Effect of Synchronization error in Multi Carrier systems

Communications as an important aspect life plays a major role in our daily routine. With the progress in age and growth in its demand, there has been rapid development in the field of communications. Analog signals which were used to send information previously are now sent in digital domain in a much wider range. For better performance in terms of transmissions, single carriers are replaced by multi-carriers Some of the methods that use multi-carriers for transmission are Orthogonal Division Frequency Multiplexing (OFDM), Code Division Multiple Access (CDMA). In OFDM system, orthogonally placed subcarriers are used to carry the data from the transmitter to the receiver. The guard band present in this system avoids the system from being effected by Inter Symbol Interference (ISI). However, Doppler Shifts and delays induced in the channel due to various reasons impose frequency offset to the carrier. This results in an error in the Synchronization between the transmitter and receiver. This leads to the loss of orthogonally between the subcarriers and thus degrades the performance of the OFDM system.In this project, the Synchronization error in OFDM is discussed in particular and a technique of estimating the Carrier Frequency Offset (CFO) using Null Subcarriers is studied