The Study on the Performance of Low Detection and Low Interception of FRFT-OFDM

The traditional orthogonal frequency division multiplexing (FT-OFDM) signals are vulnerable to be detected and intercepted, which limit the application in secure communication. In this paper, we use the OFDM systems based on fractional Fourier transform (FRFT-OFDM), then analyze their advantage of low detection and low interception through peak-to-average power ratio and encrypted modulation parameters. First, the PAPR of this system is lower than the counterpart of traditional OFDM systems by inhibiting PAPR in some fractional orders due to the difference of chirp signals´ energy collect. So the symbol characteristics are not obvious, and the signals are difficult to be detected by non-cooperative receiver. Second, non-cooperative receiver is difficult to demodulate signals correctly for the demodulation is sensitive to different fractional orders. Finally, the BER performance of the system is about 1.5 dB lower than traditional OFDM systems after zero-forcing equalization under the same channel condition.