CFO Impact Analysis on Cell Free MIMO-OFDM in Millimeter Wave Spectrum

This paper presents a study of a downlink (DL) cell-free MIMO-OFDM transmission under maximal ratio transmission (MRT) and full pilot zero-forcing precoding (FZF) in the presence of carrier frequency offsets (CFO). This hardware impairment causes intercarrier interference (ICI) which degrades the transmission performance. We derive exact closed form expressions of the achievable spectral efficiency considering frequency selective, uncorrelated, Rayleigh fading channels. Numerical results are obtained considering a transmission scenario using 5G RedCap specifications in the millimeter wave band to illustrate our derivations and quantify the performance for different values of the CFO.