Investigation on Channel Estimation techniques for MIMO- OFDM System for QAM/QPSK Modulation

Multiple Input Multiple Output (MIMO) systems has provide high transmission data rate without increasing transmitting power for wireless communication systems. The performance can be further improved by properly estimating the channel at the receiver side. In this paper, investigation on various channel estimation techniques for MIMO-OFDM has been done and a new approach based on time-domain interpolation (TDI) has been presented. TDI is obtained by transforming output of estimator to time domain through Inverse Discrete Fourier Transform (IDFT), zero padding and going back to frequency domain through Discrete Fourier Transform (DFT). The comparison has been carried out between power of true channel and estimated power for the given channel using LS, LS-Spline and MMSE for QPSK/QAM modulation at SNR 30dB. It is investigated that by applying the DFT over the estimated power of channel for QPSK, the performance of the channel estimators becomes better.