mmWave Wireless Communication Systems Research Articles

3-D printed triple-band metasurface filter based on groove gap waveguide technology

This article proposes a 3-D printed high selectivity triple-band metasurface bandpass filter (BPF) for millimeter-wave applications using groove gap waveguide (GGW) technology. Firstly, the metasurface composed of electromagnetic bandgap elements in GGW technology is designed and analyzed. This configuration effectively mitigates radiation and electromagnetic wave leakage. Subsequently, the multimode split-type topology under the resonances of TE102 and TE201 modes is utilized to realize a triple-band bandpass response with a compact circuit size. Additionally, the TE101 mode considered as an extra energy coupling path is used to introduce more transmission zeros (TZs). Finally, the design prototype is fabricated using 3D printing technology. The measured results are in good agreement with the simulated ones, providing an excellent option for mm-wave wireless communication systems.

3D-Printed Conformal Meta-Lens with Multiple Beam-Shaping Functionalities for Mm-Wave Sensing Applications.

In this paper, a 3D conformal meta-lens designed for manipulating electromagnetic beams via height-to-phase control is proposed. The structure consists of a 40 × 20 array of tunable unit cells fabricated using 3D printing, enabling full 360° phase compensation. A novel automatic synthesizing method (ASM) with an integrated optimization process based on genetic algorithm (GA) is adopted here to create the meta-lens. Simulation using CST Microwave Studio and MATLAB reveals the antenna's beam deflection capability by adjusting phase compensations for each unit cell. Various beam scanning techniques are demonstrated, including single-beam, dual-beam generation, and orbital angular momentum (OAM) beam deflection at different angles of 0°, 10°, 15°, 25°, 30°, and 45°. A 3D-printed prototype of the dual-beam feature has been fabricated and measured for validation purposes, with good agreement between both simulation and measurement results, with small discrepancies due to 3D printing's low resolution and fabrication errors. This meta-lens shows promise for low-cost, high-gain beam deflection in mm-wave wireless communication systems, especially for sensing applications, with potential for wider 2D beam scanning and independent beam deflection enhancements.

Empirical modelling of dust storm path attenuation for 5G mmWave

The rapid evolution of communication technologies, particularly the emergence of 5G mm-wave networks, presents unprecedented challenges, particularly in regions prone to dust and sandstorms. These environmental factors can significantly impact 5G signals by attenuating radio waves, leading to signal degradation. This paper investigates the complex interplay between dust storms and 5G mm-wave wireless communication, offering a novel and comprehensive analysis that extends beyond existing models. Our study investigates into the impact of dust storms on 5G mm-wave wireless communication, specifically focusing on signal attenuations under both non-line of sight (NLOS) and line of sight (LOS) conditions. Through the utilize of the NYUSIM channel simulator and exploration of parameters such as dust particle size, storm duration, and environmental factors, we present a detailed numerical results. In the NLOS scenario, path loss measurements record substantial values, highlighting the significant impact of dust storms across different mm-wave frequencies. Conversely, in the LOS scenario, our findings reveal distinct patterns of path loss and shadow fading, shedding light on the complex interaction between dust storms and signal propagation. This research marks a significant advancement in the field, providing a quantitative foundation for addressing dust-induced attenuation in 5G mm-wave communication. By emphasizing novel research methodologies and innovative ideas, our study contributes to a deeper understanding of the challenges posed by dust storms in 5G mm-wave wireless communication systems, paving the way for more effective mitigation strategies and network optimization techniques.

A Quad-Port Design of a Bow-Tie Shaped Slot Loaded Wideband (24.2–30.8GHz) MIMO Antenna Array for 26/28GHz mm-Wave 5G NR n257/n258/n260 Band Applications

This paper describes a four-port MIMO antenna array design featuring bow-tie-shaped slot-loaded patches with wideband capabilities that cover the frequency range from 24.2[Formula: see text]GHz to 30.8[Formula: see text]GHz. The proposed antenna design is printed on an FR4 substrate and occupies an area of 25[Formula: see text]×[Formula: see text]24[Formula: see text]mm2. The MIMO antenna consists of four antenna arrays that are symmetrically placed in an upper-lower configuration. The bow-tie-shaped slots loaded radiators are separated horizontally by 3.48[Formula: see text]mm and vertically by 5.94[Formula: see text]mm. Each antenna array contains two elements that are separated by a distance of wavelength/4. The suggested MIMO antenna array delivers a high gain of 19.09[Formula: see text]dB at 27.8[Formula: see text]GHz and has a bandwidth of 6.6[Formula: see text]GHz that covers the frequency band of 24.2–30.8[Formula: see text]GHz. The research demonstrates the quality of the proposed MIMO antenna through various diversity parameters such as mutual coupling, port correlation, diversity gain, and data rate that can be transmitted over a communication medium. The simulation results are validated and found to be consistent with the experimental results. The presented antenna covers the entire bandwidth allocated to different regions, including Europe (24.25–27.5[Formula: see text]GHz), Sweden (26.5–27.5[Formula: see text]GHz), USA (27.5–28.35[Formula: see text]GHz), China (24.25–27.5[Formula: see text]GHz), Japan (27.5–28.28[Formula: see text]GHz), and Korea (26.5–29.5[Formula: see text]GHz). The proposed MIMO antenna design could be an excellent option for 26/28[Formula: see text]GHz 5G NR n257, n258, and n260 bands under mm-wave wireless communication systems.

