Showing papers on "Active antenna published in 2020"
Posted Content•
TL;DR: This article aims for the implementation of single-RF MIMO by shifting the focus from SM to metasurface-based modulation and investigates the research challenges and opportunities in the context of metasURface- based modulation.
Abstract: In multiple-input multiple-output (MIMO), multiple radio frequency (RF) chains are usually required to simultaneously transmit multiple data streams. As a special MIMO technology, spatial modulation (SM) activates one transmit antenna with one RF chain and exploits the index of the active antenna for information transfer at each time slot. Recently, reconfigurable metasurfaces have emerged as a promising technology that is able to reconfigure the wireless propagation environment by altering the amplitude and/or phase of the incident signal. In this article, we aim for the implementation of single-RF MIMO by shifting the focus from SM to metasurface-based modulation. Specifically, the principles of SM and metasurfaces are first presented. After reviewing the evolution of SM, we elaborate on the idea of metasurface-aided single-RF MIMO and discuss some implementations for it in line with notable variants of SM. A comparison between antenna-based and metasurface-based modulation is made to highlight the advantages of using metasurfaces. We finally investigate the research challenges and opportunities in the context of metasurface-based modulation.
44 citations
Posted Content•
TL;DR: Simulation results show that the proposed optimal antenna selection outperforms the trivial uniform antenna selection, and the performance of beam searching is more stable than that of channel extrapolation with fewer active antennas.
Abstract: To capture the communications gain of the massive radiating elements with low power cost, the conventional reconfigurable intelligent surface (RIS) usually works in passive mode. However, due to the cascaded channel structure and the lack of signal processing ability, it is difficult for RIS to obtain the individual channel state information and optimize the beamforming vector. In this paper, we add signal processing units for a few antennas at RIS to partially acquire the channels. To solve the crucial active antenna selection problem, we construct an active antenna selection network that utilizes the probabilistic sampling theory to select the optimal locations of these active antennas. With this active antenna selection network, we further design two deep learning (DL) based schemes, i.e., the channel extrapolation scheme and the beam searching scheme, to enable the RIS communication system. The former utilizes the selection network and a convolutional neural network to extrapolate the full channels from the partial channels received by the active RIS antennas, while the latter adopts a fully-connected neural network to achieve the direct mapping between the partial channels and the optimal beamforming vector with maximal transmission rate. Simulation results are provided to demonstrate the effectiveness of the designed DL-based schemes.
41 citations
TL;DR: The proposed PW-CL DPD is shown to outperform the state-of-the-art PW DPD based on the indirect learning architecture, as well as the classical single-polynomial-based DPD solutions in terms of linearization performance and computational complexity by a clear margin.
Abstract: In this paper, we describe a novel framework for digital predistortion (DPD) based linearization of strongly nonlinear millimeter-wave active antenna arrays. Specifically, we formulate a piecewise (PW) closed-loop (CL) DPD solution and low-complexity gradient-adaptive parameter learning algorithms, together with a region partitioning method, that can efficiently handle deep compression of the PA units. The impact of beamsteering on the DPD performance is studied, showing strong beam-dependence, thus necessitating frequent updating of the DPD. In order to facilitate fast adaptation, an inexpensive, non-iterative, pruning algorithm is introduced, which allows to significantly reduce the amount of model coefficients. The proposed methods are validated with extensive over-the-air RF measurements on a 64-element active antenna array transmitter operating at 28 GHz carrier frequency and transmitting a 400 MHz 5G New Radio (NR) standard-compliant orthogonal frequency division multiplexing waveform. The obtained results demonstrate the excellent linearization capabilities of the proposed solution, conforming to the new 5G NR requirements for frequency range 2 (FR2) in terms of both inband waveform quality and out-of-band emissions. The proposed PW-CL DPD is shown to outperform the state-of-the-art PW DPD based on the indirect learning architecture, as well as the classical single-polynomial based DPD solutions in terms of linearization performance and computational complexity by a clear margin.
41 citations
TL;DR: The proposed method offers a framework to optimize nanophotonic structures at the array level that is potentially applicable to a wide variety of objective functions and actively tunable metasurface antenna array platforms.
