Earth station in motion (ESIM) is a technology that provides wireless communication to users at their locations and is considered to operate at 27.5-29.5 GHz. The next-generation mobile communication service, 5G, is expected to operate at 24.25-27.5 GHz. These systems can experience interference because both the frequency bands are contiguous. The possibility of the adjacent channel compatibility between an ESIM and 5G should be verified by an interference analysis. However, ESIMs are mounted on ships, aircraft, and land vehicles. Therefore, the analysis methods and scenarios should be applied differently. We propose orthogonal frequency division multiplexing (OFDM) waveforms of an ESIM for their coexistence. Because OFDM has a lower out-of-band emission (OOBE) than a single carrier signal, this proposed approach can save frequency resources. Minimum coupling loss (MCL) and Monte Carlo (MC) methods are used to obtain the minimum separation distance and guard band according to the frequency-dependent rejection for determining the adjacent channel compatibility.