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This paper investigates a heterogeneous cellular network (HCN) topology, where multiple sub-6 GHz bands are available for access and device-to-device (D2D) links with the full-duplex (FD) mode, and an integrated millimeter-wave (mm-wave) band is added to the D2D links’ sub-channel resource options. D2D links share spectrum resources of cellular users or dedicated mm-wave sub-channel. Densely deployed small cells scenario provides an ideal platform to implement mm-wave, FD and D2D communications. With large bandwidths available, mm-wave has the potential to meet the expected extreme data rate demands. Leveraging highly directional beamforming, severe transmission loss and the blockage phenomenon of mm-wave can be alleviated. Theoretically, FD communications can double the spectral efficiency due to bi-directional communications with the same spectral and temporal resources. However, such benefit comes at the cost of residual self-interference (RSI). Multi-user interference (MUI) and RSI among network uplink, downlink and D2D links are the main challenges. In the paper, we formulate an optimization problem for FD access and D2D links sub-channel allocation underlaying HCNs combining sub-6 GHz and mm-wave bands to make the system transmission rate maximized. Then, a scheme based on the coalition formation game is proposed to deal with this challenging NP-complete optimization. Finally, performance evaluation investigates the suitable conditions for FD and HD operations. Under different network parameter settings, we quantify associated performance of proposed scheme. [ABSTRACT FROM AUTHOR]

In this article, a 60-GHz frequency-modulated continuous-wave (FMCW) multiple-input multiple-output (MIMO) radar system using frequency-division multiplexing for TX signal separation is presented. Four-channel transmitter and receiver chips were designed using 130 nm SiGe process. The total number of TX and RX channels can be scaled by the number of chips in the system while still maintaining phase coherence between the channels. 2-D and 3-D object localization measurements are made with four TX and eight RX channel systems. In the 2-D configuration, the radar system is capable of a 5-cm range resolution and 3.5° angular resolution. [ABSTRACT FROM AUTHOR]

Millimeter wave (mmWave) communication in typical wearable and data center settings is short range. As the distance between the transmitter and the receiver in short range scenarios can be comparable to the length of the antenna arrays, the common far field approximation for the channel may not be applicable. As a result, dictionaries that result in a sparse channel representation in the far field setting may not be appropriate for short distances. In this paper, we develop a novel framework to exploit the structure in short range mmWave channels. The proposed method splits the channel into several subchannels for which the far field approximation can be applied. Then, the structure within and across different subchannels is leveraged using message passing. We show how information about the antenna array geometry can be used to design message passing factors that incorporate structure across successive subchannels. Simulation results indicate that our framework can be used to achieve better beam alignment with fewer channel measurements when compared to standard compressed sensing-based techniques that do not exploit structure across subchannels. [ABSTRACT FROM AUTHOR]

This paper proposes a low-loss and high-isolation transformer (TF)-based mm-wave single-pole double-throw (SPDT) switch. The center-tapped technique is employed at the secondary coil of TF to improve isolation performance. The TF is implemented with the metals in redistribution layers (RDLs) in integrated fan-out (InFO) wafer level packaging technology to obtain low insertion loss (IL) and small chip size as the TF usually dominates the area of SPDT. The control device of the SPDT is realized in 40 nm bulk CMOS process. The simulated result shows the proposed SPDT achieves a minimum IL of 1.34 dB and the IL is less than 2.2 dB at 24–31 GHz. The isolations are better than 27 dB between two double-throw ports and better than 20 dB between single-pole and double-throw ports, respectively. The proposed SPDT has a compact silicon size of 220 μ m × 1 4 0 μ m (with PADs) and its return losses are better than − 9 dB at 24–31 GHz and. This work explores a new chip-package co-design method for the SPDT and may have some guidance for the co-design of SPDT and antenna in package (AiP). [ABSTRACT FROM AUTHOR]

Millimetre wave (mm-Wave) bands and sub-6 GHz are key technologies in solving the spectrum critical situation in the fifth generation (5G) wireless networks in achieving high throughput with low transmission power. This paper studies the performance of dense small cells that involve a millimetre wave (mm-Wave) band and sub-6 GHz that operate in high frequency to support massive multiple-input-multiple-output systems (MIMO). In this paper, we analyse the propagation path loss and wireless powered transfer for a 5G wireless cellular system from both macro cells and femtocells in the sub-6 GHz (μWave) and mm-Wave tiers. This paper also analyses the tier heterogeneous in downlink for both mm-Wave and sub-6 GHz. It further proposes a novel distributed power to mitigate the inter-beam interference directors and achieve high throughput under game theory-based power constraints across the sub-6 GHz and mm-Wave interfaces. From the simulation results, the proposed distributed powers in femtocell suppresses inter-beam interference by minimising path loss to active users (UEs) and provides substantial power saving by controlling the distributed power algorithm to achieve high throughout. [ABSTRACT FROM AUTHOR]

A low-loss multifeed antenna with controlled polarization and beam steering is presented. A low-profile resonant cavity antenna is fed by multiple spherical dielectric resonators (DRs), demonstrating its multifeed capabilities. Each of the DRs are themselves fed from four different sides by microstrip resonators on a planar circuit board. The beam pointing direction and polarization of the antenna are controlled by the signal phases at the respective input ports. Several antennas with varying feed topology are investigated, showing the versatility of this method. A 16-way 34 GHz prototype is built and measured, demonstrating high overall efficiency (considering power combining loss and antenna loss) of 80%. [ABSTRACT FROM AUTHOR]

