Abstract: Synchronization is an essential task for any digital communication system. Without a proper accurate synchronization method, it is not possible to reliably receive the transmitted data. Synchronization is the first and most important task that must be performed at the receiver. So, whole receiver architecture depends on the synchronization method that is used. Orthogonal frequency division multiplexing (OFDM) is one of the most favourable technologies deployed in fourth generation systems. It is a multicarrier transmission technique, which essentially transforms the frequency selective fading channel into flat fading channel by divides the single wideband channel into number of parallel narrowband channels. Thus, simplifies the equalizer complexity. As we know every system has its own advantages and disadvantages, OFDM also suffers from its disadvantages. One of the main disadvantages of OFDM is its sensitivity to Carrier Frequency Offset (CFO). So, accurate estimation and compensation of CFO is the major task to be performed for proper reception of data. Furthermore, when OFDM technique is used along with MIMO systems, the task of CFO estimation becomes much more difficult due to the presence of multiple antenna interference (MAI). This paper takes an overall look at this issue. In this paper, we will discuss about Chu sequences and training sequence based CFO estimation for MIMO OFDM systems which use Chu sequence based training sequences for estimation purpose.

Keywords: MIMO, OFDM, Carrier Frequency Offset.