Abstract: We report an array-level inverse design approach to optimize the beam steering performance of active metasurfaces, thus overcoming the limitations posed by nonideal metasurface phase and amplitude tuning. In contrast to device-level topology optimization of passive metasurfaces, the outlined system-level optimization framework relies on the electrical tunability of geometrically identical nanoantennas, enabling the design of active antenna arrays with variable spatial phase and amplitude profiles. Based on this method, we demonstrate high-directivity, continuous beam steering up to 70° for phased arrays with realistic tunable antenna designs, despite nonidealities such as strong covariation of scattered light amplitude with phase. Nonintuitive array phase and amplitude profiles further facilitate beam steering with a phase modulation range as low as 180°. Furthermore, we use the device geometries presented in this work for experimental validation of the system-level inverse design approach of active beam steering metasurfaces. The proposed method offers a framework to optimize nanophotonic structures at the array level that is potentially applicable to a wide variety of objective functions and actively tunable metasurface antenna array platforms.
41 citations
TL;DR: The proposed rectifier circuit and active antenna configuration are the first demonstration of a high-power beam tracking system for WPT scenarios, being different from previously reported near-field coupling and other lower power harvesting schemes.
Abstract: This article describes a full-bridge rectifier and a receiving antenna array for operation within an innovative wireless power transmission (WPT) system. A high-power transmitter using circularly polarized free-space waves and based on a retrodirective antenna array technology is also employed to boost the overall received RF power at the input of the rectenna. To the best of our knowledge, the proposed rectifier circuit and active antenna configuration are the first demonstration of a high-power beam tracking system for WPT scenarios, being different from previously reported near-field coupling and other lower power harvesting schemes. The main focus of this article is the rectifier design, its bench-top measurements, and operation in such a retrodirective, self-tracking microwave system. A novel approach based on in-phase multitone input signals is also developed to improve rectifier efficiency. The rectifier size is 4.5 cm by 2 cm and can offer more than 86% and 75% RF-to-dc rectification efficiency at 27 dBm for an input signal at 1.7 and 2.4 GHz, respectively. This rectifier circuit component can also be employed in other communication applications or WPT systems, for example, to convert to dc received RF signals or power in the radiating near- and far-field in order to wirelessly charge the batteries of home electronics, such as smartphones, tablets, or Internet of Things (IoT) devices.
33 citations
TL;DR: A dense neural network is considered that is capable of modeling the correlation between the nonlinear distortion characteristics among different beams, which allows providing consistently good linearization regardless of the beamforming direction, thus avoiding the necessity of executing continuous digital predistortion parameter learning.
Abstract: In this letter, we propose an efficient solution to linearize mmWave active antenna array transmitters that suffer from beam-dependent load modulation. We consider a dense neural network that is capable of modeling the correlation between the nonlinear distortion characteristics among different beams. This allows providing consistently good linearization regardless of the beamforming direction, thus avoiding the necessity of executing continuous digital predistortion parameter learning. The proposed solution is validated, conforming to 5G new radio transmit signal quality requirements, with extensive over-the-air RF measurements utilizing a state-of-the-art 64-element active antenna array operating at 28-GHz carrier frequency.
24 citations
TL;DR: The joint optimization problem of maximizing the secrecy rate (Max-SR) over the transmit antenna selection and ANP in the context of secure SM-aided networks is formulated and a significant computational complexity reduction can be achieved.
Abstract: The security of spatial modulation (SM) aided networks can always be improved by reducing the desired link’s power at the cost of degrading its bit error ratio performance and assuming the power consumed to artificial noise (AN) projection (ANP). We formulate the joint optimization problem of maximizing the secrecy rate (Max-SR) over the transmit antenna selection and ANP in the context of secure SM-aided networks. In order to solve this problem, we provide a pair of solutions, namely joint and separate solutions. Specifically, an accurate approximation of the SR is used for reducing the computational complexity, and the optimal AN covariance matrix (ANCM) is found by convex optimization for any given active antenna group (AAG). Then, given a large set of AAGs, simulated annealing mechanism is invoked for optimizing the choice of AAG, where the corresponding ANCM is recomputed by this optimization method as well when the AAG changes. To further reduce the complexity of the above-mentioned joint optimization, a low-complexity two-stage separate optimization method is also proposed. Moreover, when the number of transmit antennas tends to infinity, the Max-SR problem becomes equivalent to that of maximizing the ratio of the desired user’s signal-to-interference-plus-noise ratio to the eavesdropper’s. Thus, our original problem reduces to a fractional programming problem and a significant computational complexity reduction can be achieved. Finally, our simulation results verify the efficiency of the proposed methods in terms of the SR performance attained.
