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In this paper, the self-interference mitigation performance of in-band full-duplex multiple-input multiple-output (MIMO) nodes is considered in the context of models for realistic hardware characteristics in which antennas are reused to transmit and receive simultaneously. The use of MIMO indicates a self-interference channel with spatially diverse inputs and outputs. Consequently, there are both...
Millimeter-wave (mmWave) systems require massive antennas at both transmitter and receiver to reach desirable link budget. Analog-digital hybrid beamforming is a promising architecture since it significantly reduces the hardware cost while approaches the performance of digital beamforming. However, the nonlinear power amplifier (PA) introduces intermodulation interference and degrades the spectral...
This paper describes the design and simulated performance of a 5G-like spectrum sharing radio that uses both Non-Contiguous-Orthogonal Frequency Domain Modulated (NC-OFDM) waveform and an electrically Reconfigurable Alford Loop Antenna (RALA) to efficiently share spectrum with a co-channel IEEE 802.15.4, or ZigBee, radio link. We present a detailed performance analysis of Monte Carlo simulation trials...
In this work, a cost-effective radio frequency (RF) beamforming array is used to orient and suppress directional interfering signals. With this frontend, both the multiple signal classification (MUSIC) algorithm used in direction-of-arrival (DOA) estimation and the optimizaoion based power inversion (PI) algorithm used to suppress the interfering signal can be significantly simplified. With a RF output,...
We report on a novel implementation of a photonics-based RF interference mitigation system which is capable of suppressing same-frequency interference from a known signal at least 40 dB stronger than the signal-of-interest. Our technique will be valuable in future simultaneous transmit and receive (STAR) systems.
We demonstrate a microwave photonic Interference canceller with a balanced architecture capable of relative-intensity noise suppression. Experimental results show that the system can cancel > 25 dB interference over 200 MHz instantaneous bandwidth and tune over a frequency range of 2–8 GHz.
In wireless sensor networks, the need for ultra- low power consuming nodes is one of the main motivations for research in such field. Because radio sections in sensor nodes contribute to a large extent to the overall power consumption, the focus of this study is on the RF transceiver. The aim is to reduce the average power consumption which depends significantly on the circuit architecture design,...
In this paper, we consider device-to-device (D2D) communication underlaying cellular networks, where D2D users harvest radio frequency (RF) power from uplink cellular transmissions. This paper addresses two important issues for energy harvesting-based D2D cellular networks. The first is how the energy harvested from cellular ambient RF signals affects the D2D spectral efficiency. Using tools from...
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...
Image frequencies and in-band interferences degrade the system performance by masking the desired down-converted signal and therefore rendering a radio receiver inoperable. This paper, elucidates an architecture for improved image rejection and interference mitigation which are critical in Cognitive Radio (CR) architectures. Many attempts have been made to mitigate these interferences in a CR receiver...
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...
Energy efficiency is one of the major challenges of 5G networks. As data rates are expected to increase by 1000x from 4G to 5G, energy efficiency will need to improve by about the same amount. Recently, energy harvesting techniques have attracted lots of attention from the scientific community, due to their ability to increase network lifetime. More specific, energy harvesting from ambient radio frequency...
As RF environments become more complex from both targeted attacks and challenging RF propagation environments (e.g. urban), pre-planned placement of deployed communications elements becomes arduous for the network planner supporting the digital battlefield. We propose a novel dynamic range extension approach that builds upon our extant planning and optimisation tool, HARLEQUIN, to automatically and...
Covert systems are designed to operate at a low probability of detection (LPD) in order to provide system protection at the physical layer level. The classical approach to covert communications hides the signal in noise; however, the increasing demand for modern covert systems that provides better protection against intercept receivers (IRs) has shifted the focus to the design of Ad-Hoc covert networks...
Recent advances in Milimeter wave (mmWave) band mobile communications may provide solutions to the increasing traffic demand in modern wireless systems. Even though mmWave bands are scarcely occupied, the design of a prospect transceiver should guarantee the efficient coexistence with the incumbent services in these bands. To that end, in this paper, two underlay cognitive transceiver designs are...
Spectrum pooling is not typically used in current cellular networks, because it only provides a slight performance improvement while requiring heavy coordination among different cellular operators. However, these problems can be potentially overcome in millimeter-wave (mmWave) networks, thanks to the use of beamforming both at base stations and at user equipments. In this paper, we develop a joint...
This paper considers a hybrid two-stage space-time receiver structure for uplink millimeter wave (mmW) based systems, where the user terminals (UTs) and the base station (BS) are equipped with a large antenna array and the number of radio frequency (RF) chains is lower than the number of antennas. In the first stage the analog transmit and receive beam-formers/precoders are computed for each UT —...
In this paper, we present the beamforming technologies used for increasing the system capacity at unlicensed band. We investigate the international research trend and the key technology of some companies, such as Wavion, GoNet, and Ruckus Inc. We also introduce the Binary CDMA technologies good at PAPR characteristics. Finally, we analysis the performance of receive beamforming using Compact MIMO...
In Wi-Fi networks, Device-to-Device (D2D) communications aim to improve the efficiency of the network by supporting direct communication between users in close proximity. However, in a congested Wi-Fi network, establishing D2D connections through a locally managed self-organising approach will intensify the congestion and reduce the scalability of the solution. Therefore, a centralised management...
As part of ONR's Integrated Topside (InTop) Program, in 2014 Northrop Grumman delivered a bi-static, active, electronic scanned array (AESA) system, capable of multifunction, simultaneous transmit and receive operation. The system is wide band, transmits high power and has high receive sensitivity. Further, there are simultaneous transmit and receive modes required, in which the transmit AESA radiates...
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