Workshops and Tutorials

Workshop on Emerging Terahertz Technologies for Future Wireless Systems

Session FWS3-S1

Keynotes and Industry Activity

Conference
9:00 AM — 10:30 AM KST
Local
May 24 Sun, 7:00 PM — 8:30 PM CDT

100-300GHz wireless: applications, systems, ICs, and transistors

Mark Rodwell (University of California, Santa Barbara, USA)

4
This talk does not have an abstract.

Channel measurements and modeling for 0.1-0.5 THz

Andy Molisch (University of Southern California, USA)

1
This talk does not have an abstract.

Design Considerations for Terahertz Wireless Communication Systems

Jeongho Jeon, Khurram Muhammad, Joonyoung Cho and Gary Xu (Samsung Research America, USA); Ilju Na (Samsung Electronics, Korea (South)); Jianzhong Zhang (Samsung, USA)

1
Current trends in the evolution of mobile communication systems address the data throughput demand by expanding to higher frequency bands as the usable spectrum in lower frequency bands is almost depleted. As the Third Generation Partnership Project (3GPP) specified the support of mmWave band operations for 5G New Radio (NR), it is expected that the next generation mobile communication system, namely 6G, will consider even higher terahertz (THz) spectrum with wider bandwidth to continue supporting exponential growth of data rates. However, the question remains how to deal with various technical challenges stemming from harsh THz radio propagation characteristics as well as the feasibility of radio frequency (RF) components, which we try to answer in this work. To this end, it is our goal to demonstrate the promise of THz spectrum for the next generation communication systems.

From sub-Terahertz to Terahertz: challenges and design considerations

Daewon Lee (Intel Corporation, USA); Alexei Davydov (Intel Corp., Russia); Bishwarup Mondal (Intel, USA); Gang Xiong (Intel Corporation, USA); Gregory Morozov (Intel Corp., Russia); Jiwoo Kim (Intel Corporation, USA)

1
NR Rel-15 physical layer specifications (released on December 2018) by 3GPP targeting IMT 2020 can support deployments in frequency ranges 410 MHz - 7.125 GHz and 24.25 GHz - 52.6 GHz. The support of higher frequency bands with large chunks of contiguous spectrum was deemed essential to fulfilling IMT 2020 vision of 20 Gbps peak data-rate in realistic deployment scenarios. It is also expected that global IMT traffic will grow 10 - 100 times from 2020 to 2030 and in order to support such growth Terahertz spectrum provides an attractive choice. In this paper, we describe the challenges in power amplifier, analog-to-digital design and impairments from phase noise that is expected in such regime. Considering such impairments, we show that realistic power amplifier backoff ratios are strongly correlated with the choice of a waveform. We provide results to show that phase noise could be mitigated by an appropriate choice of waveform and reference signals for compensation while a judicious choice of frame structure can be used to maintain reasonable scheduling and processing complexity. In order to maintain simultaneous connectivity to multiple base-stations resulting in large timing differences at the receiver, the isolation between panels at the user equipment can be successfully used.

Session Chair

Juho Lee (Samsung Electronics. Co., Ltd, Korea)

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Session FWS3-S2

Measurements, RFIC, and Optical Methods

Conference
10:45 AM — 12:15 PM KST
Local
May 24 Sun, 8:45 PM — 10:15 PM CDT

Measurement of Directionally Resolved Radar Cross Section of Human Body for 140 and 220 GHz Bands

Naveed Ahmed Abbasi and Andreas Molisch (University of Southern California, USA); Charlie Zhang (Samsung Telecommunications America, USA)

0
To explore the eventual deployment of communication systems in Terahertz (THz) band (0.1-10 THz) frequencies, extensive measurements of various aspects of the channels are essential. Humans form an integral part of any communication environment, therefore, it is of interest to explore the impact of a human body on the propagation characteristics in any given channel. This is particularly relevant because at higher frequencies, such as those in the THz band, human bodies are significantly larger than a wavelength and can thus constitute effective scatterers. Motivated by this, we conducted measurements of the radar cross section for the human body in the 140 and 220 GHz bands and show how the reflectivity of the human body varies as a function of both the angle of incidence and the angle of observation. Our results show an average scattering cross sections on the order of -15 dBsm; with variations as a function of the angle of incidence of less than +/- 5 dBsm.

