Measurement of Multipath Waves at 160 GHz and 300 GHz in an Indoor Conference Room

For the 6th generation mobile communication system (6G), realization of extremely high-speed communication over 100 Gbps is examined. To achieve the over-100 Gbps communication, one method is using sub-terahertz bands from 100 GHz to 300 GHz that provide ultra-wide bandwidth. However, because of large propagation loss, these bands are suitable for a short-range communication, and indoor environments will be an important scenario. In the indoor environments due to large blocking loss of obstacle, it is necessary to investigate methods to reduce the effects of blocking, such as utilizing reflected waves from walls and ceilings. Therefore, it is important to clarify the path loss of direct and reflected waves and the direction of arrival waves. In this paper, we measured the path loss and the direction of arrival of multipath waves in sub-terahertz-wave bands of 160 GHz and 300 GHz in an indoor conference room. The measurement used a directional antenna for the transmitting (Tx) and receiving (Rx) antennas. The horizontal and vertical directions of the Tx antenna were changed every 10 degrees, and the Rx antenna was rotated by 360 degrees horizontally while changing the angle of elevation. Measurements were carried out at two Rx antenna points. It was found that the arrival of the multiple waves reflected from wall and ceiling are observed and path loss of the multiple waves are approximately 10 dB to 30 dB larger than the free space path loss at 160 GHz and 300 GHz.