In the recent decade, multi-carrier modulation is considered by wireless system designers due to its high data rate and resistance against multipath fading effects. Orthogonal frequency division multiplexing (OFDM) is widely known and is the most commonly used multi-carrier modulation scheme in many communication standards. MIMO technology has been used due to the increase of the request for higher data rate, quality of transmission, and transmission energy limitation. Wireless cellular communication system is one of the most popular application of multi-user MIMO. Thus by combining of MIMO and OFDM, MIMO-OFDM is introduced. In the recent years, many research work have been devoted to the proposal of new techniques for the 5G cellular system. Multi-user MIMO with high number of antennas is widely considered and this has been the first assumption of many researches. Synchronization error is one of the most challenging problems in an OFDM system and carrier frequency offset is the reason for synchronization error. CFO can degrade the system performance. Therefore synchronization is one of the most important aspects of these communication systems. Synchronization is done in two ste first estimation and second correction or compensation. CFO estimation i multi user system uplink is a challenging task because the values of CFO for each user is different. In this thesis CFO and channel estimation will be performed jointly with low computational complexity by using CAZAC sequence which has attractive properties such as constant amplitude and zero autocorrelation. In addition by introducing an iterative scheme, the performance of estimation is improved. Then the performance of estimation is deliberated by CRLB calculation. Also, CFO compensation is done by introducing a new algorithm for uplink. This algorithm is improved by applying windowing and iterative schemes. Finally the simulation results will be shown the performance analysis. Keywords: Massive MIMO system based on OFDM, Massive MIMO, MIMO-OFDM, CFO estimation, Channel estimation, Intercarrier interference, Carrier frequency offset, Pilot, CFO compensation, Channel equalization