23 citations
01 Jan 2020
TL;DR: In this paper, a cold-source and calibration method that can measure both the gain of the antenna and the G/T, utilizing a Vector Network Analyzer with integrated noise Figure measurement, is presented.
Abstract: G/T is a common Figure of merit, which replaces noise Figure for active antennas. An active antenna has both antenna gain from the configuration of the elements as well as from active electronic amplification integrated with the antenna. The integration precludes measuring the noise Figure of the active element directly. Active phased-array antennas have many elements, each contributing some noise (uncorrelated)) and some signal (correlated). Traditional Y-factor (Hot/Cold) methods don’t work well for active antennas; here is introduced a cold-source and calibration method that can measure both the gain of the antenna and the G/T, utilizing a Vector Network Analyzer with integrated noise Figure measurement.
21 citations
TL;DR: In this article, the electrical properties of the paper substrates, the printed silver nanoparticle-based thin films, the dielectric layers, and the catalyst-based metallization process are discussed.
Abstract: The newly developed research area of inkjet-printed radio frequency (RF) electronics on cellulose-based and synthetic paper substrates is introduced in this paper. This review paper presents the electrical properties of the paper substrates, the printed silver nanoparticle-based thin films, the dielectric layers, and the catalyst-based metallization process. Numerous inkjet-printed microwave passive/ative systems on paper, such as a printed radio frequency identification (RFID) tag, an RFID-enabled sensor utilizing carbon nanotubes (CNTs), a substrate-integrated waveguide (SIW), fully printed vias, an autonomous solar-powered beacon oscillator (active antenna), and artificial magnetic conductors (AMC), are discussed. The reported technology could potentially act as the foundation for true “green” low-cost scalable wireless topologies for autonomous Internet-of-Things (IoT), bio-monitoring, and “smart skin” applications.
20 citations
TL;DR: In this article, a piecewise closed-loop (PW) DPD solution and low-complexity gradient-adaptive parameter learning algorithms, together with a region partitioning method, are proposed for digital predistortion (DPD)-based linearization of strongly nonlinear mm-wave active antenna arrays.
Abstract: In this article, we describe a novel framework for digital predistortion (DPD)-based linearization of strongly nonlinear millimeter-wave active antenna arrays. Specifically, we formulate a piecewise (PW) closed-loop (CL) DPD solution and low-complexity gradient-adaptive parameter learning algorithms, together with a region partitioning method, which can efficiently handle deep compression of the PA units. The impact of beamsteering on the DPD performance is studied, showing strong beam-dependence, thus necessitating frequent updating of the DPD. In order to facilitate fast adaptation, an inexpensive, noniterative, pruning algorithm is introduced, which allows us to significantly reduce the number of model coefficients. The proposed methods are validated with extensive over-the-air RF measurements on a 64-element active antenna array transmitter operating at 28-GHz carrier frequency and transmitting a 400-MHz 5G new radio (NR) standard-compliant orthogonal frequency-division multiplexing waveform. The obtained results demonstrate the excellent linearization capabilities of the proposed solution, conforming to the new 5G NR requirements for frequency range 2 (FR2) in terms of both in-band waveform quality and out-of-band emissions. The proposed PW-CL DPD is shown to outperform the state-of-the-art PW DPD based on the indirect learning architecture, as well as the classical single-polynomial-based DPD solutions in terms of linearization performance and computational complexity by a clear margin.
19 citations
TL;DR: The experimental results proved the correctness of the basic idea and showed stable self-oscillations with a tuning range from 1:2 to 1:3 and the influence of NIC dispersion, non-linearity, and antenna type on the system performances is discussed and appropriate design guidelines are given.
