Use of Interleaving to Reduce the Peak-to-Average Power Ratio of an OFDM Signals

Abstract- An interleaver based technique for improving the Peak-to-Average Power Ratio (PAP) of an orthogonal frequency division multiplexing (OFDM) signal is presented. For this tech-nique, K-1 random interleavers are used to produce K-1 permuted sequences from the same information sequence. PAPS of the per-muted sequences and the original information sequence are then computed using of K oversampled FFTs (OFFTs). The sequence with the lowest PAP is chosen for transmission. Complementary cumulative density function (CCDF), of PAP of an interleaved OFDM signal is observed. Results show that for 256 subcarriers and QPSK data symbols, even with K =2, the 0.1 % CCDF is re-duced by 13 dB and with K 4, is reduced by 2dB. The 0.1% CCDF can be reduced by 3 dB and 0.01 % CCDF by 4dB at a cost of 16 OFFTs and a data rate loss of less than 0.8 % with K=Z6. Further statistical improvement for the PAP is obtained by com-bining this approach and the partial transmit sequence (PTS) ap-proach. This paper also proposes an adaptive approach to reduce the complexity of the interleaving technique. I