This paper considers a Fluid Antenna (FA) system comprising a single-antenna transmitter that communicates with a receiver equipped with an FA array with N ports. The transmitter is assumed to deploy any of the modulation schemes: \textit{i}) two-sided M-ary amplitude-shift keying, \textit{ii}) M-ary phase-shift keying, iii) M-ary quadrature-amplitude modulation, and \textit{iv}) binary frequency-shift keying, the channels between its antenna and the receiver ports are subjected to Rayleigh fading, and the receiver chooses the best K out of its N ports for symbol detection. Considering that the receiver combines the signals from the best K ports using maximal-ratio combining, the optimal reception structures for all the considered signaling schemes are obtained. We also present novel exact closed-form expressions for the respective symbol error probabilities (SEPs) of the FA system, as well as asymptotic approximations valid at high signal-to-noise ratios. The presented analysis is corroborated through comparisons with simulation results, showcasing the critical role of various system parameters on the SEP performance.
@article{arxiv.2604.06852,
title = {Symbol Error Analysis for Fluid Antenna Systems with One- and Two-Dimensional Modulation Schemes},
author = {Soumya P. Dash and George C. Alexandropoulos},
journal= {arXiv preprint arXiv:2604.06852},
year = {2026}
}