The massive growth of mobile users and various applications in coming days requires an enhanced Radio Access Technology (eRAT) to improve the diversity gain and spectral efficiency. Current research on Generalized Frequency Division Multiplexing (GFDM) modulation technique combined with Multi-Input Multi-Output (MIMO) antenna system gives good resource allocation, out band emission and better signal strengths over the existing Orthogonal Multiple Access (OMA) techniques. The proposed scheme explains the improvement of diversity gain, spectral efficiency and energy efficiency of MIMO-GFMD system by combining the benefits of Subcarrier Index Modulation (SIM) and Constellation Precoding (CP) Technique. It is referred as SIM-CP-MIMO-GFDM system. In order to achieve the requirements, in proposed scheme few subcarriers are activated by index modulation bits in quadrature/in-phase dimensions and then data symbols are constellation Precoded. At the receiver, data blocks are detected by using QR Decomposition based Maximum Likelihood (ML) detection. Finally, this paper explains both theoretical and simulation result analysis that the proposed SIM-CP-MIMO-GFDM system outperforms compared to existing systems.