Evelio M. García Fernández

Universidade Federal do Paraná | UFPR

The Wi-SUN FAN (Wireless Smart Ubiquitous Network Field Area Network) standard is attracting great interest in various applications such as smart meters, smart cities and Internet of Things (IoT) devices due to the attractive features that the standard offers, such as multihop and mesh topologies, a relatively high data rate, frequency hopping, and...

The linear combination of Student’s t random variables (RVs) appears in many statistical applications. Unfortunately, the Student’s t distribution is not closed under convolution, thus, deriving an exact and general distribution for the linear combination of K Student’s t RVs is infeasible, which motivates a fitting/approximation approach. Here, we...

The linear combination of Student's $t$ random variables (RVs) appears in many statistical applications. Unfortunately, the Student's $t$ distribution is not closed under convolution, thus, deriving an exact and general distribution for the linear combination of $K$ Student's $t$ RVs is infeasible, which motivates a fitting/approximation approach....

Physical Layer Security (PLS) is an emerging concept in the field of secrecy for wireless communications that can be used alongside cryptography to prevent unauthorized devices from eavesdropping a legitimate transmission. It offers low computational cost and overhead by injecting an interfering signal in the wiretap channels of potential eavesdrop...

The energy and time efficiency of wireless sensor networks (WSNs) is frequently affected by the low reliability of their links. To mitigate the outage probability, cooperation topologies are used. However, these topologies have particular challenges since the relay consumes energy in assisting a foreign communication, and the successful transmissio...

Vehicular Ad Hoc Networks (VANETs) are expected to be the next big step towards safer road transport, supporting applications to exchange information between vehicles. To develop novel applications for this area a high number of tests, considering all traffic situations, are demanded. However, it is unfeasible to reproduce these tests in real life,...

Spectrum sharing and successive interference cancellation (SIC) techniques used in power-domain non-orthogonal multiple access (NOMA) systems impose secrecy challenges because untrusted users can decode the information of trusted ones. In this context, physical layer security (PLS) appears as an alternative to address the possible risks. In this pa...

Recent advances on wireless energy transfer (WET) make it a promising solution for powering future Internet-of-Things (IoT) devices enabled by the upcoming sixth-generation (6G) era. The main architectures, challenges and techniques for efficient and scalable wireless powering are overviewed in this article. Candidates enablers, such as energy beam...

Closed-form expressions for the detection probability, the false alarm probability and the energy detector constant threshold are derived using approximations of the central chi-square and non-central chi-square distributions. The approximations used show closer proximity to the original functions when compared to the expressions used in the litera...

Novel methods to approximate the probability density function of the product, ratio, and sum of α‐μ random variables are presented in this article. The approximations are simple to compute and produce results that range from fairly accurate to perfectly accurate, depending on the parameters of the involved α‐μ distributions. In addition, as an appl...

Internet traffic is already dominated by video streaming applications. The quality of transmitted videos and the number of content available online is expected to increase in the upcoming years, which will further pressure the available network infrastructures. In this scenario, Video‐on‐Demand services require that distribution mechanisms improve...

This paper analyzes multi-step-ahead spectrum prediction for Cognitive Radio (CR) systems using several future states. A slot-based scenario is used, and prediction is based on the Support Vector Machine (SVM) algorithm. The aim is to determine whether multi-step-ahead spectrum prediction has gains in terms of reduced channel-switching and increase...

Vehicular Ad Hoc Networks (VANETs) are expected to be the next big step towards safer road transport, supporting applications to exchange information between vehicles. To develop novel applications for this area a high number of tests, considering all traffic situations, are demanded. However, it is unfeasible to reproduce these tests in real life,...

The Time Slotted Channel Hopping (TSCH) mode of the standard IEEE 802.15.4 provides Medium Access Control (MAC) for most Low power and Lossy Network (LLN) applications in the Internet of Things (IoT). TSCH uses a synchronized schedule with frequency diversity to allow flexible, reliable and resilient communication. The standard defines an associati...

