Dual-polarized MIMO Research Articles

Eigth-Port Orthogonally Dual-Polarized MIMO Novel Antenna with Non-Contact Feed for 5G Smartphone

In this paper, an eight-port orthogonally dual-polarized MIMO novel antenna using a non-contact feed for 5G smartphone applications in the 3.5-GHz band (3.3–3.6 GHz) is presented. The antenna consists of a 2*2 array with (eight-port Orthogonally dual-polarised with non-contact feed), which are symmetrically distributed in the inner of the smartphone frame. The dimension of the system circuit board is (25*25*1.6 mm3) with epsilon and loss tangent are 4.3 and 0.025, respectively. The proposed MIMO array is simulated, and a prototype is fabricated and tested. The results show that all the elements can cover the desired band of 3.3–3.6 GHz under the condition of −6-dB impedance bandwidth. The isolations are enhanced to 17 dB by combining the inverted-I ground slots with a neutralization line (NL) structure. In addition, the envelope correlation coefficient (ECC) via any two elements is below 0.15 which shows good independence in far-field radiation characteristics. The measured efficiencies of the elements in the operating band are higher than 40%. Moreover, the array ergodic channel capacity is also calculated based on the correlation matrix method to be about 35 bps/Hz with a 20-dB signal-to-noise ratio. In addition, the effects of the user’s hand and the head has been analyzed as well. Based on the above, the proposed eight-port dual-polarized MIMO antenna using a non-contact feed is a prospective candidate for future 5G smartphone applications.

Dual‐polarized stacked microstrip antenna with trident‐shaped baluns for MIMO array development

Owing to the high cross-polarization discrimination (XPD) and high isolation characteristics, differential excitation is often employed in dual-polarized microstrip antennas. However, the number of excitation ports will be doubled, and the power dividers in the differential circuit will introduce additional loss, the differential excitation scheme is thus not suitable for dual-polarized large-scale MIMO antenna arrays. In this work, a novel dual-polarized stacked microstrip antenna with trident-shaped baluns is proposed for base station MIMO array development. The trident-shaped balun is proposed to replace the traditional differential excitation structures, while keeping the merits of high XPD and high isolation. The proposed antenna operates in the frequency band of 3.3-3.8 GHz. The profile height of the antenna is only 0.09λ0 (λ0 is the free-space wavelength at the central frequency), which is much lower than traditional base station antennas (0.25λ0) in the sub-6 GHz band. Moreover, a defective ground structure is implemented in a 2 × 2 MIMO antenna array to efficiently suppress the mutual coupling among antenna elements. Both simulated and measured results validate the design. Owing to its low-profile height and low mutual coupling characteristic, the proposed design is a good candidate for sub-6 GHz band base station MIMO array developments.

Sectoral dual-polarized MIMO antenna for 5G-NR band N77 base station

Sectoral dual-polarized MIMO antenna for 5G-NR band N77 base station

A Low Profile, Dual-Band, Dual-Polarized Patch Antenna With Antenna-Filter Functions and Its Application in MIMO Systems

In this paper, a low profile, dual-band dual-polarized patch antenna is proposed for antenna-filter function with a relatively low profile of 0.032 wavelength. A simple symmetric open/short-circuited stub (O/SCS) is proposed to excite a square radiating patch, and an additional resonant mode is generated except for the patch-mode. At the lower band, the proposed antenna works as a dual-polarized patch antenna. At the upper band, transmission characteristic is obtained between the two ports, and the antenna structure can be used as a bandpass filter. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 2$ </tex-math></inline-formula> array is also designed to validate its application potential in MIMO system. The two antennas can operate as radiators with high port isolation levels at the lower band. Meanwhile, at the upper band, the two antenna elements can act as one bandpass filter as the good transmission characteristic. In addition, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> array is also developed meet dual-function demands in dual-polarized MIMO systems. The low profile, simple structures and excellent performances indicate that the proposed antenna can be a good candidate in future wireless communication applications with shared functions.