This article reports on the extraction of the electron velocity as a function of gate bias from N-polar GaN deep recess high-electron-mobility transistors (HEMTs) designed for mm-wave power amplification. Bias-dependent small-signal S-parameter measurements are used to obtain small-signal equivalent circuit parameters, which are applied to a transit delay model. The model accounts for fringing capacitance to arrive at an electron velocity associated with the transit of the physical gate length. A peak electron velocity of 1.4 × 107 cm/s was obtained at a drain current of 700 mA/mm corresponding to a channel charge density of 0.3 × 1013 cm−2. At higher current, the velocity slowly decreased with the electron velocity crossing below 107 cm/s at 1.8 A/mm. This behavior was found to be in good agreement with a previously proposed model based on optical phonon scattering at the source injection point. An analysis of the delay components is used to provide guidance for the factors influencing the device performance. [ABSTRACT FROM AUTHOR]

A wideband high‐gain mm‐Wave antenna array operating in Ka‐band is reported. The antenna element consists of an antipodal Vivaldi antenna (AVA) with plated through vias on the edges of the radiating arms, which is utilized to eliminate the harmful gap resonance due to the electrically discontinuity. A modified wideband 8‐way substrate integrated waveguide (SIW) power divider is proposed to feed the linear array. In addition, in order to enhance antenna gain, a stacked dielectric superstrate is employed, which achieves 2.3 dBi average gain improvement over 25‐40 GHz. The proposed structure provides superior bandwidth of 25.4‐40 GHz with S11 < −9.5 dB (corresponding to VSWR < 2). The modified SIW power divider, 1 × 8 AVA array and the dielectric superstrate are designed and fabricated, resulting in a wideband and high‐gain structure as compared to other SIW‐fed antennas. A prototype is experimentally verified. The measured results show that the impedance bandwidth ranges from 25.37 to 39.48 GHz (S11 < −9.6 dB, relative bandwidth of 43%). The measured gain varies from 15.5 to 18.5 dBi in the frequency range with an average gain of 16.6 dBi. [ABSTRACT FROM AUTHOR]

Millimeter wave (mmWave) systems can enable high data rates if the link between the transmitting and receiving radios is configured properly. Fast configuration of mmWave links, however, is challenging due to the use of large antenna arrays and hardware constraints. For example, a large amount of training overhead is incurred by exhaustive search-based beam alignment in typical mmWave phased arrays. In this paper, we present a framework called FALP for Fast beam Alignment with Low-resolution Phase shifters. FALP uses an efficient set of antenna weight vectors to acquire channel measurements, and allows faster beam alignment when compared to exhaustive scan. The antenna weight vectors in FALP can be realized in ultra-low power phase shifters whose resolution can be as low as one-bit. From a compressed sensing (CS) perspective, the CS matrix designed in FALP satisfies the restricted isometry property and allows CS algorithms to exploit the fast Fourier transform. The proposed framework also establishes a new connection between channel acquisition in phased arrays and magnetic resonance imaging. [ABSTRACT FROM AUTHOR]

In this paper, a low-profile, compact, high-gain antenna solution for four-port mm-wave broadband MIMO communication in a 5G environment is presented. The proposed antenna design consists of two rectangular patches connected through a corporate feed network and two quarter-wavelength square-shaped CSRRs on the ground plane. The overall size of the proposed four-port orthogonal MIMO configuration is 28.3 mm × 28.3 mm × 0.508 mm. The antenna operates on the 5G frequency bands of n257, n258, and n261 with an effective bandwidth of 3.9 GHz covering the range of 26.5 GHz to 30.4 GHz. The suggested MIMO antenna attained a peak gain of 11 dBi and radiation efficiency of 96% at 28 GHz resonating frequency. The MIMO configuration utilized DGS to minimize near-field coupling current at the ground plane, resulting in high port-to-port isolation of > 40 dB, and co-pol to X-pol isolation improvements of > 9 dB and > 19 dB in the boresight direction of E-plane and H-plane at 28 GHz resonating frequency. The antenna's superior diversity performance is supported by several performance metrics, including ECC(< 0.0001), DG(> 9.999 dB), CCL(< 0.12 bits/s/Hz), MEG (< −3 dB), and TARC. Moreover, the linear transmission property of the proposed MIMO antenna is also validated through the variation of group delay (< 0.6 ns) over operating frequency bands in the far-field region. [ABSTRACT FROM AUTHOR]

In this paper, a low insertion loss (IL) wideband millimeter wave (mm-Wave) crossover with three-section branch-line structure based on ridge gap waveguide (RGW) technology is proposed. Firstly, the central-crossover is designed, especially two types of tuning pins are introduced, which greatly improves the performance of the crossover. In addition, in order to facilitate the measurement, the transition from rectangular waveguide (RWG) to RGW is designed. Finally, a prototype is manufactured and measured. The simulation results show that in the frequency range of 28.9 GHz to 36.6 GHz, RL is better than 20 dB, while the isolation levels of | S 21 |, | S 41 |, and | S 43 | are lower than −20 dB, −10 dB, and −20 dB over the same band, respectively. IL is below 0.5 dB in the frequency range of 28.15 GHz to 36.65 GHz. Good consistency was observed between the simulation results and the measurement results. [ABSTRACT FROM AUTHOR]

