This paper introduces a multicarrier communication technique termed orthogonal chirp-frequency division multiplexing (OCFDM). It relies on a unitary transform named discrete modular chirp transform. The proposed OCFDM amalgamates characteristics from the orthogonal frequency division multiplexing (OFDM) and orthogonal chirp division multiplexing (OCDM), partitioning the frequency spectrum into distinct subbands and populating each of them with orthogonal chirps. By deriving the reconstructed signal at the receiver, the paper shows that the normalized signal-to-noise ratio exhibits changes across subbands, allowing the use of resource allocation, for instance, for power allocation or bit-loading. Moreover, it is shown that the OCFDM introduces an additional degree of freedom through its tile geometries, allowing it to be configured to perform in between OFDM and OCDM and, consequently, to offer novel and balanced trade-offs among symbol error rate, data rate, and robustness to interference. Numerical analyses illustrate those trade-offs and confirm the versatility and efficacy of the OCFDM.

This article focuses on the hidden benefits of harvesting the wasted energy from undesirable components of electric signals in electric power systems for powering the transceivers of Internet of Things (IoT) devices. These components, mainly harmonics and interharmonics, occupy the ultranarrowband power line communication spectrum (i.e., frequencies below 3 kHz). In this context, we introduce a mathematical formulation that allows us to quantify the number of transceivers of IoT devices that this kind of wasted energy can power. Based on a measurement campaign in a building facility, we show that the wasted energy can be modeled as a cyclostationary random process on weekdays and a stationary one on weekends, mimicking the energy consumption profile in a building facility. Numerical results also highlight achievable data rates obtained in the building facility if the wasted energy is reused. This analysis shows that this kind of harvested energy from wasted energy is suitable for powering numerous transceivers of IoT devices in practical scenarios.

This paper proposes the hybrid power line/wireless system (HPWS) based on the orthogonal chirp-division mul-tiplexing (OCDM) scheme. In this system, the same discrete- Fresnel domain symbols are transmitted through power line and wireless channels, enabling the application of combining techniques in the same domain and hence the signal-to-noise ratio increase at the receiver side. Furthermore, the optimal power allocation for maximizing the achievable data rate or minimizing the average bit error probability is discussed for OCDM-based HPWS. Finally, numerical analyses demonstrate that the OCDM- based HPWS is more appropriate for minimizing the average bit error probability if the transmitter is unaware of the channel state information.

This paper advances the studies regarding inter-ference caused by the cyclic prefix violation and the symbol timing offset in data communication schemes applied to power line communication systems. In this sense, it is shown that a few closed-form expressions can be used to characterize the orthogonal Stockwell division multiplexing (OSDM) scheme, as long it follows a couple of conditions. Moreover, the OSDM is compared to the Hermitian symmetric orthogonal frequency division multiplexing (HS-OFDM) scheme in terms of data rate and bit error probability (BEP) while contemplating narrowband power line channels corrupted by an additive colored Gaussian noise. The numerical results show that the OSDM performs better in terms of data rate than the HS-OFDM when interference affects the data communication system. In addition, the OSDM also surpasses the HS-OFDM in terms of BEP when the data communication system operates without interference or weak interference.

This article studies optimal subcarrier permutation in hybrid power line/wireless systems to either maximize the achievable data rate or minimize the average bit error probability (BEP). In order to better exploit the frequency selectivity of power line and wireless media, subcarrier permutation is optimized under uniform or optimal power allocation over an orthogonal frequency-division multiplexing scheme using maximal-ratio combining. Different from previous works, we demonstrate that the normalized signal-to-noise (nSNR) must be considered instead of the SNR and prove that it can be extended to cases where the minimization of the average BEP and optimal power allocation are considered. Moreover, we show that subcarrier permutation and power allocation problems can be assumed to be decoupled. Numerical results show that performance gains associated with subcarrier permutation become more relevant as the frequency selectivity of the nSNRs increases. In addition, the optimal subcarrier permutation is more effective for minimizing the average BEP than maximizing the achievable data rate and yields similar improvement under the usage of uniform and optimal power allocations.

This paper investigates power allocation for minimizing the average bit error probability (BEP) in hybrid communication systems, more specifically hybrid power line/wireless systems (HPWSs). In this regard, a brief discussion of HPWSs is presented in order to point out the complementary characteristics of power line and wireless media. By considering orthogonal frequency-division multiplexing and maximal-ratio combining, optimization problems associated with the minimization of the average BEP in hybrid communication systems are formulated under two distinct transmission power constraints, called sum power and sum power-channel constraints. For both constraints, it is demonstrated that at most one medium should be used for data transmission over subchannels with the same index in order to minimize the average BEP in hybrid communication systems. Based on this finding, power allocation algorithms are derived for this purpose in HPWSs. Numerical analyses are then used to validate the proposed algorithms by comparing them with interior-point-based power allocation algorithms. In addition, performance comparisons show the advantage of the proposals over alternative algorithms from the literature, including previous algorithms proposed for maximizing the achievable data rate.