Abstract: The concept of a self-oscillating non-Foster unit cell, intended for use in future active metasurfaces, is introduced. It is based on two orthogonally polarized small antennas connected via a negative impedance converter (NIC). An NIC converts the admittance of the first antenna into a negative admittance, canceling the admittance of the second antenna within a theoretically infinite bandwidth. This system behaves as a special kind of a nearly perfectly matched small active antenna that supports oscillations at every frequency within NIC’s operating bandwidth. Frequency tuning is achieved either by inclusion of a resonant circuit or by injection locking from an external source. The influence of NIC dispersion, non-linearity, and antenna type on the system performances is discussed, and appropriate design guidelines are given. Several scaled experimental demonstrators of non-Foster self-oscillating unit cell, operating in lower RF range, were designed, manufactured, and tested. The experimental results proved the correctness of the basic idea and showed stable self-oscillations with a tuning range from 1:2 to 1:3.
TL;DR: In this paper, an electronically scannable phased array antenna architecture is proposed with a drastically reduced number of active antenna elements. But, the possible beampointing directions are constrained.
Abstract: An electronically scannable phased array antenna architecture is proposed with a drastically reduced number of active antenna elements. The proposed approach is based on the concept of Huygens’ metasurfaces, where the fields in a given region are controlled by active or passive electromagnetic sources on the boundary surface of this region. Using this approach, arbitrary plane waves are excited inside a metallic cavity by peripheral sources, and the cavity is engineered to radiate a single or multiple pencil beams through appropriately perforated slots on its top surface. The proposed peripherally excited (PEX) phased array architecture generates pencil beams that are electronically scanned by controlling the amplitudes and phases of the peripheral sources. The proposed concept has the potential to drastically reduce the required number of active elements in 2-D phased arrays without compromising directivity. However, the possible beam-pointing directions are constrained.
TL;DR: Comparisons with stochastic models and results reported in recent literature show that the formulas obtained allow to obtain a useful approximation of the power reduction factor, making the formulas suitable for a preliminary fast estimation of the Electromagnetic Field in 5G cells for human exposure assessment.
Abstract: Maximum power extrapolation techniques from measured data are usually employed to assess the compliance with standards of average fields radiated by base stations. However, such techniques provide an upper bound, which is not reached in real scenarios. This is particularly true in 5G Communications, where Active Antenna Systems allow a decrease of the average power density according to the adopted scheduling strategy. This paper is focused on the power reduction estimation in realistic scenarios. In particular a deterministic model of a communication system is used to obtain simple formulas only requiring the knowledge of the served area angular extension and of the Envelope Radiation Pattern of the antenna. The model, developed for beam steering and grid of beams antennas, is also extended to analyze the case of Multi User massive Multiple Input Multiple Output (MU-mMIMO) antennas with single layer per user, showing that under proper hypothesis on the beams of the antenna it is possible to estimate the reduction parameter without the explicit knowledge of the number of layers of MU-mMIMO systems. In spite of the simplicity of the approach, comparison with stochastic models and results reported in recent literature show that the formulas obtained using the model proposed in this paper allow to obtain a useful approximation of the power reduction factor, making the formulas suitable for a preliminary fast estimation of the Electromagnetic Field in 5G cells for human exposure assessment.
TL;DR: A new integration scheme of a GaN power amplifier transistor with an antenna without using any output matching network (OMN) and harmonic tuning network (HTN) is proposed to construct a seamlessly integrated AIA, achieved by a novel design of a slot antenna with optimized input impedance at its fundamental frequency.
Abstract: Loss reduction to improve the power efficiency in active integrated antenna (AIA) is a key design drive. This paper first analyzes the loss mechanism in a convention AIA structure. A new integration scheme of a GaN power amplifier (PA) transistor with an antenna without using any output matching network (OMN) and harmonic tuning network (HTN) is then proposed to construct a seamlessly integrated AIA. This is achieved by a novel design of a slot antenna with optimized input impedance at its fundamental frequency as well as for harmonic tuning, which essentially absorbs the OMN and HTN functions in the conventional Class-F power amplifier design. By eliminating these passive networks between the transistor and the antenna, the associated insertion and mismatch losses as well as the overall circuit size are reduced. For verification, two prototypes are designed, fabricated and measured, one with the integrated design and the other with a conventional design for comparison. Both AIAs operate between 3.4 and 3.6 GHz. Experimental results show that the power-added efficiency (PAE) of the seamlessly integrated AIA is over 52% within the operating band. Compared with the conventional cascaded design of a PA and an antenna, the PAE is improved by 14.2%.
15 Mar 2020
TL;DR: Novel wideband passive and active efficient wearable metamaterial antennas for IOT, BAN and 5G applications are presented in this paper.
