Spectrum sensing is the first step in the cognitive cycle and represents the most critical function in cognitive radio-based dynamic spectrum management. Recently, a new technology termed reconfigurable smart surfaces has emerged as a promising enabler of smart radio environments to control the signal propagation further and improve signal coverage and spectrum management capabilities. This paper investigates how the adoption of reconfigurable intelligent surfaces (RISs) can increase spectral efficiency in a cognitive radio environment. To this end, we optimize the parameters of the new RIS technology by determining the optimal transmit powers and the optimal number of these elements. Next, we derive expressions for the false alarm and detection probabilities of the cognitive radio (CR) node and the transmission probability and throughput. Finally, we demonstrate how the detection phase of the CR spectrum can be improved by employing RIS technology at the UP. Simulation results show that RIS achieves higher energy efficiency than SISO communication for different configurations. In addition, the RISs can significantly improve the wireless communication quality and spectrum sensing performance in a CR environment.

Nowadays, there is an important need for fault-tolerant and energy-efficient self-organization systems, especially within smart cities. Internet of Things (IoT) proved capable of observing and examining the environment, generating & processing data. IoT is now applicable to almost every industry, including transportation and logistics, utilities, agriculture, smart cities, and more. In these industries, various types of meters, sensors, and trackers are used to constantly monitor activities, automate processes and optimize tasks. With the help of big data analytics, they can drive decision-making systems based on observations. As a result, the cities-management challenges are growing. The smart cities requirements are increasing to remedy the challenges, which requires a self-organized network composed of a sizeable number of nodes distributed across an area of interest. The traditional communication systems show limitations, especially when dealing with massive data rates, latency, the explosive growth of vehicular communication, and dynamic mobility. In this study, we explore a way to leverage the capabilities of wireless communication and big data analytics in favor of Smart Cities.

Reconfigurable Intelligent Surfaces (RISs) have been recently considered in communication environments for focusing signal reflections to create smart radio environments. As it can create favorable propagation conditions by controlling the phase shifts of the reflected signals at the surface to enhance the communication quality. However, the current proofs of concept require complex operations for the RIS configuration, which are mainly realized via wired control connections. When used in wireless networks, RISs may contribute enhance wireless communications. The present paper, compares the RIS technology with the SISO case and evaluates the performance of RIS assisted communication system by giving an approximation of the achievable data rate and the energy efficiency, and investigates the effect of the achievable data rate and distances on the energy efficiency. In this work, based on a work by Emil Björnson [18], we have studied the impact of RIS on the wireless sensor networks by modifying some parameters and giving more interpretations. In particular, we illustrate numerical results that highlight the spectral efficiency gains of RISs when their size is sufficiently large as compared with the wavelength of the radio waves. In addition, we discuss key open issues that need to be addressed for unlocking the potential benefits of RISs for application to wireless communications and networks.

The massive growth of wireless communications in recent years is mostly due to new connectivity demands and advances in technology development of low power) transceivers. An example of the unique demands is the increasing exchange of data in Internet services, which has led to wireless network deployment for data transmissions. The coordination of the IoT devices, smart systems, and agriculture can contribute directly to the development of the farmer’s practices by building their farm more intelligent and digital. However, enhancing farming practices requires inspecting farm equipment and farmer’s experiences, which can be analyzed through the interconnectedness of IoT objects to collect farm data over the Internet to launch smart digital agriculture. It is challenging to control all farming processes (especially in real-time), this remaining as the main limitation of traditional farming. In this work, we focus on how wireless sensors can play a vital role in smart farm systems and allow processing the large amount of data generated in batches or real-time to analyze it, retrieve insights from it, and create a Smart Digital Farm. This paper proposes hierarchical-logic mapping and deployment algorithms to tackle the problem of poor network connectivity and sensing coverage in random IoT deployment.

