthogonal frequency division multiple access (OFDMA) system under spectral efficiency (SE) metric when deploying superposition coding (SC) transmission... more
This paper addresses the optimization problem on subcarrier and power allocation of orthogonal frequency division multiple access (OFDMA) system under spectral efficiency (SE) metric when deploying superposition coding (SC) transmission strategy. An algorithm with polynomial time complexity, of the order of (UN log 2(N)) has been proposed for sub-optimal SE maximization. Results indicate that the system SE increases with the use of SC technique. Besides, the throughput gain with SC adoption increases when the number of users (U) approaches the number of subcarriers (N) available in the system.
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Abstract This paper presents an anomaly detection method using Digital Signature of Network Segment (DSNS) and Particle Swarm Optimization-based clustering (PSO-Cls). The PSO algorithm is an evolutionary computation technique whose main... more
Abstract This paper presents an anomaly detection method using Digital Signature of Network Segment (DSNS) and Particle Swarm Optimization-based clustering (PSO-Cls). The PSO algorithm is an evolutionary computation technique whose main characteristics ...
Research Interests: Computer Science, Computational Complexity, Digital Signature, Swarm Intelligence, Genetic Algorithm, and 11 moreAnomaly Detection, IEEE, Convergence Rate, Data Clustering, Evolutionary Computing, Evolutionary Algorithm, Communication Complexity, Network Traffic, K means Clustering, Particle Swarm Optimizer, and Anomaly based network intrusion detection
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Abstract This paper proposes to extend the discrete Verhulst power equilibrium approach, previously suggested in [1], to the power-rate optimal allocation problem. Multirate users associated to different types of traffic are aggregated to... more
Abstract This paper proposes to extend the discrete Verhulst power equilibrium approach, previously suggested in [1], to the power-rate optimal allocation problem. Multirate users associated to different types of traffic are aggregated to distinct user'classes, with the ...
Research Interests: Computational Complexity, Resource Allocation, Matrix Inversion, Quality of Service, Power Control, and 9 moreBit Error Rate, Rate Control, Power allocation, Signal to Noise Ratio, Code Division Multiple Access, Normalized Mean Square Error, convergence time, Direct sequence, and Multiaccess communication
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ABSTRACT This work makes a review of the main Adaptives Multi-user Detectors (MuD-Adpt) for Direct Sequence - Code Division Multiple Access (DS-CDMA) systems. The MuD-Adpt based on Minimum Mean Square Error (MMSE) and Decorrelator... more
ABSTRACT This work makes a review of the main Adaptives Multi-user Detectors (MuD-Adpt) for Direct Sequence - Code Division Multiple Access (DS-CDMA) systems. The MuD-Adpt based on Minimum Mean Square Error (MMSE) and Decorrelator (MuD-Dec) are focused. Multi-user detectors show great resistance to the near-far effect and combat effectively the Multiple Access Interference (MAI). Comparative numeric results characterize the substantial performance improvement of those detectors in relation to the matched filter conventional receiver (Conv). Este trabalho faz uma revisão dos principais detectores multiusuários adaptativos ((MuD-Adpt) subótimos para sistemas DS-CDMA (Direct Sequence - Code Division Multiple Access). São enfocados os detectores adaptativos baseados no erro quadrático médio mínimo (MMSE - Minimum Mean Square Error) e os de descorrelação (MuD-Dec). Detectores multiusuários apresentam ótima resistência ao efeito perto-longe (near-far effect) e combatem efetivamente a interferência de múltiplo acesso (MAI). Resultados numéricos comparativos caracterizam o aumento substancial de desempenho desses detectores adaptativos em relação ao receptor convencional com filtro casado (Conv).
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Abstract: Anomaly detection refers to methods that provide warnings of unusual behaviors which may compromise the security and performance of communication networks. In this paper it is proposed a novel model for network anomaly detection... more
Abstract: Anomaly detection refers to methods that provide warnings of unusual behaviors which may compromise the security and performance of communication networks. In this paper it is proposed a novel model for network anomaly detection combining baseline, K-means ...
Research Interests: Computer Science, Computational Complexity, Anomaly Detection, Software, Supervised Learning, and 9 moreCluster Analysis, Data Clustering, Community Networks, Computer Network Security, K Means, Network Traffic, K means Clustering, Particle Swarm Optimizer, and Anomaly based network intrusion detection
In a cell-free massive multiple-input multiple-output (CF-mMIMO) network, multiple access points (APs) actively cooperate to serve users' equipment (UEs). We consider how the random access (RA) problem can be addressed by such a network... more
In a cell-free massive multiple-input multiple-output (CF-mMIMO) network, multiple access points (APs) actively cooperate to serve users' equipment (UEs). We consider how the random access (RA) problem can be addressed by such a network under the occurrence of pilot collisions. To find a solution, we embrace the user-centric perspective, which basically dictates that only a preferred set of APs needs to serve a UE. Due to the success of the strongest-user collision resolution (SUCRe) protocol for cellular (Ce) mMIMO, we extend it by considering the new setting. Besides, we establish that the usercentric perspective naturally equips a CF network with robust fundamentals for resolving collisions. We refer to this foundation as spatial separability, which enables multiple colliding UEs to access the network simultaneously. We then propose two novel RA protocols for CF-mMIMO: i) the baseline cell-free (BCF) that resolves collisions with the concept of spatial separability alone, and ii) the cell-free SUCRe (CF-SUCRe) that combines SUCRe and spatial separability principle to resolve collisions. We evaluate our proposed RA protocols against the Ce-SUCRe. Respectively, the BCF and CF-SUCRe can support 7× and 4× more UEs' access on average compared to the Ce-SUCRe with an average energy efficiency gain based on total power consumed (TPC) by the network per access attempt of 52× and 340×. Among our procedures, even with a higher overhead, the CF-SUCRe is superior to BCF regarding TPC per access attempt. This is because the combination of methods for collision resolution allows many APs to be disconnected from the RA process without sacrificing much the performance. Finally, our numerical results can be reproduced using the code package available on: github.com/victorcroisfelt/cf-ra-spatial-separability.