Performance analysis of SC-FDMA uplink communication systems using multiple carrier frequency offset synchronization with null subcarriers

3rd Generation Partnership Project has selected Single-Carrier Frequency-Division Multiple-Access (SC-FDMA) for Long Term Evolution (LTE) uplink access scheme. However, like all Orthogonal Frequency-Division Multiplexing (OFDM) based schemes, SC-FDMA also suffers from carrier frequency offset (CFO), and this is a major problem especially for LTE uplink, where multiple CFOs exist. There are two kinds of effects caused by CFO; inter-carrier interference (ICI), occuring between a user's own subcarriers and multiple-access interference (MAI), occuring between different users' subcarriers. This thesis's goal is to introduce a null subcarriers using synchronization algorithm which can estimate and supress multiple CFOs and their effects accurately for an uplink system utilizing SC-FDMA, the main technique of LTE uplink and to show its performance depending on various variables (Fast Fourier Transform (FFT) size, user number, subcarrier mapping method). In this context firstly general information about LTE and SC-FDMA is given, past works about CFO synchronization are mentioned and later the proposed synchronization algorithm is introduced. Finally, simulations and analyses examining the performance of the algorithm according to predefined variables are given. To realize simulations, MATLAB is used and Bit-Error Rate graphics are obtained. From these results, it is understood that the proposed algorithm in the thesis successfully achieves CFO synchronization and improves the performance significantly. Besides, it is observed that increasing FFT size, decreasing user number and utilizing Localized Frequency Division Multiplexing Access subcarrier mapping with sub-bands also increases the performance of the algorithm and system.