Secure Two-Way Transmission via Wireless-Powered Untrusted Relay and External Jammer

In this paper, we propose a two-way secure communication scheme where two transceivers exchange confidential messages via a wireless powered untrusted amplify-and-forward (AF) relay in the presence of an external jammer. We take into account both friendly jamming (FJ) and Gaussian noise jamming (GNJ) scenarios. Based on the time switching (TS) architecture at the relay, the data transmission is done in three phases. In the first phase, both the energy-starved nodes, the untrustworthy relay and the jammer, are charged by non-information radio frequency (RF) signals from the sources. In the second phase, the two sources send their information signals and concurrently, the jammer transmits artificial noise to confuse the curious relay. Finally, the third phase is dedicated to forward a scaled version of the received signal from the relay to the sources. For the proposed secure transmission schemes, we derive new closed-form lower-bound expressions for the ergodic secrecy sum rate (ESSR) in the high signal-to-noise ratio (SNR) regime. We further analyze the asymptotic ESSR to determine the key parameters; the high SNR slope and the high SNR power offset of the jamming based scenarios. To highlight the performance advantage of the proposed FJ, we also examine the scenario of without jamming (WoJ). Finally, numerical examples and discussions are provided to acquire some engineering insights, and to demonstrate the impacts of different system parameters on the secrecy performance of the considered communication scenarios. The numerical results illustrate that the proposed FJ significantly outperforms the traditional one-way communication and the Constellation rotation approach, as well as our proposed benchmarks, the two-way WoJ and GNJ scenarios.Comment: 14 pages, 6 figures, Submitted to IEEE Transactions on Vehicular Technolog

Steinernema feltiae- Xenorhabdus bovienii: more information on this bactohelminthic complex from Iran

Two families of entomopathogenic nematodes (EPNs), Steinernematidae and Heterorhabditidae, that are symbiotically associated with Xenorhabdus and Photorhabdus bacteria, are one of the effective biological control agents of insect pests. Native isolates can probably be more efficacious to control insect pests than exotic ones due to their adaptability to indigenous environmental conditions. In this study, Steinernema feltiae isolate FUM221, was recovered from soil samples collected from the Ardabil Province, Iran. Morphological and morphometric investigations of the first and second-generation adults, infective juveniles, and molecular characterizations were given based on ITS and 18S rDNA genes. Besides, molecular analysis based on the 16S rRNA region and phenetic data recognized Xenorhabdus bovienii as its symbiont bacterium. The scanning electron microscopy (SEM) images verified the identification of this isolate. The molecular characterization using two loci and phylogenetic analyses provided more evidence for the classification of this steinernematid and its difference of the same species from other countries. Moreover, molecular and phenetic characterizations of its symbiotic bacterium were provided with low variations compared to other isolates. Herein, the comprehensive taxonomic data of this steinernematid and its symbiont bacterium, is presented from Iran

Optimal Power Allocation by Imperfect Hardware Analysis in Untrusted Relaying Networks

By taking a variety of realistic hardware imperfections into consideration, we propose an optimal power allocation (OPA) strategy to maximize the instantaneous secrecy rate of a cooperative wireless network comprised of a source, a destination and an untrusted amplify-and-forward (AF) relay. We assume that either the source or the destination is equipped with a large-scale multiple antennas (LSMA) system, while the rest are equipped with a single antenna. To prevent the untrusted relay from intercepting the source message, the destination sends an intended jamming noise to the relay, which is referred to as destination-based cooperative jamming (DBCJ). Given this system model, novel closed-form expressions are presented in the high signal-to-noise ratio (SNR) regime for the ergodic secrecy rate (ESR) and the secrecy outage probability (SOP). We further improve the secrecy performance of the system by optimizing the associated hardware design. The results reveal that by beneficially distributing the tolerable hardware imperfections across the transmission and reception radio-frequency (RF) front ends of each node, the system's secrecy rate may be improved. The engineering insight is that equally sharing the total imperfections at the relay between the transmitter and the receiver provides the best secrecy performance. Numerical results illustrate that the proposed OPA together with the most appropriate hardware design significantly increases the secrecy rate.Comment: 29 pages, 7 figures, Submitted to IEEE Transactions on Wireless Communication

Short-packet amplify-and-forward relaying for the Internet-of-Things in the face of imperfect channel estimation and hardware impairments

In next-generation wireless systems ultra-reliable low-latency communications (URLLC) have to be realized in support of the Internet-of-things (IoT). However, this is quite a challenge in the face of channel estimation errors (CEEs) and hardware imperfections (HWIs). Hence, we consider a variety of realistic HWIs as well as CEEs and evaluate the average block error rate (BLER) of a short-packet based cooperative amplify-and-forward (AF) relaying network. Our simulation and analytical results reveal that as expected, both the CEEs and HWIs lead to a substantial average BLER degradation. In particular, CEEs lead to a BLER floor, which is further aggravated by the increase in HWIs. A high level of HWIs results in a BLER tending to one, regardless of the transmit power. Furthermore, it is shown that the CEEs and HWIs gravely degrade the energy efficiency of the idealized perfect scenario. This observation shows that both the CEEs and HWIs constitute critical issues in the design of energy efficient communication systems. However, through solving the optimization problems formulated, we conceived several schemes for mitigating the degradations imposed by the CEEs and HWIs. e.g. in our adaptive-duration training scheme the total CEE of the hops is shared in line with the current status of the two channels. Our simulation results show that this scheme significantly reduces the BLER and mitigates the deleterious effects of CEE