In the next‐generation wireless networks, cooperative communication is one of the auspicious techniques through which spatial diversity could be achieved by permitting the single antenna to act as virtual multiple input multiple output (VMIMO). The fundamental principle of cooperative communication was established on different types of relaying protocols and implementation of different relaying protocols according to the requirements of communication scenarios. The challenging task for achieving a high performance in cooperative communication is to find out the optimal relay node (RN) among different prevailing RNs. The basic purpose of cooperative communication is to maximize the performance of the network and minimize the overhead triggered by RNs by considering different communication metrics, i.e., signal to noise ratio (SNR), channel state information (CSI), and bit error rate (BER). This study presents a review of different cooperative relaying protocols with best relay selection techniques in the next‐generation wireless network. Moreover, the different challenges faced by millimeter wave in 5G wireless networks and the role of cooperative communication to overcome those challenges are discussed. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

This paper reports on the first demonstration of an experimental millimeter‐wave (mm‐wave) beamforming based on the conformal Rotman lens. The passive switched‐beam network is intended for operation in the 28‐GHz band, covering the 18‐38 GHz range, for the deployment in the fifth generation (5G) subsystems. The primary objective of this work is to conduct the feasibility of designing a beamforming network (BFN) based on the liquid‐crystal polymer substrate, and to evaluate the performances in terms of the scattering (S)‐parameters and surface currents for the proposed flexural case of the convex‐circumferential bending. A prototype has been accurately fabricated, and a setup has also been deployed to conduct the measurements. The performance in terms of the linear progressive phase behavior, as the main figure of merit, has been shown. The BFN exhibits significant characteristics to be used as a low‐profile unit of the transceivers with the in‐built beam steering for the conformal 5G subsystems. [ABSTRACT FROM AUTHOR]

Abstract A comprehensive design methodology for microstrip broadband attenuators is presented. Closed-form design equations are given for two types of distributed attenuators. The attenuators are based on a cascade connection of thin-film resistors and microstrip line sections. The structure provides maximally flat attenuation and wideband performance without the need of plated via holes to ground, facilitating manufacture as well as achieving proper performance at millimeter wave frequencies. Experimental results demonstrate the validity of the technique applied to 3 dB and 13 dB broadband attenuators on alumina substrate up to 67 GHz. The proposed topology can be applied not only to MIC, but also to MMIC designs at the highest frequencies. [ABSTRACT FROM AUTHOR]

In this paper, a novel direct learning algorithm is proposed to identify the digital predistortion (DPD) coefficients that linearize a power amplifier (PA) using sub-Nyquist sampled intermediate frequency (IF) output of a heterodyne transmitter observation receiver (TOR). The learning algorithm is complemented with a joint time and phase alignment procedure to compensate for the unknown phase of the IF carrier as well as the delay between the PA input and output signals. By sub-Nyquist sampling at IF, the proposed method avoids the need for challenging receiver calibration that compensates for significant IQ imbalance exhibited by direct conversion receivers. Furthermore, it provides a very attractive flexibility in choosing the IF and consequently allows for a high subsampling factor. It is also extended to account for the nonflat frequency response of the TOR, thus avoiding the need for an explicit calibration step. Finally, measurement results were performed to linearize a PA demonstrator driven by a 320-MHz wide carrier aggregated LTE signal centered at 31 GHz using a complexity reduced Volterra-based DPD. Excellent linearization capacity (ACPR of 50 dBc and normalized mean square error of 2%) using significantly low sampling rates (as low as 40 Msps) is reported. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • High-resolution absorption spectra of 6 TiO isotopologues between 240 and 380 GHz. • Mass-independent Dunham parametrization. • Determination of the molecular bond length r e BO = 1.62009060(31) Å with sub-fm accuracy. • Accurate 44TiO molecular parameters. • Analysis of fine- and hyperfine-structure reveals insight to the electronic structure. Abstract More than 130 pure rotational transitions of 46TiO, 47TiO, 48TiO, 49TiO, 50TiO, and 48Ti18O are recorded using a high-resolution mm-wave supersonic jet spectrometer in combination with a laser ablation source. For the first time a mass-independent Dunham-like analysis is performed encompassing rare titanium monoxide isotopologues, and are compared to results from high-accuracy quantum-chemical calculations. The obtained parametrization reveals for titanium monoxide effects due to deviations from the Born-Oppenheimer approximation. Additionally, the dominant titanium properties enable an insight into the electronic structure of TiO by analyzing its hyperfine interactions. Further, based on the mass-independent analysis, the frequency positions of the pure rotational transitions of the short lived rare isotopologue 44TiO are predicted with high accuracy, i.e., on a sub-MHz uncertainty level. This allows for dedicated radio-astronomical searches of this species in core-collapse environments of supernovae. [ABSTRACT FROM AUTHOR]

For the first time, a mm-wave personal exposure meter (mm-PEM) for the 5th generation of mobile networks (5G) exposure assessment in indoor diffuse fields is presented. The design is based on simulations and on-phantom calibration measurements in a mm-wave reverberation chamber (RC) at 60 GHz. The mm-PEM consists of an array of nine antennas on the body. Using the mm-PEM, the incident power density (IPD) is measured in the unloaded RC, for the antenna(s) on the phantom and RC loaded with phantom. The uncertainty of the mm-PEM is then determined in terms of its response, which is defined as the ratio of antenna aperture for the above measurement scenarios. Using nine antennas, the designed meter has a response of 1.043 (0.17 dB) at 60 GHz, which is very close to 1 (0 dB), the desired ideal response value. The mm-PEM measured an IPD of 96.6 Wm− 2 at 60 GHz in the RC, for an input power of 1 W. In addition, the average absorption cross-section of the phantom is determined as 225 cm2, which is an excellent agreement with its physical dimensions. [ABSTRACT FROM AUTHOR]