Hypergraphical games provides a compact model of a network of self-interested agents, each involved in simultaneous subgames with its neighbors. The overall aim is for the agents in the network to reach a Nash Equilibrium, in which no agent has an incentive to change their response, but without revealing all their private information. Asymmetric Distributed constraint satisfaction (ADisCSP) has been proposed as a solution to this search problem. In this paper, we propose a new model of hypergraphical games as an ADisCSP based on a new global constraint, and a new asynchronous algorithm for solving ADisCSP that is able to find a Nash Equilibrium. We show empirically that we significantly reduce both message passing and computation time, achieving an order of magnitude improvement in messaging and in non-concurrent computation time on dense problems compared to state-of-the art algorithms.

Prognostic of future health state relies on the estimation of the Remaining Useful Life (RUL) of physical systems or components based on their current health state. RUL estimation can be done by using three main approaches: model-based, experience-based and data-driven approaches. This paper deals with a data-driven prognostics method which is based on the transformation of the data provided by the sensors into models that are able to characterize the behavior of the degradation of bearings. For this purpose, we used Support Vector Machine (SVM) as modeling tool. The experiments on the recently published data base taken from the platform PRONOSTIA clearly show the superiority of the proposed approach compared to well established method in literature like Mixture of Gaussian Hidden Markov Models (MoG-HMMs).

We recently proposed No good-Based Asynchronous Forward Checking (AFC-ng), an efficient and robust algorithm for solving Distributed Constraint Satisfaction Problems (DisCSPs). AFC-ng performs an asynchronous forward checking phase during synchronous search. In this paper, we propose two new algorithms based on the same mechanism as AFC-ng. However, instead of using forward checking as a filtering property, we propose to maintain arc consistency asynchronously (MACA). The first algorithm we propose, MACA-del, enforces arc consistency thanks to an additional type of messages, deletion messages. The second algorithm, MACA-not, achieves arc consistency without any new type of message. We provide a theoretical analysis and an experimental evaluation of the proposed approach. Our experiments show the good performance of MACA algorithms, particularly those of MACA-not.

Asynchronous Backtracking is the standard search procedure for distributed constraint reasoning. It requires a total ordering on the agents. All polynomial space algorithms proposed so far to improve Asynchronous Backtracking by reordering agents during search only allow a limited amount of reordering. In this paper, we propose Agile-ABT, a search procedure that is able to change the ordering of agents more than previous approaches. This is done via the original notion of termination value, a vector of stamps labelling the new orders exchanged by agents during search. In Agile-ABT, agents can reorder themselves as much as they want as long as the termination value decreases as the search progresses. Our experiments show the good performance of Agile-ABT when compared to other dynamic reordering techniques.

In this paper, based on a set of Ultra Wide Bandwidth Channel (UWB) measurements the dependance between Path Loss and frequency is investigated. The measurements are provided in frequency domain over a channel bandwidth 6 GHz (from 3 to 9 GHz) in different locations. A Vector Network Analyzer is used to measure the frequency channel response of the frequency bandwidth of interest. An Omni-directional antennas are used for both the transmitter (Tx) and receiver (Rx) antennas. Probability Density Function (PDF) and Cumulative Distribution Function (CDF) of received signal, power variation and path loss fluctuations are evaluated in frequency domain. An investigation of path loss shows no dependency between frequency and the path loss, but the path loss and central frequency present a correlation.

1Next generation wireless personal area networks (WPAN) are intended for a variety of applications. The Multiband OFDM Alliance (MBOA) is currently developing a new physical layer (PHY) and medium access control (MAC) protocol, which fit the needs of this mass market. The MBOA standards provide wireless technology offering data rates of up to 480 Mbit/s [1]. Motivated by the sub-band approach, this paper presents measurement analysis of the mean (excess) delay, RMS delay spread and number of significants paths for different locations. First, we present the channel measurements based in this study. Secondly, the interpretation of the obtained results show a correlation between the channel bandwidth and the tow main dispersion parameters namely τrmsand τmin all tested settings, Laboratory, Corridor and Outdoor. Our measurement included terminal separations of 1 – 14 meters, the based data are for terminal separation 6 m.