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In this study the negative impacts of interference transmitters on automatic modulation classification (AMC) have been discussed. The authors proposed two approaches for AMC in the presence of interference: single user modulation classification (SUMC) and multiuser modulation classification (MUMC). When the received power of one transmitter is larger than the other transmitters, SUMC approach recognises the modulation type of the dominant transmitter and other transmitters are treated as interferences. Alternatively when the received powers of all the transmitters are close to each other the authors propose MUMC method to recognise the modulation type of all of the transmitted signals. The features being used to recognise the modulation types of transmitted signals for the both approaches, SUMC and MUMC are higher order cumulants. The superposition property of cumulants for independent random variables is utilised for SUMC and MUMC. The authors investigated the robustness of their classifier with respect to different powers of the received signals via analytical and simulation results and the authors have shown the analytical results will be confirmed by simulations. Also the authors studied the effects of signal synchronisation error, phase jitter and frequency offset on their proposed methods via simulations in the both condition for MUMC and SUMC.