Generalized frequency-division multiplexing (GFDM) is one of the promising multi-carrier modulation schemes suitable for next-generation wireless communication systems. The main characteristic of GFDM is the flexible time-frequency structure of data blocks. However, this degree of freedom is obtained at the cost of loss of sub-carrier orthogonality, which leads to self-interference. In this paper, we propose a new model that classifies the GFDM self-interferences into two independent categories as inband and adjacent sub-carriers interferences and show their corresponding mathematical formulations. Building on this model, we propose a successive interference cancellation (SIC) technique with low complexity to eliminate these self-interference effectively. The main distinct feature of our proposed technique is its low computational complexity compared to similar interference cancellation techniques. Our analytical findings and numerical experiments indicate that the proposed model and SIC technique considerably improve the system performance in terms of bit error rate (BER) and signal to interference ratio (SIR). We also show that the results of our analytical findings are in good agreement with those of computer simulations.INDEX TERMS 5G, GFDM, multi-carrier, SIC, BER.