Abstract: Today’s communication scenario demands high data rates and large system capacity where MIMO-OFDM proves to be an ultimate combination .The never ending thirst for such high performance wireless communication results in signal vulnerability to channel impairments. One of the primary causes resulting in signal degradation due to the multipath propagation is channel ISI (Inter symbol interference). The process of channel estimation and equalization together accomplishes the job of combating the effect of ISI. Initially CIR(Channel Impulse Response) is estimated based on a known sequence of bits(Pilot sequence) followed by equalization process which takes care of altering the channel response based on the estimated behavior thereby extracting the signal of interest. It is also possible to implement non pilot aided approaches like blind channel equalizer algorithms without possessing knowledge of the channel. This paper does a comprehensive survey of different types of equalizers thereby providing an in depth understanding of equalization.
Keywords: MIMO, OFDM, ISI, ICI, CSI, MMSE.