Showing papers on "Antenna array published in 2018"
TL;DR: The potential of data transmission in a system with a massive number of radiating and sensing elements, thought of as a contiguous surface of electromagnetically active material, is considered as a large intelligent surface (LIS), which is a newly proposed concept and conceptually goes beyond contemporary massive MIMO technology.
Abstract: In this paper, we consider the potential of data transmission in a system with a massive number of radiating and sensing elements, thought of as a contiguous surface of electromagnetically active material. We refer to this as a large intelligent surface (LIS), which is a newly proposed concept and conceptually goes beyond contemporary massive MIMO technology. First, we consider capacities of single-antenna autonomous terminals communicating to the LIS where the entire surface is used as a receiving antenna array in a perfect line-of-sight propagation environment. Under the condition that the surface area is sufficiently large, the received signal after a matched-filtering operation can be closely approximated by a sinc-function-like intersymbol interference channel. Second, we analyze a normalized capacity measured per unit surface, for a fixed transmit power per volume unit with different terminal deployments. As terminal density increases, the limit of the normalized capacity [nats/s/Hz/volume-unit] achieved when wavelength $\lambda$ approaches zero is equal to half of the transmit power per volume unit divided by the noise spatial power spectral density. Third, we show that the number of independent signal dimensions that can be harvested per meter deployed surface is $2/\lambda$ for one-dimensional terminal deployment, and $\pi /\lambda ^2$ per square meter for two- and three-dimensional terminal deployments. Finally, we consider implementations of the LIS in the form of a grid of conventional antenna elements, and show that the sampling lattice that minimizes the surface area and simultaneously obtains one independent signal dimension for every spent antenna is the hexagonal lattice.
712 citations
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TL;DR: In this article, Orthogonal Time Frequency Space (OTFS) modulation is proposed to exploit the full channel diversity over both time and frequency, which obviates the need for transmitter adaptation, and greatly simplifies system operation.
Abstract: This paper introduces a new two-dimensional modulation technique called Orthogonal Time Frequency Space (OTFS) modulation. OTFS has the novel and important feature of being designed in the delay-Doppler domain. When coupled with a suitable equalizer, OTFS modulation is able to exploit the full channel diversity over both time and frequency. Moreover, it converts the fading, time-varying wireless channel experienced by modulated signals such as OFDM into a time-independent channel with a complex channel gain that is essentially constant for all symbols.
This design obviates the need for transmitter adaptation, and greatly simplifies system operation. The paper describes the basic operating principles of OTFS as well as a possible implementation as an overlay to current or anticipated standardized systems. OTFS is shown to provide significant performance improvement in systems with high Doppler, short packets, and/or large antenna array. In particular, simulation results indicate at least several dB of block error rate performance improvement for OTFS over OFDM in all of these settings.
394 citations
TL;DR: The results show that the proposed antenna array can still exhibit good radiation and MIMO performances when operating under data mode and read mode conditions.
Abstract: A 12-port antenna array operating in the long term evolution (LTE) band 42 (3400–3600 MHz), LTE band 43 (3600–3800 MHz), and LTE band 46 (5150–5925 MHz) for 5G massive multiple-input multiple-output (MIMO) applications in mobile handsets is presented. The proposed MIMO antenna is composed of three different antenna element types, namely, inverted $\pi $ -shaped antenna, longer inverted L-shaped open slot antenna, and shorter inverted L-shaped open slot antenna. In total, eight antenna elements are used for the $8 \times 8$ MIMO in LTE bands 42/43, and six antenna elements are designed for the $6 \times 6$ MIMO in LTE band 46. The proposed antenna was simulated, and a prototype was fabricated and tested. The measured results show that the LTE bands 42/43/46 are satisfied with reflection coefficient better than −6 dB, isolation lower than −12 dB, and total efficiencies of higher than 40%. In addition to that, the proposed antenna array has also shown good MIMO performances with an envelope correlation coefficient lower than 0.15, and ergodic channel capacities higher than 34 and 26.5 b/s/Hz in the LTE bands 42/43 and LTE band 46, respectively. The hand phantom effects are also investigated, and the results show that the proposed antenna array can still exhibit good radiation and MIMO performances when operating under data mode and read mode conditions.
185 citations
TL;DR: A multi-band 10-antenna array working at the sub-6-GHz spectrum (LTE bands 42/43 and LTE band 46) for massive multiple-input multiple-output (MIMO) applications in future 5G smartphones is proposed.