Linear and Decoupled Decoders for Dual-Polarized Antenna-Based MIMO Systems

Quaternion orthogonal designs (QODs) have been used to design STBCs that provide improved performance in terms of various design parameters. In this paper, we show that all QODs obtained from generic iterative construction techniques based on the Adams-Lax-Phillips approach have linear and decoupled decoders which significantly reduce the computational complexity at the receiver. Our result is based on the quaternionic description of communication channels among dual-polarized antennas. Another contribution of this work is the linear and decoupled decoder for quasi-orthogonal codes for non-square as well as square designs. The proposed solution promises diversity gains with the quaternionic channel model and the decoding solution is independent of the number of receive dual-polarized antennas. A brief comparison is presented at the end to demonstrate the effectiveness of quaternion designs in two dual-polarized antennas over available STBCs for four single-polarized antennas. Linear and decoupled decoding of two quasi-orthogonal designs is shown, which has failed to exit previously. In addition, a QOD for dual-polarized antenna configuration using quaternionic channel model shows a 3 dB gain at in comparison to the same code evaluated for complex representation of the quaternionic channel. This gain is further enhanced when the received diversity for these the cases is matched i.e., . The code using the quaternionic channel model shows a further 13 dB improvement at BER.

Single split-ring resonator loaded self-decoupled dual-polarized MIMO antenna for mid-band 5G and C-band applications

This paper presents the design and development of a dual-band and dual-polarized two-port multiple-input-multiple-output (MIMO) antenna for mid-band 5G (3.4–3.6 GHz), and C-band (4–8 GHz) applications. The antenna design is very simple and it mainly consists of a circular-shaped single split-ring resonator on the top side of the substrate which is coupled with the microstrip line feed line. The bottom side is comprised of a rectangular-shaped defected ground structure. Due to this dual-band response is obtained and the first band shows linear polarization and the second band provides circular polarization. The entire dimensions of the intended two-port MIMO antenna are 46 mm × 21 mm × 1.6 mm. The antenna measured results offer a wider impedance bandwidth (IBW) of 20.22% and 44.07% for the two bands centered at 3.54 GHz and 6.33 GHz respectively. Also, the proposed MIMO antenna shows minimum isolation of 15 dB for the two frequency bands with a smaller edge-to-edge spacing of 4 mm (0.04λ0) between the two antenna elements. Moreover, the second band provides an axial ratio bandwidth of 3.97% centered at 6.78 GHz. The antenna shows excellent IBW, good isolation between the single antenna elements without the use of any decoupling mechanism, better antenna gain, and improved envelope correlation coefficient by maintaining smaller antenna size compared to similar types of existing two-port MIMO antennas in literature.

Some limitations of evaluating dual-polarized MIMO channel capacity

This article discusses possible bandwidth limitations of a radio access channel using MIMO technology with polarization-orthogonal channels, or dual polarization channels. The main attention is paid to the presence of cross-polarization isolation between channels, or cross-polarization relation, or Cross Polar Discrimination. The indicated ratio is determined mainly by the design features of the antennas. It is proposed to choose antennas with the minimum required values of cross-polarization ratio, which limit a given channel bandwidth.

Triple band MIMO dielectric resonator antenna for LTE applications

A triple band dual-polarized MIMO square dielectric resonator antenna (DRA) for fourth generation (4G) and fifth generation (5G) is proposed and analyzed in this paper. It covers LTE band 9/24 (1.63–1.84) GHz at lower frequency, LTE band 38/41 (2.43–2.71) GHz at middle frequency and LTE band 48/52 (3.27–3.75) GHz at higher frequency. The aperture coupling feeding mechanism techniques such as position of slot/feeding and L-monopole feeding have been explored to obtain triple band operation by exciting TE1δ1 (1.8 GHz), TE2δ1 (2.6 GHz) and TE44δ (3.6 GHz) radiating modes inside the DRA respectively. The proposed MIMO antenna provide impedance bandwidth of 12% at 1.7 GHz, 10.89% at 2.6 GHz and 13.68% at 3.6 GHz. Measured antenna gain obtained at 1.7 GHz is 5.5 dBi, at 2.6 GHz is 5.9 dBi and at 3.6 GHz is 6.9 dBi. Obtained envelope correlation coefficient (ECC) is less than 0.02, and the diversity gain is about 10 dB at the desired frequency band.

