Constant envelope FrFT-OFDM with physical layer security

Physical layer security uses channel characteristics to increases security of the communicating entities. In this paper, channel signature were used to improve the security of wireless communications uses constant envelope with fractional Fourier transform OFDM (CE-FrFT-OFDM) as its multiplexing technique instead of traditional OFDM. The chosen technique is power efficient and poses the same implementation complexity and performance as traditional OFDM. The physical layer security proposed is easily deployed in CE-FrFT-OFDM than in OFDM and maintains its performance advantages. The proposed system secure a communication system by dynamic arrangement of subcarriers (DAS) based on the average channel gain of the subcarriers. The random variation of the wireless channel and its reciprocity between the transmitter and the legal receiver ensures that the communicating entities shares the same channel impulse response (CIR). The DAS also reduces the signal correlation between the communication pairs 40% while that of transmitter eavesdropper is reduced by 95% and it increases the computation cost of the eavesdropper in obtaining the transmitted information which leaves guessing of the channel gain the only viable choice of obtaining the transmitted information. By increasing the accepted lever of a channel gain we can increase the secrete capacity of the communication system while maintaining CE-FrFT-OFDM advantages.