Novel Multi User Detection (MUD) techniques to improve the efficiency of receiver in 5G wireless communications with the Frequency Division Multicarrier CDMA (FD-MC- CDMA) receiver are suggested in this research paper. Carrier frequency offset (CFO) on Multi-Carrier systems minimizes the efficiency of system; therefore, it is essential to estimate of CFO and minimize the influence on multiple carrier modulations systems. Introduction of novel MUD Schemes, Carrier Frequency Offset Estimation techniques on FD-MC-CDMA system are also focussed. There are several existing Multiuser Detection (MUD) schemes that suffer from performance degradation issues like optimisation in MAI and noise in the system, Near-far effect and Inter Symbol Interference (ISI). The combination of FD- MC-CDMA and MUD system is introduced and is designed for a novel Adaptive Genetic Algorithm (AGA) aided MUD using the Soft Computing Approaches such as Adaptive Population Sizing in Genetic Approach and Fuzzy Logic Controllers into the Adaptive Genetic Algorithm are simulated and analysed. The Bit Error Rate (BER) and Evaluation Complexity of the suggested MUD Schemes has been investigated under various Frequency Selective Fading Channels such as Additive white Gaussian noise (AWGN) channel, Rayleigh Fading Channel, and Rician Fading Channel. The simulation results are compared with existing non-linear MUD schemes, Successive Interference Canceller (SIC) and Parallel Interference Canceller (PIC). From the simulations, it is indicative that the efficiency of suggested AGA aided MUD is superior when compared to mentioned approaches.