Deep Reinforcement Learning-Based Coordinated Beamforming for mmWave Massive MIMO Vehicular Networks

As a critical enabler for beyond fifth-generation (B5G) technology, millimeter wave (mmWave) beamforming for mmWave has been studied for many years. Multi-input multi-output (MIMO) system, which is the baseline for beamforming operation, rely heavily on multiple antennas to stream data in mmWave wireless communication systems. High-speed mmWave applications face challenges such as blockage and latency overhead. In addition, the efficiency of the mobile systems is severely impacted by the high training overhead required to discover the best beamforming vectors in large antenna array mmWave systems. In order to mitigate the stated challenges, in this paper, we propose a novel deep reinforcement learning (DRL) based coordinated beamforming scheme where multiple base stations serve one mobile station (MS) jointly. The constructed solution then uses a proposed DRL model and predicts the suboptimal beamforming vectors at the base stations (BSs) out of possible beamforming codebook candidates. This solution enables a complete system that facilitates highly mobile mmWave applications with dependable coverage, minimal training overhead, and low latency. Numerical results demonstrate that our proposed algorithm remarkably increases the achievable sum rate capacity for the highly mobile mmWave massive MIMO scenario while ensuring low training and latency overhead.

Towards Practical Path Loss Predictions in Indoor Corridors Considering 5G mmWave Three-Dimensional Measurements

Theoretical and empirical foundations of how radio waves behave in practical wireless channels need to be fully revisited for millimeter-wave (mmWave) frequencies so that fifth-generation (5G) technologies may be successful. Kriging is an outstanding geostatistal interpolation technique that employs variography to understand the spatial variability of known samples at specific locations to predict unmeasured samples, based on the fact that there is an implied connection between the measured value and its location in space. The research we here report is aimed at validating the improvement in predictions when this tool is included for mmWave frequency path loss modeling in a long indoor corridor with break. In order to quantify the accuracy of the proposed methodology, it is compared with a well-established procedure described in the literature. Extensive path-loss measurements were collected through specialized narrowband sounders at 28 and 60 GHz. Spatially averaged power measurements using omnidirectional and directive antennas at different heights provided the empirical basis for the three-dimensional Kriging-aided model. It was found that this method significantly improves the accuracy as it considers all the singularities and site-associated features that are implicit in measured samples. This is important to obtain a reliable path loss model for planning and deployment of mmWave wireless communication systems in indoor scenarios.

Accurate and broadband manipulations of harmonic amplitudes and phases to reach 256 QAM millimeter-wave wireless communications by time-domain digital coding metasurface

We propose a theoretical mechanism and new coding strategy to realize extremely accurate manipulations of nonlinear electromagnetic harmonics in ultrawide frequency band based on a time-domain digital coding metasurface (TDCM). Using the proposed mechanism and coding strategy, we design and fabricate a millimeter-wave (mmWave) TDCM, which is composed of reprogrammable meta-atoms embedded with positive-intrinsic-negative diodes. By controlling the duty ratios and time delays of the digital coding sequences loaded on a TDCM, experimental results show that both amplitudes and phases of different harmonics can be engineered at will simultaneously and precisely in broad frequency band from 22 to 33 GHz, even when the coding states are imperfect, which is in good agreement with theoretical calculations. Based on the fabricated high-performance TDCM, we further propose and experimentally realize a large-capacity mmWave wireless communication system, where 256 quadrature amplitude modulation, along with other schemes, is demonstrated. The new wireless communication system has a much simpler architecture than the currently used mmWave wireless systems, and hence can significantly reduce the hardware cost. We believe that the proposed method and system architecture can find vast application in future mmWave and terahertz-wave wireless communication and radar systems.

A Millimeter-Wave Triple-Band SIW Antenna With Dual-Sense Circular Polarization

A millimeter-wave (mmWave) triple-band substrate integrated waveguide (SIW) antenna with dual-sense circular polarization (CP) etched on a single substrate is proposed. A SIW cavity operating in TM210 mode is carved with a circular slot to realize upper band radiation. A circular patch is placed in the circular slot for lower band radiation. Middle band radiation is realized by the coupling between the SIW cavity and circular patch. By introducing asymmetry on both circular slot and circular patch, CP is obtained at two bands. The polarization states of the three bands are right-hand circular polarization (RHCP), linear polarization (LP), and left-hand circular polarization (LHCP). Three pairs of vias are introduced in the SIW transmission line to realize good impedance matching for the three bands. A prototype is fabricated and its performances are evaluated. Simulated and measured results agree very well. Small frequency ratios are achieved and each band can be adjusted flexibly. The proposed antenna has characteristics of low-profile and simple structure which will make it easy to be applied in future mmWave wireless communication systems.