Abstract: A multi-band 10-antenna array working at the sub-6-GHz spectrum (LTE bands 42/43 and LTE band 46) for massive multiple-input multiple-output (MIMO) applications in future 5G smartphones is proposed. To realize $10\times 10$ MIMO applications in three LTE bands, 10 T-shaped coupled-fed slot antenna elements that can excite dual resonant modes are integrated into a system circuit board. Spatial and polarization diversity techniques are implemented on these elements so that the improved isolation and mitigated coupling effects can be achieved. The proposed antenna array was manufactured and experimentally measured. Desirable antenna efficiencies of higher than 42% and 62% were measured in the low band and high band, respectively. Vital results, such as the envelope correlation coefficient, channel capacity, and mean effective gain ratio, have also been computed and analyzed. The calculated ergodic channel capacities of the $10\times 10$ MIMO system working in the LTE bands 42/43 and LTE band 46 reached up to 48 and 51.4 b/s/Hz, respectively.
184 citations
TL;DR: In this paper, an eight-port antenna array operating in 3.5 GHz band and 5 GHz band for 5G MIMO in mobile handsets is presented, and the measured results have exhibited good impedance matching and isolation.
Abstract: An eight-port antenna array operating in 3.5 GHz band (3400–3600 MHz) and 5 GHz band (4800–5100 MHz) for fifth-generation multiple-input multiple-output (MIMO) in mobile handsets is presented. To reserve space for 2G/3G/4G antenna configuration, the eight-antenna array formed by two quad-antenna arrays is printed along the two long frames of the smartphone. Each antenna array unit is formed by a folded monopole and a gap-coupled loop branch, and they are disposed on the upper and bottom sides of the system circuit board, respectively. As the gap between each array unit is only 10 mm, a neutralized line is introduced between the two middle antenna units for reducing the mutual coupling. The measured results have exhibited good impedance matching and isolation. To evaluate the MIMO performance, the envelope correlation coefficient, mean effective gain, and ergodic channel capacity are investigated. Furthermore, the hand phantom effects and display panel effects are also given.
181 citations
TL;DR: In this paper, the authors investigated low RF-complexity technologies to solve the problem of hardware cost and power consumption in mmWave MIMO systems, and compared the performance of PAHP and LAHP in practice.
Abstract: mmWave MIMO with large antenna array has attracted considerable interest from the academic and industry communities, as it can provide larger bandwidth and higher spectrum efficiency. However, with hundreds of antennas, the number of RF chains required by mmWave MIMO is also huge, leading to unaffordable hardware cost and power consumption in practice. In this article, we investigate low RF-complexity technologies to solve this bottleneck. We first review the evolution of low RF-complexity technologies from microwave frequencies to mmWave frequencies. Then, we discuss two promising low RF-complexity technologies for mmWave MIMO systems in detail, that is PAHP and LAHP, including their principles, advantages, challenges, and recent results. We compare the performance of these two technologies to draw some insights about how they can be deployed in practice. Finally, we conclude this article and point out some future research directions in this area.
180 citations
TL;DR: This paper describes a 28-GHz CMOS direct conversion transceiver with packaged patch antenna array for 5G communication with well-fit beam control capability with low error vector magnitude.
Abstract: This paper describes a 28-GHz CMOS direct conversion transceiver with packaged $2 \times 4$ patch antenna array for 5G communication. Beamforming antenna and reconfigurable transceiver architecture are used for high effective isotropic radiated power (EIRP). For low error vector magnitude (EVM), switchless matching transmitter (Tx)/receiver (Rx) to antenna and 28-GHz injection-locked local oscillator (LO) generator are employed. Test chip was fabricated in 28-nm RF CMOS process. Measurement results show Tx EIRPsat of 31.5 dBm ( $P_{\mathrm {sat}}$ of 10.5 dBm in one power amplifier (PA)), EIRPmax 24 dBm ( $P_{\mathrm {max}}$ of 2 dBm with backoff of 7.5 dB in one PA), Rx noise figure of 6.7 dB, and integrated LO phase noise of −38.7 dBc (0.67°). After IQ mismatch calibration, Tx LO leakage and image power are less than −35 dBc. Rx and Tx EVM show 2.2% (−33 dB) at medium RF power (Rx $P_{\mathrm {in}}$ of −60 dBm and Tx EIRP of 0 dBm) with well-fit beam control capability.
180 citations
TL;DR: In this article, a broadband multibeam endfire dual-circularly polarized (CP) antenna array using dielectric-loaded stepped slot antennas for millimeter-wave (mmWave) applications is proposed.
Abstract: A broadband multibeam endfire dual-circularly polarized (CP) antenna array using dielectric-loaded stepped slot antennas for millimeter-wave (mmWave) applications is proposed. First, a dual-CP endfire antenna element is designed for broadband mmWave applications. Additional loaded dielectric is utilized to improve the interelement isolation, the polarization purity, and the gain performance. Second, a substrate integrated waveguide (SIW) feeding network is designed for multibeam array applications. The broadband $4\times 4$ SIW Butler matrix, interconnections, and transitions are designed and applied in the antenna array. Third, mutual coupling and its influence on the array performance are investigated. Additional air gaps between elements are designed for axial ratio performance enhancement. Finally, the proposed multibeam array is designed, fabricated, and measured. The fabricated prototype achieves wide impedance bandwidth of 29.3% with the interbeam isolation greater than 15 dB, and a wide axial ratio bandwidth of 22.5%. The proposed multibeam endfire dual-CP antenna array would be a very attractive candidate for 5G mmWave wireless applications.
