Carrier Frequency offset problem in DCT-SC-FDMA Systems: Investigation and Compensation

摘要

Single-carrier frequency division multiple access (SC-FDMA) is one well-known scheme, whichrnhas recently become a preferred choice for uplink channels. In this system, the carrier frequency offsets (CFOs) disrupt the orthogonality between subcarriers and give rise to inter-carrier interference (ICI), and multiple access interference (MAI) among users. In this paper, firstly, the impact of the CFOs on the performance of the discrete cosine transform (DCT) SC-FDMA (DCT SC-FDMA) system is investigated. Then, a new low-complexity joint equalization and CFOs compensation scheme is proposed to cancel the interference in frequency domain. It is called minimum mean square error (MMSE) equalizer. A hybrid scheme comprising the proposed MMSE scheme and a parallel interference cancellation (PIC) (MMSE+PIC) is also suggested and investigated to further enhance the performance of the interleaved DCT-SC-FDMA. From the obtained simulation results, it is found that CFOs disrupt the orthogonality between the subcarriers in DCT-SC-FDMA systems and degrade the bit error rate (BER) performance. The proposed compensation schemes are found to be able to enhance the system performance, even in the presence of the estimation errors.