This paper presents a monitoring and control system for MEMS tunable evanescent-mode cavity filters. Inductive proximity sensing is utilized to detect the deflection of the tuning MEMS membrane. The sensed deflection is used as a feedback for a closed-loop control of the MEMS bias voltage to deliver the desired deflection and, hence, desired RF response based on an input from the user. The sensing spiral inductor also functions as an electrode for the electrostatic actuation of the membrane. The presented system is analyzed, optimized, and experimentally implemented on a bandstop filter tunable in the 30–42-GHz range. The measured results show that the system is capable of tuning the filter to the desired response with good repeatability of notch frequency (less than 1% error) and with stable long-term response (better than 1.6% drift), which falls within the 20-dB bandwidth of the filter. [ABSTRACT FROM AUTHOR]

This paper presents a 64-element 28-GHz phased-array transceiver for 5G communications based on $2\times 2$ transmit/ receive (TRX) beamformer chips. Sixteen of the $2\times 2$ TRX chips are assembled on a 12-layer printed circuit board (PCB) together with a Wilkinson combiner/divider network and 28–32-GHz stacked-patch antennas. The 64-element array results in 1.1 dB and 8.9° rms amplitude and phase error, respectively, with no calibration due to the symmetric design of the $2\times 2$ beamformer chips and the PCB Wilkinson network. The effect of phase and amplitude mismatch between the 64 elements is analyzed and shown to have little impact on the 64-element array performance due to the averaging effects of phased arrays. Detailed pattern, effective isotropic radiated power (EIRP), and link measurements performed without any array calibration are presented and show the robustness of the symmetrical design technique. The phased array can scan to ±50° in azimuth ($H$ -plane) and ±25° in elevation ($E$ -plane) with low sidelobes and achieves a saturated EIRP of 52 dBm with 4-GHz 3-dB bandwidth. A 300-m wireless link is demonstrated with a record-setting data rate of 8–12 Gb/s over all scan angles using two 64-element TRX arrays and 16-/64-QAM waveforms. [ABSTRACT FROM AUTHOR]

We review advances in low-temperature detector (LTD) arrays for cosmic microwave background (CMB) polarization experiments, with a particular emphasis on imaging arrays. We briefly motivate the science case, which has spurred a large number of independent experimental efforts. We describe the challenges associated with CMB polarization measurements, and how these challenges impact LTD design. Key aspects of an ideal CMB polarization imaging array are developed and compared to the current state of the art. These aspects include dual-polarization sensitivity, background-limited detection over a 10:1 bandwidth ratio, and frequency-independent angular responses. Although existing technology lacks all of this capability, today’s CMB imaging arrays achieve many of these ideals and are highly advanced superconducting integrated circuits. Deployed arrays map the sky with pixels that contain elements for beam formation, polarization diplexing, passband definition in multiple frequency channels, and bolometric sensing. Several detector architectures are presented. We comment on the implementation of both transition-edge sensor bolometers and microwave kinetic inductance detectors for CMB applications. Lastly, we discuss fabrication capability in the context of next-generation instruments that call for ∼106 sensors. [ABSTRACT FROM AUTHOR]

SuperSpec is a new technology for mm and sub-mm spectroscopy. It is an on-chip spectrometer being developed for multi-object, moderate-resolution (R∼300), large bandwidth survey spectroscopy of high-redshift galaxies for the 1 mm atmospheric window. This band accesses the CO ladder in the redshift range of z= 0-4 and the [CII] 158 μm line from redshift z=  5-9. SuperSpec employs a novel architecture in which detectors are coupled to a series of resonant filters along a single microwave feedline instead of using dispersive optics. This construction allows for the creation of a full spectrometer occupying only ∼10cm2 of silicon, a reduction in size of several orders of magnitude when compared to standard grating spectrometers. This small profile enables the production of future multi-beam spectroscopic instruments envisioned for the millimeter band to measure the redshifts of dusty galaxies efficiently. The SuperSpec collaboration is currently pushing toward the deployment of a SuperSpec demonstration instrument in fall of 2018. The progress with the latest SuperSpec prototype devices is presented; reporting increased responsivity via a reduced inductor volume (2.6 μm3) and the incorporation of a new broadband antenna. A detector NEP of 3-4 ×10-18 W/Hz0.5 is obtained, sufficient for background-limited observation on mountaintop sites. In addition, beam maps and efficiency measurements of a new wide-band dual bow-tie slot antenna are shown. [ABSTRACT FROM AUTHOR]

Abstract The development of 5G communication systems is underway. When employing 64 QAM, very low phase noise levels are required to limit EVM - i.e. less than −117 dBc/Hz at 1 MHz offset from f = 20 GHz. In this paper, the challenges of achieving such a low phase noise are discussed in detail. The choice between CMOS vs BJT devices is investigated and the impact of the base resistance intrinsic in BJT-based VCOs is addressed. BJT-based VCO shows ∼2 dB better phase noise when compared to CMOS-based VCO and low supply is employed. When higher supply is leveraged, BJT-based VCO advantage is kept while CMOS-based VCO is not able to reach the targeted tuning range due to thick-oxide devices parasitics. Emphasis is on the minimization of L/Q inductor versus quality factor ratio, to further minimize phase noise. Prototypes in a 55 nm BiCMOS technology were operated at 2.5 V supply with the largest amplitude allowed by reliability constraints. Measurements show a phase noise as low as −119 dBc/Hz at 1 MHz from a 20 GHz carrier offset with a tuning range (TR) of 19% and FoM = −187 dBc/Hz. Power consumption is 56 mW. To the best of authors' knowledge, the presented VCO shows the lowest reported phase noise among state-of-the-art BiCMOS VCOs with TR>10%. Highlights • Minimization of L/Q ratio is key to achieve very low phase noise levels. • A comparison between class-B/class-C VCOs with BJT/MOS active devices is presented. • BJTs offer several advantages over CMOS for VCO design. • Trade-off between base resistance noise and tuning-range is addressed for BJT/MOS VCOs. • A class-C BJT-based VCO is presented with record phase noise. [ABSTRACT FROM AUTHOR]

