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Millimeter-wave (mm-Wave) systems with $\mbox{hybrid digital-to-analog beamforming (D-A BF)}$ have the potential to fulfill 5G traffic demands. The capacity of mm-Wave systems is severely limited as each radio frequency (RF) transceiver chain in current base station (BS) architectures support only a particular user. In order to overcome this problem when high density of users are present, a new algorithm...
In cognitive radio (CR), the spectrum sensing of the primary user (PU) may consume some electrical power from the battery capacity of the secondary user (SU), yielding to decrease the transmission power of the SU. In this paper, a multislot simultaneous spectrum sensing and energy harvesting model is proposed, which uses the harvested radio frequency (RF) energy of the PU signal to supply the spectrum...
Wireless covert systems use low probability of detection (LPD) techniques to hide transmission and protect the transmitter. Traditionally, spread spectrum has been used to hide the covert signal in noise. Recently, research has focused on covert systems that sense the RF channel and hide their transmission in the RF band of a primary network (PN). A widely used metric to quantify covertness is the...
In this paper, we investigate the performance analysis of dual hop relaying system consisting of asymmetric Radio Frequency (RF)/Free Optical Space (FSO) links. The RF channels follow a Rayleigh distribution and the optical links are subject to Gamma-Gamma fading. We also introduce impairments to our model and we suggest Partial Relay Selection (PRS) protocol with Amplify-and-Forward (AF) fixed gain...
The focus of this work is on cost and complexity- induced rank-constrained precoding for millimeter- wave (mmW) multi-input multi-output (MIMO) systems. The higher antenna dimensionality and sparse channel structure of mmW systems motivate directional precoding schemes over more complex and less robust eigen-mode-based precoding schemes. Building on a prior work that illustrated the superiority in...
We establish the generalized likelihood ratio (GLR) test for a Gaussian signal of known power spectral shape and unknown rank-one spatial signature in additive white Gaussian noise with an unknown diagonal spatial correlation matrix. This is motivated by spectrum sensing problems in dynamic spectrum access, in which the temporal correlation of the primary signal can be assumed known up to a scaling,...
In this paper, we present an amplify and forward based dual-hop free space optical communication (FSO) system with a radio frequency (RF) backup link. In which, the dual-hop FSO links are modeled by log-normal distribution turbulence, and the RF link is assumed to follow the Rayleigh distribution. For the proposed system, analytical expressions for the cumulative distribution function and the probability...
In this paper, the problem of fairly balancing the radar and communication performance in a dual communication and radar system is studied. To gain insight into the problem, a simple model of such a system using OFDM-style waveforms with SNR as the radar's objective and throughput as the communication's objective is explored. As a criteria for balancing the performance of both objectives, α fairness...
Conventional centralized data detection algorithms for massive multi-user multiple-input multiple-output (MU-MIMO) systems, such as minimum mean square error (MMSE) equalization, result in excessively high raw baseband data rates and computing complexity at the centralized processing unit. Hence, practical base-station (BS) designs for massive MU-MIMO that rely on state-of-the-art hardware processors...
We investigate the performance analysis of dualhop free-space optical/radio frequency (FSO/RF) transmission systems where the FSO link is modeled by the double generalized Gamma (DGG) distribution with pointing error impairments under both heterodyne detection and intensity modulation with direct detection (IM/DD), and the RF link experiences the Generalized Nakagami-m fading. Under the assumption...
We investigate the performance of dual-hop fixed gain amplify-and-forward (AF) relaying systems over Nakagami-m and double generalized Gamma (DGG) fading channels for mixed radio frequency/free space optical (RF/FSO) wireless systems. The FSO links account for pointing errors and two types of detection techniques. Our adopted turbulence and fading statistical models are the most general ones. To mitigate...
The modern direction finders (DF) are able to process the frequency band that is much wider than usual signal spectrum. Therefore, as several radio transmitters can be active in the observed frequency range, a further assessment of the active transmitter number as well as their parameters is needed. This additional processing is labeled as spectrum segmentation or preclassification. This paper discusses...
This paper presents analysis of a dual-hop multiple relaying system, which consists of radio frequency (RF)/free-space optical (FSO) links. The analysis is performed under consideration that the system employs partial relay selection (PRS). Variable gain amplify-and-forward (AF) relays are assumed. The estimated channel state information (CSI) is outdated, which is used for both relay selection and...
Future systems of the 5th generation are slated to use the mm-wave bands due to the large slices of bandwidth available at those frequencies. Relative to the contemporary microwave bands, to compensate for the harsh propagation conditions, highly directional communication using beamforming methods is necessary to achieve a level of reliable communication, however minimal. Due to the fragile nature...
The current state of the art for attempting to geolocate co-located, moving RF coincident emitters employs sensing from multiple moving sensors. In this case the RF coincident emitters will be transmitting similar but not identical RF signals overlapping temporally, spectrally and spatially, e.g. two nodes near each other simultaneously transmitting Wifi and Bluetooth. We use a set of distributed...
We review our recent work on the application of advanced electromagnetic structures for Magnetic Resonance Imaging. We discuss the use of metasurfaces and metamaterials resonators in order to locally enhance the sensitivity of radiofrequency coils in daily medical examinations. We will show in particular our recent experimental results about giant signal-to-noise ratio enhancement by arrays of nonmagnetic...
Reconfigurable antenna arrays provide important advantages such as reduction on the number of the physical antennas or reduced hardware complexity in terms of receiving radio frequency chains. Both these properties are critical in vehicle-to-vehicle (V2V) communication systems, which are characterized by inflexible dimensions and cost constraints. In this paper, a new pattern reconfigurable antenna...
In this paper, a novel two-way relaying technique based on network coding is proposed to improve the throughput of dual-hop mixed free-space optics (FSO)/radio-frequency (RF) communication systems. We investigate the performance of the proposed systems over Gamma-Gamma atmospheric turbulence and Rice/Rayleigh channels. The effect of pointing error on FSO link is also considered in our analysis. Closed-form...
Long Term Evolution Advanced (LTE-A) supports a wide range of applications that continuously demand for more resources in order to satisfy the customers' needs. Starting from release 10, Carrier Aggregation (CA) technology has been embedded in the standard to increase the available resources and thus higher performance is offered to users. The Bidirectional real-time applications where large requirements...
Spectrum sensing is a key function of cognitive radio (CR) to identify the vacant frequency bands (which is also referred to as spectrum holes). The future technology of CR networks should be capable to scan wideband frequencies to increase spectrum utilization. To reduce high sampling rate for sampling wideband signal, Modulated Wideband Converter (MWC) is used for data acquisition. In this paper,...
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