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The goal of this paper is to expand on previously researched Eutectic Gallium-Indium (EGaIn) alloy liquid metal antennas to create an antenna that can change both polarization and frequency to meet the users needs. This concept is described through analytical models of helix antennas, simulations performed in FEKO, and measured results of a proof-of-concept dual frequency L-band GPS-focused hardware...
The goal of this paper is to expand from previously researched liquid metal linear array models into a dynamically driven two dimensional liquid metal array. Simulations were performed using FEKO to prove the concept that a multi-dimensional array will provide the user more control over the direction of the main beam and also the direction of the nulls, making the resulting array useful for spatially...
This work presents distributed beamforming using three dimensional randomly distributed volumetric arrays. This work examines a statistical ensemble (mean-valued) of average beampattern behavior for canonical and non-canonical volumetrically bound distributed (random) antenna arrays. Cubical, cylindrical, and spherical topologies of isotropic elements are analyzed to show beamforming and scanning...
Sophisticated cyber attacks by state-sponsored and criminal actors continue to plague government and industrial infrastructure. Intuitively, partitioning cyber systems into survivable, intrusion tolerant compartments is a good idea. This prevents witting and unwitting insiders from moving laterally and reaching back to their command and control (C2) servers. However, there is a lack of artifacts that...
With the growing number of cyberattack incidents, organizations are required to have proactive knowledge on the cybersecurity landscape for efficiently defending their resources. To achieve this, organizations must develop the culture of sharing their threat information with others for effectively assessing the associated risks. However, sharing cybersecurity information is costly for the organizations...
Cooperative spectrum sensing is often necessary in cognitive radios systems to localize a transmitter by fusing the measurements from multiple sensing radios. However, revealing spectrum sensing information also generally leaks information about the location of the radio that made those measurements. We propose a protocol for performing cooperative spectrum sensing while preserving the privacy of...
The generation of pseudorandom number sequences can be achieved in a variety of ways, with the most secure methods generally requiring substantial processing to generate. Other pseudorandom number generation (PRNG) methods accept a compromise between processing power and security by mixing two independent, but less secure, PRNG outputs with each other. This paper presents a generalized mixing method...
There are two broad safety related message categories in vehicular networks: emergency and periodic messages that should share the scarce wireless resource simultaneously. Emergency messages deliver time-critical information with guaranteed reliability, e.g., road-safety information, whereas periodic ones convey normal status update information, e.g., vehicular positions, that is less time- and loss-critical...
In this paper, a transmission mode selection scheme is proposed for device-to-device (D2D) communications underlay cellular networks, where potential D2D (p-D2D) users reuse the spectrum of uplink cellular users (CUEs). The developed framework is used to analyze and understand how the underlay D2D communication affects the cellular network performance. Unlike most of the previous researchers who only...
This paper presents the joint design of network coding and backpressure algorithm for cognitive radio networks and its implementation with software-defined radios (SDRs) in a high fidelity network emulation testbed. The backpressure algorithm is known to provide throughput optimal solutions to joint routing and scheduling for dynamic packet traffic. This solution applies to cognitive radio networks...
The applications for MANETs have increased rapidly and today MANETs are capable of providing a variety of services. One of the major contributing factors is the availability of radios that are able to adapt to the channel conditions and can transmit at multiple data rates. A common approach for channel access is to employ a CSMA/CA based mechanism. However, these protocols tend to under perform at...
Using Commercial off-the-shelf (COTS) software over networks that are Disconnected, Intermittent and Limited (DIL) may not offer acceptable performance. Frequent network interruptions for both shorter and longer periods, as well as long delays, low data and high packet error rates characterize DIL networks. In this paper, we designed and implemented a prototype proxy to improve the performance of...
As cloud services become mature and provide capabilities for elastic computation and data management, hosting services become increasingly prevalent such as Amazon Web Services, Microsoft Azure, or RedHat OpenStack. Workloads are hosted in these platforms using hypervisors running on physical machines which host virtual machines (VMs) presented to the customer. Software-defined network (SDN) technologies...
Ground personnel at the tactical edge often lack data and analytics that would increase their effectiveness. To address this problem, this work investigates methods to deploy cloud computing capabilities in tactical environments. Our approach is to identify representative applications and to design a system that spans the software/hardware stack to support such applications while optimizing the use...
In this paper, we present a generalized polyphase representation for Continuous Phase Modulation (CPM) signals suited to the detection over frequency-selective channels. We first develop two different equalizers based on this representation and relate them to the State of Art. We also derive a Least Squares (LS) channel estimation and an improved LS estimation using a priori on the channel. Simulation...
This paper analyzes the outage probability of a multicarrier signal, using the Protected Tactical Waveform (PTW) on the return link (RL). The signal is relayed over a nonlinear distorted satellite transponder. The transponder is modelled to include a gain element, a soft limiter, and a travelling wave tube amplifier (TWTA); a Shaleh model is used to model the TWTA. The outage probability is determined...
The Hoyt distribution can be used to characterize two types of fading in satellite communications. In this paper, the secrecy of the Hoyt-Hoyt fading channel is investigated. A set of exact formulas of the probability of strictly positive secrecy capacity are derived. Profile examples are illustrated to show the effects of secrecy capacity.
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