Outage probability analysis of correlated fluid-antenna-assisted OTFS systems
AEU - International Journal of Electronics and Communications, cilt.217, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 217
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.aeue.2026.156607
- Dergi Adı: AEU - International Journal of Electronics and Communications
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Applied Science & Technology Source, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO), Technology Collection (ProQuest)
- Anahtar Kelimeler: Correlated fading channels, Diversity analysis, Fluid antenna system (FAS), Gaussian copula, Orthogonal time frequency space (OTFS), Outage probability, Spatial correlation
- İstanbul Gelişim Üniversitesi Adresli: Evet
Özet
This paper investigates the outage probability (OP) performance of orthogonal time frequency space (OTFS) systems assisted by fluid antenna systems (FASs) over doubly selective fading channels. An OTFS–FAS receiver architecture is considered, where multiple fluid antenna ports are available and the receiver selects the port with the highest detector-output effective signal-to-noise ratio (SNR) of the complete delay–Doppler (DD) channel matrix. To account for the spatial dependence among closely spaced FAS ports, a correlation-aware analytical framework based on Gaussian copula theory is developed, with a marginal distribution that incorporates multiple resolvable OTFS paths. First, an OTFS–FAS system model is established in the DD domain. Then, the OP of the correlated FAS receiver is formulated through a multivariate Gaussian cumulative distribution function, while a closed-form OP expression is derived for the uncorrelated FAS case. The high-SNR analysis distinguishes the outage-decay behavior predicted by the adopted Gaussian-copula approximation from the exact physical correlated-Rayleigh result. In the copula model, the decay rate combines path diversity with a correlation-dependent measure of effective spatial diversity. In the full-rank physical model, the diversity order is the product of the numbers of resolvable paths and selectable ports, while correlation affects the coding gain. Monte Carlo simulation results validate the developed analytical expressions and demonstrate excellent agreement with the theoretical analysis. The results further show that increasing the number and spacing of the FAS ports improves reliability, whereas strong spatial correlation degrades the achievable finite-SNR performance. Additional full DD-domain simulations quantify the effects of resolvable paths, fractional Doppler, frame size, detector choice, channel-estimation error, and pulse/tap alignment.