The pervasiveness of wireless sensor networks (WSNs) across different applications keeps increasing due to their versatility, although energy consumption is a huge constraint for these types of networks. Therefore, it is essential to incorporate consistent and reliable energy sources. Mobile nodes require independent sources, often composed of a battery with one or more energy harvesting devices (EHDs). The exigency for energy-efficiency improvements is a collateral effect of the growth of WSNs. Different methods have been proposed to improve the energy efficiency of these systems. This article focuses on the techniques of energy-efficiency developed in the medium access control (MAC) layer. The proposed solution incorporates EHDs and analytic information, such as the estimation of the network lifetime (NL), to achieve an energy efficient system, potentially self-sustainable. A widely used MAC-protocol technique for energy conservation is duty cycling, because it facilitates the control over the transitions of the active and sleep modes of the node, conserving energy if used efficiently. Due to the importance of MAC protocols in energy conservation, it is necessary to compile a review of the MAC protocols that address this issue, covering the traditional way of classifying them, the characteristics presented by each group and how they have been adapted to the appearance of new tools such as EHDs and the information obtained from the battery to estimate the lifetime of the sensor node.

The Levelized Cost of Driving (LCOD) calculates how much it costs to drive a vehicle, per kilometer, over the vehicle lifespan, and it is typically measured in USD/km. LCOD has been widely applied to assess and compare the performance of Electric Vehicles (EVs) and Internal Combustion engine Vehicles (ICVs). Unfortunately, there is no common methodology to establish how to compute LCOD. As authors use different criteria to determine which elements are relevant in LCOD, it is difficult to compare results. To overcome this issue, we re-introduce the LCOD concept, where the most relevant expenditures and incomes are included. This novel LCOD definition also incorporates key elements that are sometimes neglected, such as the second life of batteries in EVs, EV battery degradation models, and stochastic models, to characterize daily operation. The proposed methodology is applied to assess the cost of using EVs as taxis in the city of Quito, Ecuador.

Multiswarm comprehensive learning particle swarm optimization (MSCLPSO) is a multiobjective metaheuristic recently proposed by the authors. MSCLPSO uses multiple swarms of particles and externally stores elitists that are nondominated solutions found so far. MSCLPSO can approximate the true Pareto front in one single run; however, it requires a large number of generations to converge, because each swarm only optimizes the associated objective and does not learn from any search experience outside the swarm. In this paper, we propose an adaptive particle velocity update strategy for MSCLPSO to improve the search efficiency. Based on whether the elitists are indifferent or complex on each dimension, each particle adaptively determines whether to just learn from some particle in the same swarm, or additionally from the difference of some pair of elitists for the velocity update on that dimension, trying to achieve a tradeoff between optimizing the associated objective and exploring diverse regions of the Pareto set. Experimental results on various two-objective and three-objective benchmark optimization problems with different dimensional complexity characteristics demonstrate that the adaptive particle velocity update strategy improves the search performance of MSCLPSO significantly and is able to help MSCLPSO locate the true Pareto front more quickly and obtain better distributed nondominated solutions over the entire Pareto front.

The rapid development of the Internet of Things (IoT) has brought about the processing and storage of sensitive information on resource-constrained devices, which are susceptible to various hardware attacks. Fault injection attacks (FIAs) stand out as one of the most widespread. Particularly, voltage-based FIAs (V-FIAs) have gained popularity due to their non-invasive nature and high effectiveness in inducing faults by pushing the IoT hardware to its operational limits. Improving the security of devices and gaining a comprehensive understanding of their vulnerabilities is of utmost importance. In this study, we present a novel fault injection method and employ it to target an 8-bit AVR microcontroller. We identify the optimal attack parameters by analyzing the detected failures and their trends. A case study is conducted to validate the efficacy of this new method in a more realistic scenario, focusing on a simple authentication method using the determined optimal parameters. This analysis not only demonstrates the feasibility of the V-FIA but also elucidates the primary characteristics of the resulting failures and their propagation in resource-constrained devices. Additionally, we devise a hardware/software countermeasure that can be integrated into any resource-constrained device to thwart such attacks in IoT scenarios.

Wireless technologies are an essential communication means that transform a branched localized fixed meshwork into a ubiquitous disconnected network. A clear trend shows that cells are becoming smaller, homogeneously distributed, operating at higher carrier frequencies, and more energy conscious. This points toward wireless picocell systems that implement millimeter-wave (mm-wave) modulation. In this work various techniques are proposed, which are oriented to specific traits of the 60-GHz mm-wave band. Two techniques oriented to solve physical and data-link layer issues are proposed. Single carrier frequency division multiple access (SC-FDMA) is proposed as the technology to be implemented at the physical layer, and a variable slot time multiplexing access technique, called variable slot time-time division multiple access (VST-TDMA), with a conscious energy-conservation protocol, is proposed for the data-link (MAC) layer. SC-FDMA with pulse shaping is implemented to minimize the peak-to-average power ratio of the system, which reduces energy consumption. The multiplexing access technique takes advantage of the reduced cell size by multiplexing data in the time domain, this allows the reduced number of users to utilize the entire available bandwidth. Incorporated into the access protocol is the option of energy pacing or even self-sustainability if an energy harvesting device is present. Self-sustainability can be achieved at the cost off throughput, some techniques are discussed to relieve this trade-off condition. Also, a thorough discussion is included on battery energy depletion, even with an energy harvesting device present, to further increase the throughput performance. Since using SC-FDMA reduces the energy consumption, it enables VST-TDMA to operate at higher speeds under self-sustainability mode. Overall the proposed set of solutions showed independently significant improvements to the system. It is also discussed how these techniques coalesce conveniently by working in unison, improving the energy efficiency and throughput capabilities of 60-GHz systems.

5 G systems address growing broadband demands with OFDM-based technologies like SC-FDMA and OFDMA in LTE. A novel pulse shape is proposed for the transmitter-side uplink scheme using single-carrier frequency division multiple access (SC-FDMA) to reduce the Peak to Average Power Ratio (PAPR). The pulse shape combines a finite impulse response (FIR) filter in the frequency domain with a Nyquist-I pulse in the time domain. The optimization of the impulse response of the new pulse shape is achieved by using an envelope-constrained (EC) filter design to suppress the amplitude of the side-lobe. A new family of Nyquist-I pulses is presented, termed exponential raised cosine (ERC), featuring a novel design parameter \(\gamma \) that offers additional degrees of freedom to minimize PAPR for a given roll-off factor \(\alpha \). The sub-optimum value of \(\gamma \) is analyzed with a defined range of values; however, \(\gamma = 0.3\) shows an impressive reduction in PAPR and \(\gamma = 0.1\) verifies an improvement in SER over the other values of \(\gamma \). The simple expression of the ERC shows a less complex design with an average elapsed time of 47.41x10\(^{-6}\) seconds. Computer-based simulations are performed to identify a sub-optimal value \(\gamma \) compared to other existing pulses, showing a significant reduction in PAPR for the interleaved mode of SC-FDMA.