Abstract: Efficient small antennas are crucial in the development of wearable wireless communications and medical systems. Low efficiency is the major disadvantage of small antennas. Meta materials technology and active components are used to improve the efficiency of small antennas. Moreover, the dynamic range and the efficiency of communication system may be improved by using active wearable antennas. Amplifiers may be connected to the wearable antenna feed line to increase the system dynamic range. Novel wideband passive and active efficient wearable metamaterial antennas for IOT, BAN and 5G applications are presented in this paper. The gain and directivity of antennas with Split-ring resonators, SRR, is higher by 2.5dB than the antennas without SRR. The resonant frequency of the antennas with SRR is lower by 4% to 11% than the antennas without SRR. The resonant frequency of the antenna with SRR on human body is shifted by 3% to 5%. Active small wearable antennas may be used in receiving or transmitting communication systems. For example, the active metamaterial antenna gain is 13+3dB for frequencies from 0.1GHz to 0.8GHz. The active antenna Noise Figure is 0.5+0.3dB for frequencies from 0.1GHz to 0.8GHz.
21 Sep 2020
TL;DR: In this paper, a dual-function radar communication (DFRC) system is proposed, which achieves high target resolution and high communication rate by using orthogonal frequency division multiplexing (OFDM) type.
Abstract: A novel dual-function radar communication (DFRC) system is proposed, that achieves high target resolution and high communication rate. It consists of a multiple-input multiple-output (MIMO) radar, where only a small number of antennas are active in each channel use. The probing waveforms are orthogonal frequency division multiplexing (OFDM) type. The OFDM carriers are divided into two groups, one that is used by the active antennas in a shared fashion, and another one, where each subcarrier is assigned to an active antenna in an exclusive fashion (private subcarriers). Target estimation is carried out based on the received and transmitted symbols. The system communicates information via the transmitted OFDM data symbols and the pattern of active antennas in a generalized spatial modulation (GSM) fashion. A multi-antenna communication receiver can identify the indices of active antennas via sparse signal recovery methods. The use of shared subcarriers enables high communication rate. The private subcarriers are used to synthesize a virtual array for high angular resolution, and also for improved estimation on the active antenna indices. The OFDM waveforms allow the communication receiver to easily mitigate the effect of frequency selective fading, while the use of a sparse array at the transmitter reduces the hardware cost of the system. The radar performance of the proposed DFRC system is evaluated via simulations, and bit error rate (BER) results for the communication system are provided.
TL;DR: This article proposes different ways for thinning this kind of antenna arrays, which can be efficiently solved via common convex-optimization solvers and has the flexibility to provide various levels of array performance with reduced hardware resources.
Abstract: For antenna arrays, the conventional beamformer (CB) is perhaps the simplest kind of beamforming techniques with only phase shifters connected to the antenna elements. However, the output signal to interference and noise ratio (SINR) performance is usually quite away from the optimum. Besides, as the number of antenna elements increases, the hardware cost and power consumption are still too high for many applications. In this article, based on the phase-only CB, we propose different ways for thinning this kind of antenna arrays, which can be efficiently solved via common convex-optimization solvers. Specifically, the first-derived phase-only thinned array can largely increase the output SINR with fewer active antenna elements than the CB. The second one can keep the output SINR performance as that of the CB with a significantly smaller number of active antenna elements than that required by the CB. The third criterion is to add an additional constraint on the number of active antenna elements while maximizing the output SINR, which may benefit the hardware planning. Simulation results confirm the feasibilities of these methods, and the above-stated tasks are all fulfilled. Therefore, the proposed phase-only thinned arrays have the flexibility to provide various levels of array performance with reduced hardware resources.
TL;DR: It is shown that, relative to conventional large scale antenna system (LSAS), the proposed ALSAS system achieves significant energy efficiency improvements under various scenarios, and can provide up to 500% power saving for the fixed bit rate requirement case.
