Comparative evaluation of OFDMA and SC-FDMA based transmission systems

New evolving standards of the cellular systems, like e.g. Long Term Evolution (LTE), WiMax and Advanced LTE, consider Orthogonal Frequency Division Multiplex Access (OFDMA) as a mature and suitable solution to cope with the Inter Symbol Interference (ISI) due to the multi-path propagation. However, a major drawback of OFDMA which largely limited its application in the real environment is large envelope fluctuation which results in strong nonlinear distortion due to the nonlinear characteristic of power amplifier (PA). One possible solution to tackle this problem has been introduced by the the 3rd Generation Partnership Project (3GPP) consortium. This solution is based on spreading the base-band modulated signal before the application of OFDMA by using Discrete Fourier Transformation (DFT) that leads eventually to lower envelope fluctuation in comparison with that of OFDMA. The presented method is widely recognized as Single Frequency Division Multiplex (SC-FDMA). This paper aims to provide general comparison of both conventional OFDMA and SC-FDMA and draws important conclusions from this comparison.