PERFORMANCE IMPROVEMENT OF THE BASE STATION ANTENNA BY USING MIMO IN MOBILE COMMUNICATION SYSTEM

This paper presents a design of base station antenna with high performance dual-polarized network sites and 4X4 MIMO Sector Antenna subscriber sites with sturdy constructions for micro-base-station applications. In this research the proposed one is design dual-polarized network sites are 5.25-5.85 GHZ, 2-FT (0.6M) height for point to point (PTP) link and point to multi point (PMP) link ePMP 4x4 MU-MIMO Sector Antenna for subscriber module at ePMP 3000, 5.8 GHz (5825 to 5875 MHz) Access Point RF frequency band for SU-MIMO 4X4 MIMO mode of transmission. Those frequencies used is the fifth generation (5G) mobile network planning and it improves the performance of the network in terms of coverage and capacity by using 4X4 MIMO antennas for indoor propagation model. Measured that the results shows the antenna has a 45MHz RF channel bandwidth with Antenna Gain is 28.58 dBi, port Free Space Path Loss is more than 117.53 dB and Performance 99.9995 % for 10.0 Mbps. This can be utilized for broadband base station in the cutting edge wireless correspondence framework. The Link Planner has been used to simulate network coverage and throughput performance of 4X4 MIMO antenna configurations of the deployed networks. The average simulated throughput per sector of 4X4 MIMO configuration was seen to be better than the 2X2 MIMO configuration.

熊本・人吉地区における偏波 MIMO-超多値 OFDM地上伝送実験 －多地点測定による所要電界強度の測定

熊本・人吉地区における偏波 MIMO-超多値 OFDM地上伝送実験 －多地点測定による所要電界強度の測定

Design of compact dual-polarized multiband MIMO antenna using near-field for IoT

This paper presents the integration of the unlicensed ultra-wideband (UWB) with the existing bands like the 1.9 GHz long‐term‐evolution (LTE) band and 2.4 GHz industrial scientific and medical (ISM) band to cater for the diverse need of the upcoming internet of things (IoT) technology. The designed compact triband antenna has a dimension of 33 × 18 mm2 (i.e. 0.2λ0 × 0.11λ0, where λ0 is calculated at 1.89 GHz in the free space). This antenna provides high-quality factor (Q) and narrow-band impedance matching at the 1.9 and 2.4 GHz bands with about 2.9% and 4.7% bandwidth respectively, which is sufficient for those IoT applications, which are supposed to support low data rate communication. Further, the triband antenna is found to be effective for IoT as the hosting effect is within the tolerable range. Finally, multiband polarization diversity antenna is designed having a size of only 33 × 57.25 mm2 (0.2λ0 × 0.36λ0) to combat the depolarization effect of signals in the indoor environment. Near-field simulations are carried out to determine the best position/orientation of MIMO elements in order to improve port-to-port isolation and envelope-correlation-coefficient (ECC). The minimum isolation and maximum ECC are found to be 14.2 dB and 0.0471, respectively across all the operating frequency bands.

Metasurface-Based Dual Polarized MIMO Antenna for 5G Smartphones Using CMA

This paper exhibits a low profile dual-polarized MIMO antenna with high isolation to meet the requirements of 5G smartphones. The integration between a vertically polarized slot and a horizontally polarized slot is investigated and applied for 28 GHz dual-polarized smartphone antenna. The antenna is combined with metasurface (MTS) to achieve high gain and more directivity. In order to design the metasurface, the characteristic mode analysis is used to investigate the performance of MTS at 28 GHz. The proposed antenna achieves high isolation coefficients better than 40 dB and cross polarization lower than -40 dB from simulated and measured results. The isolation between elements is achieved without any additional decoupling techniques. The proposed MTS slot antenna operates with 4 GHz bandwidth (26-30 GHz) with a realized gain of 11 dBi and efficiency of 90%. Four antennas (with eight ports) are positioned orthogonally at the corners of the mobile PCB to serve MIMO for 5G applications. The effect of MIMO antenna on the human is taken into consideration in power density term. Furthermore, the housing and components of smartphones are taken into our consideration in this paper.