Abstract: This paper proposes an adaptive large scale antenna system (ALSAS) for enhancing energy efficiency in low density wireless network scenarios. The proposed ALSAS comprises of two stages, a novel adaptive discontinuous transmission (ADTx) stage and an antenna array optimization (AAO) one. The basic idea is to utilize prior knowledge of the users' quality of service (QoS) requirements as well as precoding selection in the ADTx stage to maximize the transmitter hibernation periods subject to a certain complexity constraint. In the AAO stage, further power saving is achieved by reducing the number of active antenna elements subject to a certain QoS requirement. It is shown that, relative to conventional large scale antenna system (LSAS), the proposed ALSAS system achieves significant energy efficiency improvements under various scenarios. The results show that the proposed technique can provide energy efficiency improvement between 125% and 1124% in the suburban scenario, and between 196% and 952% in the rural scenario. It is also demonstrated that for rural environments with relatively small short inter-site-distance (ISD) values, ALSAS can provide up to 500% power saving for the fixed bit rate requirement case.
15 Mar 2020
TL;DR: This work presents a 5G active antenna tile system, enabling the flexible construction of hybrid beamforming (HBF) arrays, and was fabricated using a standard PCB manufacturing process and to validate its performance.
Abstract: This work presents a 5G active antenna tile system, enabling the flexible construction of hybrid beamforming (HBF) arrays. The proposed tile was fabricated using a standard PCB manufacturing process and to validate its performance. Using a Reverberation Chamber (RC), the tile was measured in both Tx and Rx mode, achieving up to 1.6 GHz in bandwidth around a central frequency of 27.8 GHz.
TL;DR: The design, fabrication and testing of a novel structurally integrated Ka-band active antenna for airborne 5G wireless communications are presented, and the results demonstrate the feasibility of theStructurally integrated active antennas for airborne wireless communications.
Abstract: Structurally integrated antenna is a kind of highly integrated microwave device with a load-bearing function, and it is usually installed on the structural surface of the air, water and ground vehicles. This paper presents the design, fabrication and testing of a novel structurally integrated Ka-band active antenna for airborne 5G wireless communications. The proposed antenna is mainly composed of three parts: a package layer, a control and signal process layer and a RF layer. In the RF layer, the microstrip antenna array, tile transmitting (Tx) modules, micro-channel heat sinks and a stripline feeding network are highly integrated into a functional block with a thickness of 2.8 mm. Electromechanical co-design methods are developed to design the active antenna array with the superstrates, and two schemes for designing micro-channel heat sinks are evaluated to obtain a uniform temperature distribution. The RF layer is fabricated by using the low-temperature cofired ceramic process, and the three layers are assembled to form the full-size antenna prototype. The mechanical and electromagnetic experiments are carried out, and the results demonstrate the feasibility of the structurally integrated active antenna for airborne wireless communications.
01 Sep 2020
TL;DR: The work is to provide a methodology to assess field strength variability which characterize future 5G scenarios with a combination of measurements carried out in a dynamic way in comparison with the static measurement approach which is commonly adopted for environmental impact assessment.
Abstract: The document presents a potentially innovative methodology for carrying out large-scale measurements of radiofrequency electromagnetic field. The system consists in performing dynamic measurements using a control unit equipped with the appropriate probes positioned on the roof of a car moving along the territory. Aim of the work is to provide a methodology to assess field strength variability which characterize future 5G scenarios with a combination of measurements carried out in a dynamic way in comparison with the static measurement approach which is commonly adopted for environmental impact assessment. The possibility to perform massive measurements in a short time could become extremely useful in the next future to evaluate electromagnetic field levels, when the implementation of the new 5G services will lead to an increased complexity in the use of the spectrum and new antenna systems (Active Antenna Systems).
TL;DR: In this paper, a low-complexity iterative detector with frequency domain equalization is proposed for generalized spatial modulation (GSM) aided single carrier (SC) transmissions operating in frequency selective channels.
Abstract: In this letter, a low-complexity iterative detector with frequency domain equalization is proposed for generalized spatial modulation (GSM) aided single carrier (SC) transmissions operating in frequency selective channels. The detector comprises three main separate tasks namely, multiple-input multiple-output (MIMO) equalization, active antenna detection per user and symbol wise demodulation. This approach makes the detector suitable for a broad range of MIMO configurations, which includes single-user and multiuser scenarios, as well as arbitrary signal constellations. Simulation results show that the receiver can cope with the intersymbol interference induced by severe time dispersive channels and operate in difficult underdetermined scenarios.
Posted Content•
TL;DR: A novel dual-function radar communication (DFRC) system is proposed, that achieves high target resolution and high communication rate, and the radar performance is evaluated via simulations, and bit error rate (BER) results for the communication system are provided.
