Turbo coded OFDM system with peak power reduction

Three turbo coded orthogonal frequency-division multiplexing (OFDM) systems which can mitigate the peak to average power ratio (PAPR) problem are proposed. For the first, we use long maximum-length sequences as test sequences to increase the capability of PAPR reduction and use a short code to protect the side information. Sufficient protection of the side information is obtained by increasing the power of subcarriers corresponding to the short code. For the second, we use several distinct interleavers to yield output symbols with various PAPR and then select the one with the lowest PAPR. In this way, no side information is needed. For the third, a combination of test sequences and interleavers are used. Simulation results show that all the three systems can achieve significant PAPR reduction and satisfactory error performance over AWGN channels.