Cooperative vehicular safety systems are expected to revolutionize the driving experience by providing road safety applications based on incident detection. Two vital quality parameters for cooperative safety applications are the position accuracy and communication reliability of the status information. The receiver may take erroneous decisions if...

Recent advances on wireless energy transfer led to a promising solution for powering future Internet of Things (IoT) devices enabled by the upcoming sixth generation (6G) era. In this paper, we overview the main architectures, challenges and techniques for efficient wireless powering. We emphasize on the suitability of Channel State Information (CS...

Robust, efficient, secure, and low-cost vehicle-to-vehicle (V2V) visible light communication (VLC) protocols, with high transmission rates, are very appealing to alleviate high traffic and to diminish air pollution in high vehicle density environments. In contrast to radio frequency (RF) protocols, where a stable communication cannot be ensured in...

Wireless Smart Ubiquitous Network Field Area Network (Wi-SUN FAN) is a profile that is part of the Wi-SUN alliance that develops specifications for field area networks, supporting Low Power and Lossy Networks (LLNs). The Wi-SUN FAN profile provides IPv6-based transport services and adopts IPv6 Routing Protocol for LLNs (RPL) for packet routing and...

We consider a two-phaseWireless-Powered Communication Network under Nakagami-m fading, where a wireless energy transfer process first powers a sensor node that then uses such energy to transmit its data in the wireless information transmission phase. We explore a fixed transmit rate scheme designed to cope with the reliability and delay constraints...

We consider a two-phase Wireless-Powered Communication Network under Nakagami-m fading, where a wireless energy transfer process first powers a sensor node that then uses such energy to transmit its data in the wireless information transmission phase. We explore a fixed transmit rate scheme designed to cope with the reliability and delay constraint...

We propose a novel transmission scheme, suitable to IoT, which sends coded redundant information in independent packets. The results indicate that this scheme outperforms, in terms of reliability, transmit power, and coverage, the typical direct transmission strategy, schemes based on replications, and methods that embed coded redundant information...

In this paper, we propose two schemes based on a full‐duplex network‐coded cooperative communication (FD‐NCC) strategy, namely, full‐duplex dynamic network coding (FD‐DNC) and full‐duplex generalized dynamic network coding (FD‐GDNC). The use of full‐duplex communication aims at improving the spectrum efficiency of a two‐user network where the users...

The next generations of wireless communications are expected to have great demand for security and spectrum efficiency, and the current secrecy solutions may not be enough. In this paper we propose an optimization framework to address the physical layer security in cogni-tive radio networks when the secondary users employ improper Gaussian signalin...

The Time-Slotted Channel Hopping (TSCH) mode of the standard IEEE~802.15.4 provides Medium Access Control (MAC) for most Low-power and Lossy Network (LLN) applications in the Internet of Things (IoT). TSCH creates a synchronized mesh network capable of delivering data packets in a reliable and timely manner. The standard defines a scan mechanism to...

We look into adopting Improper Gaussian Signaling (IGS) in order to enhance the secrecy performance of an underlay Cognitive Radio (CR) network, since in interference-limited networks asymmetric signals have been proven to achieve better performance than proper ones. In this letter, we analyze a scenario where a secondary user (SU) being eavesdropp...

Cognitive radio (CR) has emerged as a key technology to deal with the frequency spectrum scarcity. The efficient and opportunistic use of the spectrum requires rapid coordination between the secondary users (SUs). Besides, future wireless networks demand even faster transmission rates, smaller end-toend delay, and greater energy efficiency. In this...

Cooperative vehicular networks require the continuous exchange of beacon messages between neighboring vehicles to support cooperative awareness applications. The position error computed by surrounding vehicles impacts on applications capability to detect and mitigate potentially dangerous trafc situations in real-time. A challenge in cooperative sa...