LOS channel response measurement at 300-GHz for short-range wireless communication

Ho-Jin Song (POSTECH, Korea (South))

0
In the last couple of decades, solid-state device technologies, particularly solid-state electronics, have been greatly advanced and investigated for possible adoption in various terahertz (THz) applications. Particularly, there have been several successful experimental demonstrations of multitens Gbps wireless communications at above 100 GHz. Recently, we have demonstrated the 20-Gbps KIOSK instant data downloading system operating at 300 GHz with InP-based transceivers. From the work, we have learned, better understanding on the wave propagation characteristics at these frequencies is needed to improve the reliability of the data transmission. In this report, we present early investigation results on LOS THz channel responses for short range wireless communications.

A 140GHz Two-Channel CMOS Transmitter using Low-Cost Packaging Technologies

Arda Simsek (University of California Santa Barbara, USA); Ahmed S. H. Ahmed (UCSB, USA); Ali A Farid (University of California, Santa Barbara, USA); Utku Solyu (UCSB, USA); Mark J W Rodwell (University of California, Santa Barbara, USA)

0
We report a 2-channel 140GHz transmitter using low-cost antenna and packaging technologies. The arrays use 8-element series-fed linear microstrip patch antenna arrays fabricated on an Isola Astra MT77 printed circuit board (PCB) . Two such antennas, connected to a CMOS multi-channel transmitter IC with 2dBm output power form the two-channel transmitter. At 145GHz, the measured transmitter EIRP is 14-15dBm in single-channel operation and 19-20dBm in two-channel operation. QPSK transmission experiments over 25 cm distance show open eye patterns at 10.0 Gb/s rates.

Providing 5G Coverage Using Optical Methods for Terahertz Frequencies

Suresh Singh (Portland State University, USA)

1
This paper studies the propagation of terahertz signals (100 GHz to 2THz) when using convex lenses. The terahertz band has a great deal of unexploited spectrum and therefore is ideally suited to provide ultra-high data rates at short ranges. The paper presents a channel model for terahertz when using convex lenses at the transmitter. The model incorporates channel impairments such as molecular absorption and lens characteristics such as a Gaussian intensity distribution. The model is verified against detailed measurements conducted using a terahertz system. We show that the model is in very close agreement with the measured data.

Session Chair

Juho Lee (Samsung Electronics. Co., Ltd, Korea)

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Session FWS3-S3

Metasurface, Lens, and OAM

Conference
2:00 PM — 3:30 PM KST
Local
May 25 Mon, 12:00 AM — 1:30 AM CDT

Polarization Dependent Beam Steerable Thin Lens Employing Spatial Filter Arrays

Yeong Myeong Park (Seoul National University, Korea (South)); Inseop Yoon (Samsung Electronics, Korea (South)); Jungsuek Oh (Seoul National University, Korea (South))

0
This paper presents thin lens (<λ/10) having differently steered beam as a function of the polarization of the incident waves. This is based on new designs of polarization dependent spatial filter arrays where tunable range of the phase shift for beam narrowing can be acquired independent of the polarization of the incident waves. The proposed lens consists of periodic unit cells that act as bandpass filters. A unique feature of the unit cell is topology asymmetry in respect to two different axes. By properly arranging these unit cells, a thin lens can be designed to achieve steered beam for the desired direction as a function of theta value. It is presented that this lens can steer the beam up to higher than 60 degrees with lens gain of higher than 9dBi. In this paper, the principles of the unit cells and macro design methodologies for the proposed polarization dependent thin lens, and their simulation result are presented.