154 citations
TL;DR: In this article, a Ka-band inset-fed microstrip patches linear antenna array is presented for 5G applications in different countries, which employs 16 elements in an H-plane new configuration.
Abstract: A Ka-band inset-fed microstrip patches linear antenna array is presented for the fifth generation (5G) applications in different countries. The bandwidth is enhanced by stacking parasitic patches on top of each inset-fed patch. The array employs 16 elements in an H-plane new configuration. The radiating patches and their feed lines are arranged in an alternating out-of-phase 180° rotating sequence to decrease the mutual coupling and improve the radiation pattern symmetry. A (24.4%) measured bandwidth (24.35–31.13 GHz) is achieved with −15 dB reflection coefficients and 20 dB mutual coupling between the elements. With uniform amplitude distribution, a maximum broadside gain of 19.88 dBi is achieved. Scanning the main beam to 49.5° from the broadside achieved 18.7 dBi gain with −12.1 dB sidelobe level. These characteristics are in good agreement with the simulations, rendering the antenna to be a good candidate for 5G applications.
154 citations
TL;DR: This paper proposes a blind beam tracking approach for Ka-band UAV-satellite communication system, where UAV is equipped with a hybrid large-scale antenna array, where an array structure based simultaneous perturbation algorithm is designed.
Abstract: Unmanned aerial vehicle (UAV)-satellite communication has drawn dramatic attention for its potential to build the integrated space-air-ground network and the seamless wide-area coverage. A key challenge to UAV-satellite communication is its unstable beam pointing due to the UAV navigation, which is a typical SatCom on-the-move scenario. In this paper, we propose a blind beam tracking approach for Ka-band UAV-satellite communication system, where UAV is equipped with a hybrid large-scale antenna array. The effects of UAV navigation are firstly released through the mechanical adjustment, which could approximately point the beam towards the target satellite through beam stabilization and dynamic isolation . Specially, the attitude information for mechanical adjustment can be realtimely derived from data fusion of low-cost sensors. Then, the precision of beam pointing is blindly refined through electrically adjusting the weight of the massive antennas, where an array structure based simultaneous perturbation algorithm is designed. Simulation results are provided to demonstrate the superiority of the proposed method over the existing ones.
145 citations
TL;DR: Simulation and analysis show that the proposed scheme actually can achieve a secure and precise wireless transmission of confidential messages in line-of-propagation channel, and the derived theoretical formula of average secrecy rate is verified to coincide with the exact results well for medium and large scale transmit antenna array or in the low and medium SNR regions.
Abstract: In this paper, a practical wireless transmission scheme is proposed to transmit confidential messages to the desired user securely and precisely by the joint use of multiple techniques, including artificial noise (AN) projection, phase alignment/beamforming, and random subcarrier selection (RSCS) based on orthogonal frequency division multiplexing (OFDM), and directional modulation (DM), namely RSCS-OFDM-DM. This RSCS-OFDM-DM scheme provides an extremely low-complexity structure for the desired receiver and makes the secure and precise wireless transmission realizable in practice. For illegal eavesdroppers, the receive power of confidential messages is so weak that their receivers cannot intercept these confidential messages successfully once it is corrupted by AN. In such a scheme, the design of phase alignment/beamforming vector and AN projection matrix depends intimately on the desired direction angle and distance. It is particularly noted that the use of RSCS leads to a significant outcome that the receive power of confidential messages mainly concentrates on the small neighboring region around the desired receiver and only small fraction of its power leaks out to the remaining large broad regions. This concept is called secure precise transmission. The probability density function of real-time receive signal-to-interference-and-noise ratio (SINR) is derived. Also, the average SINR and its tight upper bound are attained. The approximate closed-form expression for average secrecy rate is derived by analyzing the first-null positions of the SINR and clarifying the wiretap region. Simulation and analysis show that the proposed scheme actually can achieve a secure and precise wireless transmission of confidential messages in line-of-propagation channel, and the derived theoretical formula of average secrecy rate is verified to coincide with the exact results well for medium and large scale transmit antenna array or in the low and medium SNR regions.
TL;DR: In this paper, a decoupling metamaterial (MTM) configuration based on fractal electromagnetic-bandgap (EMBG) structure is shown to significantly enhance isolation between transmitting and receiving antenna elements in a closely-packed patch antenna array.