Lens Antenna Subarrays in mmWave Hybrid MIMO Systems

Data rate and energy efficiency performance of mmWave wireless communication systems consisting of a new lens antenna subarray (LAS) based hybrid multiple input multiple output (MIMO) architecture is investigated. The LAS architecture degenerates into traditional hybrid MIMO architecture (TA) or single lens antenna array architecture (SLA) when the lens diameter of the subarray is reduced or enlarged, respectively. It is shown that under mmWave channel scattering conditions, LAS architecture operates with a data rate approaching that of TA while significantly exceeding the data rate of the SLA. Due to the reduced hardware complexity and power consumption, LAS architectures operate with a significantly improved energy efficiency. In an example system consisting of 64 and 16 transmitter and receiver antennas with 2 RF chains, it is shown that the LAS architecture operates with $2\times $ energy efficiency and 98% spectrum efficiency. In a larger hybrid MIMO antenna systems, LAS architecture is expected to benefit even more.

Statistical Analysis of Rain at Millimeter Waves in Tropical Area

The high frequencies of millimeter wave (mm-wave) bands have been recognized for the fifth generation (5G) and beyond wireless communication networks. However, the radio propagation channel at high frequencies can be largely influenced by rain attenuation, especially in tropical regions with high rainfall intensity. In this paper, we present the results of rainfall intensity and rain attenuation in tropical regions based on one-year measurement campaign. The measurements were conducted from September 2018 until September 2019 at 21.8 GHz (K-band) and 73.5 GHz (E-band) in Malaysia. The rainfall intensity was collected using three rain gauges installed along a 1.8 km link. The rain attenuation is computed from the difference between the measured minimum received signal level (RSL) during clear sky and rain conditions. The measured rain rate and rain attenuation distributions are then analysed and benchmarked with several previous measurements and well-known prediction models such as the ITU-R P. 530-17. The rainfall rate results showed that the best agreement between the measured rainfall rate in Malaysia and the ITU-R PN.837-1 prediction value for Zone P is up to 0.01% of time (99.99% of time agrees well and only disagrees for 0.01% of time). For the E-band, the maximum measured rain attenuation exceeding 0.03% of the year is around 40.1 and 20 dB for 1.8 and 0.3 km links, respectively, at the maximum rain rate of 108 mm/h. For the K-band, the maximum rain attenuation exceeding 0.01% of the year is around 31 dB for the 1.8 km link. Finally, the rain rates exceeding 108 and 180 mm/h at 73.5 and 21.8 GHz, respectively, along the 1.8 km path caused an outage on our measurement setup. The rain rate of 193 mm/h and above caused an outage for the 0.3 km E-band link. The experimental data as well as the presented data analysis can be utilized for efficient planning and deployments of mm-wave wireless communication systems in tropical regions.

Performance Evaluation and Analysis of Millimeter Wave Communication System

Millimeter wave (mmWave) communication leverages the large bandwidth potentially available at mmWave frequency band to provide high data rate, and is proved to be a promising technology for future wireless communication. Prior work mainly investigates the partial performance instead of the overall mmWave communication system design and performance evaluation. Different from the existing work, in this paper, we evaluate the link-level performance of mmWave wireless communication system operating on a 39.5-GHz frequency band. We first propose a new transmission scheme based on orthogonal frequency division multiplexing mechanism for mmWave communication by taking the characteristics of mmWave into account. We design a long-term evolution-like frame structure and optimize some key parameters for the mmWave communication system to support higher data rate. Second, according to the designed frame structure, we design a reference signal and a synchronization signal, and develop a synchronization algorithm. Finally, the downlink performance of system information, control information, and user data is evaluated. Numerical results show that the mmWave communication is a promising approach to realize the Gb/s transmission rate.

Automatic Monitor-Based Tuning of an RF Silicon Photonic 1X4 Asymmetric Binary Tree True-Time-Delay Beamforming Network

Photonic beamforming networks are promising candidates to achieve power-efficient transmission in future cellular communication systems. However, sensitivity to process and temperature variations necessitates an automatic calibration solution to enable robust operation. This paper demonstrates fully automatic monitor-based tuning of an integrated optical ring resonator-based 1X4 asymmetric binary tree optical beamforming network (OBFN). The proposed monitor-based tuning algorithm compensates fabrication variations and thermal crosstalk by controlling micro-heaters individually using information from electrical monitors. This algorithm is demonstrated on an OBFN that operates at 30 GHz with 2 GHz bandwidth and is fabricated in a standard silicon photonics foundry process. Successful calibration of the OBFN from a severely degraded initial response to the well-defined group delay responses required for a targeted radiating angle over 60 $^{\circ }$ (−30 $^{\circ }$ to 30 $^{\circ }$ ) in a linear beamforming antenna array is achieved. This fully automatic tuning approach opens the possibility of employing silicon OBFNs in real wideband mm-wave wireless communication systems.