stems. The aim of this chapter is, therefore, to analyse and design FBMC-OQAM-based multiple-input multiple-output (MIMO) and multi- user massive MIMO systems. For brevity, FBMC-OQAM is referred to as FBMC in the sequel. The subcarrier in FBMC waveform, unlike OFDM, is orthogonal in the real domain only [15]. The resulting intrinsic interference challenges amalgamation of FBMC signalling with future mobile communication systems. Furthermore, the overlapping of FBMC symbols in the time-domain poses additional challenges. For example, FBMC channel state information (CSI) estimation needs the placement of zeros between the adjacent training symbols [24]. Thus, one has to carefully compute the intrinsic interference for constructing the virtual training symbols at the receiver. Moreover, one also needs to find the optimal number of zeros required to avoid overdesign/underdesign of FBMC systems. In light of the above challenges, it is not always feasible to use the existing solutions or corresponding analysis for OFDM-based systems, while designing FBMC aided future wireless systems. Organization of Chapter The next section discusses single-input single-output (SISO) and MIMO-FBMC system models and the key differences between OFDM and FBMC waveforms. 3 FBMC: A Waveform Candidate for Beyond 5G Section 3.4 demonstrates a semi-blind channel estimator for MIMO-FBMC sys- items. Section 3.5 demonstrates and compares the performance of FBMC and OFDM waveforms in the uplink transmission of MU massive MIMO systems. Section 3.6 concludes the chapter and provides future directions. 3.3 FBMC System Model The continuous-time baseband FBMC transmitted signal is expressed as [15, 25] (3.1) where dm,n are real-valued OQAM symbols at the mth subcarrier and the nth symbol instant. The parameter N symbolises the number of subcarriers. The FBMC basis function Xm,n (t) is defined as (3.2) where T is the QAM symbol duration, F = 1/T is the spacing between two consecutive subcarriers, T/2 is the offset between the in-phase and quadrature pa