The paper presents the first in vivo glucose monitoring animal study in a pig, which correlates radio frequency signal transmission changes with changes in blood glucose concentration in the 58-62 GHz frequency range. The presented non-invasive glucose sensing system consists of two opposite facing patch antennas sandwiching glucose-loaded samples. Prior to the animal study, the system was tested using saline solution samples, for which a linear relationship between changes in transmitted signal and glucose concentration was observed. In the animal study, glucose concentration changes were induced by injecting a known glucose solution in the blood stream. The non-invasive transmission measurements were compared to the glucose levels obtained invasively from the animal. Our results suggest that the system can detect spikes in glucose concentration in the blood, which is an important milestone towards non-invasive glucose monitoring. [ABSTRACT FROM AUTHOR]

This paper studies a variant of hybrid beamforming, namely, hybrid beamforming with selection (HBwS), as an attractive solution to reduce the hardware cost of multiuser Massive Multiple-Input-Multiple-Output systems, while retaining good performance. Unlike conventional hybrid beamforming, in a transceiver with HBwS, the antenna array is fed by an analog beamforming matrix with $\bar{L}$ input ports, where $\bar{L}$ is larger than the number of up/down-conversion chains $\bar{K}$. A bank of switches connects the instantaneously best $\bar{K}$ out of the $\bar{L}$ input ports to the up/down-conversion chains. The analog beamformer is designed based on average channel statistics and therefore needs to be updated only infrequently, while the switches operate based on instantaneous channel knowledge. HBwS allows use of simpler hardware in the beamformer that only need to adjust to the statistics, while also enabling the effective analog beams to adapt to the instantaneous channel variations via switching. This provides better user separability, beamforming gain, and/or simpler hardware than some conventional hybrid schemes. In this paper, a novel design for the analog beamformer is derived and approaches to reduce the hardware and computational cost of a multiuser HBwS system are explored. In addition, we study how $\bar{L}$ , the switch bank architecture, the number of users and the channel estimation overhead impact system performance. [ABSTRACT FROM AUTHOR]

This paper focused on designing a bi-directional beams waveguide slotted antenna at millimetre wave spectrum. Waveguide slotted antenna is known for its highly directional pattern. By having bi-directional pattern, the capacity of system coverage can be expanded. The design is implemented by using antenna slot theory on a waveguide structure. The slotted are made on two wall surfaces and the performance is compared to the slotted on single wall. The two models designs are simulated using Computer Simulation Technology (CST) microwave software. The simulation results show that both models operate at 30 GHz with minimum reflection coefficient of -24.63 and -25.01 dB respectively. The two models achieved a fair high gain at 15.5 dB and 13.3 dB with directional beamwidth of 8.9 degree. The proposed bi-directional beams structure achieved a comparable gain in both directions when compared to the single direction. [ABSTRACT FROM AUTHOR]

A polarization division multiplexed (PDM) microwave photonic link for the millimeter (MM)-wave signal with hybrid modulation scheme is proposed in this paper, which is based on the combination of quadrature amplitude modulation, multi-pulse pulse-position modulation and return to zero modulation (QAM-MPPM-RZ). In this scheme, the two orthogonal polarization states enable simultaneous transmission of four data flows, which can provide different services for users according to the data rate requirement. To generate hybrid QAM-MPPM-RZ mm-wave signal, the QAM mm-wave signal is directly modulated by MPPM-RZ signal without using digital signal processing (DSP) devices, which reduces the overhead of the encoding process. Then, the generated QAM-MPPM-RZ mm-wave signal is transmitted in PDM microwave photonic link based on SSB modulation. The sparsity characteristic of QAM-MPPM-RZ not only improves the power efficiency, but also decreases the degradation caused by the fiber chromatic dispersion. The simulation results show that, under the constraint of the same transmitted data rate, the PDM microwave photonic link with 50 GHz QAM-MPPM-RZ mm-wave signal achieves much lower levels of bit-error rate than ordinary 32-QAM. In addition, the increase of laser linewidth brings no additional impact to the proposed scheme. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a 4G/5G multiple‐input multiple‐output (MIMO) antenna system is presented for smart phone applications. The 4G antenna operates from 1900 to 3212 MHz and 3517 to 3712 MHz with 1312 (69%) and 195 (5.5%) MHz measured bandwidths, respectively. The 5G antenna covers 25.7–30.50 GHz band with 4.8 GHz (18.7%) measured bandwidth. The 4G MIMO antenna system is based on 4‐element wideband monopoles, while the 5G one is based on 2‐element linear connected arrays (LCA). Four slots are etched to improve the isolation between the 4G MIMO antenna elements and then a 4 × 1 power divider/combiner is used to excite two of these slots to act as a LCA at mm‐waves. The concept of dual function ground slots is very useful to implement 4G and 5G MIMO antenna systems on the single substrate. The proposed design is fabricated on RO4350B substrate with a height of 0.76 mm and dielectric constant of 3.5. The overall size of the substrate is 115 × 65 × 0.76 mm3. The integrated wideband 4G/5G antenna system is a compact, low profile, and suitable for future smart phone applications. Isolation obtained was at least 15 dB and the envelope correlation coefficient (ECC) values did not exceed 0.16 between all elements. [ABSTRACT FROM AUTHOR]