Mutual Coupling Reduction of ±45° Dual-Polarized Closely Spaced MIMO Antenna by Topology Optimization

A hybrid topology optimization (HTO) method is adopted to reduce the mutual coupling of a ±45° dual-polarized closely spaced MIMO antenna. In order to shorten the optimization time, only the isolation structure region of the two-element MIMO antenna is selected for optimization. More importantly, by exploiting the symmetry of both the MIMO antenna and the isolation structure, only a quarter of the isolation structure needs to be optimized to achieve good antenna performance. In this way, not only the optimization variables, but also the optimization sub-objectives are greatly reduced, and the optimization time is further diminished. The performance of the dual-polarized MIMO antenna with the optimized isolation structure (OIS) is validated by both simulation and measurement. The OIS resonates in both polarizations, thus lowering the mutual coupling between co-polarization ports ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert S_{31}\vert $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert S_{42}\vert$ </tex-math></inline-formula> ) and between cross-polarization ports ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert S_{41}\vert $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert S_{32}\vert$ </tex-math></inline-formula> ) simultaneously. With the center distance of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.35\lambda _{0}$ </tex-math></inline-formula> , the measured mutual coupling between different ports are reduced by 6~11 dB within the 10-dB impedance bandwidth (Reflection coefficients < −10 dB) by adding the OIS, and the highest mutual coupling between different ports is reduced from −15 to −21 dB. Besides, the antenna maintains a low profile ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.026\lambda _{0}$ </tex-math></inline-formula> ), low cross-polarization and excellent radiation pattern performance.

Tensor-Based Channel Estimation for Dual-Polarized Massive MIMO Systems

The 3GPP suggests to combine dual polarized (DP) antenna arrays with the double directional (DD) channel model for downlink channel estimation. This combination strikes a good balance between high-capacity communications and parsimonious channel modeling, and also brings limited feedback schemes for downlink channel state information within reach---since such channel can be fully characterized by several key parameters. However, most existing channel estimation work under the DD model has not yet considered DP arrays, perhaps because of the complex array manifold and the resulting difficulty in algorithm design. In this paper, we first reveal that the DD channel with DP arrays at the transmitter and receiver can be naturally modeled as a low-rank tensor, and thus the key parameters of the channel can be effectively estimated via tensor decomposition algorithms. On the theory side, we show that the DD-DP parameters are identifiable under very mild conditions, by leveraging identifiability of low-rank tensors. Furthermore, a compressed tensor decomposition algorithm is developed for alleviating the downlink training overhead. We show that, by using judiciously designed pilot structure, the channel parameters are still guaranteed to be identified via the compressed tensor decomposition formulation even when the size of the pilot sequence is much smaller than what is needed for conventional channel identification methods, such as linear least squares and matched filtering. Numerical simulations are presented to showcase the effectiveness of the proposed methods.

Multiple Scattering Modeling for Dual-Polarized MIMO Land Mobile Satellite Channels

This communication investigates the validity of application of a multiple-scattering model to a dual-polarized multiple-input-multiple-output land mobile satellite (LMS) channel based on a measurement campaign. Two LMS link scenarios in an urban pedestrian environment are examined. In the first one, the transmitter was located at the top of a tall building and in the second one, on an airship. The third-order scattering model is utilized to statistically characterize the measured channels, and the results reveal that the model provides an excellent fit to the LMS composite fading amplitude in the line-of-sight (LOS) and non-LOS scenarios. For this generic radio channel, asymptotic expressions for the theoretical probability density function and the cumulative distribution function are derived. The comparison of the third-order scattering model with existing LMS ones showed that it provides better overall accuracy together with a physical interpretation of the propagation mechanisms involved.

