For wireless applications, Multicarrier transmission, also known as orthogonal frequency division multiplexing (OFDM) or discrete multitone (DMT), based system can be of huge interest because it provides greater immunity to multipath fading and impulse noise, and eliminates the need for equalizers, while efficient hardware implementation can be realized using fast Fourier transform (FFT) techniques with high-speed wireless communications and recent advances in digital signal processing technology In this paper, two aims will be studied. First, it introduces a practical technique for evaluating the continuous-time PAPR of OFDM signals using complex modulation is presented. Using the proposed scheme, it is observed that the TWO-times or more over sampled discrete-time PAPR is a good approximation of the continuous-time PAPR even for complex OFDM signals. Second, it introduces a conventional OFDM systems with the limitation of their behavior with peak-to-average-power ratio (PAPR). Computing the continuous-time PAPR of OFDM signals is computationally challenging. It is shown that the instantaneous envelope power function (EPF) can be transformed into a linear sum of Chebyshev polynomials. Consequently, the roots of the derivative of EPF can be obtained by solving a polynomial. The pioneering work of calculating PAPR of single carrier FDMA, multi-carrier BPSK-OFDM(Real-Valued Modulation) and multi-carrier QPSK-OFDM(Complex Modulation) is achieved.

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OFDM DMT peak-to-average-power ratio EPF multicarrier modulation SC-FDMA MC-BPSK MC-QPSK