Outage Performance of Generalized Cooperative NOMA Systems with SWIPT in Nakagami-m Fading

This paper investigates cooperative non-orthogonal multiple access (NOMA) with simultaneous wireless informationand power transfer (SWIPT) radio networks. A decode-andforward relay deserves a base station to transmit informationto two users. Two access schemes are addressed: direct andrelay assisted transmission (DRAT) where a line-of-sight existsbetween the source and destination, and non-direct and relayassisted transmission (nDRAT) where the only access to the finalusers is through the relay. New closed-form expressions of outageprobability are derived at these schemes. A generalization usingNakagami-m fading channels in considered, in order to present acomplete cover of relayed NOMA systems with energy harvestingbehavior in small scale fading.We consider the impact of time splitting fraction, power allocation and channel parameters on system maintainability andevaluate its maximum data rate transmission with full autonomy.By comparing the two schemes, cooperative NOMA with energyharvesting (EH) in nDRAT scenario outperforms transmissionwith direct link in terms of outage probability and transmissiondata rate

Location privacy preservation in secure crowdsourcing-based cooperative spectrum sensing

Spectrum sensing is one of the most essential components of cognitive radio since it detects whether the spectrum is available or not. However, spectrum sensing accuracy is often degraded due to path loss, interference, and shadowing. Cooperative spectrum sensing (CSS) is one of the proposed solutions to overcome these challenges. It is a key function for dynamic spectrum access that can increase largely the reliability in cognitive radio networks. In fact, several users cooperate to detect the availability of a wireless channel by exploiting spatial diversity. However, cooperative sensing is also facing some series of security threats. In this paper, we focus on two major problems. The first problem is the localization preservation of the secondary users. In fact, malicious users can exploit spatial diversity to localize a secondary user by linking his location-dependent sensing report to his physical position. The existing solutions present a high level of complexity which decreases the performance of the systems. The second problem is the data injection attack, in which malicious CR users may affect the decisions taken by the cognitive users by providing false information, introducing spectrum sensing data falsification (SSDF). In fact, they can submit false sensing reports containing power measurements much larger (or smaller) than the true value to inflate (or deflate) the final average, in which case the fusion center may falsely determine that the channel is busy (or vacant) which increases the false alarm and miss detection probabilities. In this paper, we propose a novel scheme to overcome these problems: iterative per cluster malicious detection (IPCMD). It utilizes applied cryptographic techniques to allow the fusion center (FC) to securely obtain the aggregated result from various secondary users without learning each individual report. IPCMD combines the aggregated sensing reports with their reputation scores during data fusion. The proposed scheme is based on a new algorithm for key generation which can significantly reduce the key management complexity and consequently increase the system performance. Therefore, it can enable secure cooperative spectrum sensing and improve the secondary user location privacy.Ooreedoo, Doha, QatarScopu

Outage Performance of Generalized Cooperative NOMA Systems with SWIPT in Nakagami-m Fading

This paper investigates cooperative non-orthogonal multiple access (NOMA) with simultaneous wireless informationand power transfer (SWIPT) radio networks. A decode-andforward relay deserves a base station to transmit informationto two users. Two access schemes are addressed: direct andrelay assisted transmission (DRAT) where a line-of-sight existsbetween the source and destination, and non-direct and relayassisted transmission (nDRAT) where the only access to the finalusers is through the relay. New closed-form expressions of outageprobability are derived at these schemes. A generalization usingNakagami-m fading channels in considered, in order to present acomplete cover of relayed NOMA systems with energy harvestingbehavior in small scale fading.We consider the impact of time splitting fraction, power allocation and channel parameters on system maintainability andevaluate its maximum data rate transmission with full autonomy.By comparing the two schemes, cooperative NOMA with energyharvesting (EH) in nDRAT scenario outperforms transmissionwith direct link in terms of outage probability and transmissiondata rate

Physicochemical Characterization of Geopolymer Binders and Foams Made from Tunisian Clay

Illito-kaolinitic clay rich in hematite from south Tunisia was investigated in view of producing geopolymer materials. Geopolymers with two different densities were elaborated: cement and foam. The effects of activator concentrations on compressive strength, water absorption (durability), open porosity, and bulk density of geopolymers cement were examined, in order to assure optimal geopolymerization conditions. Geopolymer cements aged 28 days with optimum performances were achieved for 13 M of alkaline solution concentration. At these conditions, the compressive strength of prepared geopolymer reaches 27.8 MPa. The addition of silica fume to reactant geopolymer mixture induces modification of geopolymer density and decrease in the compressive strength of the final product. Geopolymer materials based on calcined Tunisian clay can be suggested as sustainable and cost-effective cement that may be applied to alternate Portland cement in many construction applications

Coverage Assessment and Target Tracking in 3D Domains

Recent advances in integrated electronic devices motivated the use of Wireless Sensor Networks (WSNs) in many applications including domain surveillance and mobile target tracking, where a number of sensors are scattered within a sensitive region to detect the presence of intruders and forward related events to some analysis center(s). Obviously, sensor deployment should guarantee an optimal event detection rate and should reduce coverage holes. Most of the coverage control approaches proposed in the literature deal with two-dimensional zones and do not develop strategies to handle coverage in three-dimensional domains, which is becoming a requirement for many applications including water monitoring, indoor surveillance, and projectile tracking. This paper proposes efficient techniques to detect coverage holes in a 3D domain using a finite set of sensors, repair the holes, and track hostile targets. To this end, we use the concepts of Voronoi tessellation, Vietoris complex, and retract by deformation. We show in particular that, through a set of iterative transformations of the Vietoris complex corresponding to the deployed sensors, the number of coverage holes can be computed with a low complexity. Mobility strategies are also proposed to repair holes by moving appropriately sensors towards the uncovered zones. The tracking objective is to set a non-uniform WSN coverage within the monitored domain to allow detecting the target(s) by the set of sensors. We show, in particular, how the proposed algorithms adapt to cope with obstacles. Simulation experiments are carried out to analyze the efficiency of the proposed models. To our knowledge, repairing and tracking is addressed for the first time in 3D spaces with different sensor coverage schemes