Vehicular networks comprise vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications based on wireless radio access technologies. These networks require the periodic exchange of beacon messages between neighboring vehicles, to support cooperative road safety applications. The regular broadcast of beacon in the common control chan...

The performance of a full-duplex cooperative cognitive network is investigated under Nakagami-m fading. The secondary source and the relays are energy-constrained nodes and harvest energy from the primary network to transmit their information. The direct link between source and destination in the secondary network is considered as useful informatio...

We analyze a cooperative wireless communication system with finite block length and finite battery energy, under quasi-static Rayleigh fading. Source and relay nodes are powered by a wireless energy transfer (WET) process, while using the harvested energy to feed their circuits, send pilot signals to estimate channels at receivers, and for wireless...

Some of the future wireless networks are related to the provision of higher data rates and lower energy consumption. In contrast to the clear increasing spectrum demand, bandwidth is a limited resource. Cooperative diversity allows to increase the spectral efficiency and the reliability of the communication. However, in scenarios with high node den...

Cooperative vehicular network is a key technology in the future implementation of ITS. To enable road safety and efficiency applications in cooperative vehicular networks is necessary the periodic exchange of status information between neighboring vehicles by broadcast beacon messages. In this paper, we propose an adaptive beaconing algorithm based...

We evaluate the performance of an energy constrained cognitive full-duplex network coding based scheme. The secondary cooperative network is composed of two energy-constrained full-duplex users that cooperate to transmit their independent information to a common destination. The secondary users do not have sources of energy and they harvest energy...

We investigate the performance of a full-duplex energy harvesting cooperative cognitive network composed by one transmitter and one destination in the primary network, and one source, one relay, and one destination in the secondary network, in which joint decoding of the signals received from source and relay is performed. The effect of self-interf...

Cooperative communications can substantially improve the performance in fading channels. However, in energy-constrained wireless sensor networks, the benefits of cooperation only go until certain limits, beyond which the energy cost of cooperation can be significant and unprofitable. We propose a cooperative scheme in which the relays activate the...

We analyze a wireless communication system with finite block length and finite battery energy, under quasi-static Nakagami-m fading. Wireless energy transfer is carried out in the downlink while information transfer occurs in the uplink. Transmission strategies for scenarios with/without energy accumulation between transmission rounds are character...

We analyze and optimize a wireless system with energy transfer in the downlink and information transfer in the uplink, under quasi-static Nakagami-m fading. We consider ultra-reliable communication scenarios representative of the fifthgeneration of wireless systems, with strict error and latency requirements. The error probability and delay are inv...

We consider a dual-hop wireless network where an energy constrained relay node first harvests energy through the received radio-frequency signal from the source, and then uses the harvested energy to forward the source's information to the destination node. The throughput and delay metrics are investigated for a decode-and-forward relaying mechanis...

This paper evaluates the use of full-duplex nodes to increase the performance of a vehicular ad hoc network (VANET) composed of one transmitter, multiple full-duplex relays and one destination, where the best relay is selected to assist communication. With the use of full-duplex communication, it is possible to obtain a better use of the radio reso...

This paper employs game theory to optimize the performance of multiple secondary users (SUs) in a cognitive radio ad hoc network where the primary and SUs have quality of service (QoS) constraints. The proposed algorithm utilizes a distributed noncooperative game theory mechanism among SUs that compete to maximize their individual capacities. We pr...

We propose a cognitive full-duplex network coding based scheme. The secondary cooperative network is composed of two secondary full-duplex users that cooperate to transmit their independent information to a common secondary destination. The transmit power is constrained by the maximum interference threshold accepted by the primary destination. We s...

In this paper, a new full-duplex (FD) relaying scheme for a cooperative cognitive underlay network is proposed. The secondary network is composed of one secondary transmitter, one full-duplex secondary relay, and one secondary destination. The relay employs the selective-decode-and-forward (SDF) protocol. The secondary destination jointly decodes t...