Abstract: A novel dual-function radar communication (DFRC) system is proposed, that achieves high target resolution and high communication rate. It consists of a multiple-input multiple-output (MIMO) radar, where only a small number of antennas are active in each channel use. The probing waveforms are orthogonal frequency division multiplexing (OFDM) type. The OFDM carriers are divided into two groups, one that is used by the active antennas in a shared fashion, and another one, where each subcarrier is assigned to an active antenna in an exclusive fashion (private subcarriers). Target estimation is carried out based on the received and transmitted symbols. The system communicates information via the transmitted OFDM data symbols and the pattern of active antennas in a generalized spatial modulation (GSM) fashion. A multi-antenna communication receiver can identify the indices of active antennas via sparse signal recovery methods. The use of shared subcarriers enables high communication rate. The private subcarriers are used to synthesize a virtual array for high angular resolution, and also for improved estimation on the active antenna indices. The OFDM waveforms allow the communication receiver to easily mitigate the effect of frequency selective fading, while the use of a sparse array at the transmitter reduces the hardware cost of the system. The radar performance of the proposed DFRC system is evaluated via simulations, and bit error rate (BER) results for the communication system are provided.
TL;DR: In this article, a 2-layer frequency reconfigurable Yagi-like multiple-input-multiple-output (MIMO) antenna system is proposed based on a closed pentagonal slot-loop excitation.
Abstract: In this work, a 2-layer frequency reconfigurable Yagi-like multiple-input–multiple-output (MIMO) antenna system is proposed based on a closed pentagonal slot-loop excitation. The MIMO system consists of 4 identical active antenna elements reactively loaded with varactor diodes to achieve frequency reconfigurability over a band from 1.5 to 2.1 GHz. The distinguishing feature of the proposed work is achieving Yagi-like directional characteristics over a very wide frequency band. The conventional omni-directional pattern of a slot antenna is made directional by using a parasitic metallic reflector layer below the substrate. By using the reflector element, the back-lobe radiation is highly suppressed and a front-to-back ratio of 5–13 dB is achieved within the entire frequency band of operation. The proposed design is compact with an overall size of 100 × 100 × 20 mm 3 , and a reflector size of 110 × 110 mm 2 . A single element has a maximum peak gain of 4 dBi and total measured radiation efficiency of 76%. The antenna system also shows good MIMO performance with high port isolation of 11.3 dB and very low envelope correlation coefficient values within the operational band.
08 Mar 2020
TL;DR: A 28 GHz radio-over-fiber system with laser-less, low-cost active antenna units using silicon photonics and a GaAs driver and LNA and 7-Gb/s downlink and uplink throughput was achieved.
Abstract: We demonstrate a 28 GHz radio-over-fiber system with laser-less, low-cost active antenna units using silicon photonics and a GaAs driver and LNA. 7-Gb/s downlink and uplink throughput was achieved over 2km SSMF and 5m wireless.
01 Aug 2020
TL;DR: The highly integrated 64 element active antenna integrates 64 element broadband array antenna, microwave feed network, wave control network and power supply network with high integration and can meet the requirements of 5g millimetre The demand of meter wave communication.
