MIMO-OFDM (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing) is a very promising technology providing high throughput and range without additional bandwidth or transmit power by using many antennas at transmitter and receiver eliminating Inter-Symbol- Interference (ISI).The capacities of MIMO-OFDM systems can be fully utilized by low complex and optimal signal detection scheme. The receiver’s detector is supposed to maximize the Signal to interference plus noise (SINR) by cancelling the spatial interference and should separate the transmitted signals. Minimum Mean Square Error (MMSE) detector is near optimal and less complex. The performance of the proposed system is analyzed using MMSE under flat and frequency selective Rayleigh channel environment, different number of antenna configurations and various modulation techniques to provide an optimum solution.