Channel Measurement, Modeling, and Performance Evaluation for Terahertz Fluid Antenna Systems

Since decades ago, multi-antenna has become a key enabling technology in the evolution of wireless communication systems. In contrast to conventional multi-antenna systems that contain antennas at fixed positions, position-flexible antenna systems have been proposed to fully utilize the spatial variation of wireless channels. In this paper, fluid antenna systems (FAS) are analyzed by channel measurement, channel modeling, and performance evaluation. First, we fill the gap in experimental analysis on terahertz (THz) FAS by developing a broadband channel measurement with physical FAS operating in the THz band, for which the extremely high movable resolution reaches 0.02 mm and the temporal resolution is 16.7 ps. Channel measurement is conducted for a two-dimensional position-flexible antenna system across 32×32 planar port positions at 300 GHz. Then, in light of the measurement results, spatial-correlated channel models for the two-dimensional FAS are proposed, which is statistically parameterized by the complex covariance matrix extracted from the measurement. Furthermore, by applying either the signal-to-interference-and-noise ratio (SINR)-maximized position selection algorithm or the movable array scheme, FAS are verified to achieve 99% of the optimal performance in terms of spectral efficiency. Finally, the performance of different FAS types is evaluated and compared for both planar and linear FAS. Extensive results demonstrate the advantage of FAS over fixed-position antennas in coping with the multi-path fading and improving the spectral efficiency by over 10% in a 300 GHz measured channel.