Cell-Free Massive MIMO-OFDM Transmission Over Frequency-Selective Fading Channels

This letter presents and analyzes orthogonal frequency-division multiplexing (OFDM)-based multi-carrier transmission for cell-free massive multi-input multi-output (CFmMIMO) over frequency-selective fading channels. Frequency-domain conjugate beamforming, pilot assignment, and user-specific resource allocation are proposed. The CFmMIMO-OFDM system is scalable to serve a massive number of users and is flexible to offer diverse data rates for heterogeneous applications.