Abstract: High‐performance, wideband three‐stage power splitters based on substrate integrated waveguide (SIW) are presented. Broadband‐tapered microstrip transitions are used for feeding the SIW structures, which provide 7.5 GHz bandwidth from 21.5 to 29 GHz with return loss below −20 dB. In addition, various T junctions are tuned, not only to provide broadband performance up to mm‐wave frequencies but also offer low‐phase and amplitude imbalance when cascaded in multistage 1 × 8 splitters. 1 × 4 and 1 × 2‐T junctions are adjusted through parametric analysis to provide wide bandwidth of 3.5 GHz at 24.5 GHz and −15 dB reflection coefficient. The optimal microstrip transitions and T junctions are used to design a broadband, eight‐way power splitter with 15 dB return loss from 23.0 to 26.4 GHz and phase and amplitude imbalance of ±2.5° and ±0.8° dB, respectively. Furthermore, optimum positions of all inductive posts in terms of guided wavelength are also provided for assisting the direct design of mm‐wave, high‐performance power splitters. [ABSTRACT FROM AUTHOR]

A U-shaped antenna is printed on polytetrafluoroethylene film, deposited on a copper base having air cavity inside, using thin film micro-strip technology. This antenna is as compact as the rectangular patch and covers the 51.5-62 GHz band. Unlike the silicon substrate, its metallic support yields better radiation patterns. [ABSTRACT FROM AUTHOR]

This paper presents the first wirelessly synchronized multichip array (WSMA) in 65-nm CMOS. The proposed architecture makes use of a central wireless signal to synchronize an mm-wave array, eliminating the need for connecting wires between the array elements. Wireless injection locking of a single chip is successfully demonstrated, and a 3-dB linewidth of 400 Hz at a carrier frequency of 50 GHz is achieved (stability ratio of 8 ppb). In addition, a two-element WSMA with an array aperture greater than 20 wavelengths is demonstrated using the proposed transceiver architecture. The reported transceiver includes a receiving on-chip antenna, a low-noise amplifier, an injection-locked voltage-controlled oscillator, a buffer amplifier, an in-phase/quadrature generator, a phase shifter, a power amplifier, and a transmitting on-chip antenna. The chip is fabricated in a 65-nm CMOS process and occupies an area of 1.7 mm $\times 3.8$ mm. This paper sets the foundation for increasing the array aperture through wireless injection locking, extending traditional array systems into the high-resolution, narrow-beamwidth regime. [ABSTRACT FROM PUBLISHER]

The Atacama Large Millimeter/Sub-millimeter Array (ALMA) is currently the largest (sub-)mm wave telescope in the world and will be used for astronomical observations in all atmospheric windows from 35 to 950 GHz when completed. The ALMA band 1 (35-50 GHz) receiver will be used for the longest wavelength observations with ALMA. Because of the longer wavelength, the size of optics and waveguide components will be larger than for other ALMA bands. In addition, all components will be placed inside the ALMA cryostat in each antenna, which will impose severe mechanical constraints on the size and position of receiver optics components. Due to these constraints, the designs of the corrugated feed horn and lens optics are highly optimized to comply with the stringent ALMA optical requirements. In this paper, we perform several tolerance analyses to check the impact of fabrication errors in such an optimized design. Secondly, we analyze the effects of operating this optics inside the ALMA cryostat, in particular the effects of having the cryostat IR filters placed next to the band 1 feed horn aperture, with the consequent near-field effects. Finally, we report on beam measurements performed on the first three ALMA band 1 receivers inside test cryostats, which satisfy ALMA specifications. In these measurements, we can clearly observe the effects of fabrication tolerances and IR filter effects on prototype receiver performance. [ABSTRACT FROM AUTHOR]

An InP Double Heterojunction Bipolar Transistor (DHBT) technology is presented for millimeter-wave power amplifiers at E-band and higher frequencies. Single- and multi-finger transistors with 0.7 μ m emitter width and emitter lengths of 5, 7, 10 μ m are designed for high frequency and high power applications. The static and AC performances of the fabricated devices are discussed. Reported cutoff frequency and maximum oscillation frequency are f t = 267 GHz and f max = 450 GHz for a 0.7 × 5 μ m P 2 single-finger device, respectively. Results from large-signal measurements at 30 GHz are reported for single and 4-finger devices. Ballasted devices are introduced to improve thermal behaviour and to increase the limits of the safe operating area (SOA). The SOA is improved approximately by 75% for 4-finger devices with 0.7 × 10 μ m 2 emitter. A fabricated monolithic microwave integrated circuit (MMIC) at E-band based on stacked InP DHBTs is presented and its performances reported to demonstrate the power capabilities of the technology. [ABSTRACT FROM AUTHOR]

The use of millimeter-wave (mm-wave) frequencies is required in order to support the increasing number of connected devices expected from the fifth generation (5G) of mobile communications. Subsequently, the generation of radio-frequency (RF) carriers ranging from 10 GHz to 300 GHz and their transport through optical distribution network (ODN) is a key element of the future 5G fronthaul. Optically assisted RF carrier generation is one of the most promising solutions to tackle this issue, allowing a wide use of analog radio-over-fiber (ARoF) architectures. However the main limitation of these optical methods is related to the finite coherence of lasers sources, which can dramatically degrade data transmission in analog formats. To mitigate its impact, the use of orthogonal frequency-division multiplexing (OFDM) as the 5G standard allows employing efficient phase noise compensation algorithms. Therefore, in this study, we present an experimental demonstration of a mm-wave generation technique based on an optical phase-locked loop (OPLL) that fulfills the frequency specifications for 5G. Then, an algorithm is introduced that improves data recovery at reception and reduces the impact of a possible high phase noise carrier. Finally, a back-to-back data transmission experiment is performed, demonstrating the efficiency of the algorithm to reach the 5G requirements. These results emphasize the use of OPLLs as a viable solution to generate mm-wave carriers for 5G and beyond. [ABSTRACT FROM AUTHOR]

