Fundamental Mobile Transmission Trial of Wideband 5G NR Signal at Sub-THz Band in Road Environment

This paper presents a world-first outdoor mobile transmission trial of 5G new radio (NR)-compliant signals with a nearly 1 GHz bandwidth at a sub-terahertz (sub-THz) band. As experimental equipment, a recently developed software-defined radio platform is used to transmit a 5G NR-compliant QPSK-orthogonal frequency division multiple access (OFDMA) signal, where the subcarrier spacing is set to 960 kHz with a large number of physical resource blocks to achieve a 920 MHz bandwidth. We conduct a field trial in a line-of-sight mobile scenario by placing the transmitter (TX) at a height of 6 m and moving the receiver (RX) in a straight road environment involving an intersection. The trial demonstrates excellent transmission characteristics, where successful reception is achieved in the entire road with a 200 m length with a carrier data rate of 1.7 Gbit/s without an accurate beam alignment from/to the TX to/from RX; instead, only two types of down-tilt angles are required in the TX beam. This result not only serves as a benchmark to assess the coverage area of sub-THz 5G NR but also sheds light on a novel system design of sub-THz communications for vehicle-related mobile environments without strict beam tracking.