Metasurface-Enhanced Antenna System for Terahertz Band Wireless Communications

Jaehyun Lee (Samsung Research & Samsung Electronics, Korea (South)); Hyojin Lee (Samsung Research, Korea (South))

0
Next generation communication system is expected to utilize extensive bandwidth including terahertz band by using novel antenna technology enhanced by metasurface.
Metasurface is a planar structure of metamaterial, which can control the direction and amplitude of electromagnetic waves to focus dispersive waves to improve the beamforming gain.
In this paper, we investigate the metasurface lens antenna design considering the physical structure and radiation pattern of antenna and metasurface.
In particular, we modeled the radiation pattern of various antennas including microstrip antenna placed on the focal and non-focal point of metasurface.
It shows that the metasurface designed for phase compensation enhances the beamforming gain of antennas located at non-focal position as well, which implies that the metasurface can be adopted for multiple antenna designs.

Rotman Lens-Fed Antenna for Generating Multiple Orbital Angular Momentum Modes

Zhiya Zhang (Xidian University, China); Bin Yu (Samsung Electronics, China); Dan Wu, Yongyan Mao and Chengbin Zhang (Xidian University, China)

1
A compact multi-layer Rotman lens-fed array antenna which can generate nine orbital angular momentum (OAM) modes is presented in this paper. The proposed antenna consists of a microstrip Rotman lens and a nine-element circular array antenna which utilizes high-gain patch element in order to enhance the gain of OAM beam. A stacked patch loaded with two slots is attached above the patch element to effectively enhance the antenna gains. By employing the Rotman lens as the feed network of the circular array, nine OAM-carrying beams of modes can be produced when different input ports are excited, respectively. 160°-phase-shift on adjacent output ports can be achieved to meet the phase requirement of OAM higher modes. Moreover, the Rotman lens is modified by adjusting the deflection angle of the beam ports and array ports so as to achieve uniform amplitude distribution on the output ports. Hence, the pattern characteristics of OAM beams can be effectively improved by making all the output ports equal in amplitude. The prototype of the antenna is fabricated and measured. Both the simulation and measurement results indicate that nine OAM modes can be generated by using the proposed structure. The proposed antenna can be used in an OAM-based wireless communication system.

Orbital Angular Momentum Multiplexing for a Wireless Backhaul Communication System

EunMi Choi (UNIST, Korea (South))

0
A novel approach for establishing a wireless communication link using orbital angular momentum (OAM) beams in E-band frequency for beyond 5G communication is studied. OAM beams have been generated by converting the high-power Gaussian beam generated from a vacuum electronics device into Laguerre-Gaussian (LG) beams using a meta-material structure to transmit the information signal to a distance of 2 meters. Objective of the system is to prepare a proof-of-concept experimental setup to demonstrate the capability of OAM communication in terms of increase of channel capacity and degree of freedom. In this paper, we focus on the generation of OAM modes by means of novel metamaterial structures in E-band.

Session Chair

Juho Lee (Samsung Electronics. Co., Ltd, Korea)

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Session FWS3-S4

Channel Sounder, Antenna Array, and MIMO

Conference
3:45 PM — 5:15 PM KST
Local
May 25 Mon, 1:45 AM — 3:15 AM CDT

THz Channel Sounding: Design and Validation of a High Performance Channel Sounder at 300 GHz

Mathis Schmieder and Wilhelm Keusgen (Fraunhofer Heinrich Hertz Institute, Germany); Michael Peter (Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, Germany); Sven Wittig (Fraunhofer Heinrich Hertz Institute, Germany); Thomas Merkle, Sandrine Wagner and Michael Kuri (Fraunhofer IAF, Germany); Taro Eichler (Rohde & Schwarz, Germany)

1
In this paper, a novel instrument-based time-domain THz channel sounder for the 300 GHz band is introduced. The performance is characterized by conducted measurements and verified by over-the-air measurements, which confirm the sensitivity and highlight the temporal resolution of the setup. Dynamic range, maximum measurable path loss and phase stability are evaluated. The results show that the performance in terms of dynamic range and maximum measurable path loss is, to the best knowledge of the authors, unprecedented in this frequency range.