Abstract: A decoupling metamaterial (MTM) configuration based on fractal electromagnetic-bandgap (EMBG) structure is shown to significantly enhance isolation between transmitting and receiving antenna elements in a closely-packed patch antenna array. The MTM-EMBG structure is cross-shaped assembly with fractal-shaped slots etched in each arm of the cross. The fractals are composed of four interconnected-`Y-shaped' slots that are separated with an inverted-`T-shaped' slot. The MTM-EMBG structure is placed between the individual patch antennas in a 2 × 2 antenna array. Measured results show the average inter-element isolation improvement in the frequency band of interest is 17, 37 and 17 dB between radiation elements #1 & #2, #1 & #3, and #1 & #4, respectively. With the proposed method there is no need for using metallic-via-holes. The proposed array covers the frequency range of 8-9.25 GHz for X-band applications, which corresponds to a fractional-bandwidth of 14.5%. With the proposed method the edge-to-edge gap between adjacent antenna elements can be reduced to 0.5λ
0
with no degradation in the antenna array's radiation gain pattern. Across the array's operating band, the measured gain varies between 4 and 7 dBi, and the radiation efficiency varies from 74.22 and 88.71%. The proposed method is applicable in the implementation of closely-packed patch antenna arrays used in SAR and MIMO systems.
TL;DR: In this article, a fast root multiple signal classification HDAPA (root-MUSIC-HDAPA) method is proposed specially for this hybrid structure to implement an approximately analytical solution.
Abstract: A large-scale fully digital receive antenna array can provide very high-resolution direction of arrival (DOA) estimation, but resulting in a significantly high RF-chain circuit cost. Thus, a hybrid analog and digital (HAD) structure is preferred. Two phase alignment (PA) methods, HAD PA (HADPA) and hybrid digital and analog PA (HDAPA), are proposed to estimate DOA based on the parametric method. Compared to analog PA (APA), they can significantly reduce the complexity in the PA phases. Subsequently, a fast root multiple signal classification HDAPA (root-MUSIC-HDAPA) method is proposed specially for this hybrid structure to implement an approximately analytical solution. Due to the HAD structure, there exists the effect of direction-finding ambiguity. A smart strategy of maximizing the average receive power is adopted to delete those spurious solutions and preserve the true optimal solution by linear searching over a set of limited finite candidate directions. This results in a significant reduction in computational complexity. Eventually, the Cramer–Rao lower bound (CRLB) of finding emitter direction using the HAD structure is derived. Simulation results show that our proposed methods, root-MUSIC-HDAPA and HDAPA, can achieve the hybrid CRLB with their complexities being significantly lower than those of pure linear searching-based methods, such as APA.
TL;DR: This paper proposes a novel direction-of-arrival (DOA)-aided channel estimation for a hybrid millimeter-wave (mm-wave) massive multiple-input multiple-output system with a uniform planar array at the base station and derives the theoretical bounds of the mean squared errors (MSEs) and the Cramér–Rao lower bounds (CRLBs) of the joint DOA and channel gain estimation.
Abstract: This paper proposes a novel direction-of-arrival (DOA)-aided channel estimation for a hybrid millimeter-wave (mm-wave) massive multiple-input multiple-output system with a uniform planar array at the base station. To explore the physical characteristics of the antenna array in mm-wave systems, the parameters of each channel path are decomposed into the DOA information and the channel gain information. We first estimate the initial DOAs of each uplink path through the 2-D discrete Fourier transform and enhance the estimation accuracy via the angle rotation technique. We then estimate the channel gain information using a small amount of training resources, which significantly reduces the training overhead and the feedback cost. More importantly, to examine the estimation performance, we derive the theoretical bounds of the mean squared errors (MSEs) and the Cramer–Rao lower bounds (CRLBs) of the joint DOA and channel gain estimation. The simulation results show that the performances of the proposed methods are close to the theoretical MSEs’ analysis. Furthermore, the theoretical MSEs are also close to the corresponding CRLBs.
TL;DR: A 144-element phased array transceiver is realized using a modular tiled approach that supports 802.11ad, MCS12 single carrier 16-quadratic-amplitude modulation (QAM) 4.6 Gbps, in the 60-GHz band and has a measured over the air (OTA) max effective isotropic radiated power (EIRP) of 51 dBm at saturated power (PSAT).
