Performance of least square based channel estimation for high order modulation QAM-OFDM-MIMO in the presence of multipath fading channel / Izham Khairulfathi Bahro

As the communication system evolving and enhancing, the need for high speed and reliable communication system is crucial. With the combination of multiple-input multiple-output (MIMO) communication system along orthogonal frequency division multiplexing (OFDM), a reliable high rate communication system can be achieved. The MIMO OFDM system with 2X2, 3x3, and 4x4 antenna configurations will use 256, 512 and 1024 QAM modulation level in the presence of multipath Rayleigh and Additive White Gaussian Noise (AWGN) channel. The performance evaluation of the system is determined in term of Bit Error Rate (BER) and Signal Energy to Noise Power Ratio (Eb/No). The MIMO OFDM system with Least Square channel estimation will be designed and simulated using MATLAB where the results will then be analyzed. From the results obtained, it can be said that as the QAM level increased the BER will increase too. Besides that, the performance of the system will improves as the number of transmit and receive antennas increase. It is known that the system performance of 4x4 antennas using 1024 QAM is the same with the system of 2x2 antennas using 256 QAM. However, the data rate increase is 40% for 1024 QAM. In addition, the great performance showed by the MIMO-OFDM system is greatly enhanced by the estimation technique used which is Least Square channel estimation. Least Square channel estimation accurately recovered the distorted signal through multipath fading channel thus improve the performance of the MIMO-OFDM system.