Cognitive radio networks (CRNs) have emerged as a promising paradigm that can solve the shortage of spectrum resources, providing the ability to adapt and opportunistically exploit the spectrum holes. The rendezvous process allows cognitive users to find a common channel and establish a communication link. In this paper, we focus on the design of f...

In this paper, a new full-duplex (FD) relaying scheme for a cooperative cognitive underlay network is proposed. The secondary network is composed of one secondary transmitter, one full-duplex secondary relay, and one secondary destination. The relay employs the selective-decode-and-forward (SDF) protocol. The secondary destination jointly decodes t...

The Stream Control Transmission Protocol (SCTP) establishes a transport layer framework for multihomed communication where the standard failover mechanism improves the transmission resilience. A delay-centric handover mechanism for SCTP have been proposed to improve the end-to-end delay of real-time multimedia transmissions. In this paper, we explo...

This paper investigates the power allocation problem in decode-and-forward cognitive dual-hop systems over Rayleigh fading channels. In order to optimize the performance of the secondary network in terms of power consumption, an outage-constrained power allocation scheme is proposed. The secondary nodes adjust their transmit power subject to an ave...

This paper investigates the outage behavior and power allocation problem in a two-user network-coded cooperative cognitive radio network over Rayleigh fading channels. First, we derive an exact expression for the outage probability of the secondary transmissions, and then we propose an approximate expression whose validity limits are later evaluate...

We study the benefits that antenna directivity and power control can bring to a cognitive radio ad hoc network, in terms of concurrent transmission probability, throughput and energy efficiency. The proposed strategies adequately adjust antenna beam pattern and the transmit power of the secondary users to increase the spectrum reuse while respectin...

We address the power control problem in cognitive radio networks where secondary users exploit spatial spectrum opportunities without causing unacceptable interference to pri-mary users. An optimization problem is formulated aiming at maximizing the utility of secondary users and to ensure the QoS for both primary and secondary users. To solve the...

The rendezvous process allows cognitive users to find an available channel and establish a communication link. The implementation of rendezvous strategies to minimize the time to rendezvous (TTR) is a major challenge in this context. In this paper we present a comprehensive analysis of the benefits of periodic channel hopping sequences in the rende...

Rendezvous is the process in which two users attempt to meet on a common channel and it is of fundamental importance in cognitive ad hoc radio networks. A cognitive radio blind rendezvous algorithm named simple role-based is proposed that exploits the common channel labelling inherent to wireless networks. The scheme guarantees the simultaneous ren...

We introduce an overlay cooperative cognitive radio scheme, in which the secondary network transmits only during the retransmissions of the primary network. The secondary network makes use of multiple relays in order to increase its performance compared to a non-cooperative scenario. Moreover, the secondary operates without harming the performance...

The deployment of femtocells comes as a solution to increase indoor coverage although it may also increase the interference level in the network. In this paper we evaluate the use of multiple co-channel femtocells as relays to the outdoor user in a cognitive radio context, where the outdoor user can be seen as a primary user and the indoor users ar...

Location awareness allows to define a concurrent transmission region where a primary and a secondary networks can coexist. We investigate the impact of joint rate and power control on the performance of a cognitive radio ad hoc network overlaying a primary system. The proposed strategies adequately adjust the secondary user transmit power to increa...

Through location awareness, cognitive radio systems can establish a scanning free region where coexistence with a primary network is possible. Exploiting the power control capability of cognitive radio devices can expand this region, improving the system throughput. In this paper we investigate the impact of power control on the concurrent transmis...

This paper studies the benefits that power control and antenna directivity can bring to the capacity of a multiuser cognitive radio network. The main objective is to optimize the secondary network sum rate under the capacity constraint of the primary network. Exploiting location awareness, antenna directivity, and the power control capability , the...

Location awareness allows to define a concurrent transmission region where a primary and a secondary networks can coexist. In this paper we investigate the impact of channel rate control on the performance of a cognitive radio ad hoc network overlaying an infrastructure-based system. The proposed algorithm adequately adjusts the secondary user rate...

