Estimation of Channel Parameters for Port Selection in Millimeter-Wave Fluid Antenna Systems

The fluid antenna system (FAS) exploits spatial diversity by adjusting a reconfigurable antenna to a position/port with the highest channel gain, and the FAS has the potential to promote the development of 6G technology [1]. Conventionally, the optimal port is chosen when all the ports are observed and all the channels are estimated, which can be impractical when the port number is large. In this paper, we propose a new method based on the least squares regression to estimate channel parameters in a multi-ray millimeter-wave (mmWave) FAS. In particular, we first estimate the channel gains at a number of ports (shall be greater than or equal to the number of paths) and then use these estimated data to reconstruct the above channel as well as to select the FAS’ best port. By using our method, the number of required channel estimates can be massively reduced. More importantly, simulation results show that our method achieves a close performance compared with the conventional method, in terms of the outage probability.