Metric based symbol predistortion for peak power reduction of space frequency coded OFDM systems

In this paper, a metric based symbol predistortion method is introduced for Peak to Average Power Ratio (PAPR) reduction of the Space Frequency Block Coded (SFBC) Orthogonal Frequency Division Multiplexing (OFDM) systems with two transmitter antennas. In the proposed method, a metric is defined which shows the contribution of each frequency domain symbol to the time domain samples with high amplitude at both antennas. Then, the symbols with the highest metric values are chosen and predistorted such that the peak powers are reduced while the SFBC relationship between two antennas holds constant. Three variants of this method will be introduced. Then, this technique is extended to the general SFBC systems with an arbitrary number of antennas and SFBC structures. Simulation results show that the proposed methods converge when a different number of transmitter antennas and different modulation techniques are used. However, the best performance is achieved in the case of two transmitter antennas with QPSK modulation.