Performance Analysis of MRT-Based Dual-Polarized Massive MIMO System with Space-Polarization Division Multiple Access

Performance Analysis of MRT-Based Dual-Polarized Massive MIMO System with Space-Polarization Division Multiple Access

Reconfigurable Hybrid Beamforming for Dual-Polarized mmWave MIMO Channels: Stochastic Channel Modeling and Architectural Adaptation Methods

A reconfigurable hybrid beamforming (HBF) system is presented to dynamically exploit the channel diversities and antenna array directivity in millimeter wave (mmWave) channels. To develop an effective method for HBF architecture adaptation in wideband mmWave channels, the performance of an architecture is evaluated based on its average frequency-domain channel capacity. According to our analysis and simulations, the spatial covariance of the frequency-domain channels of using HBF can still be approximately modeled in a Kronecker form. Furthermore, beamforming directivity and channel spatial diversity have different advantages on capacity improvement in different transceiving conditions. Based on the results of channel modeling, system analysis, and simulations, a reconfigurable HBF architecture is thus proposed to enable flexible adjustments of the active subarrays, the antennas and polarizations of each subarray, and the active analog front-end and radio frequency chains linked to the active subarrays. A training procedure is meanwhile developed for the HBF system to learn proper architectures according to the system constraints, the channel statistics, the baseband precoder structure, and the channel capacity between the transmitter and the receiver. Compared with a fixed HBF system, such a reconfigurable system provides 3–15-dB power gains in channel capacity under various simulated channel conditions.

An Efficient CSI Feedback Scheme for Dual-Polarized Massive MIMO

As an effective solution to the tradeoff between array size and the number of antenna elements, dual-polarization antenna is widely utilized in massive MIMO systems. However, the existing channel state information (CSI) feedback schemes are not suitable for dual-polarized massive MIMO as they ignore the polarization leakage between the polarization directions, causing significant performance degradation. To facilitate accurate channel acquisition, this paper proposes a practical channel model for dual-polarized massive MIMO by taking polarization leakage into consideration. The model formulates the channel as the sum of two components, i.e., the ideal polarization channel and the polarization leakage channel between the polarization directions. Based on the channel model, the eigenvector structures of both the ideal polarization channel and the polarization leakage channel are analyzed. Moreover, two novel CSI feedback schemes are also designed, i.e., explicit feedback scheme (EFS) and implicit feedback scheme (IFS). In EFS, the parameters determining the eigenvectors of the two channels are fed back explicitly, while the two channels are fed back using predetermined codebook in IFS. Extensive link level and system level simulations are conducted to validate the performance of the proposed schemes and the results show that they significantly outperform the existing CSI feedback schemes.

Two-Dimensional AoD and AoA Acquisition for Wideband Millimeter-Wave Systems With Dual-Polarized MIMO

In this paper, a novel two-dimensional super-resolution angle-of-departure (AoD) and angle-of-arrival (AoA) estimation technique is proposed for wideband millimeter-wave multiple-input multiple-output systems with dual-polarized antenna elements. The key ingredient of the proposed method is the custom designed beam pairs, from which there exists an invertible function of the AoD/AoA. A new multi-layer reference signal structure is developed for the proposed method to facilitate angle estimation for wideband channels with dual-polarized antenna elements. To reduce feedback in closed-loop frequency division duplexing systems, a novel differential feedback strategy is proposed to feedback the estimated angle pairs. Numerical results demonstrate that good azimuth/elevation AoD and AoA estimation performance can be achieved under different levels of signal-to-noise ratio, channel conditions, and antenna array configurations.

Investigations on Dual Slant Polarized Cavity-Backed Massive MIMO Antenna Panel With Beamforming

A cavity-backed dual slant polarized and low mutual coupling antenna array panel with frequency band from 4.9 to 6 GHz is analyzed and realized for the MIMO antenna 5G applications. The beamforming capability of this array is also explored. The printed cross dipoles fed with balun and enclosed in a cavity are used as radiating elements. The two cross dipoles are placed at an angle of 45° and 135° giving slant polarizations. A $4 \times 4$ subarray of dimension $2.8\lambda \times 2.8\lambda \times 0.26\lambda $ where $\lambda $ is free space wavelength at 6 GHz is designed, fabricated, and experimentally verified. It shows good impedance matching, port isolation, envelope correlation coefficient, and radiation characteristics which are desired for MIMO applications. Beamforming capability in the digital domain is verified using the Keysight SystemVue simulation tool for both $4 \times 4$ and $16\times 16$ panel arrays which employ measured 3-D embedded element radiation pattern data of the fabricated $4 \times 4$ subarray. Four simultaneous beams using digital beamforming approach are also presented for the $16 \times 16$ array for multiuser environment base station antenna applications.