Millimeter Wave Channel Measurements in an Intra-Wagon Environment

© 2019 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works."[EN] In this correspondence, useful measurement results of the propagation channel characteristics in an intra-wagon environment at millimeter wave (mmWave) frequencies are presented. The measurements were collected inside an underground convoy from 25 to 40 GHz in the frequency domain. A broadband radio over fiber (RoF) link was used in order to avoid the high losses introduced by cables at these frequencies, thus allowing long distances between the transmitter and receiver antennas. Values of the path loss exponent and delay spread are reported at the potential 26, 28 and 38 GHz bands to deploy the future fifth-generation (5G) systems. These results allow us to have a better knowledge of the path loss and time dispersion characteristics of the propagation channel in this particular environment, characterized by rich-scattering with long delays.This work was supported by the Ministerio de Economia, Industria y Competitividad of the Spanish Government under the National Projects TEC2016-78028-C3-2-P and TEC2017-86779-C2-2-R, through the Agencia Estatal de Investigacion (AEI) and the Fondo Europeo deDesarrollo Regional (FEDER). The review of this article was coordinated by Prof. J. F. Paris. The authors would like to thank the staff of FGV who have facilitated the realization of the measurements campaing, in particular J. Iserte Villalba and F. M. Brox López.Rubio Arjona, L.; Rodrigo Peñarrocha, VM.; Molina-García-Pardo, JM.; Juan Llacer, L.; Pascual Garcia, J.; Reig, J.; Sanchis Borrás, C. (2019). Millimeter Wave Channel Measurements in an Intra-Wagon Environment. IEEE Transactions on Vehicular Technology. 68(12):12427-12431. https://doi.org/10.1109/TVT.2019.2947205S1242712431681

Millimeter Wave MISO-OFDM Transmissions in an Intra-Wagon Environment

[EN] In this paper, the maximum achievable throughput is analyzed in the intra-wagon channel when multiple-input single-output (MISO) and orthogonal frequency division multiplexing (OFDM), MISO-OFDM, techniques are used. This analysis is performed from real wideband propagation channel measurements at 28 and 37 GHz, two potential frequency bands to deploy the future fifth-generation (5G) wireless communications networks. Four different scenarios in terms of the access point (AP) and user equipment (UE) positions inside the wagon have been considered, using 4 and 8 antennas at the AP. The performance of both quasi-orthogonal space-time block code (QSTBC), combined with Hadamard matrices, and transmit beamforming techniques is studied and evaluated from simulation results. The simulation results take into account the signal-to-noise ratio (SNR) and the antenna correlation for each antenna array configuration at the AP. These results provide useful insight to better understand the intra-wagon channel properties and deploy the future 5G wireless networks in this particular scenario at mmWave frequencies, where high-data-rates are expected to support different types of digital applications.This work was supported in part by the Ministerio de Economia y Competitividad MINECO, Spain, under Grant TEC2016-78028C3-2-P and Grant TEC2017-86779-C2-2-R and in part by the European FEDER Funds.Sanchis Borrás, C.; Molina-García-Pardo, J.; Rubio Arjona, L.; Pascual-García, J.; Rodrigo Peñarrocha, VM.; Juan Llacer, L.; Reig, J. (2021). Millimeter Wave MISO-OFDM Transmissions in an Intra-Wagon Environment. IEEE Transactions on Intelligent Transportation Systems. 22(8):4899-4908. https://doi.org/10.1109/TITS.2020.2983028S4899490822

Terahertz Wireless Channels: A Holistic Survey on Measurement, Modeling, and Analysis

Terahertz (0.1-10 THz) communications are envisioned as a key technology for sixth generation (6G) wireless systems. The study of underlying THz wireless propagation channels provides the foundations for the development of reliable THz communication systems and their applications. This article provides a comprehensive overview of the study of THz wireless channels. First, the three most popular THz channel measurement methodologies, namely, frequency-domain channel measurement based on a vector network analyzer (VNA), time-domain channel measurement based on sliding correlation, and time-domain channel measurement based on THz pulses from time-domain spectroscopy (THz-TDS), are introduced and compared. Current channel measurement systems and measurement campaigns are reviewed. Then, existing channel modeling methodologies are categorized into deterministic, stochastic, and hybrid approaches. State-of-the-art THz channel models are analyzed, and the channel simulators that are based on them are introduced. Next, an in-depth review of channel characteristics in the THz band is presented. Finally, open problems and future research directions for research studies on THz wireless channels for 6G are elaborated.Comment: to appear in IEEE Communications Surveys and Tutorial

Directive mmWave radio channel modeling in a ship hull

Wireless connectivity has been realized for multiple environments and different frequency bands. However, little research exists about mmWave communication in industrial environments. This paper presents the 60 GHz double-directional radio channel for mmWave communication in a ship hull for Line-of-Sight (LOS) and non-Line-of-Sight (NLOS) conditions. We performed channel measurements using the Terragraph channel sounder at different locations in the ship hull and fitted LOS path loss to a one-slope path loss model. Path loss and root-mean-square delay spread of the LOS path is compared to the reflected path with lowest path loss. NLOS communication via this first-order reflected path is modeled by calculating the path distance and determining the reflection loss. The reflection losses have a considerable contribution to the signal attenuation of the reflected path. The channel models are implemented in an indoor coverage prediction tool, which was extended with a ray launching algorithm and validated by comparison with an analytical electromagnetic solver. The results show that the mmWave radio channel allows high-throughput communication within a ship hull compartment, even when no LOS path between the transmitter and receiver is present.This work was executed within the Internet-of-Shipping (IoS) research project, co-financed by imec with support from Flanders Innovation & Entrepreneurship. The channel sounder has been granted as part of the Channel Sounder Program of the Telecom Infra Project (TIP). The authors would like to thank Ivan Renette and Franck Ntibashirakandi from Exmar Shipmanagement to facilitate the measurement campaign.Peer ReviewedPostprint (author's final draft

QoS-aware User Association and Transmission Scheduling for Millimeter-Wave Train-ground Communications

With the development of wireless communication, people have put forward higher requirements for train-ground communications in the high-speed railway (HSR) scenarios. With the help of mobile relays (MRs) installed on the roof of the train, the application of Millimeter-Wave (mm-wave) communication which has rich spectrum resources to the train-ground communication system can realize high data rate, so as to meet users' increasing demand for broad-band multimedia access. Also, full-duplex (FD) technology can theoretically double the spectral efficiency. In this paper, we formulate the user association and transmission scheduling problem in the mm-wave train-ground communication system with MR operating in the FD mode as a nonlinear programming problem. In order to maximize the system throughput and the number of users meeting quality of service (QoS) requirements, we propose an algorithm based on coalition game to solve the challenging NP-hard problem, and also prove the convergence and Nash-stable structure of the proposed algorithm. Extensive simulation results demonstrate that the proposed coalition game based algorithm can effectively improve the system throughput and meet the QoS requirements of as many users as possible, so that the communication system has a certain QoS awareness.Comment: 14 page