Three Different Compact Elliptical Slot Ultra -Wide band Antennas for Wireless Communication Applications

From this current paper, 3 separate elliptical slotted ultra- wide band (UWB) antennas are being proposed. These antennas have been designed with a standard PCB design process to be capable of integrating with radiofrequency or microwave circuitry. Two designs were presented in which the initial design comprised a half circular ring radiator and the remaining one considers a half elliptical ring radiator. The third design of the radiator is in the shape of a crescent. The impedance bandwidth of all these presented antenna designs varies from 2.5GHz and reaches to 14GHz with a S11 less than -10GHz. Here, every proposed antenna design also has a consistent radiation pattern across its frequency band of interest. The performance of the antenna is impressive for lower band frequency in UWB system, which differs in a range of 3.1GHz to 5.1GHz. Across the whole frequency band the antenna shows a 10db return loss bandwidth. The antenna is fabricated on RT-duroid substrate and fed with 50 Ω coupled tappered transmission line.

An FPGA Scalable Software-Defined Radio Platform for UAS Communications Research

In the framework of modern Unmanned Aerial System (UAS) ground-board communications, a data-link system should provide with the following features [1]: multiband and adaptive modulations for responding to channel conditions changes and multi-standard interoperability, interferences resilience with a secure physical layer, incorporation of an air-to-air link complementary to the classical air-to-ground links. Varying the available communication functions to provide the above features without the need to substitute on-board components is a desired target. For this purpose, a Field Programmable Gate Aray (FPGA) scalable Software Defined Radio hardware Platform (SDRP) and its control and baseband signal processing architecture have been developed. The platform is composed by means of three boards which provide respectively the power supply, an FPGA based processing core and the radio frequency front-end. The control and baseband signal processing architecture, implemented on the FPGA, is designed with an application-independent section, working as a base reference design, and a reconfigurable section that implements communication functions and algorithms. The overall platform, at the board and FPGA architecture level, has been designed considering scalability and modularity as key features. Thanks to this platform a data-link which responds to the above target can be easily implemented. As a case study a reconfigurable data-link between a UAS and a Ground Control Station (GCS), designed to establish reliable communication in all the phases of a flight (parking, taxiing, taking off, cruising and landing), is presented.

AOMDV-OAM: A Security Routing Protocol Using OAM on Mobile Ad Hoc Network

On-demand routing protocol is designed to work efficiently on mobile ad hoc networks (MANET). They operate with the belief that all nodes in the network are friendly, thus hackers exploiting security vulnerabilities to carry out some form of cyber attacks, especially Flooding attacks. This form of attack is easily accomplished by overflowing route request packets into the network. Once the attack frequency is large enough, it shall interfere with the route discovery of other network nodes, damaging network performance. In this article, we will analyze and evaluate the impact of flood attacks on the performance of two routing protocols AOMDV. Thereby, we describe a security solutions using the One Time Password (OTP) authentication mechanism (OAM) and implementing AOMDV-OAM security protocol, which is improved from the AOMDV protocol by using OAM to reduce the harmful effects of flood attacks. Using NS2, we assess the security effectiveness of the AOMDV-OAM protocol in random waypoint network topologies where has flooding attacks. Simulation results show that AOMDV-OAM protocol is very effective in minimizing the harmful effects of flood attacks, the rate of successful packet delivery reached over 99% when the one malicious node attacked with a frequency of 20pkt/s and 50pkt/s for Grid network topology.

On Golden Code Performances in Impulsive Noise MIMO Channels

Wireless technologies are the ones who provide fast communications on long distances. MIMO (Multiple-Input-Multiple-Output) Systems become an important factor in communication standards. At the beginning, this technology involved several antennas for both transmission and reception. Nowadays, in order to improve the performance of wireless transmissions, in addition to multi-channel propagation, error correction codes are used. Golden Code has some advantages, such as: maximum rate and diversity or coding gain. In this paper it is proposed an approach of using this code to mitigate the impulsive noise effects in a MIMO communication system. The Middleton Class-A noise was considered. The simulation was done for different values of the impulsive noise model parameters and showed that the probability density function depends on index impulse and on gaussian factor and the number of noise sources has no influence.

STE-AMM: Secret Twist Encryption Standard Access Mechanism Model in Cloud Environment

The advent of the cloud computing has provided the opportunity for various organizations and enterprises to store the data effectively at low cost. With the advancement, the cloud environment manages to have mutli-users to access the data in the cloud based on their request. The requests and the activities of users are monitored and controlled by the group manager based on the roles of them. However due to the dynamic nature of the multi -user clouds result in challenges for ensuring the security of the cloud. Additionally, the revocation of existing users often results in increased overheads. A novel framework of Secret Twisted Encryption based access mechanism model (STE-AMM) is proposed to resolve these issues with two modules. The Square Decisional Diffie-Hellman (SDDH) technique is employed to generate the digital signature for users and used to govern the user in group module. The secret keys to secure the data is generated with the STE algorithm which is the improved Advanced Encryption Standard (AES) and used in the data module. The proposed STE-AMM framework is implemented and evaluated with the metrics of time and cost. The obtained results showed that the performance of the proposed framework is effective than the existing models for securing the data in the cloud. The proposed framework may be enhanced with random size for signature and security key.