Abstract: In order to meet the needs of 5G communication, 5G millimeter wave phased array antenna vehicle components are developed. The traditional phased array antenna technology is mostly based on the building block transceiver or tile transceiver module of discrete devices. Using traditional MCM technology, it is difficult to realize thin, homomorphic and modular phased array antenna due to its complex process, high cost and large thickness. Therefore, simplifying the topology of phased array antenna and realizing thinning and modularization are the main trends of phased array antenna development. The highly integrated 64 element active antenna integrates 64 element broadband array antenna, microwave feed network, wave control network and power supply network with high integration. The millimeter wave active phased array antenna module developed for 5g millimeter wave communication is innovative and unique. Multi functional antenna board is used to integrate antenna array, feed network, power supply network and wave control network. Silicon based multi-functional transceiver chip is used to integrate transceiver channel, simplify antenna transceiver link, reduce antenna thickness, improve antenna productivity and reduce antenna loss. Antenna cost meets the requirements of high integration, modularization, easy assembly, low cost and strong scalability, and can meet the requirements of 5g millimetre The demand of meter wave communication.The on-board antenna is in the form of microstrip antenna. The whole on-board microstrip antenna consists of seven layers. It is fed by a stripline and coupled to the main patch antenna through an H-shaped through-hole. A layer of dielectric and parasitic patch antenna are added to the upper layer of the main patch antenna, which can expand the bandwidth to meet the requirement of 5g broadband. The feed network is a signal synthesis network that provides beamforming for the on-board phased array antenna. The feeding network adopts the structure of Wilkinson power divider with stripline, which has the advantages of miniaturization, lightweight and high reliability.The millimeter wave phased array antenna on board is tested. The results show that the normalized emission scanning pattern has good pattern characteristics in the range of ± 45 degrees, and the side lobe level is lower than - 12dB. The EIRP value is greater than 51 dBm. In the range of ± 45 degrees, the cross polarization isolation of on board phased array antenna is better than -30 dB. The test results of 5G millimeter wave phased array antenna for broadband communication show that the data transmission rate is more than 2.8Gbps when the bandwidth is 800MHz and the modulation mode is 64QAM. At the same time, high integration millimeter wave communication active phased array antenna can also be used in satellite communication, tactical mobile hot spots and other fields.
TL;DR: The theoretical analysis and the simulation results show that the use of active-antenna dependent signature constellations which are derived from each other through successive geometric interpolations preserves the minimum inter-constellation Euclidean distance given the primary constellation.
TL;DR: A new joint-mapping based variable active antenna spatial modulation scheme, which varies the number of active antennas in each transmit vector to avoid detection ambiguity and achieve low bit error rate and comparable maximum likelihood detection complexity as that of existing SM schemes.
Abstract: Spatial modulation (SM) maps information to both spatial dimensions (active antenna indices) and conventional 2D ${M}$ -ary symbols. The existing SM schemes use fixed number of active antennas in each transmit vector as varying them causes detection ambiguity. Motivated by this, we introduce a new joint-mapping based variable active antenna spatial modulation scheme, which varies the number of active antennas in each transmit vector. It alleviates detection ambiguity by jointly mapping information to the complete 3D constellation consisting of active antenna indices (spatial dimension) and the 2D ${M}$ -ary symbols. This is unlike the existing SM schemes which separately map information to the active antenna indices and the 2D symbols. This idea enables us to i) avoid detection ambiguity; and ii) achieve low bit error rate and comparable maximum likelihood detection complexity as that of existing SM schemes.
15 Mar 2020
TL;DR: In this article, a verification setup using a polar near-field scanner and a vector network analyzer is presented with description of the main hardware components, instrument settings and correction techniques for raw measurement data.
Abstract: 5G active antenna system base stations operating in frequencies below 7.125 GHz (FR1) need to be tested using a cost-effective OTA measurement solution since traditional farfield antenna ranges are too large. Plane wave synthesizer (PWS) allows testing with far-field conditions at the near-field distance with the minimum system dimensions. Uniformity of the synthesized plane wave field in the quiet zone (QZ) is a key performance parameter of PWS. QZ verification setup using a polar near-field scanner and a vector network analyzer is presented with description of the main hardware components, instrument settings and correction techniques for raw measurement data. Various field uniformity metrics are defined and calculated for one measurement example. Measurement repeatability is also verified to evaluate stochastic errors in the verification.
01 Jan 2020
TL;DR: This chapter illuminates the details of noise figure and noise‐power measurements, including their uncertainty, verification, and methods to improve them, as well as carrier‐to‐noise measurements.
Abstract: One of the challenges in noise‐figure measurements is in determining the noise figure of systems that integrate the low‐noise amplifier (LNA) stage into a single‐chip down‐converter, where the output is not at the same frequency as the input and the LNA cannot be separated from the rest of the system. This chapter illuminates the details of noise figure and noise‐power measurements, including their uncertainty, verification, and methods to improve them. It discusses active antenna noise‐figure measurements and describes noise figure in mixers and frequency converters. Mixers and frequency converters are often the first component after the antenna in a receiver system, and as such the noise figure of the first converter predominantly sets the noise figure of the system. The chapter also discusses noise power measurements with a vector network analyzer spectrum analyzer and noise figure measurements using spectrum analysis as well as carrier‐to‐noise measurements.