1. Introduction
Multiple-input Multiple-output (MIMO) works with multiple antennas at the transmitting end as well as at the receiving end. This structure helps to create sub-channels which are parallel over the common time and frequency axis. As a result of this, within the same bandwidth, the high transmission rate can be achieved [1] . In contrast to this, OFDM is a promising technique in terms of high spectral efficiency, bandwidth efficiency, robustness against frequency selectivity and simple implementation. With the help of this, the available spectrum will get divided into a number of orthogonal and narrowband subchannels which are overlapping on each other. So it increases its demand in a next-generation wireless communication system as one of the promising modulation schemes for higher data rate transmission. MIMO combines with OFDM in order to offer high diversity as well as multiplexing gain with the help of multiple antennas [2] , [3] and achieves the potential of both techniques and produces frequency flat MIMO channels. So in the downlink of LTE commercially