The main basic components for selecting modulation technique are Bit Error Rate (BER) and Signal to Noise
Ratio (SNR). This paper examined the performance of different modulation in Multiple Input and Multiple
Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system. A model of 2 × 2 MIMO-OFDM
has been developed utilizing the communication tools of MATLAB/Simulink. The model was used to carry out
comprehensive analyzed the performance of different digital modulation techniques namely, 8-PSK, 16-PSK,
32-PSK, 64-PSK, 8-QAM, 16-QAM, 32-QAM, 64-QAM and QPSK in terms of BER with respect to SNR over
Additive White Gaussian Noise (AGWN) and Rayleigh fading channels. Having conducted extensive simulation
and performance evaluation, results indicated that lower order modulation techniques outperform the higher
order schemes for transmission of data over both AGWN and Rayleigh fading channels such that for M-PSK
modulation, 8-PSK offered the lowest BER of (0.0010 and 0.0333) while 16-PSK, 32-PSk, and 64-PSK showed
BER of (0.0202 and 0.0792), (0.061 and 0.1317), and (0.116 and 0.1832) against increasing SNR at 10dB in
AGWN and Rayleigh channels respectively. Similarly, for QAM modulation, 8-QAM provided the finest BER
with value of (0.000652 and 0.0231), while 16-QAM, 32-QAM, and 64-QAM yielded BER performance of
(0.017 and 0.0301), (0.0161 and 0.0665), (0.0265 and 0.0792) with respect to increasing SNR at 10 dB in
AGWN and Rayleigh channel. However, this comes at the cost of the data rate since lower order techniques
have lower data rates than their higher order counterpart. Furthermore, it was found that the performance over
AGWN channel was better than the performance over Rayleigh fading channel for all considered modulation
schemes. On which modulation technique provided the best BER performance, it was observed that QPSK
modulation technique outperformed other modulation schemes with BER of 3.8 ×10-6
in AGWN channel and
0.0010 in Rayleigh fading channel at SNR of 10 dB. Generally, the simulation results showed that the BER
performance improves as the SNR increases.
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