Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) is appealing for the provision of high spectral efficiency in digital terrestrial broadcast systems. To fully obtain its advantageous features, it is very important to remove the frequency mismatch between the transmitter and the receiver. In this paper, we present the performance analysis of joint estimation of carrier and sampling frequency offsets in the MIMO-OFDM-based advanced television systems committee (ATSC) 3.0 system. In the MIMO-OFDM ATSC system, the continual pilot (CP) is primarily utilized to perform frequency synchronization. To efficiently suppress an unwanted bias introduced by the presence of random-likely located CPs, an optimal pilot subset is selected to form the basis of least squares frequency-offset estimation. A closed-form mean squared error is derived in the context of MIMO-OFDM, considering the multipath fading channel. We show via computer simulations and numerical analysis that the proposed estimation method achieves higher estimation accuracy than the existing estimation method.Despite many advantageous features, the OFDM-based ATSC 3.0 system has a few key issues that have to be addressed. One of the biggest weaknesses of OFDM is its vulnerability to synchronization mismatches, including symbol timing offset (STO), carrier frequency offset (CFO), and sampling frequency offset (SFO) in a frequency-selective fading environment [17]. If these effects are not properly compensated, OFDM systems can suffer from severe inter-symbol interference (ISI) or inter-channel interference (ICI), which downgrades the performance of OFDM and MIMO-OFDM systems. To eliminate ICI and ISI effects, the receiver must first estimate the correct STO [18,19]. Second, it is essential that the frequency offset on the OFDM block is estimated and corrected to remove ICI. In particular, the performance of OFDM receivers is greatly affected by SFO as the fast Fourier transform (FFT) size becomes larger [20], which usually occurs in a typical broadcast system. Therefore, the challenges in the MIMO-OFDM-based ATSC 3.0 system are its susceptibility to the frequency synchronization between the transmitter and the receiver. In order to help acquire synchronization, the ATSC 3.0 system provides several types of pilot symbols such as scattered pilots (SPs), edge pilots (EPs), continual pilots (CPs), and subframe boundary pilots (SBPs) [10]. The SPs, EPs, and SBPs are mainly dedicated to estimate the channel, whereas CPs are present to assist time and frequency estimation [21]. To maximize the advantages of MIMO-OFDM, it is therefore of crucial importance to accurately estimate the CFO and SFO [22,23]. In the literature, a number of pilot-assisted approaches, from maximum likelihood estimation (MLE) to linear least-squares estimation (LSE) strategies [22][23][24][25][26][27][28][29][30][31][32][33][34][35], have been presented to obtain accurate CFO and SFO estimates. The MLE is well known to be capable of achieving high accuracy in joi...