Fundamental Field Transmission Trials of Wideband 5G NR Signals for Sub-THz V2I Communication Using a Software Defined Radio Platform

Abstract

Targeting vehicular-to-infrastructure (V2I) communication systems in the sub-terahertz (sub-THz) band, this article presents fundamental proof-of-concept field experiments of wideband 5G new radio (NR) signal transmission under vehicle-induced mobility and evaluates a coverage area in the form of a straight-line region stretching along a road. Sub-THz bands offer abundant bandwidth, enabling higher data rates than millimeter-wave bands, which is a key enabler for sharing various sensor modalities, such as radar and lidar data, among autonomous vehicles to construct a high-definition map. Field transmission trials were conducted to obtain practical insights into the feasibility and design guidelines of such sub-THz V2I systems, using a recently developed software-defined radio platform tailored for mobile scenarios and customized for wideband transmission in the sub-THz band. Specifically, 5G NR signals at 105.8 GHz with a bandwidth of 920 MHz were transmitted along a straight road to a single vehicle in a line-of-sight (LOS) condition under vehicle-induced mobility up to 30 km/h. The field trials demonstrated that successful transmission at a carrier data rate of 1.7 Gbit/s and effective information data rate of 650 Mbit/s was achieved up to 300 m ahead of an intersection using a single fixed transmitter and receiver beam with a 10$^\circ $ half-power beamwidth (HPBW). The coverage lengths on a straight road, where decoding the 5G NR signals was stable, were evaluated to be up to 200 m. Furthermore, the coverage length was shown to be controllable by adjusting the down-tilt angle of transmitter beam. These experimental results provided valuable insights into sub-THz V2I communication systems, demonstrating that straight single-lane roads can be covered for hundreds of meters when the transmitter and receiver beams with 10$^\circ $ HPBW are horizontally aligned toward each other under LOS conditions, and a single receiver vehicle travels at a speed up to 30 km/h.