Broadband interference suppression in fractional fourier domain communication system

Transform domain communication system (TDCS) has been proposed as a new kind of anti-jamming communication system, which has the advantages of the adaptive interference avoiding capability under adverse electromagnetic environments. To avoid the interference spectral regions, the system synthesizes the fundamental modulation waveform (FMW) in the transform domain rather than in the time domain at both the transmitter and the receiver. Based on the architecture of TDCS, this paper presents a fractional Fourier domain communication system (FRFDCS) for the broadband interference suppression, especially for the linear frequency modulation (LFM) jammer. It has been demonstrated that by choosing the order of the fractional Fourier transform (FRFT) optimally, the LFM signal has the best localization and energy concentration in the fractional Fourier domain. Therefore, the LFM jammer can be identified and suppressed accurately in the FRFDCS. The numerical results indicate that the FRFDCS achieves lower bit error rate (BER) and larger channel capacity comparing to the conventional TDCS. Moreover, by virtue of its flexibility and adaptive interference avoiding capability, the FRFDCS can be regarded as a potential candidate for the reliable communication system and the cognitive radio technology.