Age of Information (AoI) measures the freshness of data in mission critical Internet-of-Things (IoT) applications i.e., industrial internet, intelligent transportation systems etc. In this paper, a new system model is proposed to estimate the average AoI (AAoI) in an ultra-reliable low latency communication (URLLC) enabled wireless communication system with decode- and-forward relay scheme over the quasi-static Rayleigh block fading channels. Short packet communication scheme is used to meet both reliability and latency requirements of the proposed wireless network. By resorting finite block length information theory, queuing theory and stochastic processes, a closed-form expression for AAoI is obtained. Finally, the impact of the system parameters, such as update generation rate, block length and block length allocation factor on the AAoI are investigated. All results are validated by the numerical results.

Abstract Aiming at reducing hardware complexity and power consumption of multicarrier‐based broadband transceivers, this contribution discusses and analyzes the implementation of clustered‐orthogonal frequency division multiplexing (OFDM)‐based transceiver in a field programmable gate array (FPGA) device. In this sense, several OFDM schemes covering baseband and passband data communications are implemented. The hardware resource utilization and power consumption related to each scheme, after being implemented in the FPGA device, are discussed and compared. Numerical results show that the OFDM scheme based on ‐II and ‐III, which is a modified version of the hermitian symmetric (HS)‐OFDM scheme, which performs both baseband and passband data communications, demands the lowest hardware resource utilization and power consumption, reducing to 1/3 the hardware resource utilization. As a result, ‐II and ‐III constitute an interesting candidate for implementing new generations of high data rate, low hardware resource utilization, and low‐power consumption clustered‐OFDM‐based transceivers for broadband data communication. Last but not least, numerical results show that the controllers used to integrate all components of a clustered‐OFDM‐based transceiver can demand sizeable hardware resource utilization and power consumption and, therefore, they have to be carefully designed.

This work addresses the use of hybrid power line-wireless channels, which are defined as the concatenation of power line communication (PLC) and wireless communication (WLC) channels, for dedicated energy harvesting purposes in in-home facilities. Based on a measured data set of hybrid PLC-WLC channels, we discuss statistical analyses concerning distinct power masks and two different regions that are associated with typical distances from the electric power grids to the wireless device. Moreover, based on the harvested energy from the hybrid PLC-WLC channels, we report the achievable data rates for data communication through narrowband PLC and WLC channels as well as through the hybrid PLC-WLC channels. The analyses show that feasible values of energy can be harvested from the hybrid PLC-WLC channels and that the high power nature of the PLC noise significantly contributes to the total harvested energy. Finally, we point out that interesting achievable data rates can be attained when the harvested energy is used for data communication purposes.

This paper investigates optimal power allocation in hybrid power line/wireless systems (HPWS). By adopting maximal-ratio combining (MRC) for the signals received from different channels, power allocation problems under sum power and sum power-channel constraints are formulated. These power constraints impose distinct bounds on the transmission power and, as a consequence, constitute different optimization problems. Therefore, two power allocation algorithms, which aim to maximize the achievable data rate in HPWS, are obtained. Furthermore, mathematical analyses show that data communication must employ only one medium per subchannel as the sum power constraint and frequency-selective channels are taken into account. Also, with high probability, the sum power-channel constraint results in the same conclusion with respect to the sole use of one medium per subchannel when the channels are frequency selective. In other words, MRC and selection-combining yield the same performance in terms of achievable data rate. Numerical analyses evaluate the proposed power allocation algorithms for exploiting the diversity between power line and wireless media by comparing them to alternative algorithms reported in the literature, especially when the total transmission power belongs to a practical range, and the attained results confirm their effectiveness and validate their usage in practical scenarios.

This paper investigates the benefits of the existing diversity in the parallel use of both power line and wireless channels, which is termed hybrid power line communication (PLC)/wireless, to improve physical layer security (PLS) for low-bit-rate applications. In this regard, mathematical formulations of the ergodic achievable secrecy rate and the secrecy outage probability are developed for the hybrid PLC/wireless channel model and its incomplete versions. The results show that the hybrid PLC/wireless channel model can provide remarkable benefits in terms of PLS for low-bit-rate applications when the eavesdropper makes use of only one data communication interface.