Frequency bands above 6 GHz are being considered for future 5G wireless systems because of the larger bandwidth availability and of the smaller wavelength, which can ease the implementation of high-throughput massive MIMO schemes. However, great challenges are around the corner at each implementation level, including the achievement of a thorough multi-dimensional characterization of the mm-wave radio channel, which represents the base for the realization of reliable and high-performance radio interfaces and system architectures. The main properties of the indoor radio channel at 70 GHz, including angular and temporal dispersion as well as an assessment of the major interaction mechanisms, are investigated in this study by means of UWB directional measurements and ray tracing simulations in a reference, small-indoor office environment. [ABSTRACT FROM AUTHOR]

This paper presents a mm-wave two-stage push-push BiCMOS frequency quadrupler for E-band wireless backhaul applications. To enhance gain-bandwidth product and overcome the limitations of classic push-push pairs, coupled resonators realized through low-k transformers are employed. A novel transformer layout is proposed for single-ended to differential conversion to achieve superior suppression of differential mismatches and enhanced gain. The measured prototype, fabricated in 55 nm BiCMOS technology, achieves a remarkable 27% fractional bandwidth around the center frequency of 74 GHz with a power consumption of 7 mW only. [ABSTRACT FROM AUTHOR]

Although wireless sensor networks (WSNs) have been an active field of research for many years, the modules incorporated by WSN nodes have been mainly manufactured utilizing conventional fabrication techniques that are mostly subtractive, requiring significant amounts of materials and increased chemical waste. The new era of the Internet of Things (IoT) will see the fabrication of numerous small form factor devices for wireless sensing for a plurality of applications, including security, health, and environmental monitoring. The large volume of these devices will require new directions in terms of manufacturing cost and energy efficiency, which will be achieved with redesigned, energy-aware modules. This paper presents the state of the art of printed passives, sensors, energy harvesting modules, actives, and communication front ends, and summarizes the challenges of implementing modules that feature low power consumptions without compromising the low fabrication cost. The plethora of the modules presented herein will facilitate the implementation of low cost, additively manufactured, energy-aware IoT nodes that can be fabricated in large volumes with green processes. [ABSTRACT FROM AUTHOR]

A millimeter (mm) wave radio is presented in this work to support wireless MRI data transmission. High path loss and availability of wide bandwidth make mm-waves an ideal candidate for short range, high data rata communication required for wireless MRI. The proposed system uses a custom designed integrated chip (IC) mm-wave radio with 60 GHz as radio frequency carrier. In this work, we assess performance in a 1.5 T MRI field, with the addition of optical links between the console room and magnet. The system uses ON-OFF keying (OOK) modulation for data transmission and supports data rates from 200 Mb/s to 2.5 Gb/s for distances up-to 65 cm. The presence of highly directional, linearly polarized, on-chip dipole antennas on the mm-wave radio along with the time division multiplexing (TDM) circuitry allows multiple wireless links to be created simultaneously with minimal inter-channel interference. This leads to a highly scalable solution for wireless MRI. [ABSTRACT FROM AUTHOR]

Hybrid wired-wireless Network-on-Chip (WiNoC) has emerged as an alternative solution to the poor scalability and performance issues of conventional wireline NoC design for future System-on-Chip (SoC). Existing feasible wireless solution for WiNoCs in the form of millimeter wave (mm-Wave) relies on free space signal radiation which has high power dissipation with high degradation rate in the signal strength per transmission distance. Moreover, over the lossy wireless medium, combining wireless and wireline channels drastically reduces the total reliability of the communication fabric. Surface wave has been proposed as an alternative wireless technology for low power on-chip communication. With the right design considerations, the reliability and performance benefits of the surface wave channel could be extended. In this paper, we propose a surface wave communication fabric for emerging WiNoCs that is able to match the reliability of traditional wireline NoCs. First, we propose a realistic channel model which demonstrates that existing mm-Wave WiNoCs suffers from not only free-space spreading loss (FSSL) but also molecular absorption attenuation (MAA), especially at high frequency band, which reduces the reliability of the system. Consequently, we employ a carefully designed transducer and commercially available thin metal conductor coated with a low cost dielectric material to generate surface wave signals with improved transmission gain. Our experimental results demonstrate that the proposed communication fabric can achieve a 5 dB operational bandwidth of about 60 GHz around the center frequency (60 GHz). By improving the transmission reliability of wireless layer, the proposed communication fabric can improve maximum sustainable load of NoCs by an average of $20.9$ and $133.3$ percent compared to existing WiNoCs and wireline NoCs, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a 67GHz LC oscillator exploiting a three-spiral transformer and implemented in 65nm bulk complementary metal-oxide-semiconductor technology by STMicroelectronics. The three-spiral transformer allows operating with a lower voltage supply, still obtaining good phase noise performance, and achieving a compact design. Measured performances when supplied with 1.2 V are: oscillation frequency of 67 GHz, phase noise ( PN) equal to −96 dBc/Hz at 1 MHz frequency offset from the carrier, power consumption ( PC) equal to 19.2 mW and figure of merit ( FOM) equal to −179.7 dB/Hz. Measured performances when supplied with 0.6 V are: oscillation frequency of 67 GHz; PN equal to −88.7 dBc/Hz at a 1 MHz frequency offset from the carrier; PC equal to 3.6 mW and FOM equal to −179.7 dB/Hz. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Fifth-generation mobile networks (5G) is the established solution to satisfy the highly demanding key performance indicators such as traffic volumes, bit-rate, latency, and power consumption, among others of the future telecommunication infrastructure. The already saturated sub-6 GHz spectral band does not accommodate such requirements and forces the move towards higher frequencies, with the millimeter-wave (mm-wave) domain being an adequate band to operate. However, the exploitation of mm-wave signals in the mobile cells implies the deployment of an enormous quantity of small cells with associated equipment, footprint, and control. Thus, analog radio-over-fiber (ARoF) emerges as a suitable technology because of their attractive benefits such as low latency, low hardware complexity, and reduced power consumption. However, through investigation of experimental ARoF systems adhering to the 5G standard is scarce. Therefore, in this work, a novel and efficient bidirectional ARoF scheme based on multicore fiber (MCF) and oriented to 5G mm-wave communications is proposed and experimentally validated. The setup configurations are according to the 5G standard, enabling a wireless link at 26 GHz (n258, K-band) and time division duplex (TDD) communication. The proposed scheme is thoroughly evaluated under all the 5G numerologies and with different bandwidth settings. Moreover, key design considerations of the experimental testbed are explained and discussed to optimize the final yields of the system. The experimental results of both transmission directions are compared and analyzed, and prove the viability of the proposed bidirectional ARoF system as an excellent solution to be part of the future 5G mm-wave network. [ABSTRACT FROM AUTHOR]