Design of Band-Notched MIMO Antenna for UWB Applications

A compact ultra-wideband (UWB) Multiple-Input-Multiple-Output (MIMO) antenna with a notched band is presented. The proposed design consists of four unipolar UWB radiators, and these monopole radiators are placed perpendicular to each other to exploit polarization diversity, where the four-element ultra-wideband (UWB) Multiple-Input-Multiple-Output (MIMO) antenna is presented. The total size of the antenna is 60x60 mm2. The operating frequency of the antenna is 3.1–11 GHz with a return loss of less than 10 dB, except at the notched band of 4.9– 5.9 GHz. This antenna consists of an isosceles trapezoidal plate with a circular notch cut and two transitional steps as well as a partial ground plane. For UWB bandwidth enhancement techniques: use of a partial ground plane, and modify the gap between the radioactive element and ground plane technique, using steps to control the resistance stability and a notch cut technique. The notch cut from the radiator is too used to reduce the size of the plane antenna. The measured -10 dB return loss bandwidth for the designed antenna is about 116.3% (8.7 GHz). The MIMO antenna does not require any additional structure to improve insulation. The proposed antenna supplies an acceptable radiation pattern and relatively flat gain over the entire frequency band.

Self-Adaptive Rectenna with High Efficiency over a Wide Dynamic Range for RF Energy Harvesting Applications

This paper presents a novel simple adaptive and efficient rectenna with automatic power distribution to achieve high radio frequency-direct current (RF-DC) power conversion efficiency (PCE) over a wide range of RF input power. This design employs two rectifier paths operating at low and high-power levels, respectively. Automatic power distribution method exploits the power-dependent input impedance of the rectifier and routes the RF input power into the assigned path according to the input power level. A distinctive enhancement in the rectifier dynamic range is achieved when dividing the high path power equally into two or more parallel diode cells, which helps the high path to camouflage the diode breakdown voltage in case of high input power level. The proposed adaptive design applies two different rectifier topologies, one by using shunt diode topology and the other by using voltage doubler topology at 2.45 GHz. Simulated PCE of this work is kept above 50% over a range of 25.1 dBm from -5.7 to 19.4 dBm of RF input power using shunt diode topology and over a range of 30 dBm from -6.3 to 23.7 dBm of RF input power using voltage doubler topology.

Energy Harvesting Enabled Full-Duplex Cooperative Relaying System over Fisher-Snedecor F-Distribution Fading Channel

In this paper, the performance of an Energy Harvesting (EH) enabled full-duplex cooperative decode-and-forward (DF) relaying system is investigated over the Fisher-Snedecor F-fading channel. The system energy-constrained relay unit utilizes time-switching relay protocol for scavenging energy from the source signal and information transmission to the destination. To quantify the system performance, the exact analytical closed-form expression for the system outage probability is derived, and then used to obtain the analytical expression for the average throughput of delay-limited transmission mode. Moreover, the exact closed-form expression for the system Ergodic capacity is derived through which the average delay-tolerant throughput is determined for the system. In addition, the results demonstrate the impact of fading and shadowing severity on the system performance. It also is noticeable from the results that the performance of system is strongly affected by the loop back interference from the relay node. Finally, the accuracy of the derived analytical expressions is then validated through the Monte-Carlo simulation.

Effect of Architectural Composition of MLP ANN in Neural Network Learning for Signal Power Loss Prediction

This work analyzes the architectural complexity of a Multi-Layer Perceptron (MLP) Artificial Neural Network (ANN) model suitable for modeling and predicting signal power loss in micro-cellular environments. The MLP neural network model with one, two, and three hidden layers respectively were trained using measurement datasets used as the target values collected from a micro-cell environment that is suitable to describe different propagation paths and conditions. The neural network training has been performed by applying different training techniques to ensure a well-trained network for good generalization and avoid over-fitting during network training. Bayesian regularization algorithm (that updates weights and biases during network training) following the Levenberg-Marquardt optimization training algorithm was used as the training algorithm. A comparative analysis of training results from one, two, and three hidden layers MLP neural networks show the best prediction result of the signal power loss using a neural network with one hidden layer. A complex architectural composition of the MLP neural network involved very high training time and higher prediction errors.

Semiorthogonal User Scheduling for Millimeter Wave Using Low-Resolution ADCs

Low-resolution Analogue-to-Digital Converters (ADCs) is a promising solution to reduce power consumption for millimeter wave (mmWave) systems in which the number of antennas at base stations is very large. In this paper, we develop downlink user scheduling for mmWave systems using low-resolution ADCs. Although the sum-rate of Maximum Rate algorithm is very impressive in mmWave systems, it is difficult to use in practice, especially for a large number of users due to exhaustive search. Therefore, we proposed a novel scheduling, termed as NOUS, which selects users who are semi-orthogonal to each other in the beamspace. A closed-form expression for the scheduling criteria in the downlink channel over a mmWave system with low-resolution ADCs and Zero-forcing precoder is derived. The numerical results show that the NOUS algorithm almost achieves the performance of Maximum Rate with lower complexity and outperforms the performance of Proportional Fair in terms of the sum rate.