This paper outlines important characteristics of hybrid power line/wireless data communication system for smart grid (SG) and Internet of Things (IoT) applications. Moreover, we discuss the hybrid systems advantages in comparison to nonhybrid ones. These advantages are demonstrated not only in the technical point of view, but also in the infrastructural perspective. Also, we highlight a connection between the capillarity of IoT and the communication infrastructure provided by SG. Furthermore, we address the environmental influence on wireless and power line communications. Additionally, we present ergodic achievable data rate expressions for the hybrid power line/wireless channel (HPWC) and hybrid power line/wireless single-relay channel (HSRC) and provide performance analyses by considering four different cases, which are associated with the relative relay position in the single-relay channel model. Based on numerical results, we show that HPWC and HSRC offer a more reliable data transmission path when compared to power line or wireless system working alone.

This paper discusses the ergodic achievable data rate of the so-called incomplete hybrid power line-wireless singlerelay channel (HSRC) model. Here, the term incomplete refers to the HSRC model, which jointly and in parallel uses power line and wireless single-relay channel (SRC) models, for low-bitrate data transmission, without a data communication link or a node communication interface. In order to analyze the behavior of such kind of defective HSRC model under the relative location of the relay node in relation to the source and destination nodes, optimal power allocation is taken into account under a sum power constraint with an amplify-and-forward relaying protocol and maximal ratio combining applied at the relay node. Analytical and numerical results show that the incomplete HSRC model, which is a defective version of the HSRC model, can remarkably outperform power line and wireless SRCs for all considered positions of the relay node and the chosen cooperative protocols.

This paper investigates the benefits that energy harvesting (EH) can offer to increase energy efficiency in hybrid power line/wireless data communication systems for smart grid (SG) and Internet of Things (IoT) applications. In this regard, the ergodic achievable data rates of a hybrid power line/wireless dual-hop system (H2HS) model that uses EH strategies and the amplify-and-forward protocol at the relay node are considered. Also, four approaches for performing EH in the H2HS system are discussed. Performance comparisons among the H2HS, a dualhop power line and a dual-hop wireless systems are performed by adopting four simulation settings, covering the combinations of optimal or uniform power allocation together with colored or white additive noise at the output of the power line channel. Numerical results show that the H2HS model with the power splitting EH strategy outperforms the other models. Moreover, if the transmission power of the source node is high, then the case with additive colored noise at the received power line signal can result in higher achievable data rates in comparison to the white noise case. Overall, the H2HS system making use of an EH strategy has the potential to increase the sustainability and energy efficiency in data communications for SG and IoT applications.

A switch machine is an electromechanical device that allows railway trains to be guided from one track to another. Among all possible faults that can occur in a switch machine, the three mains ones are: lack of lubrication, lack of adjustment and malfunction of a component. Aiming to classify these faults, an important contribution of this work is to address the height type-reduction and interval singleton type-2 fuzzy logic system derivatives. The computational simulations are performed with real data set provided by a Brazilian company of the railway sector. The obtained results are compared with other models reported in the literature (Bayes theory, multilayer perceptron neural network and type-1 fuzzy logic system), demonstrating the effectiveness of the proposed classifier and revealing that the proposal is able to properly handle with uncertainties associated with the measurements and with the data that are used to tune the parameters of the model. In addition, the convergence speed and performance analysis show that the proposed interval singleton type-2 fuzzy logic system is attractive for classifying faults in a switch machine.

This paper focuses on the benefits of the existing relationship among consecutive subchannels (spectral information) in a multi-carrier modulation-based power line communication system for reducing the computational complexity and signaling overhead associated with resource allocation techniques. In this regard, we introduce the spectral compressive resource allocation technique, which reduces the computational complexity and the signaling overhead by grouping subcarriers into chunks, whose length/bandwidth is defined with basis on the so-called normalized signal to noise ratio coherence bandwidth. Moreover, we address the combination of the proposal with another technique that exploits the existing temporal relationship within periodically time-varying power line channels. Based on a data set composed of in-home power line channel estimates and additive noise measurements, we quantify the tradeoff between computational complexity reduction and data rate degradation under distinct scenarios and conditions, and indicate circumstances in which the proposed technique is more useful. Finally, we show that the exploitation of both temporal and spectral information altogether results in more computational complexity reduction and/or less data rate degradation in comparison to other techniques.

