The need of Modern wireless communication is achieving high data transmission rate and its robustness against multipath fading & good spectral efficiency MIMO-OFDM system is popular because it provides reliable communication & wide coverage. Orthogonal Frequency Division Multiplexing is a multicarrier modulation technique which is prime choice for high data rate application. To improve performance of OFDM we use various techniques such as channel estimation, signal detection, frequency offset estimation and correction, PAPR reduction (Peak-To-Average-Power-Ratio), Bit Error Rate Reduction using equalization technique and MIMO techniques. MIMO (Multiple Input Multiple Output) wireless communication systems employ multiple transmit and receiving antennas for the improvement in channel capacity. This paper describes the basic introduction of OFDM, MIMO-OFDM system and explains the different channel estimation, optimization techniques and their utilization in communication systems.Keywords - OFDM, MIMO, PAPR, ISI.