Abstract: A 144-element phased array transceiver is realized using a modular tiled approach that supports 802.11ad, MCS12 single carrier 16-quadratic-amplitude modulation (QAM) 4.6 Gbps, in the 60-GHz band. It consists of a system-on-a chip (SOC) (MAC/PHY/BB to IF) in 28-nm CMOS, and one IF-to-60-GHz transceiver master chip driving twelve 60-GHz phased array transceiver slave chips fabricated in a 40-nm CMOS. Using the master-slave configuration, the 60-GHz transceiver with 12 phase-controlled TX/RX slices is expanded to 144 phase-controlled slices. Each final TX/RX slice is then connected to two patch antennas on LTCC substrate. A tiled approach is used to create the 288 patch antenna array out of six identical tiles each with two slave 60-GHz transceivers connected to a 48-element antenna array. The single tile phased array with 48 antennas has a measured beam steering scan angle of 60° in azimuth and 10° in elevation. The full phased array transceiver with 288 antennas has a measured over the air (OTA) max effective isotropic radiated power (EIRP) of 51 dBm at saturated power (PSAT), and EIRP of 44.8 dBm with −22 dB EVM for MCS12 (16QAM-4.6 Gbps) at broadside. It has an OTA measured sensitivity of −87.3 and −80.4 dBm for MCS9 (QPSK-2.5 Gbps) and MCS12, respectively, at broadside. A packet error rate of 10−5 was measured for MCS9 and MCS12 with an OTA input power of −85 and −77.5 dBm, respectively, for the full phased array transceiver at broadside.
TL;DR: This paper considers the effects of channel estimation, transmitter impairments, and multiple simultaneous users for a wideband multipath model, and considers the correlation of the quantization error, and generalizes the modeling of it to nonuniform quantizers and different quantizers at each antenna.
Abstract: For 5G, it will be important to leverage the available millimeter wave spectrum. To achieve an approximately omnidirectional coverage with a similar effective antenna aperture compared to state-of-the-art cellular systems, an antenna array is required at both the mobile and base station. Due to the large bandwidth and inefficient amplifiers available in CMOS for mmWave, the analog front end of the receiver with a large number of antennas becomes especially power hungry. Two main solutions exist to reduce the power consumption: hybrid beam forming and digital beam forming with low resolution Analog to digital converters (ADCs). In this paper, we compare the spectral and energy efficiency of both systems under practical system constraints. We consider the effects of channel estimation, transmitter impairments, and multiple simultaneous users for a wideband multipath model. Our power consumption model considers components reported in the literature at 60 GHz. In contrast to many other works, we also consider the correlation of the quantization error, and generalize the modeling of it to nonuniform quantizers and different quantizers at each antenna. The result shows that as the signal-to-noise ratio (SNR) gets larger the ADC resolution achieving the optimal energy efficiency gets also larger. The energy efficiency peaks for 5-b resolution at high SNR, since due to other limiting factors, the achievable rate almost saturates at this resolution. We also show that in the multiuser scenario digital beamforming is in any case more energy efficient than hybrid beamforming. In addition, we show that if mixed ADC resolutions are used, we can achieve any desired tradeoff between power consumption and rate close to those achieved with only one ADC resolution.
TL;DR: In this paper, a relatively new optimization technique, namely flower pollination algorithm (FPA) for the design of linear antenna array (LAA) for reducing the maximum side lobe level (SLL) and null control.
Abstract: Linear antenna array (LAA) design is a classical electromagnetic problem. It has been extensively dealt by number of researchers in the past, and different optimization algorithms have been applied for the synthesis of LAA. This paper presents a relatively new optimization technique, namely flower pollination algorithm (FPA) for the design of LAA for reducing the maximum side lobe level (SLL) and null control. The desired antenna is achieved by controlling only amplitudes or positions of the array elements. FPA is a novel meta-heuristic optimization method based on the process of pollination of flowers. The effectiveness and capability of FPA have been proved by taking difficult instances of antenna array design with single and multiple objectives. It is found that FPA is able to provide SLL reduction and steering the nulls in the undesired interference directions. Numerical results of FPA are also compared with the available results in the literature of state-of-the-art algorithms like genetic algorithm, particle swarm optimization, cuckoo search, tabu search, biogeography based optimization (BBO) and others which also proves the better performance of the proposed method. Moreover, FPA is more consistent in giving optimum results as compared to BBO method reported recently in the literature.
TL;DR: In this article, a planar millimeter-wave 2D beam-scanning multibeam array antenna fed by compact 16-way beamforming network (BFN) in multilayered substrate integrated waveguide (SIW) technology is addressed.
Abstract: A planar millimeter-wave 2-D beam-scanning multibeam array antenna fed by compact 16-way beam-forming network (BFN) in multilayered substrate integrated waveguide (SIW) technology is addressed. The BFN is formed by connecting two stacks of sub-BFNs, the E-plane sub-BFN and the H-plane sub-BFN. The H-plane sub-BFN is realized by a traditional H-plane $4 \times 4$ Butler matrix (BM). The key point of this design is to propose an E-plane $4 \times 4$ BM which realizes a planar E-plane sub-BFN. These two sets of sub-BFNs can joint directly without resorting to any connectors or connecting networks to form such a compact 16-way BFN with a reduced area of merely $3\lambda \times 12\lambda $ . After that, to be compatible with the proposed BFN, a ladder-type $4 \times 4$ slot antenna array is employed, which is comprised of four linear $1 \times 4$ slot antenna arrays. Different from traditional array, the four subarrays are distributed in separate layers for the purpose of jointing to the BFN more conveniently. Transition network are also required to connect the BFN with the antenna array. Finally, a compact 2-D scanning multibeam array antenna based on the planar SIW BFN are fabricated and measured, which would be an attractive candidate for 5G application.