This paper presents a wideband millimeter wave (mm-Wave) high-gain multibeam antenna array fed by Butler Matrix (BM) based on groove gap waveguide (GGW) technology. First, the components of 4 × 4 GGW BM have been designed and analyzed, especially the proposed modified crossover, which greatly improves the performance of BM as feeding network. Then a 2 × 2-element subarray with three layers has been proposed, combined with the 4 × 4 GGW BM to form a 1 × 4 broadside antenna array. Finally, the prototype of high-gain wideband four-beam antenna array has been manufactured and measured. The measured results verify the superior performance of the multibeam antenna array between 26.3-29.7 GHz. The return loss (RL) can reach 15 dB and isolation between ports is also less than 15 dB, and the measured maximum gain of radiation patterns and the maximum radiation efficiency can also reach 19.05 dBi and 86.8%, respectively. The measured results have a good agreement with the simulated results. [ABSTRACT FROM AUTHOR]

In this work, a wide-band Frequency-Tripler is designed to cover Frequency-Modulated Continuous Wave radar (FMCW) in 22-nm CMOS-FDSOI Technology. The designed frequency Tripler upconverts sub-30 GHz signal to cover a wide-band FMCW spectrum (72–84 GHz). In this paper, the silicon validated results of a VCO combined with the proposed frequency Tripler are presented. The design architecture, EM simulation results, measurement setup and silicon result of our fabricated die are covered in this paper. The designed circuit consumes 20 mA of current at the supply voltage of 800 mV. The Tripler works in the input frequency range from 24 GHz to 32 GHz, delivering a wide-band frequency output of 72–96 GHz. The differential output of VCO is capacitively coupled with the input of the multiplier. [ABSTRACT FROM AUTHOR]

• Parasitic surface conduction of high-resistivity substrates degrades quality factor of inductors. • RF inductors quality factor strongly improves with high-resistivity substrate. • mm-wave inductors need re-design for large gain in quality factor with high-resistivity substrate. The quality factor (Q) of two inductors for 5–60 GHz applications fabricated in an industrial back-end of line (22FDX® from GlobalFoundries) with thick Cu metal layers on top of several Si substrates of different bulk resistivities is analyzed in this paper. The low frequency RF inductor shows an improvement of up to 44% in Q with a high-resistivity substrate. However, no significant improvement is observed for the high-frequency MMW fabricated inductor. This is identified to be due to lower electric field concentration in the substrate due to the small geometry of this MMW inductor that is realized in the top metal Cu layer. Nevertheless, simulations show that a 30% improvement can be achieved with a low loss substrate when designing a MMW inductor as a stacked coil of all BEOL thick metal layers. [ABSTRACT FROM AUTHOR]

• FDSOI characterized from 2 to 400 K at DC and with S-parameters from DC – 67 GHz. • Measurements and discussion of quantum effects in minimum size MOSFETs up to 50 K. • CMOS TIA design methodology for minimum noise and arbitrary source over temperature. • Analysis of optimal CMOS switch size to maximize bandwidth in high-speed ADCs. • Backgate voltage-controlled mm-wave stacked cascode amplifiers and large-swing DACs. Starting with the full characterization of the n- and p- MOSFETs in a 22-nm FDSOI CMOS process from DC and S-parameter measurements over temperature in the 2 K to 400 K range, we develop circuit design guidelines and design methodologies for digital, analog mixed-signal and mm-wave circuit building blocks that take advantage of the unique features of FDSOI transistors enabled by the presence of the back gate and buried oxide. A constant-current–density-to-backgate-voltage-conversion bias circuit, operating across the entire temperature range is demonstrated to optimally bias CMOS inverters in a variety of digital, analog-mixed-signal and mm-wave circuits for different use scenarios that optimize noise, gain, linearity, and/or bandwidth. Measurement data and constant current density design methodologies are used to illustrate the design of transimpedance amplifiers for qubit readout and fibreoptic receivers, broadband switches, mm-wave time-interleaved ADC samplers, large-swing DACs, and power amplifiers. [ABSTRACT FROM AUTHOR]