Design, comparative study and analysis of CDMA for different modulation techniques

In this work, we have design a MIMO–CDMA using 4 ∗ 8 antennas with the combination of MMSE (Minimum Mean square Error Equalizer) for BPSK (Binary Phase shift Keying), QPSK (Quadrature Phase Shift Keying), 16-QAM, 64-QAM and 256-QAM (Quadrature Amplitude Modulation) modulation schemes. The analysis is built on the basis of transmit–received signal, constellation and MMSE plot simulated on a MatLab/Simulink. On the basis of BER (Bit-Error-Rate), it is also concluded that this work is mostly suitable for high order modulation schemes as the BER of 16-qam, 64-QAM and 256-QAM is zero. The proposed study has increased the quality of the wireless link and Inter-Symbol-Interference (ISI) is likewise cut by applying a combination of MMSE and MIMO (Multiple In and Multiple Out) with OSTBC (Orthogonal space Time Block Code) encoder and combiner.