We consider a cooperative overlay cognitive network, where the secondary exploits the primary retransmissions. We show that by using cooperation, the secondary rate can be considerably increased when compared to other schemes, without causing major impact on the primary performance. The best configuration for the proposed scheme is that in which th...

This paper presents a new model for VoIP workload generation. The novelty of our proposal consists in modeling the sessions by characterizing both the user behavior (session level) and the packet generation for an active call (intra-session level) with easily measured parameters and low computational complexity. This approach also facilitates syste...

This paper investigate the impact on the QoS offered by IP networks that transport real-time H.264/MPEG-4 AVC video streams when applying adaptive random early detection (ARED) as an active queue management technique instead of traditional drop-tail. Simulation results indicate that the ARED technique reduces the loss of video packets but degrades...

Cognitive radio ad hoc systems can coexist with a primary network in a scanning-free region, which can be dimensioned by location awareness. This coexistence of networks improves system throughput and increases the efficiency of radio spectrum utilization. However, the location accuracy of real positioning systems affects the right dimen-sioning of...

Cognitive radio systems can coexist with a primary network in a scanning-free region, which can be dimensioned by location awareness. This coexistence of networks improves the system throughput and increases the efficient use of radio spectrum. However, the accuracy of traditional positioning systems affects the correct dimensioning of the concurre...

Playout buffer absorbs packet jitter in order to compensate network delay variations. In the last decades a great number of playout buffer algorithms have been proposed for voice over IP applications. However, only a few have received the attention of the research community. In this paper we study four variations of a classical algorithm under actu...

This article provides a new analytical method based on a fixed point approach to estimate the impact of active queue management schemes on the quality of service of voice over IP applications. The results obtained by the proposed method were validated using discrete event simulation techniques. In all the studied cases it was observed a great deal...

This paper assesses the impact of active queue management schemes on the quality of service of voice over Internet protocol applications. A new analytical method based on a fixed point approach to estimate the end-user satisfaction is proposed. The results obtained were validated using discrete event simulation techniques. In all the studied cases...

In this paper, we assess the impact of active queue management (AQM) on the quality of service of voice over IP (VoIP). Some of the most representative AQM schemes are analyzed through extensive simulations; evaluating its effect on the perceived quality of voice calls. We investigate different network scenarios, changing network loads and scheme c...

The search to increase the error performance of algebraic soft-decision decoding of high rate Reed-Solomon (RS) codes motivates the development of this work in an attempt to determine the ultimate error-correcting capabilities of algebraic soft-decision decoding of RS codes in Gaussian channels with erasures. It is showed through simulation that a...

This paper presents a comprehensive study about the impact of active queue management (AQM) on voice over Internet protocol (VoIP) quality of service. One of the most representative AQM scheme is analyzed through extensive simulation and its effect on the perceived quality of voice calls is evaluated. Different network scenarios, changing network l...

This paper presents a simple multiple-input multiple output (MIMO) hybrid system for wireless channels trying to achieve near optimal values of diversity-multiplexing tradeoff. The hybrid systems studied combine well known space time codes and full multiplexing schemes. A decoding procedure for the hybrid systems using linear combinatorial nulling...

This paper presents a concatenated coding scheme for error correction in (0,k) constraint channels with hard and soft decision decoding. The scheme is based on a Reed-Solomon code as an outer code and a runlength limited code as an inner code

Two examples are presented to find runlength-limited error control codes from linear transparent binary expansions of Reed-Solomon codes. The codes obtained can correct burst and random errors and are suitable for digital transmission and recording systems

This paper presents a method to find runlength limited block error control codes which are formed by taking an appropriate coset of a modified linear transparent error control code. The main advantages of this method are its simplicity and generality, i.e., it can be applied in any block code with no restriction of block length or minimum Hamming d...