This paper focuses on the classification of faults in an electromechanical switch machine, which is an equipment used for handling railroad switches. In this paper, we introduce the use of Set-Membership concept, derived from the adaptive filter theory, into the training procedure of type-1 and singleton/non-singleton fuzzy logic systems, in order to reduce computational complexity and to increase convergence speed. We also present different criteria for using along with Set-Membership. Furthermore, we discuss the usefulness of delta rule delta, local Lipschitz estimation, variable step size, and variable step size adaptive techniques to yield additional improvement in terms of computational complexity reduction and convergence speed. Based on data set provided by a Brazilian railway company, which covers the four possible faults in a switch machine, we present performance analysis in terms of classification ratio, convergence speed, and computational complexity reduction. The reported results show that the proposed models result in improved convergence speed, slightly higher classification ratio, and remarkable computation complexity reduction when we limit the number of epochs for training, which may be required due to real-time constraint or low computational resource availability.

Power line communication systems face several challenges which degrade data communication quality. To overcome such issues, we propose CodePLC, a network coding Power Line Communication MAC protocol. We use a single relay node to intermediate communication, storing, and forwarding linear combinations of data packets. We evaluate CodePLC performance through simulations of a common topology for a PLC system under a wide range of scenarios. In sum, our results show that in a broadcast like transmission, the use of network coding enhances overall system performance. When compared to a traditional PLC system, we have observed an average of 115% goodput increase. Moreover, our protocol reduces in 112% the average of network occupancy buffers. Finally, CodePLC reduces mean latency by four times.

This work focuses on analyses of cooperative protocols to enhance the performance of power line communication systems. Based on a measurement campaign and considering a sum power constraint, achievable data rates for amplify-and-forward (AF) and decode-and-forward (DF) protocols are analyzed. Similar investigations are performed for the maximum data rates attained using Hermitian-symmetric orthogonal frequency division multiplexing (HS-OFDM) together with equal gain combining (EGC), selection combining (SC) and maximal ratio combining (MRC) techniques. The influences of optimally and uniformly allocated transmission power and frequency bandwidth are are also analyzed and the efficiency of combination before and after equalization is compared. Results show that the relative distances among source, relay and destination nodes significantly impact system performance. Also, they reveal a range of total transmission power and bandwidth in which benefits can be verified. Among combining techniques, MRC and SC present similar results, but MRC offers a slightly better performance. In relation to computational complexity, SC is the most favorable. Maximum data rate analyses of HS-OFDM with frequency domain equalization based on zero forcing and minimum mean square error criteria show that the former scheme offers almost the same performance as the latter. Furthermore, it is shown that equalization after combination is more advantageous.

This study presents a comprehensive analysis to highlight advantages and disadvantages, in terms of channel capacity and computational complexity (CC), of a so‐called clustered‐orthogonal frequency division multiplexing (OFDM) scheme for power line communication (PLC) technologies for access networks. By taking into account filtering, decimation and upsampling techniques, the implementations of two transmitter schemes, named (·)‐I and (·)‐II, and three receivers ones, named (·)‐I, (·)‐II and (·)‐III, that can be easily derived from the hermitian symmetric OFDM (HS‐OFDM) scheme are discussed. Numerical results show that the clustered‐OFDM schemes based on HS‐OFDM provide the same bit‐error‐rate performance as that of HS‐OFDM, double sideband‐OFDM and single sideband‐OFDM. Also, clustered‐OFDM based on the combination of (·)‐II and (·)‐III offers the lowest CC for both baseband and passband data communications. Further, it is demonstrated that the clustered‐OFDM schemes can trade off channel capacity for CC, which can give rise to low‐priced transceivers for PLC technologies. Finally, a comparative analysis of clustered‐OFDM and orthogonal frequency division multiple access (OFDMA) points out the scenarios in which clustered‐OFDM can be competitive if the complexity of the OFDM transceiver is a primary consideration.

This paper introduces an interconnected type-1 fuzzy algorithm which is trained by a modified version of the Scaled Conjugated Gradient method for impulsive noise cancellation in discrete multitone/orthogonal frequency-division multiplexing (DMT/OFDM)-based systems for broadband power line communications. The advanced algorithm makes use of the fuzzy systems capacity of dealing with uncertainties to reduce the presence of high-power impulsive noises while the DMT/OFDM technique copes with the severe intersymbol interference observed in power line channels. As a result, for a given error probability, a high number of bits can be allotted to each subchannel due to the signal-to-noise ratio enhancements achieved by the proposed fuzzy algorithm. The simulation results show that the novel fuzzy algorithm not only achieve a high data rate, but it also outperforms the standard impulsive noises techniques and other computational intelligence-based techniques, especially in the presence of additive and high-power impulsive noises.