Orthogonal frequency division multiplexing communication systems have a drawback that some signal values can be much higher than the average signal value. Transmitting such a high signal increases symbol error rate (SER) significantly, as the signal is usually distorted by the non-linearity of power amplifiers. Most of previous methods presented to reduce the peak-to-average-power ratio are based on iterative computations of the fast Fourier transform (FFT) and inverse FFT associated with large computational complexity. To lower the computational complexity of the tone reservation method, this paper proposes approximate algorithms and their implementation structures. Simulation results show that the SER performance of the proposed structure is similar to that of the conventional one. Compared to the conventional structure, the proposed structure reduces hardware complexity and power consumption by 62.2% and 58.4%, respectively.