Subterahertz Radio Channel Emulation With Band-Stitching Scheme: Framework, Resource Optimization, and Validation

Sub-terahertz (Sub-THz) technology, due to its abundant spectrum resources, is considered one of the key candidates for sixth-generation communication and sensing systems. To facilitate the design of sub-THz systems, it is essential to evaluate the performance of sub-THz radios within realistic propagation environments in the laboratory. Channel emulator (CE), which can emulate radio channels between the transmitter and receiver, is a key instrument for wireless system air-interface testing. Sub-THz radio channel emulation faces many challenges due to hardware and resource limitation in the CE, e.g. the misalignment between the gridded tap delays in the CE and the arbitrary tap delays in simulated and measured channels, the limited number of tap delays in the CE, the limited system bandwidth and restricted system carrier frequency, the non-ideal frequency response over system band. In this paper, we proposed a framework for emulating sub-THz channels that can simultaneously address tap delay misalignment, tap resource limitations, and radio frequency branch frequency response inconsistency during the band-stitching process. To efficiently perform sub-THz channel emulation, we also introduced several effective optimization methods to solve the problems formulated within the framework. To evaluate the effectiveness of the proposed framework, we carried out channel measurements at two frequency bands, i.e. 100 GHz and 300 GHz in two representative scenarios. Moreover, we performed the channel emulation of the measured channel frequency responses over many spatial locations using the proposed framework. The numerical emulation results demonstrate the effectiveness and robustness of the proposed framework.