Switched Combining for Reconfigurable Fluid Antenna Systems

Reconfigurable fluid antennas (FAs) is an antenna technology suitable for future 6G networks due to their flexibility and the extra degrees of freedom they provide. Nevertheless, FAs suffer from high channel estimation overhead as a result of the large number of antenna ports. This paper studies the performance of a switched combining (SDC) scheme for FAs, which aims to decrease this overhead. A novel analytical approximation is derived for the statistical distribution of the signal-to-interference-plus-noise ratio (SINR). A theoretical framework is provided for the outage probability, the average number of port SINR estimations, and the probability of switching to a different port between consecutive time slots. The presented results demonstrate that the SDC-based FA can match the performance of a selection combining FA, achieving maximum diversity gains with lower complexity.