Performance Analysis of IRS-Aided OTFS Over Generalized Fading Channels

Abstract

In high-mobility wireless environments, conventional multi-carrier waveforms often suffer from severe Doppler effects, resulting in significant performance degradation. Orthogonal time frequency space (OTFS) modulation offers improved reliability in such scenarios by representing information symbols in the delay-Doppler domain. By using intelligent reflecting surfaces (IRS), propagation conditions can be improved by enabling passive beamforming. However, most IRS-aided OTFS studies are limited to Rayleigh or Rician fading and do not consider generalized non-Gaussian channel models. This work examines the performance of the IRS-aided OTFS system under $\eta-\mu$, $\kappa-\mu$, and $\alpha-\mu$  fading models. The IRS phases are designed to coherently strengthen the dominant cascaded path, thereby improving the power of the received signal under MMSE and MMSE-SIC algorithms.  Simulations are conducted to evaluate the BER and achievable rate for OTFS and IRS-aided OTFS. Simulations suggest that  $\kappa-\mu$ provides better BER performance than the other fading channels irrespective of the number of delay values, Doppler values, and modulation scheme.