Nanoantenna Array Design on Grounded Dielectric Substrate for High Field Enhancement and Absorption

Sangjo Choi (University of Ulsan, Korea (South)); Mohamad Khoirul Anam (University of Ulsan & Indonesian Institute of Sciences (LIPI), Korea (South))

2
Plasmonic nanoantenna can efficiently absorb electromagnetic waves and confine that into a nano-meter scale volume due to localized surface plasmon (LSP). Thus, the antenna design methods used in the microwave band cannot be used directly to the nanoantenna design. In this study, we introduce a nanoantenna array design method for high field enhancement and absorption at the IR range and explain the working principles regarding coupling between the LSP and the scattered field from the antenna element in the array. In the design process, a bowtie antenna mounted on a grounded SiO2 substrate is chosen and the optimum thickness of the substrate and distance between the antennas are determined. The final bowtie nanoantenna array shows an electric field enhancement factor (E/E0) of 223 and an absorption rate of 93%, respectively, at 230 THz. The high field enhancement and the absorption rate from the bowtie nanoantenna array are worth to be investigated to realize an efficient receiver system in wireless nano-link for terahertz and optical communications.

Taylor Expansion Aided Gradient Descent Schemes for IRS-Enabled Terahertz MIMO Systems

Zhi Chen (University of Electronic Science and Technology of China, China); Wenjie Chen (University Of Electronic Science And Technology Of China, China); Xinying Ma, Zhuoxun Li and Yaojia Chi (University of Electronic Science and Technology of China, China); Chong Han (Shanghai Jiao Tong University, China)

2
Terahertz (THz) communication has been regarded as an emerging technology for diverse sixth generation (6G) application scenarios, which possesses large bandwidth and provides ultra-high data transmission up to several terabit per
second (Tbps). With regard to the severe path attenuation of THz waves, the short-distance indoor scenario is an appropriate choice for THz communication. However, the THz signals are readily blocked by the indoor obstacles, leading to a communication interruption. To tackle this issue, an intelligent reflecting surface (IRS) is proposed to control the propagation direction
of THz beam and enhance the coverage performance by smartly adjusting the phase shifts of reflecting elements. For sake of a desired phase shift combination of IRS elements in the IRS assisted THz multiple-input multiple-output (MIMO) system, an efficient Taylor expansion aided gradient descent (TE-GD) scheme is developed by dynamically updating the step size during the iterative process, where the step size is determined by the coefficients of second-order Taylor expansion formulation. Simulation results shows that, in contrast with the exhaustive search method, the developed TE-GD scheme realizes the basically consistent spectral efficiency with ignorable complexity. Moreover, compared with conventional gradient descent (C-GD) with fixed step size, the developed TE-GD scheme achieves 4.3 bps/Hz spectral efficiency improvement and 80.17% complexity reduction.

An Energy-Efficient Hybrid Precoding Based on MPBIL Algorithm for mmWave Massive MIMO Systems

Yang Liu (Institute of Electronic Information Engineering, Inner Mongolia University, China); Lina Hou and Lei Liu (Inner Mongolia University, China); Yinghui Zhang (Institute of Electronic Information Engineering, Inner Mongolia University, China); Minglu Jin (Dalian University of Technology, China)

3
To reduce power consumption while ensuring the spectral efficiency of millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems, we propose an energy-efficient hybrid precoding based on the improved population based incremental learning (PBIL) algorithm which introduced the random mutation (called as MPBIL hybrid precoding). Specifically, the MPBIL hybrid precoding using switches and inverters in analog part, which can greatly reduce energy consumption. Additionally, we utilize the proposed MPBIL algorithm to iteratively search for the best analog beamformer. The number of iterations is greatly reduced because that the search efficiency of the proposed MPBIL algorithm is significantly improved by introducing the random mutation which increase the diversity of the population. As a result, the proposed MPBIL-based hybrid precoding has lower complexity and higher energy efficiency than some other traditional algorithms.

Session Chair

Byonghyo Shim (Seoul National University, Korea)

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