TL;DR: An improved fruit-fly optimization algorithm (FOA) is proposed to be used in antenna array synthesis, which includes adding a new search mechanism to enhance the efficiency of algorithm during high-dimensional problems.
Abstract: Synthesizing antenna arrays is one of the most influential optimization problems in the electromagnetics community. In this paper, an improved fruit-fly optimization algorithm (FOA) [entitled averager engine linear generation mechanism of candidate solution of FOA (AE-LGMS-FOA)] is proposed to be used in antenna array synthesis. This improvement includes adding a new search mechanism to enhance the efficiency of algorithm during high-dimensional problems. After investigating its performance through a variety of benchmark functions, the proposed method is applied to several linear and planar array problems in terms of sidelobe reduction, null control, and thinning. During the problems, some properties of the algorithm are analyzed and the associated results are compared with other state-of-the-art methods and popular algorithms. Furthermore, various boundary conditions are reformulated for the algorithm and examined during the planar array synthesis. Finally, the AE-LGMS-FOA is utilized in synthesizing a U-slot microstrip array antenna with ultrawideband characteristics to verify its versatility and robustness in real-world array antenna problems. The optimized structure has an impedance bandwidth of 3.38 GHz, which indicates 181.6% improvement over the original structure’s bandwidth.
TL;DR: In this paper, a photonic TTD beamforming network based on a miniature microresonator frequency comb (microcomb) source and dispersive time delay is proposed for positive and negative apodization weighting.
Abstract: Microwave phased array antennas (PAAs) are very attractive to defense applications and high-speed wireless communications for their abilities of fast beam scanning and complex beam pattern control. However, traditional PAAs based on phase shifters suffer from the beam-squint problem and have limited bandwidths. True-time-delay (TTD) beamforming based on low-loss photonic delay lines can solve this problem. But it is still quite challenging to build large-scale photonic TTD beamformers due to their high hardware complexity. In this paper, we demonstrate a photonic TTD beamforming network based on a miniature microresonator frequency comb (microcomb) source and dispersive time delay. A method incorporating optical phase modulation and programmable spectral shaping is proposed for positive and negative apodization weighting to achieve arbitrary microwave beam pattern control. The experimentally demonstrated TTD beamforming network can support a PAA with 21 elements. The microwave frequency range is 8-20 GHz; and the beam scanning range is ±60.2°. Detailed measurements of the microwave amplitudes and phases are performed. The beamforming performances of Gaussian, rectangular beams, and beam notch steering are evaluated through simulations by assuming a uniform radiating antenna array. The scheme can potentially support larger PAAs with hundreds of elements by increasing the number of comb lines with broadband microcomb generation.
TL;DR: The proposed planar antenna array based on ridge gap waveguide feeding network, consisting of four radiating slots which are excited by a groove gap cavity layer, is a promising candidate for mmWave communication systems.
Abstract: A wideband $8 \times 8$ element slot antenna array based on ridge gap waveguide feeding network has been proposed for mmWave applications. The antenna subarray consists of four radiating slots which are excited by a groove gap cavity layer. Compared with previously published works, the proposed planar antenna array has quite wide impedance bandwidth. The antenna covers a wideband of 50–67.8 GHz with 30% impedance bandwidth (VSWR < 2). Also, the antenna has only 2.5 dB gain variation over the entire bandwidth which implies also good radiation characteristics for the proposed antenna. The maximum measured gain value is about 27.5 dBi with a total efficiency of 80% for the proposed antenna within the band of interest. With this performance, the proposed antenna array is a promising candidate for mmWave communication systems.
TL;DR: In this paper, a dual-polarized array of connected slots radiating in the presence of an artificial dielectric superstrate was designed and tested, and the performance was investigated in terms of simulated and measured matching characteristics and radiation patterns.
Abstract: In this communication, we report on the design, manufacturing, and testing of a dual-polarized array of connected slots radiating in the presence of an artificial dielectric superstrate. The prototype array consists of 512 elements, i.e., $16\times 16$ connected slots for each of the two polarizations. The antenna array is realized with a single multilayer printed circuit board (PCB), which represents an advantage in terms of cost and complexity with respect to the typical configuration based on multiple vertically arranged PCBs. The performance is investigated in terms of simulated and measured matching characteristics and radiation patterns. The proposed structure achieves active voltage standing wave ratio lower than 3.1 over about an octave bandwidth (6–15 GHz), within a wide scan range (±60° in the H-plane and ±80° in the E-plane).
TL;DR: This paper proposes a novel transmitter design at the IoT devices with zero-forcing beamforming to cancel the intranode interference and uniform-forcing power control to compensate the nonuniform fading and proposes a corresponding signaling procedure utilizing the “OR” property of the wireless channel.
