Low Complexity CFO Compensation Scheme for SC-FDMA Uplink System

Single Carrier Frequency Division Multiple Access (SC-FDMA) has been adopted for fourth generation (4G) mobile uplink transmission schemes because of its low Peak to Average Power Ratio (PAPR) as compared to that of Orthogonal Frequency-Division Multiple Access (OFDMA).Since SC-FDMA has low PAPR, it is sensitive to Carrier Frequency Offsets (CFOs) similar to that of OFDMA. To minimize and compensate CFO effects on SC-FDMA, the uplink system with ZeroForcing (ZF) equalization can be used. In this, the method involves is an inverse of an N × N CFO induced intercarrier interference (ICI) matrix, where N denotes the number of subcarriers. When N is large, it will leads to large number computational complexity of the system and the performance of the system will degrade. To overcome this complexity, we propose a lowcomplexity ZF method and Newton’s method with fast Fourier transforms which is used to solve the matrix inversion problem. This reduces the complexity from O(N 3 ) to O(2N log2N). The proposed compensation scheme can able to improve the system performance. Keywords— SingleCarrier Frequency Division Multiple Access (SC-FDMA), Carrier Frequency Offsets (CFO), Fast Fourier Transform (FFT), Zero-Forcing (ZF), Newton’s method.