Carrier frequency offset (CFO) is a challenging problem in the uplink of the single-carrier frequency division multiple access (SC-FDMA) system. CFOs effect on the orthogonality between subcarriers and cause inter-carrier interference (ICI) and multiple access interference (MAI). This paper, analyzes the impact of the CFOs on the performance of the Discrete Sine Transform (DST) SC-FDMA (DST-SC-FDMA) system and investigates with different wireless channels, different modulation schemes and different subcarriers mapping schemes. Furthermore, an efficient equalization and CFOs compensation scheme is proposed to enhance the performance of the DST-SC-FDMA system and transmit images efficiently over DST-SC-FDMA system. The proposed scheme combines the minimum mean square error (MMSE) equalizer and the parallel interference cancellation (PIC). The combined method is referred to as MMSE+PIC. The results show that CFOs degrades the DST-FDMA performance. The obtained results show a noticeable performance improvement of the proposed MMSE-PIC scheme over the conventional MMSE equalizer. Moreover, it is found that it is possible to efficiently transmit wireless image using the proposed MMSE+PIC scheme,This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

This paper proposes, a DFT-based OFDMA with phase modulation (DFT-OFDMA-PM) system. One main advantage of the phase modulated system is the constant envelope (CE) resulted signal, i.e, 0 dB PAPR, the second advantage is the ability to improve the diversity of multipath channels. These advantages have been exploited in the proposed system of this paper. The performance of the proposed system in terms of the bit error rate (BER) is studied and investigated and compared to the previously proposed DCT-OFDMA-PM system and the conventional OFDMA system without PM via computer simulation. The key parameter that affects the performance of the PM systems, the modulation index, is also studied and the optimum value is selected using exhaustive simulation scenarios. Moreover, the PAPR is also simulated for the proposed system and compared to the conventional system. Simulation results show the significant improvement of the proposed system in terms of PAPR and BER when compared to the conventional system. The simulation results for the proposed system show the effectiveness of the proposed system for wireless broadband communications.