Abstract: Over-the-air computation combines communication and computation efficiently by utilizing the superposition property of wireless channels, when Internet of Things (IoT) networks focus more on the computed functions than the individual messages. In this paper, we study the computation of multiple linear functions of Gaussian sources over-the-air using antenna arrays at both the IoT devices and the IoT access point (AP). The key challenges in this paper are the intranode interference of multiple functions, the nonuniform fading between different IoT devices and the massive channel state information (CSI) required at the IoT AP. We propose a novel transmitter design at the IoT devices with zero-forcing beamforming to cancel the intranode interference and uniform-forcing power control to compensate the nonuniform fading. In order to avoid massive CSI requirement, receive antenna selection is adopted at the IoT AP and a corresponding signaling procedure is proposed utilizing the “OR” property of the wireless channel. The performance of the proposed transceiver design is analyzed. The closed-form expression for the mean squared function error (MSFE) outage is derived. Due to the complexity of the expression, an asymptotic analysis of the MSFE outage is further provided to demonstrate the diversity order in terms of the transmit power constraint and the number of IoT devices. Simulation results are presented to show the performance of the proposed design.
04 Oct 2018
TL;DR: Drawing inspiration from coded random access, one of the main contributions of the paper is the design of low complexity scheme that exploits the non-stationary nature of xMaMIMO systems and where the data processing is decentralized.
Abstract: This paper focuses on new communication paradigms arising in massive multiple-input-multiple-output systems where the antenna array at the base station is of extremely large dimension (xMaMIMO). Due to the extreme dimension of the array, xMaMIMO is characterized by spatial non-stationary field properties along the array; this calls for a multi-antenna transceiver design that is adapted to the array dimension but also its non-stationary properties. We address implementation aspects of xMaMIMO, with computational efficiency as our primary objective. To reduce the computational burden of centralized schemes, we distribute the processing into smaller, disjoint sub-arrays. Then, we consider several low-complexity data detection algorithms as candidates for uplink communication in crowded xMaMIMO systems. Drawing inspiration from coded random access, one of the main contributions of the paper is the design of low complexity scheme that exploits the non-stationary nature of xMaMIMO systems and where the data processing is decentralized. We evaluate the bit-error-rate performance of the transceivers in crowded xMaMIMO scenarios. The results confirm their practical potential.
TL;DR: In this article, a dual-polarized high-isolation multiple input multiple output (MIMO) antenna array for wideband base-station applications is presented, where the antenna array consisting of four elements is working within the frequency band from 2.4 to 3 GHz and decoupling branches among the elements are introduced to improve the isolation by about 10 dB.
Abstract: A low-profile dual-polarized high-isolation multiple input multiple output (MIMO) antenna array for wideband base-station applications is presented in this paper. The proposed dual-polarized antenna element has the advantage of lower profile ( $0.067\lambda $ ) by utilizing artificial magnetic conductor structure. The antenna array consisting of four elements is working within the frequency band from 2.4 to 3 GHz. Furthermore, decoupling branches among the elements are introduced to improve the isolation by about 10 dB. Both simulation and measured results indicate that the proposed dual-polarized antenna element has a good isolation over 28 dB. Moreover, the beamwidth of the antenna array can be effectively broadened by the adjustment of phase distributions of corresponding artificial material plane. Finally, a larger MIMO system is also investigated, and the simulation and measured results prove that dual-polarized dipole antenna MIMO array has good system performance.
TL;DR: The results show that the proposed 3-D channel model is in close agreement with previously reported results, thereby validating the generalization of the proposed model.
Abstract: This paper presents 3-D vehicle massive multiple-input multiple-output (MIMO) antenna array model for vehicle-to-vehicle (V2V) communication environments. A spherical wavefront is assumed in the proposed model instead of the plane wavefront assumption used in the conventional MIMO channel model. Using the proposed V2V channel model, we first derive the closed-form expressions for the joint and marginal probability density functions of the angle of departure at the transmitter and angle of arrival at the receiver in the azimuth and elevation planes. We additionally analyze the time and frequency cross-correlation functions for different propagation paths. In the proposed model, we derive the expression of the Doppler spectrum due to the relative motion between the mobile transmitter and mobile receiver. The results show that the proposed 3-D channel model is in close agreement with previously reported results, thereby validating the generalization of the proposed model.
TL;DR: In this article, a quad-mode end-fire planar phased antenna array with wide scan angle and 1.2 mm clearance is proposed for 5G mobile terminals, which can obtain over 8 GHz of impedance bandwidth.
