Long-range VNA-based channel sounder: Design and measurement validation at MmWave and sub-THz frequency bands

With the increasing demand for high bandwidth wireless communication systems, and with a congested spectrum in the sub-6 GHz frequency bands, researchers have been looking into exploration of millimeter wave (mmWave) and sub-terahertz (sub-THz) frequency bands. Channel modeling is essential for system design and performance evaluation of new wireless communication systems. Accurate channel modeling relies on reliable measured channel data, which is collected by high-fidelity channel sounders. Furthermore, it is of importance to understand to which extent channel parameters are frequency dependent in typical deployment scenario (including both indoor short-range and outdoor long-range scenarios). To achieve this purpose, this paper presents a state-of-art long-range 28 GHz and 300 GHz VNA-based channel sounder using optical cable solutions, which can support a measurement range up to 300 m and 600 m in principle, respectively. The design, development and validation of the long-range channel sounders at mmWave and sub-THz bands are reported, with a focus on their system principle, link budget, and back-to-back measurements. Furthermore, a measurement campaign in an indoor corridor is performed using the developed 300 GHz system and 28 GHz channel sounding systems. Both measured channels at the 28 GHz and 300 GHz channels are shown to be highly sparse and specular. A higher number of Multi Path Components (MPC) are observed for the 28 GHz system, while the same main MPC are observed for both systems.