Abstract: In this paper, a quad-mode endfire planar phased antenna array with wide scan angle and 1.2 mm clearance is proposed for 5G mobile terminals. The proposed antenna can obtain over 8 GHz of impedance bandwidth. In this paper, it is suggested to efficiently combine a multimode array element with different radiation patterns for each mode into a phased antenna array. In the array, similar and wide embedded radiation patterns are obtained for the all four modes. Furthermore, a coaxial to differential stripline transition is designed in this paper. The differential feeding structure is very compact and utilizes only MMPX connector and vias. The total scan pattern and coverage efficiency of the measured and simulated phased array antenna are calculated in the range from 25 to 33 GHz, and good agreement between measured and simulated results is observed. The mean coverage efficiency along the frequency range is very similar, but minor difference in variance of coverage efficiency is observed in the measurements. The coverage efficiency of around 50% for the threshold gain of 5 dBi is achieved in the chosen frequency range.
TL;DR: A “fully-connected” hybrid beamforming receiver that independently weights each element in an antenna array prior to separate downconversion chains that output independent baseband streams is presented.
Abstract: This paper presents a “fully-connected” hybrid beamforming receiver that independently weights each element in an antenna array prior to separate downconversion chains that output independent baseband streams. A receiver architecture is introduced, which implements RF-domain complex-valued Cartesian weighting, RF-domain combining, and multi-stream heterodyne complex-quadrature downconversion. Each RF-domain Cartesian weight is implemented by a pair of 5-bit digitally controlled programmable-gain amplifiers, whose outputs are combined with the weighted signals from other antennas prior to complex-quadrature downconversion. Signal combination is performed by a wideband small-footprint distributed active combiner. A 25–30 GHz hybrid beamforming receiver with eight antenna inputs and two baseband output streams is designed in 65-nm CMOS. In each antenna path, the receiver achieves 34-dB conversion gain, 7.3-dB minimum noise figure, and 5 GHz of RF bandwidth. The entire receiver consumes 340 mW (equivalent to 27.5 mW per antenna per stream) including low-noise amplification, RF-domain beamforming, multi-stream downconversion, and local oscillator generation and distribution circuitry. The receiver occupies 3.86 mm2 excluding pads, equivalent to 0.36 mm2 per antenna per stream. Single-element characterization results are presented, along with characterization of several spatial processing techniques including interference cancellation (20 dB peak to null for two elements), simultaneous two-stream reception, and adaptive-codebook-search-based beam acquisition.
TL;DR: A suspended meta-surface composed periodic square split ring resonators (SRRs) is placed above the antenna array for decoupling and the total efficiency and peak gain of each element, the envelope correlation coefficient (ECC) between the two elements are improved by considerable amounts.
Abstract: In this paper, a method to reduce the inevitable mutual coupling between antennas in an extremely closely spaced two-element MIMO antenna array is proposed. A suspended meta-surface composed periodic square split ring resonators (SRRs) is placed above the antenna array for decoupling. The meta-surface is equivalent to a negative permeability medium, along which wave propagation is rejected. By properly designing the rejection frequency band of the SRR unit, the mutual coupling between the antenna elements in the MIMO antenna system can be significantly reduced. Two prototypes of microstrip antenna arrays at 5.8 GHz band with and without the metasurface have been fabricated and measured. The matching bandwidths of antennas with reflection coefficient smaller than −15 dB for the arrays without and with the metasurface are 360 MHz and 900 MHz respectively. Using the meta-surface, the isolation between elements is increased from around 8 dB to more than 27 dB within the band of interest. Meanwhile, the total efficiency and peak gain of each element, the envelope correlation coefficient (ECC) between the two elements are also improved by considerable amounts. All the results demonstrate that the proposed method is very efficient for enhancing the performance of MIMO antenna arrays.
TL;DR: In this paper, a near-field focused (NFF) substrate-integrated waveguide (SIW) antenna at a center frequency of 35 GHz with 2-D steerable focus is achieved by combining an NFF leakywave slot antenna array with a focused multibeam SIW Rotman lens.
Abstract: This paper presents a near-field-focused (NFF) substrate-integrated waveguide (SIW) antenna at a center frequency of 35 GHz with 2-D steerable focus. The proposed antenna is achieved by combining an NFF leaky-wave slot antenna array with a focused multibeam SIW Rotman lens. In most of the existing NFF planar antennas, the total phase distribution on the radiating aperture is separated into two parts with respect to the E-plane and the H-plane, which leads to a large error and deteriorates the NFF performance. Here, a modified NFF planar antenna synthesis method is proposed to calculate the desired phase distribution on the aperture and completely eliminate such an error at the center frequency. The linear NFF leaky-wave slot antenna is designed to scan the focal point in the H-plane with the frequency. The 15 leaky-wave slot antennas are grouped in a special topology and excited by the focused SIW Rotman lens. In this case, multiple focal points can be generated in the E-plane. Moreover, an SIW matching load is developed to improve the NFF beam performance. The whole NFF antenna is integrated into a single-layer substrate. The measured results are in agreement with the simulated ones.